tag:theconversation.com,2011:/fr/topics/iron-5370/articles
Iron – The Conversation
2023-10-23T12:25:38Z
tag:theconversation.com,2011:article/210997
2023-10-23T12:25:38Z
2023-10-23T12:25:38Z
A layered lake is a little like Earth’s early oceans − and lets researchers explore how oxygen built up in our atmosphere billions of years ago
<figure><img src="https://images.theconversation.com/files/542374/original/file-20230811-17-9wl0g5.jpeg?ixlib=rb-1.1.0&rect=0%2C12%2C4031%2C2692&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Researchers sample water from various layers to analyze back in the lab.</span> <span class="attribution"><span class="source">Elizabeth Swanner</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Little Deming Lake doesn’t get much notice from visitors to <a href="https://www.dnr.state.mn.us/state_parks/park.html?id=spk00181#homepage">Itasca State Park</a> in Minnesota. There’s better boating on nearby Lake Itasca, the headwaters of the Mississippi River. My colleagues and I need to maneuver hundreds of pounds of equipment down a hidden path made narrow by late-summer poison ivy to launch our rowboats.</p>
<p>But modest Deming Lake offers more than meets the eye for <a href="https://scholar.google.com/citations?user=QopCtZ4AAAAJ&hl=en&oi=ao">me, a geochemist</a> interested in how oxygen built up in the atmosphere 2.4 billion years ago. The absence of oxygen in the deep layers of Deming Lake is something this small body of water has in common with early Earth’s oceans.</p>
<p>On each of our several expeditions here each year, we row our boats out into the deepest part of the lake – over 60 feet (18 meters), despite the lake’s surface area being only 13 acres. We drop an anchor and connect our boats in a flotilla, readying ourselves for the work ahead.</p>
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<a href="https://images.theconversation.com/files/554300/original/file-20231017-27-mjcpvk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Smooth lake with boats in the distance against woodsy shoreline" src="https://images.theconversation.com/files/554300/original/file-20231017-27-mjcpvk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554300/original/file-20231017-27-mjcpvk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554300/original/file-20231017-27-mjcpvk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554300/original/file-20231017-27-mjcpvk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554300/original/file-20231017-27-mjcpvk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554300/original/file-20231017-27-mjcpvk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554300/original/file-20231017-27-mjcpvk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Researchers’ boats on Deming Lake.</span>
<span class="attribution"><span class="source">Elizabeth Swanner</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
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<p>Deming Lake is <a href="https://www.worldatlas.com/articles/what-is-a-meromictic-lake.html">meromictic</a>, a term from Greek that means only partially mixing. In most lakes, at least once a year, the water at the top sinks while the water at the bottom rises because of wind and seasonal temperature changes that affect water’s density. But the <a href="https://eartharxiv.org/repository/view/4827/">deepest waters of Deming Lake never reach the surface</a>. This prevents oxygen in its top layer of water from ever mixing into its deep layer.</p>
<p>Less than 1% of lakes are meromictic, and most that are have dense, salty bottom waters. Deming Lake’s deep waters are not very salty, but of the salts in its bottom waters, <a href="https://doi.org/10.1016/j.earscirev.2020.103430">iron is one of the most abundant</a>. This makes Deming Lake one of the rarest <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/meromictic-lake">types of meromictic lakes</a>.</p>
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<a href="https://images.theconversation.com/files/554302/original/file-20231017-23-utrjoi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="man seated in small boat wearing gloves injecting water into a collection tube" src="https://images.theconversation.com/files/554302/original/file-20231017-23-utrjoi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/554302/original/file-20231017-23-utrjoi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554302/original/file-20231017-23-utrjoi.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554302/original/file-20231017-23-utrjoi.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554302/original/file-20231017-23-utrjoi.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554302/original/file-20231017-23-utrjoi.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554302/original/file-20231017-23-utrjoi.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Postdoc researcher Sajjad Akam collects a water sample for chemical analysis back in the lab.</span>
<span class="attribution"><span class="source">Elizabeth Swanner</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>The lake surface is calm, and the still air is glorious on this cool, cloudless August morning. We lower a 2-foot-long water pump zip-tied to a cable attached to four sensors. The sensors measure the temperature, amount of oxygen, pH and amount of chlorophyll in the water at each layer we encounter. We pump water from the most intriguing layers up to the boat and fill a myriad of bottles and tubes, each destined for a different chemical or biological analysis.</p>
<p>My colleagues and I have homed in on Deming Lake to explore questions about how microbial life adapted to and changed the environmental conditions on early Earth. Our planet was inhabited <a href="https://theconversation.com/were-viruses-around-on-earth-before-living-cells-emerged-a-microbiologist-explains-197880">only by microbes</a> for most of its history. The atmosphere and the oceans’ depths didn’t have much oxygen, but they did have a lot of iron, just like Deming Lake does. By investigating what Deming Lake’s microbes are doing, we can better understand how billions of years ago they helped to transform the Earth’s atmosphere and oceans into what they’re like now.</p>
<h2>Layer by layer, into the lake</h2>
<p>Two and a half billion years ago, ocean waters had enough iron to form today’s globally distributed <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/banded-iron-formation">rusty iron deposits called</a> <a href="https://www.amnh.org/exhibitions/permanent/planet-earth/how-has-the-earth-evolved/banded-iron-formation">banded iron formations</a> that supply iron for the modern global steel industry. Nowadays, oceans have only <a href="https://youtu.be/EpzEv0H4lvg">trace amounts of iron</a> but abundant oxygen. In most waters, iron and oxygen are antithetical. Rapid <a href="https://bio.libretexts.org/Bookshelves/Microbiology/Microbiology_(Boundless)/05%3A_Microbial_Metabolism/5.10%3A_Chemolithotrophy/5.10D%3A__Iron_Oxidation">chemical and biological reactions between iron and oxygen</a> mean you can’t have much of one while the other is present.</p>
<p>The rise of oxygen in the early atmosphere and ocean was due to <a href="https://ucmp.berkeley.edu/bacteria/cyanointro.html">cyanobacteria</a>. These single-celled organisms <a href="https://asm.org/Articles/2022/February/The-Great-Oxidation-Event-How-Cyanobacteria-Change">emerged at least 2.5 billion years ago</a>. But it took roughly 2 billion years for the oxygen they produce via photosynthesis to build up to <a href="https://askanearthspacescientist.asu.edu/oxygen-animal-evolution">levels that allowed for the first animals</a> to appear on Earth.</p>
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<a href="https://images.theconversation.com/files/554308/original/file-20231017-27-m0c4vb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="water concentrated on a filter looks pale green" src="https://images.theconversation.com/files/554308/original/file-20231017-27-m0c4vb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/554308/original/file-20231017-27-m0c4vb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=471&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554308/original/file-20231017-27-m0c4vb.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=471&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554308/original/file-20231017-27-m0c4vb.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=471&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554308/original/file-20231017-27-m0c4vb.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=592&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554308/original/file-20231017-27-m0c4vb.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=592&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554308/original/file-20231017-27-m0c4vb.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=592&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chlorophyll colors water from the lake slightly green.</span>
<span class="attribution"><span class="source">Elizabeth Swanner</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
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<p>At Deming Lake, my colleagues and I pay special attention to the water layer where the chlorophyll readings jump. <a href="https://www.britannica.com/science/chlorophyll">Chlorophyll is the pigment</a> that makes plants green. It harnesses sunlight energy to turn water and carbon dioxide into oxygen and sugars. Nearly 20 feet (6 meters) below Deming’s surface, the chlorophyll is in cyanobacteria and photosynthetic algae, not plants. </p>
<p>But the curious thing about this layer is that we don’t detect oxygen, despite the abundance of these oxygen-producing organisms. This is the depth where iron concentrations start to climb to the high levels present at the lake’s bottom.</p>
<p>This high-chlorophyll, high-iron and low-oxygen layer is of special interest to us because it might help us understand where cyanobacteria lived in the ancient ocean, how well they were growing and how much oxygen they produced. </p>
<p>We suspect the reason cyanobacteria gather at this depth in Deming Lake is that there is more iron there than at the top of the lake. Just like <a href="https://theconversation.com/blood-in-your-veins-is-not-blue-heres-why-its-always-red-97064">humans need iron for red blood cells</a>, cyanobacteria need lots of iron to help catalyze the reactions of photosynthesis.</p>
<p>A likely reason we can’t measure any oxygen in this layer is that in addition to cyanobacteria, there are a lot of other bacteria here. After a good long life of a few days, the cyanobacteria die, and the other bacteria feed on their remains. These bacteria rapidly use up any oxygen produced by still photosynthesizing cyanobacteria the way a fire does as it burns through wood.</p>
<p>We know there are lots of bacteria here based on how cloudy the water is, and we see them when we inspect a drop of this water under a microscope. But we need another way to measure photosynthesis besides measuring oxygen levels. </p>
<h2>Long-running lakeside laboratory</h2>
<p>The other important function of photosynthesis is converting carbon dioxide into sugars, which eventually are used to make more cells. We need a way to track whether new sugars are being made, and if they are, whether it’s by photosynthetic cyanobacteria. So we fill glass bottles with samples of water from this lake layer and seal them tight with rubber stoppers.</p>
<p>We drive the 3 miles back to the <a href="https://cbs.umn.edu/itasca">Itasca Biological Station and Laboratories</a> where we will set up our experiments. The station opened in 1909 and is home base for us this week, providing comfy cabins, warm meals and this laboratory space.</p>
<p>In the lab, we inject our glass bottle with carbon dioxide that carries an <a href="https://www.britannica.com/science/isotopic-tracer">isotopic tracer</a>. If cyanobacteria grow, their cells will incorporate this isotopic marker. </p>
<p>We had a little help to formulate our questions and experiments. University of Minnesota students attending summer field courses collected decades worth of data in Itasca State Park. A diligent university librarian digitized <a href="https://cbs.umn.edu/itasca/research/student-research-papers">thousands of those students’ final papers</a>.</p>
<p>My students and I pored over the papers concerning Deming Lake, many of which tried to determine whether the cyanobacteria in the chlorophyll-rich layer are doing photosynthesis. While most indicated yes, those students were measuring only oxygen and got ambiguous results. Our use of the isotopic tracer is trickier to implement but will give clearer results.</p>
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<a href="https://images.theconversation.com/files/554313/original/file-20231017-17-p7jytu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="woman holds a clear plastic bag aloft, she and man are seated in boat" src="https://images.theconversation.com/files/554313/original/file-20231017-17-p7jytu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554313/original/file-20231017-17-p7jytu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554313/original/file-20231017-17-p7jytu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554313/original/file-20231017-17-p7jytu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554313/original/file-20231017-17-p7jytu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554313/original/file-20231017-17-p7jytu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554313/original/file-20231017-17-p7jytu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Graduate students Michelle Chamberlain and Zackry Stevenson about to sink the bottles for incubation in Deming Lake.</span>
<span class="attribution"><span class="source">Elizabeth Swanner</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>That afternoon, we’re back on the lake. We toss an anchor; attached to its rope is a clear plastic bag holding the sealed bottles of lake water now amended with the isotopic tracer. They’ll spend the night in the chlorophyll-rich layer, and we’ll retrieve them after 24 hours. Any longer than that and the isotopic label might end up in the bacteria that eat the dying cyanobacteria instead of the cyanobacteria themselves. We tie off the rope to a floating buoy and head back to the station’s dining hall for our evening meal.</p>
<h2>Iron, chlorophyll, oxygen</h2>
<p>The next morning, as we wait for the bottles to finish their incubation, we collect water from the different layers of the lake and add some chemicals that kill the cells but preserve their bodies. We’ll look at these samples under the microscope to figure out how many cyanobacteria are in the water, and we’ll measure how much iron is inside the cyanobacteria. </p>
<p>That’s easier said than done, because we have to first separate all the “needles” (cyanobacteria) from the “hay” (other cells) and then clean any iron off the outside of the cyanobacteria. Back at Iowa State University, we’ll shoot the individual cells one by one into a flame that incinerates them, which liberates all the iron they contain so we can measure it.</p>
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<a href="https://images.theconversation.com/files/554323/original/file-20231017-27-p7jytu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="rowboat with one woman in it on a lake with woodsy shoreline" src="https://images.theconversation.com/files/554323/original/file-20231017-27-p7jytu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/554323/original/file-20231017-27-p7jytu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554323/original/file-20231017-27-p7jytu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554323/original/file-20231017-27-p7jytu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554323/original/file-20231017-27-p7jytu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554323/original/file-20231017-27-p7jytu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554323/original/file-20231017-27-p7jytu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Biogeochemist Katy Sparrow rows a research vessel to shore.</span>
<span class="attribution"><span class="source">Elizabeth Swanner</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Our scientific hunch, or <a href="https://www.britannica.com/science/scientific-hypothesis">hypothesis</a>, is that the cyanobacteria that live in the chlorophyll- and iron-rich layer will contain more iron than cyanobacteria that live in the top lake layer. If they do, it will help us establish that greater access to iron is a motive for living in that deeper and dimmer layer.</p>
<p>These experiments won’t tell the whole story of why it took so long for Earth to build up oxygen, but they will help us to understand a piece of it – where oxygen might have been produced and why, and what happened to oxygen in that environment.</p>
<p>Deming Lake is quickly becoming its own attraction for those with a curiosity about what goes on beneath its tranquil surface – and what that might be able to tell us about how new forms of life took hold long ago on Earth.</p><img src="https://counter.theconversation.com/content/210997/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizabeth Swanner receives funding from the U.S. National Science Foundation and the National Aeronautics and Space Administration. </span></em></p>
An unusual lake with distinct layers of low-oxygen and high-iron water lets researchers investigate conditions like those in the early Earth’s oceans.
Elizabeth Swanner, Associate Professor of Geology, Iowa State University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/198345
2023-02-02T12:23:35Z
2023-02-02T12:23:35Z
Vitamins and supplements: what you need to know before taking them
<figure><img src="https://images.theconversation.com/files/507046/original/file-20230130-20-x1ljxi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Supitcha McAdam/Shutterstock </span></span></figcaption></figure><p>If you were to open your medicine cabinet right now, there’s a fair chance that you’d find at least one bottle of vitamins alongside the painkillers, plasters and cough syrup.</p>
<p>After all, people are definitely buying vitamins: in 2020, the global market for complementary and alternative medicines, which includes multivitamin supplements, had an estimated value of <a href="https://www.grandviewresearch.com/industry-analysis/complementary-alternative-medicine-market">US$82.27 billion</a>. The use of natural health products such as minerals and amino acids has <a href="https://journals.lww.com/nutritiontodayonline/Abstract/2007/03000/Why_People_Use_Vitamin_and_Mineral_Supplements.4.aspx">increased</a> – and continues to rise, partly driven by consumers’ buying habits during the COVID-19 pandemic.</p>
<p>People <a href="https://www.businesslive.co.za/bd/companies/healthcare/2021-02-08-native-sales-of-sas-vitamins-and-nutritional-supplements-boom/">sought out</a> vitamins C and D, as well as zinc supplements, as potential preventive measures against the virus – even though the <a href="https://www.health.harvard.edu/blog/do-vitamin-d-zinc-and-other-supplements-help-prevent-covid-19-or-hasten-healing-2021040522310">evidence</a> for their efficacy was, and <a href="https://pubmed.ncbi.nlm.nih.gov/35888660/#:%7E:text=Concluding%2C%20available%20data%20on%20the,trials%20(RCTs)%20are%20inconsistent">remains</a>, inconclusive. </p>
<p>Multivitamins and mineral supplements are easily accessible to consumers. They are often marketed for their health claims and benefits – sometimes unsubstantiated. But their potential adverse effects are not always stated on the packaging.</p>
<p>Collectively, vitamins and minerals are known as micronutrients. They are essential elements needed for our bodies to function properly. Our bodies can only produce micronutrients in small amounts or not at all. We get the bulk of these nutrients <a href="https://www.iprjb.org/journals/index.php/IJF/article/view/1024">from our diets</a>. </p>
<p>People usually buy micronutrients to protect against disease or as dietary “insurance”, in case they are not getting sufficient quantities from their diets. </p>
<p>There’s a common perception that these supplements are harmless. But they can be dangerous at incorrect dosages. They provide a false sense of hope, pose a risk of drug interactions – and can delay more effective treatment. </p>
<h2>Benefits</h2>
<p>Vitamins are beneficial if taken for the correct reasons and as prescribed by your doctor. For example, folic acid supplementation in pregnant women has been shown to prevent neural tube defects. And individuals who reduce their intake of red meat without increasing legume consumption require a vitamin B6 supplement. </p>
<p>But a worrying trend is increasing among consumers: intravenous vitamin therapy, which is often punted by celebrities and social media marketing. Intravenous vitamins, nutrients and fluids are administered at pharmacies as well as beauty spas, and more recently “<a href="https://www.health.harvard.edu/blog/drip-bar-should-you-get-an-iv-on-demand-2018092814899">IV bars</a>”. Users believe these treatments can quell a cold, slow the effects of ageing, brighten skin, fix a hangover or just make them feel well. </p>
<p>Intravenous vitamin therapy was previously only used in medical settings to help patients who could not swallow, needed fluid replacements or had an electrolyte imbalance. </p>
<p>However, the evidence to support other benefits of intravenous vitamin therapy is limited. No matter how you choose to get additional vitamins, there are risks. </p>
<h2>Warning bells</h2>
<p>Most consumers use multivitamins. But others take large doses of single nutrients, especially vitamin C, iron and calcium. </p>
<p>As lecturers in pharmacy practice, we think it’s important to highlight the potential adverse effects of commonly used vitamins and minerals: </p>
<ul>
<li><p><a href="https://www.hsph.harvard.edu/nutritionsource/vitamin-a/">Vitamin A/retinol</a> is beneficial in maintaining good eye health. But it can cause toxicity if more than 300,000IU (units) is ingested. Chronic toxicity (hypervitaminosis) has been <a href="https://www.ncbi.nlm.nih.gov/books/NBK532916/">associated</a> with doses higher than 10,000IU a day. Symptoms include liver impairment, loss of vision and intracranial hypertension. It can cause birth defects in pregnant women.</p></li>
<li><p><a href="https://www.hsph.harvard.edu/nutritionsource/niacin-vitamin-b3/">Vitamin B3</a> is beneficial for nervous and digestive system health. At moderate to high doses it can cause peripheral vasodilation (widening or dilating of the blood vessels at the extremities, such as the legs and arms), resulting in skin flushing, burning sensation, pruritis (itchiness of the skin) and hypotension (low blood pressure). </p></li>
<li><p><a href="https://www.hsph.harvard.edu/nutritionsource/vitamin-b6/">Vitamin B6</a> is essential for brain development and in ensuring that the immune system remains healthy. But it can result in damage to the peripheral nerves, such as those in the hands and feet (causing a sensation of numbness and often referred to as pins and needles) at doses over 200mg/daily.</p></li>
<li><p><a href="https://www.hsph.harvard.edu/nutritionsource/vitamin-c/">Vitamin C</a> is an antioxidant and assists in the repair of body tissue. Taken in high doses it can cause kidney stones and interactions with drugs, such as the oncology drugs doxorubicin, methotrexate, cisplatin and vincristine. </p></li>
<li><p><a href="https://www.hsph.harvard.edu/nutritionsource/vitamin-d/">Vitamin D</a> is essential for bone and teeth development. At high doses it can cause hypercalcaemia (calcium level in the blood is above normal) that results in thirst, excessive urination, seizures, coma and death.</p></li>
<li><p><a href="https://www.hsph.harvard.edu/nutritionsource/calcium/#:%7E:text=Calcium%20is%20a%20mineral%20most,heart%20rhythms%20and%20nerve%20functions">Calcium</a> is essential for bone health, but can cause constipation and gastric reflux. High doses can cause hypercalciuria (increased calcium in the urine), kidney stones and secondary hypoparathyroidism (underactive parathyroid gland). It can have drug interactions with zinc, magnesium and iron. </p></li>
<li><p><a href="https://www.hsph.harvard.edu/nutritionsource/magnesium/">Magnesium</a> is important for muscle and nerve functioning. At high doses it can cause diarrhoea, nausea and abdominal cramping, and can interact with tetracyclines (antibiotics).</p></li>
<li><p>Zinc <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7781367/">can impair</a> taste and smell, and doses over 80mg daily have been <a href="https://link.springer.com/article/10.1007/s10654-022-00922-0#:%7E:text=Zinc%20supplementation%20of%20more%20than,zinc%20supplements%20among%20adult%20men.">shown</a> to have adverse prostate effects.</p></li>
<li><p><a href="https://www.hsph.harvard.edu/nutritionsource/selenium/">Selenium</a> can cause hair and nail loss or brittleness, lesions of the skin and nervous system, skin rashes, fatigue and mood irritability at high doses.</p></li>
<li><p><a href="https://www.sciencedirect.com/science/article/pii/S0098299720300364#:%7E:text=Expert%20guidelines%20for%20oral%20iron%20supplementation&text=Traditionally%2C%20the%20recommended%20daily%20dose,iron%20(Brittenham%2C%202018).">Iron</a> at 100-200mg/day can cause constipation, black faeces, black discoloration of teeth and abdominal pain.</p></li>
</ul>
<h2>Recommendations</h2>
<p>People need to make <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8377299/">informed decisions</a> based on evidence before consuming health products. </p>
<p>Regular exercise and a well-balanced diet are more likely to do us good, as well as being lighter on the pocket.</p>
<p>Seeking advice from a healthcare professional before consuming supplements can reduce the risk of adverse effects.</p>
<p>Be aware of the potential adverse effects of vitamins and seek a healthcare professional’s guidance if you have symptoms.</p><img src="https://counter.theconversation.com/content/198345/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
There’s a common perception that supplements are harmless. But they can be dangerous at incorrect dosages.
Neelaveni Padayachee, Senior Lecturer, Department of Pharmacy and Pharmacology, University of the Witwatersrand
Varsha Bangalee, Associate Professor, Pharmaceutical Sciences, University of KwaZulu-Natal
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/197134
2023-02-01T13:24:59Z
2023-02-01T13:24:59Z
Scientists envision an ‘internet of the ocean,’ with sensors and autonomous vehicles that can explore the deep sea and monitor its vital signs
<figure><img src="https://images.theconversation.com/files/505223/original/file-20230118-24-dogl3z.jpg?ixlib=rb-1.1.0&rect=753%2C753%2C7205%2C4708&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A large robot, loaded with sensors and cameras, designed to explore the ocean twilight zone.</span> <span class="attribution"><a class="source" href="https://twilightzone.whoi.edu/work-impact/technology/mesobot/">Marine Imaging Technologies, LLC © Woods Hole Oceanographic Institution</a></span></figcaption></figure><p><em>Deep below the ocean surface, the light fades into a twilight zone where whales and fish migrate and dead algae and zooplankton rain down from above. This is the <a href="https://www.youtube.com/watch?v=Fma6MM359Z0">heart of the ocean’s carbon pump</a>, part of the natural ocean processes that capture about a third of all human-produced carbon dioxide and sink it into the deep sea, where it remains for <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4838858/">hundreds of years</a>.</em> </p>
<p><em>There may be ways to enhance these processes so the ocean pulls more carbon out of the atmosphere to help slow climate change. Yet little is known about the consequences.</em></p>
<p><em>Peter de Menocal, a <a href="https://scholar.google.com/citations?hl=en&user=Etpzd_UAAAAJ&view_op=list_works&sortby=pubdate">marine paleoclimatologist</a> and director of Woods Hole Oceanographic Institution, discussed ocean carbon dioxide removal at a recent <a href="https://tedxboston.com/planetary-stewardship/">TEDxBoston:</a> <a href="https://www.youtube.com/playlist?list=PLLZP1f7L84FqRhJeC_72AsKm4ZvJgdqwT">Planetary Stewardship</a> event. In this interview, he dives deeper into the risks and benefits of human intervention and describes an ambitious plan to build a vast monitoring network of autonomous sensors in the ocean to help humanity understand the impact.</em></p>
<h2>First, what is ocean carbon dioxide removal, and how does it work in nature?</h2>
<p>The ocean is like a big carbonated beverage. Although it doesn’t fizz, it has <a href="https://science.nasa.gov/earth-science/oceanography/ocean-earth-system/ocean-carbon-cycle">about 50 times more carbon</a> than the atmosphere. So, for taking carbon out of the atmosphere and storing it someplace where it won’t continue to warm the planet, the ocean is the <a href="https://essd.copernicus.org/articles/14/4811/2022/">single biggest place it can go</a>.</p>
<p>Ocean carbon dioxide removal, or ocean CDR, uses the ocean’s natural ability to take up carbon on a large scale and amplifies it.</p>
<figure class="align-center ">
<img alt="Illustration showing methods of carbon storage, including growing kelp" src="https://images.theconversation.com/files/505217/original/file-20230118-23-d817gq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505217/original/file-20230118-23-d817gq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=331&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505217/original/file-20230118-23-d817gq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=331&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505217/original/file-20230118-23-d817gq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=331&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505217/original/file-20230118-23-d817gq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=416&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505217/original/file-20230118-23-d817gq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=416&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505217/original/file-20230118-23-d817gq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=416&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Methods of ocean carbon storage.</span>
<span class="attribution"><span class="source">Natalie Renier/©Woods Hole Oceanographic Institution</span></span>
</figcaption>
</figure>
<p><iframe id="XZVDq" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/XZVDq/3/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Carbon gets into the ocean from the atmosphere in two ways.</p>
<p>In the first, air <a href="https://www.whoi.edu/press-room/news-release/the-oceans-biological-pump-captures-more-carbon-than-expected/">dissolves into the ocean surface</a>. Winds and crashing waves mix it into the upper half-mile or so, and because seawater is slightly alkaline, the carbon dioxide is absorbed into the ocean.</p>
<p>The second involves the biologic pump. The ocean is a living medium – it has algae and fish and whales, and when that organic material is eaten or dies, it gets recycled. It rains down through the ocean and makes its way to the ocean twilight zone, a level around 650 to 3300 feet (roughly 200 to 1,000 meters) deep.</p>
<figure><img src="https://cdn.theconversation.com/static_files/files/2494/whoi2.gif?1672717556"><figcaption>The years indicate how long deposited carbon is expected to remain before the water cycles to the surface. Woods Hole Oceanographic Institution</figcaption></figure>
<p>The ocean twilight zone sustains biologic activity in the oceans. It is the “soil” of the ocean where organic carbon and nutrients accumulate and are recycled by microbes. It is also home to the largest animal migration on the planet. Each day trillions of fish and other organisms migrate from the depths to the surface to feed on plankton and one another, and go back down, acting like a large carbon pump that captures carbon from the surface and shunts it down into the deep oceans where it is stored away from the atmosphere.</p>
<h2>Why is ocean CDR drawing so much attention right now?</h2>
<p>The single most shocking sentence I have read in my career was in the <a href="https://www.ipcc.ch/report/sixth-assessment-report-working-group-3/">Intergovernmental Panel on Climate Change’s Sixth Assessment Report</a>, released in 2021. It said that we have delayed action on climate change for so long that removing carbon dioxide from the atmosphere is now necessary for all pathways to keep global warming <a href="https://climate.nasa.gov/news/2865/a-degree-of-concern-why-global-temperatures-matter/">under 1.5 degrees Celsius</a> (2.7 F). Beyond that, climate change’s impacts become increasingly dangerous and unpredictable.</p>
<p>Because of its volume and carbon storage potential, the ocean is really the only arrow in our quiver that has the ability to take up and store carbon at the scale and urgency required.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/JeYjSPuyjgc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Peter de Menocal at TEDxBoston: Planetary Stewardship.</span></figcaption>
</figure>
<p>A 2022 <a href="https://nap.nationalacademies.org/catalog/26278/a-research-strategy-for-ocean-based-carbon-dioxide-removal-and-sequestration">report by the national academies</a> outlined a research strategy for ocean carbon dioxide removal. The three most promising methods all explore ways to enhance the ocean’s natural ability to take up more carbon.</p>
<p>The first is <a href="https://www.whoi.edu/know-your-ocean/ocean-topics/climate-weather/ocean-based-climate-solutions/">ocean alkalinity enhancement</a>. The oceans are salty – they’re naturally alkaline, with a <a href="https://www.whoi.edu/know-your-ocean/ocean-topics/how-the-ocean-works/ocean-chemistry/ocean-acidification/">pH of about 8.1</a>. Increasing alkalinity by dissolving certain powdered rocks and minerals makes the ocean a chemical sponge for atmospheric CO2.</p>
<figure class="align-center ">
<img alt="Vibrant corals of many types and colorful fish." src="https://images.theconversation.com/files/503166/original/file-20230105-129741-5tcaos.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/503166/original/file-20230105-129741-5tcaos.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/503166/original/file-20230105-129741-5tcaos.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/503166/original/file-20230105-129741-5tcaos.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/503166/original/file-20230105-129741-5tcaos.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/503166/original/file-20230105-129741-5tcaos.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/503166/original/file-20230105-129741-5tcaos.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Studies show increasing alkalinity can also reduce ocean acidification stress on corals.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Great_barrier_reef.JPG">Wise Hok Wai Lum/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>A second method adds micronutrients to the surface ocean, particularly soluble iron. Very small amounts of <a href="https://www.nature.com/articles/s41612-022-00250-w">soluble iron can stimulate greater productivity</a>, or algae growth, which drives a more vigorous biologic pump. Over a dozen of these experiments have been done, so we know it works.</p>
<p>Third is perhaps the easiest to understand – <a href="https://nap.nationalacademies.org/read/26278/chapter/1">grow kelp in the ocean</a>, which captures carbon at the surface through photosynthesis, then bale it and sink it to the deep ocean. </p>
<p>But all of these methods have drawbacks for large-scale use, including cost and <a href="https://www.smithsonianmag.com/science-nature/complicated-role-iron-ocean-health-and-climate-change-180973893/">unanticipated consequences</a>.</p>
<figure class="align-center ">
<img alt="The view looking toward the ocean surface through a kelp forest." src="https://images.theconversation.com/files/505225/original/file-20230118-7884-4i46xa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505225/original/file-20230118-7884-4i46xa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505225/original/file-20230118-7884-4i46xa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505225/original/file-20230118-7884-4i46xa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505225/original/file-20230118-7884-4i46xa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505225/original/file-20230118-7884-4i46xa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505225/original/file-20230118-7884-4i46xa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Kelp takes up carbon dioxide during photosynthesis.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/sunlight-streaming-through-a-forest-of-giant-kelp-news-photo/635826440">David Fleetham/VW PICS/Universal Images Group via Getty Images</a></span>
</figcaption>
</figure>
<p>I’m not advocating for any one of these, or for ocean CDR more generally. But I do believe accelerating research to understand the impacts of these methods is essential. The ocean is essential for everything humans depend on – food, water, shelter, crops, climate stability. It’s the <a href="https://sos.noaa.gov/catalog/datasets/ocean-atmosphere-co2-exchange/">lungs of the planet</a>. So we need to know if these ocean-based technologies to reduce carbon dioxide and climate risk are viable, safe and scalable.</p>
<h2>You’ve talked about building an ‘internet of the ocean’ to monitor changes there. What would that involve?</h2>
<p>The ocean is changing rapidly, and it is the single biggest cog in Earth’s climate engine, yet we have almost no observations of the subsurface ocean to understand how these changes are affecting the things we care about. We’re basically flying blind at a <a href="https://www.nature.com/articles/d41586-020-00915-7">time when we most need observations</a>. Moreover, if we were to try any of these carbon removal technologies at any scale right now, we wouldn’t be able to measure or verify their effectiveness or assess impacts on ocean health and ecosystems.</p>
<p>So, we are leading an initiative at Woods Hole Oceanographic Institution to build the <a href="https://www.whoi.edu/wp-content/uploads/2022/07/OVSN_Carbon.mp4?_=1">world’s first internet for the ocean</a>, called the <a href="https://www.whoi.edu/fowler-center-ocean-climate/related-activities-and-initiatives/">Ocean Vital Signs Network</a>. It’s a large network of moorings and sensors that provides 4D eyes on the oceans – the fourth dimension being time – that are always on, always connected to monitor these carbon cycling processes and ocean health. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/505221/original/file-20230118-17-lamel0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration showing where different species live at different depths in the ocean." src="https://images.theconversation.com/files/505221/original/file-20230118-17-lamel0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505221/original/file-20230118-17-lamel0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505221/original/file-20230118-17-lamel0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505221/original/file-20230118-17-lamel0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505221/original/file-20230118-17-lamel0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505221/original/file-20230118-17-lamel0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505221/original/file-20230118-17-lamel0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Top predators such as whales, tuna, swordfish and sharks rely on the twilight zone for food, diving down hundreds or even thousands of feet to catch their prey.</span>
<span class="attribution"><span class="source">Eric S. Taylor /© Woods Hole Oceanographic Institution</span></span>
</figcaption>
</figure>
<p>Right now, there is about one <a href="https://argo.ucsd.edu/">ocean sensor</a> in the global Argo program for every patch of ocean the size of Texas. These go up and down like pogo sticks, mostly measuring temperature and salinity.</p>
<p>We envision <a href="https://www.whoi.edu/fowler-center-ocean-climate/related-activities-and-initiatives/#:%7E:text=The%20Ocean%20Vital%20Signs%20Network,circulation%20patterns%2C%20geochemical%20reactions%2C%20and">a central hub in the middle of an ocean basin</a> where a dense network of intelligent gliders and autonomous vehicles measure ocean properties including carbon and other vital signs of ocean and planetary health. These vehicles can dock, repower, upload data they’ve collected and go out to collect more. The vehicles would be sharing information and making intelligent sampling decisions as they measure the chemistry, biology and environmental DNA for a volume of the ocean that’s really representative of how the ocean works.</p>
<figure class="align-center ">
<img alt="A large robot with a light and sensors descends into darker water" src="https://images.theconversation.com/files/505212/original/file-20230118-14-8t42gg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505212/original/file-20230118-14-8t42gg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505212/original/file-20230118-14-8t42gg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505212/original/file-20230118-14-8t42gg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505212/original/file-20230118-14-8t42gg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505212/original/file-20230118-14-8t42gg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505212/original/file-20230118-14-8t42gg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mesobot starts its descent toward the ocean twilight zone.</span>
<span class="attribution"><span class="source">Marine Imaging Technologies, LLC © Woods Hole Oceanographic Institution</span></span>
</figcaption>
</figure>
<p>Having that kind of network of autonomous vehicles, able to come back in and power up in the middle of the ocean from wave or solar or wind energy at the mooring site and send data to a satellite, could launch a new era of ocean observing and discovery.</p>
<h2>Does the technology needed for this level of monitoring exist?</h2>
<p>We’re already doing much of this engineering and technology development. What we haven’t done yet is stitch it all together.</p>
<p>For example, we have a team that works with <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5240338/">blue light lasers</a> for communicating in the ocean. Underwater, you can’t use electromagnetic radiation as cellphones do, because seawater is conductive. Instead, you have to use sound or light to communicate underwater.</p>
<p>We also have an <a href="https://acomms.whoi.edu/">acoustics communications</a> group that works on <a href="https://techtransfer.whoi.edu/whoi-engineers-work-to-adapt-swarming-capabilities-for-low-cost-uuvs/">swarming technologies</a> and communications between nearby vehicles. Another group works on how to dock vehicles into <a href="https://www.whoi.edu/know-your-ocean/ocean-topics/ocean-tech/moorings-buoys/">moorings in the middle of the ocean</a>. Another specializes in mooring design. Another is building chemical sensors and physical sensors that measure ocean properties and environmental DNA. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Fma6MM359Z0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A tour of sea life in the ocean twilight zone.</span></figcaption>
</figure>
<p>This summer, 2023, <a href="https://twilightzone.whoi.edu/about/">an experiment in the North Atlantic</a> called the Ocean Twilight Zone Project will image the larger functioning of the ocean over a big piece of real estate at the scale at which ocean processes actually work.</p>
<p>We’ll have acoustic transceivers that can create a 4D image over time of these dark, hidden regions, along with gliders, new sensors we call “minions” that will be looking at ocean <a href="https://twilightzone.whoi.edu/work-impact/technology/">carbon flow, nutrients and oxygen changes</a>. “<a href="https://www.youtube.com/watch?v=TaNZH1sXGEo">Minions</a>” are basically sensors the size of a soda bottle that go down to a fixed depth, say 1,000 meters (0.6 miles), and use essentially an iPhone camera pointing up to take pictures of all the material floating down through the water column. That lets us quantify how much organic carbon is making its way into this old, cold deep water, where it can remain for centuries.</p>
<p>For the first time we’ll be able to <a href="https://twilightzone.whoi.edu/work-impact/technology/">see just how patchy productivity is</a> in the ocean, how carbon gets into the ocean and if we can quantify those carbon flows. </p>
<p>That’s a game-changer. The results can help establish the effectiveness and ground rules for using CDR. It’s a Wild West out there – nobody is watching the oceans or paying attention. This network makes observation possible for making decisions that will affect future generations.</p>
<h2>Do you believe ocean CDR is the right answer?</h2>
<p>Humanity doesn’t have a lot of time to reduce carbon emissions and to lower carbon dioxide concentrations in the atmosphere.</p>
<p>The reason scientists are working so diligently on this is not because we’re big fans of CDR, but because we know the oceans may be able to help. With an ocean internet of sensors, we can really understand how the ocean works including the risks and benefits of ocean CDR.</p><img src="https://counter.theconversation.com/content/197134/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter de Menocal is the president and director of Woods Hole Oceanographic Institution.</span></em></p>
The ocean twilight zone could store vast amounts of carbon captured from the atmosphere, but first we need a 4D monitoring system to ensure ramping up carbon storage does no harm.
Peter de Menocal, Director, Woods Hole Oceanographic Institution
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/182820
2022-05-11T12:06:26Z
2022-05-11T12:06:26Z
Wealthy nations are carving up space and its riches – and leaving other countries behind
<figure><img src="https://images.theconversation.com/files/462334/original/file-20220510-10405-28cfr8.jpg?ixlib=rb-1.1.0&rect=52%2C152%2C3870%2C3205&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There is a U.S. flag on the Moon, but in the future, countries may start to turn access to the Moon and asteroids into serious wealth.</span> <span class="attribution"><a class="source" href="https://www.hq.nasa.gov/alsj/a11/AS11-40-5874HR.jpg">NASA/Neil A. Armstrong</a></span></figcaption></figure><p>Satellites help run the internet and television and are central to the Global Positioning System. They <a href="https://theconversation.com/eyes-in-the-sky-cutting-nasa-earth-observations-would-be-a-costly-mistake-69705">enable modern weather forecasting</a>, help scientists <a href="https://theconversation.com/smallsat-revolution-tiny-satellites-poised-to-make-big-contributions-to-essential-science-71440">track environmental degradation</a> and play a <a href="https://theconversation.com/intelligence-information-warfare-cyber-warfare-electronic-warfare-what-they-are-and-how-russia-is-using-them-in-ukraine-177899">huge role in modern military technology</a>.</p>
<p>Nations that don’t have their own satellites providing these services rely on other countries. For those that want to develop their own satellite infrastructure, options are running out as space fills up.</p>
<p><a href="https://news.asu.edu/20220127-interplanetary-initiative-welcomes-its-first-fellow">I am a research fellow</a> at Arizona State University, studying the wider benefits of space and ways to make it more accessible to developing countries. </p>
<p>Inequity is already playing out in access to satellites. In the not-so-distant future, the ability to extract resources from the Moon and asteroids could become a major point of difference between the space haves and have-nots. As policies emerge, there is the risk that these inequities become permanent.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/462337/original/file-20220510-26-94yfv7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing a satellite orbiting Earth." src="https://images.theconversation.com/files/462337/original/file-20220510-26-94yfv7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/462337/original/file-20220510-26-94yfv7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=602&fit=crop&dpr=1 600w, https://images.theconversation.com/files/462337/original/file-20220510-26-94yfv7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=602&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/462337/original/file-20220510-26-94yfv7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=602&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/462337/original/file-20220510-26-94yfv7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=756&fit=crop&dpr=1 754w, https://images.theconversation.com/files/462337/original/file-20220510-26-94yfv7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=756&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/462337/original/file-20220510-26-94yfv7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=756&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Geostationary orbits, where a satellite stays above a single point along the Earth’s equator, are very valuable. But there is only enough room for 1,800 satellites in this orbit, and many of these slots are already taken or spoken for.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Geosynchronous-orbit.svg#/media/File:Geosynchronous-orbit.svg">MikeRun/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Where to park a satellite</h2>
<p>Thanks to the rapid commercialization, miniaturization and <a href="https://www.globalpoliticsreview.com/publications/2464-9929_v04_i02.pdf#page=72">plummeting costs of satellite technology in recent years</a>, more <a href="https://theconversation.com/how-many-satellites-are-orbiting-earth-166715">countries are able to reap the benefits of space</a>. </p>
<p>CubeSats are small, cheap, customizable satellites that are <a href="https://www.nasa.gov/feature/nasa-mission-supports-launch-of-cubesats-built-by-middle-and-high-school-students">simple enough to be built by high school students</a>. Companies such as SpaceX can launch one of these satellites into orbit for relatively cheap – <a href="https://www.cnbc.com/2022/03/23/spacex-raises-prices-for-launches-and-starlink-due-to-inflation.html">from $1,300 per pound</a>. However, there are only so many places to “park” a satellite in orbit around Earth, and these are quickly filling up. </p>
<p>The best parking is in geostationary orbit, around 22,250 miles (35,800 kilometers) above the equator. A satellite in geostationary orbit <a href="https://www.space.com/29222-geosynchronous-orbit.html">rotates at the same rate as Earth</a>, remaining directly above a single location on Earth’s surface – which can be very useful for telecommunications, broadcasting and weather satellites. </p>
<p>There are only 1,800 geostationary orbital slots, and as of February 2022, <a href="https://www.satsig.net/sslist.htm">541 of them were occupied by active satellites</a>. Countries and private companies have already claimed most of the <a href="https://www.spacelegalissues.com/orbital-slots-and-space-congestion/">unoccupied slots</a> that offer access to major markets, and the satellites to fill them are currently being assembled or awaiting launch. If, for example, a new spacefaring nation wants to put a weather satellite over a specific spot in the Atlantic Ocean that is already claimed, they would either have to choose a less optimal location for the satellite or buy services from the country occupying the spot they wanted.</p>
<p>Orbital slots are allocated by an agency of the United Nations called the <a href="https://www.itu.int/en/Pages/default.aspx">International Telecommunication Union</a>. Slots are free, but they <a href="https://theconversation.com/theres-a-parking-crisis-in-space-and-you-should-be-worried-about-it-83479">go to countries on a first-come, first-served basis</a>. When a satellite reaches the end of its 15- to 20-year lifespan, a country can simply replace it and renew its hold on the slot. This effectively allows countries to <a href="http://www.mjilonline.org/are-the-non-appropriation-principle-and-the-current-regulatory-regime-governing-geostationary-orbit-equitable-for-all-of-earths-states/">keep these positions indefinitely</a>. Countries that already have the technology to utilize geostationary orbit have a major advantage over those that do not.</p>
<p>While geostationary orbital slots are the most useful and limited, there are many other orbits around Earth. These, too, are filling up – adding to the <a href="https://theconversation.com/us/topics/space-debris-8399">growing problem of space debris</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/462339/original/file-20220510-16-hx0izt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A row of small satellites attached to a rocket with Earth in the background." src="https://images.theconversation.com/files/462339/original/file-20220510-16-hx0izt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/462339/original/file-20220510-16-hx0izt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/462339/original/file-20220510-16-hx0izt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/462339/original/file-20220510-16-hx0izt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/462339/original/file-20220510-16-hx0izt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/462339/original/file-20220510-16-hx0izt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/462339/original/file-20220510-16-hx0izt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Companies like SpaceX and Blue Origin are planning to put thousands of satellites in orbit – as seen in the photo of 60 SpaceX Starlink satellites about to detach from a rocket.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/people/130608600@N05">SpaceX/Flickr</a></span>
</figcaption>
</figure>
<p>Low Earth orbit is around <a href="https://www.esa.int/ESA_Multimedia/Images/2020/03/Low_Earth_orbit#:%7E:text=A%20low%20Earth%20orbit%20">1,000 miles (1,600 km) above the surface</a>. Satellites in low Earth orbit are moving fast in a highly congested environment. While this may be a good place for Earth imaging satellites, it is not ideal for single communication satellites – like those used to broadcast television, radio and the internet.</p>
<p>Low Earth orbit can be used for communications if multiple satellites work together to form a constellation. Companies like SpaceX and Blue Origin are working on projects to <a href="https://www.space.com/megaconstellations-could-destroy-astronomy-no-easy-fix">put thousands of satellites into low Earth orbit</a> over the next few years to provide internet across the globe. The first generation of SpaceX’s Starlink consists of 1,926 satellites, and the second generation <a href="https://www.space.com/megaconstellations-could-destroy-astronomy-no-easy-fix">will add another 30,000 to orbit</a>.</p>
<p>At the current rate, the major space players are rapidly occupying geostationary and low Earth orbits, potentially monopolizing access to important satellite capabilities and <a href="https://www.theverge.com/2018/9/28/17906158/nasa-spacex-oneweb-satellite-large-constellations-orbital-debris">adding to space junk</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/462338/original/file-20220510-22-kcqmf2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A rendering of a brown and silver asteroid in space." src="https://images.theconversation.com/files/462338/original/file-20220510-22-kcqmf2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/462338/original/file-20220510-22-kcqmf2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/462338/original/file-20220510-22-kcqmf2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/462338/original/file-20220510-22-kcqmf2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/462338/original/file-20220510-22-kcqmf2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/462338/original/file-20220510-22-kcqmf2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/462338/original/file-20220510-22-kcqmf2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Asteroids contain mind-boggling amounts of valuable metals – like 16 Psyche, seen here, which holds massive reserves of US$10 quintillion worth of iron.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/feature/jpl/how-nasa-s-psyche-mission-will-explore-an-unexplored-world">NASA/JPL-Caltech</a></span>
</figcaption>
</figure>
<h2>Access to resources in space</h2>
<p>Orbital slots are an area where inequity exists today. The future of space could be a gold rush for resources – and not everyone will benefit.</p>
<p>Asteroids hold astounding amounts of <a href="https://www.manufacturing.net/technology/blog/21113380/asteroid-mining-could-solve-rare-metal-shortage">valuable minerals and metals</a>. Later this year, <a href="https://solarsystem.nasa.gov/missions/psyche/in-depth/">NASA is launching a probe</a> to explore an asteroid named 16 Psyche, which scientists estimate contains over <a href="https://globalnews.ca/news/3175097/nasa-plans-mission-to-a-metal-rich-asteroid-worth-quadrillions/">US$10 quintillion worth of iron</a>. Tapping huge resource deposits like this and transporting them to Earth could provide massive boosts to the economies of spacefaring nations while disrupting the economies of countries that currently depend on exporting minerals and metals.</p>
<p>Another highly valuable resource in space is helium-3, a rare version of helium that scientists think could be used in nuclear fusion reactions <a href="https://www.esa.int/Enabling_Support/Preparing_for_the_Future/Space_for_Earth/Energy/Helium-3_mining_on_the_lunar_surface">without producing radioactive waste</a>. While there are <a href="https://www.thespacereview.com/article/2834/1">considerable technological obstacles to overcome</a> before helium-3 is a feasible energy source, if it works, there are enough deposits on the Moon and elsewhere in the solar system to <a href="https://www.mining.com/web/quest-find-trillion-dollar-nuclear-fuel-moon/">satisfy Earth’s energy requirements for several centuries</a>. If powerful spacefaring countries develop the technology to use and mine helium-3 – and choose not to share the benefits with other nations – it could result in lasting inequities. </p>
<p>Existing international space laws are <a href="https://www.rand.org/pubs/external_publications/EP68859.html">not well suited</a> to handle the complicated web of private companies and nations competing for resources in space. Countries are organizing into groups – or “space blocs” – that are <a href="https://theconversation.com/space-blocs-the-future-of-international-cooperation-in-space-is-splitting-along-lines-of-power-on-earth-180221">uniting on goals and rules for future space missions</a>. Two notable space blocs are planning missions to set up bases and potential mining operations on the Moon: the <a href="https://www.nasa.gov/specials/artemis-accords/index.html">Artemis Accords</a>, led by the U.S., as well as joint <a href="https://carnegiemoscow.org/commentary/86094">Chinese and Russian plans</a>. </p>
<p>Right now, the major players in space are establishing the norms for exploiting resources. There is a risk that instead of focusing on what is best for everyone on Earth, competition will drive these decisions, damaging the space environment and causing conflict. History shows that it is <a href="https://legal.un.org/avl/pdf/ls/greenwood_outline.pdf">hard to challenge international norms once they are established</a>.</p>
<h2>Moving forward</h2>
<p>Access to space is critical for the functioning of a modern nation. Space access will only become more important as humanity rapidly advances toward a future of <a href="http://edition.cnn.com/travel/article/space-hotel-orbital-assembly-scn/index.html">space hotels</a> and <a href="https://www.space.com/nasa-3d-printed-habitat-competition-winners.html">colonies on Mars</a>. </p>
<p>The 1967 Outer Space Treaty, the founding document of space law, says that space should be used “<a href="https://www.unoosa.org/oosa/en/ourwork/spacelaw/treaties/outerspacetreaty.html">for the benefit and in the interests of all countries</a>.” The policies taking shape today will dictate whether this is the case in the future.</p><img src="https://counter.theconversation.com/content/182820/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Theodora Ogden is a full-time research fellow at the Interplanetary Initiative at Arizona State University. She is currently on secondment from RAND Europe. The views are the author's own and do not represent the organizations with which she is affiliated. </span></em></p>
Current trends suggest that powerful nations are defining the rules of resource use in space and satellite access in ways that will make it hard for developing nations to ever catch up.
Theodora Ogden, Research Fellow in Emerging Space Countries, Arizona State University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/172821
2021-12-07T08:46:55Z
2021-12-07T08:46:55Z
How changing levels of iron shaped the evolution of life on Earth – and why alien hunters should take note
<figure><img src="https://images.theconversation.com/files/434722/original/file-20211130-19-ydbxib.jpg?ixlib=rb-1.1.0&rect=120%2C105%2C3375%2C2341&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Early Earth on the left, had seas infused with life-enhancing iron, whereas Earth today, seen on the right, does not.
</span> <span class="attribution"><span class="source">Credit: Image courtesy of Mark A. Garlick / markgarlick.com</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Our red blood is full of iron. We need iron for growth and for immunity. It is even added to foodstuffs, such as cereals, to ensure that <a href="https://www.thetimes.co.uk/article/how-can-i-combat-iron-deficiency-anaemia-rb0cnzgfv">there is enough</a> of this nutrient in the diet to prevent iron deficiency. </p>
<p>However, on a very different scale, during the development of life on planet Earth over billions of years, iron deficiency may have stimulated evolution. According to our new research, <a href="https://doi.org/10.1073/pnas.2109865118">published in the Proceedings of the National Academy of Sciences</a> (PNAS), rising and falling levels of iron on our planet may have enabled complex organisms to evolve from simpler forebears. </p>
<p>The terrestrial planets in our solar system – Mercury, Venus, Earth and Mars – have different amounts of iron in their rocky mantles, the layer below the outermost planetary crust. Mercury’s mantle has the least amount of iron, and Mars’ has the most. This variation is due to differences in distance from the Sun. It is also down to the varying conditions under which the planets initially formed their metallic, iron-rich cores.</p>
<p>The amount of iron in the mantle regulates several planetary processes, including the <a href="https://www.thetimes.co.uk/article/how-can-i-combat-iron-deficiency-anaemia-rb0cnzgfv">retention of surface water</a>. And without water, life as we know it <a href="https://www.youtube.com/watch?v=pTka51ky9TE">cannot exist</a>. Astronomical observations of other solar systems may <a href="https://iopscience.iop.org/article/10.3847/2041-8213/abf7ca">enable estimates</a> of a planet’s mantle iron, helping to narrow the search for planets capable of harbouring life. </p>
<p>As well as contributing to planetary habitability, iron is fundamental for the <a href="https://www.tandfonline.com/doi/pdf/10.3109/15563657108990976">biochemistry that allows life to happen</a>. Iron has a unique combination of properties, including the ability to form chemical bonds in multiple orientations and relative ease of gaining or losing one electron. As a result, iron mediates many biochemical processes in cells, especially by enabling catalysis – a process that speeds up chemical reactions. Metabolic processes <a href="https://www.nature.com/articles/s41586-019-1151-1">that are vital to life</a>, such as DNA synthesis and cellular energy generation, rely on iron.</p>
<p>In our work, we calculated the amount of iron in Earth’s seas over billions of years. We then considered the effect on evolution of enormous amounts of iron falling out of the seas.</p>
<h2>Iron through the ages</h2>
<p>The initial formative events of geochemistry evolving into biochemistry, life, took place more than 4 billion years ago. And there is an consensus that <a href="https://iubmb.onlinelibrary.wiley.com/doi/full/10.1002/iub.1632">iron was a pivotal element</a> for this process. The conditions of early Earth were very different to those now. In particular, there was almost no oxygen in the atmosphere, which meant that iron was easily soluble in water as “ferrous iron” (Fe2+). The abundance of nutritious iron in the Earth’s early seas helped life to evolve. However, this “<a href="https://doi.org/10.1016/j.bbagen.2011.08.002">ferrous paradise</a>” was not to last.</p>
<p>The <a href="https://slate.com/technology/2014/07/the-great-oxygenation-event-the-earths-first-mass-extinction.html">Great Oxygenation Event</a> resulted in the appearance of oxygen in the Earth’s atmosphere. It occurred from around 2.43 billion years ago. This changed the surface of Earth and caused a <a href="https://www.science.org/doi/10.1126/sciadv.1603076">profound loss of soluble iron</a> from the upper ocean and surface waters of the planet. A second, more recent “oxygenation event”, the Neoproterozoic, occurred between 800 to 500 million years ago. This raised oxygen concentrations yet higher. As a consequence of these two events, oxygen combined with iron and gigatons of oxidised, insoluble, “ferric iron” (Fe3+) dropped out of ocean waters, becoming unavailable to most lifeforms.</p>
<figure class="align-center ">
<img alt="Image of the Pilbara region in Western Australia known for the red earth and its vast mineral deposits in iron ore – oxygen and iron atoms bonded together into molecules." src="https://images.theconversation.com/files/435291/original/file-20211202-21-22o85a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/435291/original/file-20211202-21-22o85a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/435291/original/file-20211202-21-22o85a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/435291/original/file-20211202-21-22o85a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/435291/original/file-20211202-21-22o85a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/435291/original/file-20211202-21-22o85a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/435291/original/file-20211202-21-22o85a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Pilbara region in Western Australia is known for the red earth and its vast mineral deposits in iron ore – oxygen and iron atoms bonded together into molecules.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/pilbara-region-western-australia-known-red-1921102964">electra/Shutterstock</a></span>
</figcaption>
</figure>
<p>Life had developed – and maintains – an inescapable dependency on iron. The loss of access to soluble iron had major consequences for the evolution of life on Earth. Behaviour that optimised the acquisition and use of iron would have had a clear selective advantage. We can still see this in genetic analysis of infections today: bacterial variants able to efficiently scavenge iron from their hosts do better than less able competitors over a few short generations. </p>
<p>A key weapon in this battle for iron was the “<a href="https://doi.org/10.1038/%20s41579-019-0284-4">siderophore</a>” – a small molecule produced by many bacteria that captures oxidised iron (Fe3+). Siderophores became spectacularly more useful after oxygenation, enabling organisms to assimilate iron from minerals containing oxidised iron. However, siderophores also helped steal iron from other organisms, including bacteria. This switch in focus, from acquiring iron from the environment to stealing it from other lifeforms, set up a new dynamic of <a href="https://www.pnas.org/content/103/44/16502">competitive interaction</a> between pathogens and their hosts. Thanks to this process, both parties continually evolved to <a href="https://www.science.org/doi/10.1126/science.aaa2468">attack and defend their iron resources</a>. Over millions of years, this powerful competitive drive led to increasingly complex behaviour, resulting in more advanced organisms. </p>
<p>However, other strategies, besides theft, can help deal with the dependency on a sparse nutrient. One such example is symbiotic, cooperative relationships that share resources. Mitochondria are iron-rich, energy-generating machines that were originally bacteria but now <a href="https://doi.org/10.1038/s41564-020-0710-4">reside in our cells</a>. Multiple cells clumping together as complex organisms enable more efficient use of rare nutrients than single-celled organisms, such as bacteria. For example, humans <a href="https://www.sciencedirect.com/science/article/pii/S0092867416317500">recycle 25 times as much iron</a> per day as we take in from our diet. From an iron-biased view, infection, symbiosis and multicellularity provided different but elegant means for lifeforms to counteract the limitation of iron. The need for iron may have shaped evolution - including life as we know it today.</p>
<p>Earth demonstrates the importance of being ironic. The combination of both an early Earth with biologically accessible iron and the subsequent removal of iron during surface oxidation, has provided unique environmental pressures facilitating the evolution of complex life from simpler precursors.</p>
<p>These specific sets of conditions and changes over such long timescales are possibly uncommon on other planets. The likelihood of other advanced lifeforms being found in our cosmic neighbourhood may therefore be low. Yet looking at the iron abundance on other worlds could also help us find such rare worlds.</p><img src="https://counter.theconversation.com/content/172821/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hal Drakesmith receives funding from Medical Research Council UK and the Bill and Melinda Gates Foundation.</span></em></p><p class="fine-print"><em><span>Jon Wade does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Life doesn’t just need water and oxygen to thrive, it also needs iron.
Hal Drakesmith, Professor of Iron Biology, University of Oxford
Jon Wade, Associate Professor of Planetary Materials, University of Oxford
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/163243
2021-08-04T18:02:18Z
2021-08-04T18:02:18Z
Moon lacked a magnetic field for nearly all its history – new research resolves mystery sparked by rocks brought back on Apollo
<figure><img src="https://images.theconversation.com/files/414219/original/file-20210802-16-1fr7zf0.jpeg?ixlib=rb-1.1.0&rect=3406%2C57%2C4240%2C2178&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists have been studying lunar samples brought back from Apollo missions to understand the geologic history of the Moon. </span> <span class="attribution"><a class="source" href="https://www.hq.nasa.gov/alsj/a16/a16pan1240222dmh.jpg">NASA</a></span></figcaption></figure><p>Surrounding Earth is a powerful magnetic field created by swirling liquid iron in the planet’s core. Earth’s magnetic field may be <a href="https://doi.org/10.1073/pnas.1916553117">nearly as old as the Earth itself</a> – and stands in stark contrast to the Moon, which completely lacks a magnetic field today.</p>
<p>But did the Moon’s core generate a magnetic field in the past? </p>
<p>In the 1980s, geophysicists studying rocks brought back by Apollo astronauts concluded the Moon <a href="https://doi.org/10.1029/JB088iS02p0A691">once had a magnetic field</a> that was as strong as Earth’s. But a robust magnetic field requires a power source, and the Moon’s core is relatively small. For decades, scientists have <a href="https://doi.org/10.1002/2017GL075441">struggled to resolve</a> this conundrum: how could such a small core create a strong magnetic field?</p>
<p>I’m a <a href="https://www.sas.rochester.edu/ees/people/faculty/tarduno_john/index.html">professor of geophysics</a> and have been <a href="http://www.sas.rochester.edu/ees/pmag/people/jtarduno/bio.html">studying Earth’s magnetic field for more than 30 years</a>. I recently assembled a team to use new scientific techniques to reexamine the evidence for lunar magnetization. We found that <a href="https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.abi7647">the Moon did not in fact have a long-lived magnetic field</a>. Not only does this finding change the modern understanding of the Moon’s geologic history, it also has major implications for the presence of resources on the Moon that could be critical to future human exploration.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/414220/original/file-20210802-18-817kht.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing cutouts of the Earth and Moon with the Moon having a much smaller core relative to its size." src="https://images.theconversation.com/files/414220/original/file-20210802-18-817kht.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414220/original/file-20210802-18-817kht.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=721&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414220/original/file-20210802-18-817kht.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=721&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414220/original/file-20210802-18-817kht.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=721&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414220/original/file-20210802-18-817kht.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=906&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414220/original/file-20210802-18-817kht.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=906&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414220/original/file-20210802-18-817kht.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=906&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Relative to the Earth, the Moon has a small core, and it is not obvious how it could have created a strong magnetic field.</span>
<span class="attribution"><span class="source">Rory Cottrell/U. Rochester</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Why a magnetic Moon?</h2>
<p>Certain rocks have the extraordinary ability to preserve records of past magnetic fields when they contain minerals with iron atoms that <a href="https://www.geo.arizona.edu/Paleomag/chap02.pdf">align with a magnetic field</a> as the rock cools and solidifies. <a href="https://doi.org/10.1029/JB080i029p04049">The best magnetic minerals at preserving evidence of a field</a>
are tiny – a thousand times smaller than the width of a human hair – because it takes a lot of energy to rearrange their atoms.</p>
<p>Geophysicists who study ancient magnetism recreate this process, reheating rock samples in the presence of known magnetic fields and comparing the new alignment of the iron atoms with the orientation of iron atoms before the rock was reheated. This allows researchers to <a href="https://earthref.org/MagIC/books/Tauxe/Essentials/">learn about past magnetic fields</a>. </p>
<p>Early researchers studying the first rocks brought back from the Moon by U.S. astronauts wanted to use this method to study the Moon’s magnetism. But they faced problems. Lunar rocks contain a certain type of iron – called native iron – that <a href="https://doi.org/10.1029/RG012i001p00023">is easily altered by heat</a>. Additionally, the native iron grains in lunar rocks <a href="https://doi.org/10.1016/j.epsl.2010.02.013">are sometimes relatively large</a>, making them less likely to reliably record past magnetic fields.</p>
<p>From the 1970s onward, geophysicists used alternative, nonheating methods to study the Moon’s magnetism. They <a href="https://doi.org/10.1016/S0079-1946(98)00083-4">found that some lunar samples</a> had <a href="https://doi.org/10.1126/science.1246753">recorded strong magnetic fields</a>, suggesting that the Moon had a magnetic field <a href="https://doi.org/10.1126/sciadv.1700207">for over 2 billion years</a>.</p>
<p>But this result only deepened the conundrum. The question of how the Moon’s core could produce a strong magnetic field <a href="https://doi.org/10.1002/2017GL075441">remained unsolved</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/414216/original/file-20210802-26072-1xy2dvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A blue-, white- and black-flecked rock in a white dish." src="https://images.theconversation.com/files/414216/original/file-20210802-26072-1xy2dvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414216/original/file-20210802-26072-1xy2dvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414216/original/file-20210802-26072-1xy2dvx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414216/original/file-20210802-26072-1xy2dvx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414216/original/file-20210802-26072-1xy2dvx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414216/original/file-20210802-26072-1xy2dvx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414216/original/file-20210802-26072-1xy2dvx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Samples from the Moon, like this lunar basalt, are a complex mix of many minerals, and only some can record signals of past magnetic fields. The white scale bar is 1 mm.</span>
<span class="attribution"><span class="source">Kristin Lawrence</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>An alternative theory</h2>
<p>In the experiments, some Apollo samples showed evidence of strong magnetic fields but <a href="https://doi.org/10.1016/j.epsl.2012.05.024">other samples did not</a>. Some researchers attributed the missing magnetization to the presence of large native iron grains that were poor magnetic recorders. But many of the samples also contained small iron grains that should have recorded a field.</p>
<p>There have been <a href="https://doi.org/10.1017/CBO9780511612794">long-standing doubts about the nonheating techniques</a> researchers used on the Apollo samples. Some scientists have called them methods of “<a href="https://doi.org/10.1017/CBO9780511612794">last resort</a>” and conclude that the uncertainties in data collected in this way were so large that any interpretation <a href="http://adsabs.harvard.edu/full/1975LPSC....6.3063D">must be viewed as speculation</a>.</p>
<p>Alternatively, another group of scientists has suggested for decades that when meteorites strike the Moon, they create a dusty plasma – a gas of ions and electrons – that <a href="https://doi.org/10.1038/336050a0">could generate a strong magnetic field</a> and magnetize lunar rocks near the impact zone. </p>
<p>In 2008, geophysicist <a href="https://www.friendsschoolboulder.org/team/kristin-lawrence/">Kristin Lawrence</a> decided to revisit the question of lunar magnetization using an improved reheating technique. In contrast to the researchers who originally studied the samples, she was unable to detect any <a href="http://doi.org/10.1016/j.pepi.2008.05.007">definitive evidence for a past magnetic field</a>. The approach Lawrence and her team used was better than the nonheating tests, but her results were still not conclusive. She felt she was on to something, though, and that is when she turned to me and my lab for help. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/414217/original/file-20210802-14-4u6p9m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A small green fleck inside of a clear cube sitting on a stand in front of the nozzle of a scientific instrument." src="https://images.theconversation.com/files/414217/original/file-20210802-14-4u6p9m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414217/original/file-20210802-14-4u6p9m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414217/original/file-20210802-14-4u6p9m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414217/original/file-20210802-14-4u6p9m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414217/original/file-20210802-14-4u6p9m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414217/original/file-20210802-14-4u6p9m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414217/original/file-20210802-14-4u6p9m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">By using a new technique, researchers were able to isolate and test tiny samples – like the piece seen here mounted inside a quartz cube – for magnetic evidence.</span>
<span class="attribution"><span class="source">Adam Fenster/U. Rochester</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>In 2011, Lawrence brought us a collection of lunar samples to test. We had been developing techniques to <a href="https://doi.org/10.2113/gselements.5.4.217">identify individual millimeter-size silicate crystals</a> that contain only very small iron grains and have ideal recording properties. We then used an ultrasensitive superconducting magnetometer and a special carbon dioxide laser to rapidly heat those samples in a way that avoids altering their iron minerals. We found that nearly all the rocks had profoundly weak magnetic signals.</p>
<p>At the time of this first test we were still improving the method, so we couldn’t say with certainty whether the samples had formed on a Moon without a magnetic field. But we have been improving our testing methods, and last year we decided to revisit the Apollo samples.</p>
<p>We definitively found that some of the samples did indeed contain magnetic minerals capable of preserving high-fidelity signals of ancient magnetic fields. But the rocks had recorded no such signals. This suggests that the Moon lacked a magnetic field for nearly all of its history.</p>
<p>So, what explains the previous findings of a magnetic Moon? The answer was in one of the samples: a small, dark piece of glass containing tiny iron-nickel particles. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/414405/original/file-20210803-27-1vt9hed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A small, dark green rock viewed under a microscope." src="https://images.theconversation.com/files/414405/original/file-20210803-27-1vt9hed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414405/original/file-20210803-27-1vt9hed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=464&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414405/original/file-20210803-27-1vt9hed.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=464&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414405/original/file-20210803-27-1vt9hed.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=464&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414405/original/file-20210803-27-1vt9hed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=583&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414405/original/file-20210803-27-1vt9hed.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=583&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414405/original/file-20210803-27-1vt9hed.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=583&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This small piece of lunar glass was formed and magnetized by a meteorite impact and could explain the strong magnetic readings from the past.</span>
<span class="attribution"><span class="source">Rory Cottrell/U. Rochester</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The glass was made by a meteorite impact and showed clear evidence of a strong magnetic field. But it was formed only about 2 million years ago. Nearly all geophysicists agree <a href="https://doi.org/10.1126/sciadv.aax0883">the Moon did not have a magnetic field</a> at that time, because after 4.5 billion years of cooling there was not enough heat left to power the churning of iron in the Moon’s core to generate a field. The magnetic signature of the glass matched simulations of magnetic fields that can be <a href="https://www.hou.usra.edu/meetings/lpsc2020/pdf/2653.pdf">generated by meteor impacts</a>. This showed that meteorite impacts alone can create strong magnetic fields that magnetize rocks nearby. This could explain the high values previously reported from some Apollo rocks. </p>
<p>Taken together, I believe these findings resolve the mystery of a seemingly magnetic Moon.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/414222/original/file-20210802-26072-12z43km.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing lines of solar radiation being deflected away by the Earth's magnetic field but hitting the Moon." src="https://images.theconversation.com/files/414222/original/file-20210802-26072-12z43km.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/414222/original/file-20210802-26072-12z43km.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=319&fit=crop&dpr=1 600w, https://images.theconversation.com/files/414222/original/file-20210802-26072-12z43km.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=319&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/414222/original/file-20210802-26072-12z43km.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=319&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/414222/original/file-20210802-26072-12z43km.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=401&fit=crop&dpr=1 754w, https://images.theconversation.com/files/414222/original/file-20210802-26072-12z43km.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=401&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/414222/original/file-20210802-26072-12z43km.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=401&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Earth’s magnetic shield blocks solar wind, whereas the lack of a magnetic field on the Moon allows the solar wind to directly hit its surface and deposit elements.</span>
<span class="attribution"><span class="source">Michael Osadciw/U. Rochester</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Magnetic shielding and lunar resources</h2>
<p>This new view of lunar magnetism has huge implications for the potential presence of valuable resources as well as information about the ancient Sun and Earth that may be buried in lunar soils.</p>
<p>Magnetic fields act as shields that <a href="https://doi.org/10.1016/j.pepi.2014.05.007">prevent solar particles from reaching a planet or moon</a>. Without a magnetic field, solar wind can hit the surface of the Moon directly and implant elements like helium-3 and hydrogen into the soil. </p>
<p>Helium-3 has many applications, but importantly, it could be a <a href="https://www.esa.int/Enabling_Support/Preparing_for_the_Future/Space_for_Earth/Energy/Helium-3_mining_on_the_lunar_surface">fuel source for nuclear fusion and future planetary exploration</a>. The value of hydrogen comes from the fact that it can combine with oxygen to <a href="https://www.nasa.gov/press-release/nasa-s-sofia-discovers-water-on-sunlit-surface-of-moon">form water</a>, another crucial resource in space.</p>
<p>Since the Moon did not have a long-lived magnetic field, these elements could have <a href="https://doi.org/10.1016/j.icarus.2009.11.033">been accumulating in soils</a> for billions of years longer than previously thought.</p>
<p>There is also scientific value. Elements embedded by solar wind could shed light on the evolution of the Sun. And as the Moon passes through Earth’s magnetic field, elements from Earth’s atmosphere <a href="https://www.sciencemag.org/news/2017/01/earth-sending-oxygen-moon">can be deposited on the lunar surface</a>, and these may hold clues about the earliest Earth. </p>
<p>The absence of a long-lived magnetic field on the Moon might strike some as a loss, but I believe it may unlock a scientific bonanza and a valuable stash of potential resources.</p>
<p>[<em>Get the best of The Conversation, every weekend.</em> <a href="https://theconversation.com/us/newsletters/weekly-highlights-61?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=weeklybest">Sign up for our weekly newsletter</a>.]</p><img src="https://counter.theconversation.com/content/163243/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>John Tarduno receives funding from NASA and the US National Science Foundation.</span></em></p>
Without a magnetic field, the Moon’s surface is exposed to solar wind. These could have been depositing resources like water and potential rocket fuel on the Moon’s surface for billions of years.
John Tarduno, Professor of Geophysics, University of Rochester
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/162242
2021-06-21T20:10:59Z
2021-06-21T20:10:59Z
Dust from exploding stars is raining down on Earth. I hunt it to learn how the elements were made
<figure><img src="https://images.theconversation.com/files/407176/original/file-20210618-12-12wo9su.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C7951%2C5297&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Dominik Koll</span>, <span class="license">Author provided</span></span></figcaption></figure><p>It is all around us. Every day in our lives we are in contact with it. In fact, we are made from it: ancient stardust. </p>
<p>All the atoms around us have witnessed the most violent explosions in the universe. Their journeys through space are the longest, roughest and loneliest voyages imaginable. </p>
<p>The hydrogen in the water we drink is the lightest of all the elements, and it dates back to the Big Bang at the beginning of the universe. Heavier elements, like the iron in our blood and the oxygen in the air we breathe, were forged in stars and ejected when they exploded at the end of their lives. </p>
<p>Dust from distant stellar explosions is still falling on Earth in a gentle, almost imperceptible rain. In my research, I hunt for traces of this dust to learn about how exploding stars have affected Earth’s history – and perhaps discover clues about the origin of the universe’s heaviest elements.</p>
<h2>Hunting atoms</h2>
<p>For many years my colleagues and I have been searching for fresh stardust (or any other kind of interstellar dust) across the giant dustbin we call home: Earth. We need dust that has fallen relatively recently (in cosmic terms), because then we have a chance of tracing it back to an event and a location like a particular exploding star.</p>
<p>Specifically, we are looking for atoms of iron-60 (or ⁶⁰Fe), a radioactive isotope of iron. Iron-60 is very rare on Earth, as it is mainly produced in massive stars and is found in minor quantities in cosmic dust and meteorites. However, it has a half-life of 2.6 million years, which means the atoms that do arrive here stick around for a long while before decaying.</p>
<p>Only a tiny amount of iron-60 rains down on Earth: each square centimetre of the planet’s surface receives a few atoms per year. If you stuck your tongue out for a full year, you might taste only a handful of atoms of iron-60.</p>
<p>To find iron-60, we need the help of nature: areas of Earth’s surface that are largely undisturbed and form a “geological archive” that concentrates and stores the iron-60 over time.</p>
<h2>Traces beneath the sea</h2>
<p>Iron-60 from the stars was <a href="https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.93.171103">first</a> discovered in 2004, in layers of deep-ocean rock called “ferromanganese crust”. These hard iron-containing layers develop very slowly: in a million years, the crust will only grow by a few millimetres. </p>
<p>These geological vaults kept their iron-60 until samples are taken and studied using an ultra-sensitive technique called accelerator mass spectrometry. </p>
<p>The iron-60 found in 2004 suggested Earth had experienced an influx of interstellar dust from an exploding star (or supernova) about 2 million years ago. In 2016, this was confirmed by several independent studies of ocean sediments, deep-sea crusts and even rocks from the Moon. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/our-oceans-give-new-insights-on-elements-made-in-supernovae-36502">Our oceans give new insights on elements made in supernovae</a>
</strong>
</em>
</p>
<hr>
<p>More recently, traces of iron-60 found in seabeds revealed <a href="https://science.sciencemag.org/content/372/6543/742">another</a> influx of interstellar dust around 7 million years ago.</p>
<p>So we know Earth was impacted by at least two nearby stellar explosions in the past several million years. The collected data further indicated some iron-60 might still have been raining down on Earth within the past couple of hundred thousand years. </p>
<h2>Is interstellar dust still falling today?</h2>
<p>The search for interstellar dust in recent times is more challenging because nature is not helping us a lot anymore. </p>
<p>First, there is no concentration of iron-60 possible over a time period of a few years. This means we need to take a sample over a much larger area to find a useful number of iron-60 atoms.</p>
<p>Second, since humans invented nuclear weapons and other nuclear technology, there are many new radioactive isotopes present on Earth. So there is a slight chance that any iron-60 you find today might have been created by humans rather than exploding stars. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/elements-from-the-stars-the-unexpected-discovery-that-upended-astrophysics-66-years-ago-93916">Elements from the stars: The unexpected discovery that upended astrophysics 66 years ago</a>
</strong>
</em>
</p>
<hr>
<p>There are not many places to look for recent interstellar dust by its iron-60 signature, but one of them is in the pure snow of remote Antarctica. Still, you need to collect several hundred kilograms of snow for a big enough sample to reliably measure whether or not it contains interstellar iron-60. </p>
<p>In 2019, we <a href="https://doi.org/10.1103/PhysRevLett.123.072701">analysed</a> 500 kilograms of Antarctic snow and found 10 atoms of iron-60. The snow we collected was no more than 20 years old, and was about the amount that would fall in one year over 6 square meters of ground in Antarctica. </p>
<p>The iron-60 was of interstellar origin and perfectly within the expectations from previous measurements, and we also excluded human nuclear activity as the source. This was the first evidence that there is still interstellar dust from supernovae raining down on us every day.</p>
<p>We were able to <a href="https://www.pnas.org/content/117/36/21873">confirm</a> this result and extend it over the past 35,000 years by searching in ocean sediments. Combining all the evidence, we now <a href="https://www.epj-conferences.org/articles/epjconf/abs/2020/08/epjconf_hias2019_02001/epjconf_hias2019_02001.html">have</a> a record of interstellar dust influxes, on a scale of years, thousands of years, and millions of years.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/407377/original/file-20210621-35700-193rn96.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/407377/original/file-20210621-35700-193rn96.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=459&fit=crop&dpr=1 600w, https://images.theconversation.com/files/407377/original/file-20210621-35700-193rn96.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=459&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/407377/original/file-20210621-35700-193rn96.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=459&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/407377/original/file-20210621-35700-193rn96.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=577&fit=crop&dpr=1 754w, https://images.theconversation.com/files/407377/original/file-20210621-35700-193rn96.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=577&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/407377/original/file-20210621-35700-193rn96.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=577&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The record we have of iron-60 influxes on Earth and the Moon. The vertical axis shows how many atoms of iron-60 were falling on one square centimetre in a year, and the horizontal axis shows the time in thousands of years before the present. The time window around 100,000 years ago is still largely unexplored.</span>
</figcaption>
</figure>
<h2>The future of ancient stardust</h2>
<p>What’s next in the hunt for stardust? First off, we still have a gap in the data in the 100,000-year range that needs to be filled to fully understand the origin and connection of the observed influxes. </p>
<p>Another line of inquiry is to use what we know about influxes of iron-60 to hunt for something much heavier, plutonium-244. This is the longest-lived radioactive isotope of plutonium with a half-life of 81 million years.</p>
<p>Like around half of the elements heavier than iron, plutonium-244 is created by a series of nuclear reactions called the astrophysical r-process. However, though scientists understand how this process works, yet we don’t know where in the universe these heavy elements are produced. </p>
<p>Supernovae were believed to entail the right conditions for the r-process to occur, but there is also some evidence suggesting that many of the heavy elements may instead be produced when neutron stars collide.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/cosmic-alchemy-colliding-neutron-stars-show-us-how-the-universe-creates-gold-86104">Cosmic alchemy: Colliding neutron stars show us how the universe creates gold</a>
</strong>
</em>
</p>
<hr>
<p>One way to shed light on this question is to look for plutonium-244 in the same places where we have found iron-60, which we know comes from supernovae. </p>
<p>In my PhD research I will go back to the roots of iron-60 hunting, the ferromanganese crusts. If we find that plutonium-244 follows the iron-60, it might point towards a stellar r-process. The hunt is ongoing.</p><img src="https://counter.theconversation.com/content/162242/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dominik Koll works for the Australian National University. He receives funding from AINSE.</span></em></p>
Traces of radioactive iron from the ocean floor, Antartica and the Moon reveal several waves of dust from distant stars over the past 10 million years.
Dominik Koll, Dual PhD Candidate, Australian National University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/156579
2021-04-21T06:59:01Z
2021-04-21T06:59:01Z
What to drink with dinner to get the most iron from your food (and what to avoid)
<figure><img src="https://images.theconversation.com/files/396221/original/file-20210421-15-1acdwvv.jpg?ixlib=rb-1.1.0&rect=529%2C0%2C5308%2C3988&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>A drink with your breakfast, lunch or dinner can make your meal more enjoyable. But have you considered whether your drink of choice may affect the way your body absorbs the nutrients in your food?</p>
<p>Dietary factors that can increase the uptake of other nutrients are called enhancers, while those that can reduce the uptake of other nutrients are called inhibitors, or <a href="https://www.sciencedirect.com/science/article/abs/pii/096399699390069U">anti-nutrients</a>.</p>
<p>One of the most common nutrient deficiencies worldwide is iron, and can result in a condition called <a href="https://www.healthline.com/health/iron-deficiency-anemia">iron deficiency anaemia</a>. </p>
<p>So if you’re looking to increase your iron levels, it’s worth thinking not just about what you’re eating — but what you’re drinking too.</p>
<h2>A bit about iron</h2>
<p>Iron deficiency can develop when <a href="https://theconversation.com/ive-been-diagnosed-with-iron-deficiency-now-what-87670">we don’t get enough iron</a>, or don’t absorb iron to the extent our body needs. It’s more common <a href="https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(13)70001-9/fulltext">in women</a>, and can cause weakness and fatigue, among other symptoms.</p>
<p>If you’re worried you may be iron deficient, you can get a blood test from your general practitioner.</p>
<p>There are <a href="https://www.betterhealth.vic.gov.au/health/ConditionsAndTreatments/iron">two forms of iron</a> in our diets; haem iron and non-haem iron. Haem is an iron-containing protein that forms part of the haemoglobin, a protein in your red blood cells that transports oxygen around your body. </p>
<p>Haem iron is found in animal sources of food, like meat, and is more easily absorbed into the body. </p>
<p>Non-haem iron is found in plant foods, like grains, beans and nuts, and is less easily absorbed. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ive-been-diagnosed-with-iron-deficiency-now-what-87670">I've been diagnosed with iron deficiency, now what?</a>
</strong>
</em>
</p>
<hr>
<h2>Some enhancers</h2>
<p>Choosing a drink that contains vitamin C — such as orange, tomato or grapefruit juice — around the time of your meal will increase the amount of the non-haem iron you can absorb. </p>
<p>In one study, 100mg of vitamin C <a href="https://academic.oup.com/ajcn/article/71/5/1147/4729231?login=true">increased iron absorption four-fold</a>. This is roughly equivalent to what you’d get from one glass of orange juice.</p>
<p>Keeping this in mind is particularly important for people who don’t eat meat, as all of their dietary iron will be non-haem iron.</p>
<h2>Some inhibitors</h2>
<p>Tea is a popular drink with meals and is often enjoyed with Asian cuisine. But tea contains a bioactive compound called tannin, which is <a href="https://academic.oup.com/cdn/article/1/2/1/4558629?login=true">an inhibitor</a> of non-haem iron absorption.</p>
<p><a href="https://www.tandfonline.com/doi/abs/10.1080/10408699891274273">Tannin</a> is classed as an organic compound called a polyphenol. It’s also found in many foods including cocoa, almonds, grapes, berries, pomegranates, and spices (for example, vanilla and cinnamon), which may find their way into drinks like smoothies.</p>
<p><a href="https://www.researchgate.net/profile/Vikas-Kumar-190/publication/309632876_Kombucha_Technology_Microbiology_Production_Composition_and_Therapeutic_Value/links/581ab50b08aed2439386c9f5/Kombucha-Technology-Microbiology-Production-Composition-and-Therapeutic-Value.pdf">Kombucha</a>, a popular fermented tea drink, still contains some tannins.</p>
<p>Unfortunately the news is no better for coffee drinkers — coffee contains tannins too. And the <a href="https://academic.oup.com/ajcn/article/71/5/1147/4729231?login=true">chlorogenic acid</a> in coffee is also an important inhibitor of iron absorption.</p>
<figure class="align-center ">
<img alt="A woman in a striped jumper holds a mug." src="https://images.theconversation.com/files/396222/original/file-20210421-15-usngrb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/396222/original/file-20210421-15-usngrb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/396222/original/file-20210421-15-usngrb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/396222/original/file-20210421-15-usngrb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/396222/original/file-20210421-15-usngrb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/396222/original/file-20210421-15-usngrb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/396222/original/file-20210421-15-usngrb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Tea and coffee contain tannins, which inhibit iron absorption.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Tea and coffee are considered the strongest inhibitors of iron. A cup of tea reduces iron absorption <a href="https://academic.oup.com/ajcn/article/71/5/1147/4729231?login=true">by about 75%-80%</a>, and a cup of coffee <a href="https://academic.oup.com/ajcn/article/71/5/1147/4729231?login=true">by about 60%</a>. The stronger you make them, the greater the effect will be. </p>
<p>So it’s best to avoid tea and coffee while eating and for two hours before and after the meal. This is roughly the <a href="https://www.tandfonline.com/doi/full/10.1080/10408398.2020.1784841">length of time</a> food and drinks sit in your stomach before they’re fully absorbed. </p>
<p>This includes breakfast, a meal at which many people most commonly consume tea and coffee. For most of us breakfast normally consists of cereal and/or bread. Both of these naturally contain significant <a href="https://www.healthdirect.gov.au/foods-high-in-iron">levels of iron</a> and sometimes these products have iron added.</p>
<p>So if you’re iron deficient, it may be time to consider opting for a small glass of orange juice at breakfast, or preferably the whole orange (as you get fibre with it too), and saving the tea or coffee for a little later.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-kombucha-and-how-do-the-health-claims-stack-up-87180">What is kombucha and how do the health claims stack up?</a>
</strong>
</em>
</p>
<hr>
<h2>A little from column A, a little from column B</h2>
<p>There has always been speculation <a href="https://econtent.hogrefe.com/doi/abs/10.1024/0300-9831/a000036">dairy may inhibit iron absorption</a>, but to date the evidence seems to suggest it has no effect. </p>
<p>However plant-based milks, such as soy milk, contain phytates, a compound that stores phosphorus in plants, which inhibit <a href="https://academic.oup.com/ajcn/article/71/5/1147/4729231">iron absorption</a>.</p>
<figure class="align-center ">
<img alt="A group of people drinking beers with a meal." src="https://images.theconversation.com/files/396223/original/file-20210421-23-d4fvuf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/396223/original/file-20210421-23-d4fvuf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/396223/original/file-20210421-23-d4fvuf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/396223/original/file-20210421-23-d4fvuf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/396223/original/file-20210421-23-d4fvuf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/396223/original/file-20210421-23-d4fvuf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/396223/original/file-20210421-23-d4fvuf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Beer increases iron absorption. But that doesn’t mean you should have it with every meal.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Meanwhile, <a href="https://academic.oup.com/ajcn/article/71/5/1147/4729231">alcohol increases the absorption of iron</a>, so a beer would be classed as an enhancer. </p>
<p>If you favour a glass of wine, you should select a white over a red. Red wine contains more tannins and other polyphenols, so overall <a href="https://academic.oup.com/ajcn/article/71/5/1147/4729231?login=true">red wine</a> inhibits iron absorption.</p>
<p>But as we know drinking alcohol increases the risk <a href="https://www.wcrf.org/dietandcancer/exposures/alcoholic-drinks">of cancer</a> and is linked to <a href="https://www.sciencedirect.com/science/article/abs/pii/S0031938410000259">other health concerns</a>, you shouldn’t start drinking alcohol to increase iron absorption.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/should-i-let-my-kids-drink-juice-we-asked-five-experts-92176">Should I let my kids drink juice? We asked five experts</a>
</strong>
</em>
</p>
<hr>
<h2>So what’s the take-home message?</h2>
<p>The bioactives I’ve mentioned also provide many nutritional and health benefits, and they’re all found in plant products. It would be virtually impossible to avoid tannins in your diet and still be consuming the healthy number of serves of fruit and vegetables. </p>
<p>This advice is mostly relevant if you’ve been diagnosed as iron deficient or with iron deficiency anaemia. And even if this is the case, you can still enjoy these drinks outside of meal times. </p>
<p>If your iron levels are within the normal range there’s no need to be concerned as your body is absorbing enough to meet your needs with what you’re drinking and eating.</p><img src="https://counter.theconversation.com/content/156579/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Evangeline Mantzioris receives funding from NHMRC. </span></em></p>
From orange juice, to tea and coffee, to alcohol — different drinks can have different effects on iron absorption. This is worth thinking about if your iron levels are low.
Evangeline Mantzioris, Program Director of Nutrition and Food Sciences, University of South Australia
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/157231
2021-03-17T04:46:53Z
2021-03-17T04:46:53Z
What is seitan? The vegan protein alternative going viral online
<figure><img src="https://images.theconversation.com/files/390039/original/file-20210317-17-htu1w8.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4500%2C2997&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The trend towards vegetarian and vegan diets means more people are looking for meat-free protein alternatives.</p>
<p>Enter seitan (pronounced say-tan), the latest food trend that’s <a href="https://www.instagram.com/p/CMQDdl8ggrs/">going viral online</a>.</p>
<p>Seitan can be made by washing the starch off flour, so what you are left with is mainly gluten. Wheat gluten has been used as a <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/1541-4337.12610?af=R">substitute for meat in Asian countries for centuries</a>, particularly among Buddhists who prefer not to eat meat. George Ohsawa, Japanese advocate for the “<a href="https://www.bbcgoodfood.com/howto/guide/what-macrobiotic-diet">macrobiotic</a>” diet, coined the term seitan for wheat gluten in the early 1960s.</p>
<p>Seitan’s versatility and “meatiness”, combined with the need for tasty, vegan protein options have contributed to its huge increase in popularity world-wide in recent years.</p>
<h2>It’s high in protein and iron</h2>
<p>As well as being flavoursome and reminiscent of meat, seitan is relatively high in protein and non-haem iron compared to other vegetarian protein foods.</p>
<p>One serving around the size of the palm of your hand <a href="https://www.foodstandards.gov.au/science/monitoringnutrients/ausnut/foodnutrient/Pages/default.aspx">contains</a> about 75 grams of protein, enough for most adults for a day. Gram for gram, that’s about three times as much protein as beef or lamb.</p>
<p>With about 5 milligrams of iron per 100 grams, seitan <a href="https://www.foodstandards.gov.au/science/monitoringnutrients/ausnut/foodnutrient/Pages/default.aspx">has</a> as much iron as kangaroo meat or beef. But as for other plant-based foods, the non-haem iron in seitan is not as readily absorbed as the haem iron in meats.</p>
<p>A small serve of seitan (100 grams) <a href="https://www.foodstandards.gov.au/science/monitoringnutrients/ausnut/foodnutrient/Pages/default.aspx">contains</a> about 14 grams of carbs, which is about the same as one slice of bread.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1369341372558368776"}"></div></p>
<p>Seitan doesn’t contain any soy, unlike tofu or tempeh. So it’s a good option for people with a soy allergy. </p>
<h2>You can make it at home</h2>
<p>You can make seitan just from flour and water, but it does take about an hour from start to finished product. </p>
<p>To prepare seitan, combine flour with a little salt and water to form a soft dough. Then keep kneading the dough under cold running water (to remove the starch) until it becomes a very stiff and stretchy dough.</p>
<hr>
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<hr>
<p>If you’re in a hurry, you can cheat by mixing commercially available “vital wheat gluten” with water.</p>
<p>Either way, once you’ve got the gluten dough, flavour it with spices or sauces and then pan fry or boil it.</p>
<p>You can serve it as a steak substitute, sliced and stir-fried, “pulled” like pork, or crumbed and made into a vegan schnitzel. Seitan meals have been known to be mistaken as meat by some fairly serious carnivores!</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1347596725188493312"}"></div></p>
<p>It might be worth taste testing ready-made seitan from a shop to check whether you like it before making it yourself, but this often contains added salt as a preservative. Make sure the sodium content is under 400 milligrams per 100 grams. It’s a good idea to limit your sodium intake, and the Heart Foundation <a href="https://www.heartfoundation.org.au/heart-health-education/salt-and-heart-health">recommends</a> no more than 2,000 milligrams per day.</p>
<h2>So what’s the downside?</h2>
<p>Well, it’s definitely not suitable for people <a href="https://www.coeliac.org.au/s/coeliac-disease/self-assessment">diagnosed with coeliac disease</a> or with a known adverse reaction to the gluten proteins in wheat.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-do-people-decide-to-go-gluten-or-wheat-free-50452">Why do people decide to go gluten- or wheat-free?</a>
</strong>
</em>
</p>
<hr>
<p>If that’s you, then tofu and legumes are suitable meat substitutes. Another sustainable, gluten-free option is <a href="https://www.quorn.com.au/company">Quorn</a>, a protein-rich food made by fungi. </p>
<p>If you get a bloated tummy or gut pain after eating bread or pasta, but definitely don’t have coeliac disease, it would be interesting to know whether you tolerate seitan. If you do, it could be you don’t tolerate the carbohydrate part of wheat, but can tolerate gluten. A research team at the University of Newcastle, of which I am a part, is <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7400003/">investigating</a> whether people who report gut pain after eating wheat are sensitive to the gluten or to the fermentable carbohydrates (FODMAPs) in wheat.</p>
<p>For everyone else who wants to decrease or avoid meat, seitan is versatile and one of the closest in texture and flavour to meat of any vegetarian protein options — so break out the mixing bowls and get kneading.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-fodmap-diet-is-everywhere-but-researchers-warn-its-not-for-weight-loss-131550">The FODMAP diet is everywhere, but researchers warn it's not for weight loss</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/157231/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kerith Duncanson receives funding from the National Health and Medical Research Council grant as an investigator in the Centre for Research Excellence in Digestive Health. </span></em></p>
A dietitian breaks down everything you need to know about this viral meat substitute.
Kerith Duncanson, Senior Research Fellow, School of Medicine and Public Health, University of Newcastle
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/152652
2021-01-21T13:13:27Z
2021-01-21T13:13:27Z
Invasive tawny crazy ants have an intense craving for calcium – with implications for their spread in the US
<figure><img src="https://images.theconversation.com/files/378340/original/file-20210112-23-1duz31c.png?ixlib=rb-1.1.0&rect=6%2C6%2C4019%2C3011&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Multiple queens ensure colonies have a steady output of workers.</span> <span class="attribution"><span class="source">Ryan Reihart</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em>The <a href="https://theconversation.com/us/topics/research-brief-83231">Research Brief</a> is a short take about interesting academic work.</em></p>
<h2>The big idea</h2>
<p>In a recent study, <a href="https://chelseprather.wordpress.com/">my colleagues</a> and <a href="https://scholar.google.com/citations?hl=en&user=6GBgzO8AAAAJ">I</a> discovered micronutrients in the ground <a href="https://www.doi.org/10.1002/ECY.3263">can control populations of invasive crazy ants</a> (<em>Nylanderia fulva</em>). </p>
<p>Tawny crazy ants – named for their fast, erratic movements – can blanket the ground by the millions. Originating in South America and now established in parts of the southern U.S., they <a href="https://www.nytimes.com/2013/12/08/magazine/crazy-ants.html">harm other insects, asphyxiate chickens and even short-circuit electronics in homes</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close up photo of a golden-colored ant against a blue background." src="https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=418&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=418&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=418&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=525&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=525&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=525&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">At only 0.125 inches (3.2 mm) long, crazy ants are tiny but mighty.</span>
<span class="attribution"><span class="source">Ryan Reihart</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Crazy ants are <a href="https://doi.org/10.1146/annurev.ecolsys.33.010802.150444">liquid feeders</a> <a href="https://doi.org/10.1653/024.096.0219">that consume nectar from plants – and honeydew (or secretions) from certain insects</a>. Ants crave these sugary resources, which <a href="https://doi.org/10.1073/pnas.1115263108">boost their colony growth</a>, enabling them to outcompete native species and ultimately spread. </p>
<p>The nutritional content of nectar and honeydew vary widely, however, <a href="https://www.britishecologicalsociety.org/ant-cravings-sugar-salt-vary-across-us/">depending on the nutrients available in a particular ecosystem</a>. There are 25 chemical elements required to build life – too much or too little of one may cause disease. So far, ecologists only really know about the importance of macronutrients, like nitrogen and phosphorus, that are abundant in living tissue. My team wanted to learn more about what micronutrients might be important to crazy ants.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A man kneeling over a small hole dug in the grass." src="https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=801&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=801&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=801&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1007&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1007&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1007&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Installing a pitfall trap in one of the 128 fertilized study plots.</span>
<span class="attribution"><span class="source">Kiersten Angelos</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>We conducted a fertilization experiment at the <a href="http://www.eih.uh.edu/">University of Houston’s Coastal Center</a> and were able to demonstrate that the abundance of tawny crazy ants decreased 24% where there was more potassium and 45% where there was more sodium and potassium. </p>
<p>What greatly surprised our team was the discovery that ants were 13% more abundant in areas where there was more calcium – even in areas that had more sodium and potassium. This finding, <a href="https://www.doi.org/10.1002/ECY.3263">published in the journal Ecology</a>, could have big implications for the continued spread of crazy ants. </p>
<h2>Why it matters</h2>
<p>Ours is the first study showing calcium is important to an invasive ant, which is somewhat surprising given ants don’t have bones. It turns out, though, calcium is important in their <a href="https://doi.org/10.1016/j.ceca.2012.11.008">egg production</a>, <a href="https://doi.org/10.1080/00218839.2015.1035074">larval development</a> and <a href="https://doi.org/10.1093/aesa/51.2.142">physiological regulation</a>. </p>
<p><a href="https://doi.org/10.1002/ece3.1737">If the spread of crazy ants continues north</a>, the calcium-rich limestone bedrock of the lower U.S. Midwest may provide ideal conditions for populations to explode. Farmlands may be at risk because calcium is found in many fertilizers. Additionally, cities often have <a href="https://doi.org/10.1007/s10980-008-9288-6">more calcium than surrounding areas</a>, thanks to heavy cement use, limestone quarrying and destruction of buildings.</p>
<p>Tawny crazy ants not only are a major threat to the biodiversity and conservation of ecosystems but also <a href="https://doi.org/10.1038/ncomms12986">cost the U.S. billions of dollars in damage annually</a>. </p>
<h2>What still isn’t known</h2>
<p>Our results add to a small but <a href="https://doi.org/10.1111/geb.13196">growing list</a> <a href="https://doi.org/10.1111/ele.13517">of other experiments</a> <a href="https://doi.org/10.1111/ele.13127">that show the importance of micronutrients</a> to insects. </p>
<p>How far will tawny crazy ants make it in the United States? Will calcium influence their spread? Could other micronutrients like magnesium or iron be important to crazy ants?</p>
<p>In a world where <a href="https://doi.org/10.1126/science.1259855">humans are changing the “ingredients” of Earth’s surface soils</a> at an alarming rate, people may be unwittingly creating more favorable habitats for some invasive species. Figuring out which elements are most important to invasive species will be key to predicting, preventing and managing their spread.</p><img src="https://counter.theconversation.com/content/152652/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ryan Reihart receives funding from the National Science Foundation (NSF) Division of Environmental Biology (DEB) grants 1457114 and 1724663 and from the University of Dayton Office for Graduate Academic Affairs through the Graduate Student Summer Fellowship Program. </span></em></p>
The spread of tawny crazy ants may be driven, in part, by their need for calcium. The calcium-rich limestone bedrock of the lower U.S. Midwest may provide ideal conditions for populations to explode.
Ryan Reihart, Teaching Assistant and Ph.D. Candidate of Ecology, University of Dayton
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/149229
2021-01-12T19:43:16Z
2021-01-12T19:43:16Z
Anti-nutrients – they’re part of a normal diet and not as scary as they sound
<figure><img src="https://images.theconversation.com/files/377416/original/file-20210106-13-22nh6o.jpg?ixlib=rb-1.1.0&rect=109%2C97%2C4164%2C2670&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">These compounds occur naturally in a number of healthy foods, including legumes and whole grains.
</span> <span class="attribution"><a class="source" href="https://unsplash.com/s/photos/legumes-whole-grains">foodism360/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Maybe you’re trying to eat healthier these days, aiming to get enough of the good stuff and limit the less-good stuff. You’re paying attention to things like fiber and fat and vitamins… and anti-nutrients?</p>
<p>What the heck are anti-nutrients and are they something you need to be concerned about in your diet?</p>
<p>Let me, as a public health nutrition researcher, reassure you that anti-nutrients aren’t the evil nemesis of all the nutritious foods you eat. As long as you’re consuming a balanced and varied diet, anti-nutrients are not a concern. In fact, scientists are realizing they actually have many health benefits.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377772/original/file-20210108-21-x8ovnm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="illustration of small intestine amid other organs" src="https://images.theconversation.com/files/377772/original/file-20210108-21-x8ovnm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377772/original/file-20210108-21-x8ovnm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377772/original/file-20210108-21-x8ovnm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377772/original/file-20210108-21-x8ovnm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377772/original/file-20210108-21-x8ovnm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377772/original/file-20210108-21-x8ovnm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377772/original/file-20210108-21-x8ovnm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nutrients get absorbed into your bloodstream – or not – as digestion occurs in your small intestine.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/small-intestine-illustration-royalty-free-illustration/1190674194">Sebastian Kaulitzki/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<h2>What are anti-nutrients?</h2>
<p><a href="https://www.hsph.harvard.edu/nutritionsource/anti-nutrients/">Anti-nutrients are substances</a> that naturally occur in plant and animal foods.</p>
<p>The name comes from how they function in your body once you eat them. They <a href="https://www.sciencedirect.com/topics/food-science/antinutrients">block or interfere with how your body</a> <a href="https://doi.org/10.1631/jzus.B0710640">absorbs other nutrients</a> out of your gut and into your bloodstream so you can then use them. Thus, anti-nutrients may decrease the amount of nutrients you actually get from your food. They most commonly interfere with the absorption of <a href="https://doi.org/10.1016/j.jand.2016.09.025">calcium, iron, potassium, magnesium and zinc</a>.</p>
<p>Plants evolved these <a href="https://www.todaysdietitian.com/newarchives/070111p54.shtml">compounds as a defensive mechanism</a> against insects, parasites, bacteria and fungi. For example, some anti-nutrients can cause a food to taste bitter; animals won’t want to eat it, leaving the seed, for instance, to provide nourishment for future seedlings. Some anti-nutrients block the digestion of seeds that are eaten. The seeds disperse when they come out the other end in the animal’s fecal matter and can go on to grow new plants. Both of these survival tactics help the plant species grow and spread.</p>
<p>In terms of foods that people eat, you’ll most commonly find anti-nutrients naturally occurring in whole grains and legumes.</p>
<h2>Time for an image makeover as health enhancers</h2>
<p>Despite sounding scary, studies show that anti-nutrients are not of concern unless consumed in <a href="https://doi.org/10.1016/j.jcs.2014.01.010">ultra, unrealistically high amounts</a> – and they have numerous health benefits. </p>
<p>Anti-nutrients are currently undergoing a change in image very similar to the one dietary fiber experienced. At one point, scientists thought dietary fiber was bad for people. Since fiber could bind to nutrients and pull them out of the digestive tract in poop, it seemed like something to avoid. To address this perceived issue, grain processing in the late 1800s removed fiber from foods.</p>
<p>But now scientists know that <a href="https://doi.org/10.1111/j.1753-4887.2009.00189.x">dietary fiber is incredibly important</a> and encourage its consumption. Eating plenty of fiber lowers the risks of obesity, high blood pressure, heart disease, stroke, diabetes and some gastrointestinal diseases.</p>
<p>In the same way, rather than something to avoid, many anti-nutrients are now considered health-promoting nutraceuticals and functional foods due to their numerous benefits. Here’s an introduction to some of the most frequently eaten anti-nutrients that come with benefits:</p>
<ul>
<li><p><a href="https://doi.org/10.1089/109662004322984734">Saponins, common in legumes</a>, can boost the immune system, reduce risk of cancer, lower cholesterol, lower blood sugar response to foods, result in fewer cavities, reduce risk of kidney stones and combat blood clotting seen in heart attacks and strokes.</p></li>
<li><p><a href="https://doi.org/10.1016/j.jcs.2014.01.010">Lectins, found in cereal grains and legumes</a>, are associated with reduced risk of cardiovascular disease, diabetes, some cancers and becoming overweight or obese.</p></li>
<li><p><a href="https://doi.org/10.1080/10408699891274273">Tannins, commonly found in teas, coffees and processed meats and cheeses</a>, are antioxidants that can inhibit growth of bacteria, viruses, fungi and yeast and may decrease cholesterol levels and blood pressure.</p></li>
<li><p><a href="https://doi.org/10.1631/jzus.B0710640">Phytates, found in wheat, barley, rice and corn</a>, are associated with increased immune function and cancer cell death, as well as reduced cancer cell growth and spread. They also have antioxidant properties and can reduce inflammation. </p></li>
<li><p>Finally, <a href="https://doi.org/10.1024/0300-9831.72.1.26">glucosinates, found in brassica vegetables</a> like cauliflower, inhibit tumor cell growth.</p></li>
</ul>
<p>Oxalates are one of the few anti-nutrients with mostly negative impacts on the body. They are <a href="https://www.uofmhealth.org/health-library/aa166321">found in lots of common foods</a>, including legumes, beets, berries, cranberries, oranges, chocolate, tofu, wheat bran, soda, coffee, tea, beer, dark green vegetables and sweet potatoes. The negative impacts of oxalates include binding to calcium in the digestive tract and removing it from the body in bowel movements. Oxalates can also <a href="https://www.uofmhealth.org/health-library/aa166321">increase the risk of kidney stones</a> in some people.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/377773/original/file-20210108-21-17lbxqq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="bowl of chickpea curry" src="https://images.theconversation.com/files/377773/original/file-20210108-21-17lbxqq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/377773/original/file-20210108-21-17lbxqq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377773/original/file-20210108-21-17lbxqq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377773/original/file-20210108-21-17lbxqq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377773/original/file-20210108-21-17lbxqq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377773/original/file-20210108-21-17lbxqq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377773/original/file-20210108-21-17lbxqq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Lots of healthy, tasty foods come with the added benefits of anti-nutrients.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/chickpea-and-spinach-curry-royalty-free-image/657152778">Joan Ransley/Moment via Getty Images</a></span>
</figcaption>
</figure>
<h2>Fitting anti-nutrients into a healthy diet</h2>
<p>Overall, comparing the benefits to the drawbacks, anti-nutrient pros actually outweigh the cons. The healthy foods that contain them – mainly fruits, vegetables, whole grains and legumes – should be encouraged not avoided.</p>
<p>Anti-nutrients become a concern only if these foods are consumed in ultra-high amounts, <a href="https://www.ars.usda.gov/research/project/?accnNo=426312">which is very unlikely</a> for most adults and children in the U.S. Additionally, a large proportion of anti-nutrients are removed or lost from foods people eat <a href="https://www.hsph.harvard.edu/nutritionsource/anti-nutrients/">as they’re processed and cooked</a>, especially if soaking, blanching, boiling or other high-heat processes are involved.</p>
<p>Vegetarians and vegans may be at higher risk of negative effects from anti-nutrients because their diet relies heavily on fruits, vegetables, whole grains and legumes. But these <a href="https://doi.org/10.1016/j.jand.2016.09.025">plant-based diets are still among the healthiest</a> and are associated with reduced risk of cardiovascular disease, obesity, diabetes and numerous types of cancers. </p>
<p>Vegetarians and vegans can take a few steps to help counteract anti-nutrients’ effects on their absorption of particular nutrients:</p>
<ul>
<li><p>Pair high iron <a href="https://doi.org/10.1093/jn/130.5.1378S">and zinc</a> <a href="https://doi.org/10.1016/bs.afnr.2014.11.003">foods with</a> <a href="https://doi.org/10.1093/ajcn/59.5.1233S">foods high in vitamin C</a> (examples: veggie meatballs with tomato sauce, tomato-based chili with beans).</p></li>
<li><p><a href="https://www.jblearning.com/catalog/productdetails/9780763779764?jblsearch">Soak legumes before cooking</a>. </p></li>
<li><p><a href="https://doi.org/10.1093/ajcn/70.3.543s">Time dairy intake</a> such that it is not always paired with high oxalate foods.</p></li>
<li><p>Purchase dairy products that are fortified with calcium.</p></li>
<li><p>Consider a multivitamin-mineral supplement with about 100% of the daily recommended dose of nutrients (check the nutrition facts panel) as nutrition insurance if you are worried, but be sure to talk to your doctor first.</p></li>
</ul>
<p>[<em>Get our best science, health and technology stories.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-best">Sign up for The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/149229/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jill Joyce does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Anti-nutrients naturally occur in food and can block the amount of other nutrients available for your body to use. But their effects aren’t all bad, which is why they’re undergoing an image makeover.
Jill Joyce, Assistant Professor of Public Health Nutrition, Oklahoma State University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/145166
2020-09-01T19:58:40Z
2020-09-01T19:58:40Z
Renewable energy can save the natural world – but if we’re not careful, it will also hurt it
<figure><img src="https://images.theconversation.com/files/355710/original/file-20200901-18-rxpx93.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5238%2C3500&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>A vast transition from fossil fuels to renewable energy is crucial to slowing climate change. But building solar panels, wind turbines and other renewable energy infrastructure requires <a href="https://www.resourcepanel.org/reports/green-energy-choices-benefits-risks-and-trade-offs-low-carbon-technologies-electricity">mining for materials</a>. If not done responsibly, this may damage species and ecosystems.</p>
<p>In <a href="https://www.nature.com/articles/s41467-020-17928-5">our research</a>, published today, we mapped the world’s potential mining areas and assessed how they overlap with biodiversity conservation sites. </p>
<p>We found renewable energy production will exacerbate the threat mining poses to biodiversity – the world’s variety of animals and plants. It’s fair to assume that in some places, the extraction of renewables minerals may cause more damage to nature than the climate change it averts.</p>
<p>Australia is well placed to become a leader in mining of renewable energy materials and drive the push to a low-carbon world. But we must act now to protect our biodiversity from being harmed in the process.</p>
<figure class="align-center ">
<img alt="A wind farm" src="https://images.theconversation.com/files/355711/original/file-20200901-18-1bcz015.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/355711/original/file-20200901-18-1bcz015.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/355711/original/file-20200901-18-1bcz015.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/355711/original/file-20200901-18-1bcz015.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/355711/original/file-20200901-18-1bcz015.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/355711/original/file-20200901-18-1bcz015.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/355711/original/file-20200901-18-1bcz015.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Renewable energy infrastructure such as wind farms are good for the planet – but it requires minerals extraction.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>Mining to prevent climate change</h2>
<p>Currently, <a href="http://documents1.worldbank.org/curated/en/207371500386458722/pdf/117581-WP-P159838-PUBLIC-ClimateSmartMiningJuly.pdf">about 17%</a> of current global energy consumption is achieved through renewable energy. To further reduce greenhouse gas emissions, this proportion must rapidly increase. </p>
<p>Building new renewable energy infrastructure will involve mining minerals and metals. Some of these include:</p>
<ul>
<li>lithium, graphite and cobalt (mostly used in battery storage)</li>
<li>zinc and titanium (used mostly for wind and geothermal energy)</li>
<li>copper, nickle and aluminium (used in a range of renewable energy technologies).</li>
</ul>
<p>The World Bank <a href="https://www.worldbank.org/en/topic/extractiveindustries/brief/climate-smart-mining-minerals-for-climate-action">estimates</a> the production of such materials could increase by 500% by 2050. It says more than 3 billion tonnes of minerals and metals will be needed to build the wind, solar and geothermal power, and energy storage, needed to keep global warming below 2°C this century.</p>
<p>However, mining can seriously damage species and places. It <a href="https://royalsocietypublishing.org/doi/full/10.1098/rspb.2018.1926">destroys natural habitat</a>, and <a href="https://www.nature.com/articles/s41467-017-00557-w">surrounding environments</a> can be harmed by the construction of transport infrastructure such as roads and railways. </p>
<figure class="align-center ">
<img alt="An evaporation pond used to measure lithium and in the Uyuni salt desert in Bolivia." src="https://images.theconversation.com/files/355698/original/file-20200901-16-1f31kdv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/355698/original/file-20200901-16-1f31kdv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/355698/original/file-20200901-16-1f31kdv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/355698/original/file-20200901-16-1f31kdv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/355698/original/file-20200901-16-1f31kdv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/355698/original/file-20200901-16-1f31kdv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/355698/original/file-20200901-16-1f31kdv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An evaporation pond used to measure lithium and in the Uyuni salt desert in Bolivia. Mining can damage the environment if not done sustainably.</span>
<span class="attribution"><span class="source">Dado Galdieri/AP</span></span>
</figcaption>
</figure>
<h2>What we found</h2>
<p>We mapped areas around the world potentially affected by mining. Our analysis involved 62,381 pre-operational, operational, and closed mines targeting 40 different materials.</p>
<p>We found mining may influence about 50 million km² of Earth’s land surface (or 37%, excluding Antarctica). Some 82% of these areas contain materials needed for renewable energy production. Of this, 12% overlaps with protected areas, 7% with “<a href="http://www.keybiodiversityareas.org/home">key biodiversity areas</a>”, and 14% with remaining <a href="https://www.nature.com/articles/d41586-018-07183-6">wilderness</a>.</p>
<p>Our results suggest mining of renewable energy materials may increase in currently untouched and “biodiverse” places. These areas are considered <a href="https://www.nature.com/articles/nclimate2918">critical</a> to helping species overcome the challenges of climate change. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/355924/original/file-20200902-16-1mntn0l.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Areas around the world potentially influenced by mining" src="https://images.theconversation.com/files/355924/original/file-20200902-16-1mntn0l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/355924/original/file-20200902-16-1mntn0l.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=317&fit=crop&dpr=1 600w, https://images.theconversation.com/files/355924/original/file-20200902-16-1mntn0l.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=317&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/355924/original/file-20200902-16-1mntn0l.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=317&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/355924/original/file-20200902-16-1mntn0l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=398&fit=crop&dpr=1 754w, https://images.theconversation.com/files/355924/original/file-20200902-16-1mntn0l.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=398&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/355924/original/file-20200902-16-1mntn0l.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=398&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Areas potentially influenced by mining, including for the minerals needed in renewable energy production (shown in blue). See paper for detailed methodology and limitations.</span>
<span class="attribution"><span class="source">Authors provided</span></span>
</figcaption>
</figure>
<h2>Threats here and abroad</h2>
<p><a href="https://www.ga.gov.au/about/projects/resources/critical-minerals">Australia is well positioned</a> to become a leading supplier of materials for renewable energy. We are also <a href="https://www.worldatlas.com/articles/ecologically-megadiverse-countries-of-the-world.html">one of only 17 nations</a> considered ecologically “megadiverse”.</p>
<p>Yet, many of the minerals needed for renewable energy exist in important conservation areas.</p>
<p>For example, Australia is rich in lithium and already accounts for <a href="https://www.ga.gov.au/scientific-topics/minerals/mineral-resources-and-advice/australian-resource-reviews/lithium#heading-6">half of world production</a>. <a href="http://www.pilbaraminerals.com.au/site/content/">Hard-rock</a> lithium mines operate in the Pilbara region of Western Australia.</p>
<p>This area has also been <a href="https://www.environment.gov.au/biodiversity/conservation/hotspots/national-biodiversity-hotspots#hotspot14">identified</a> as a national biodiversity hotspot and is home to many native species. These include small marsupials such as the little red antechinus and the pebble-mound mouse, and reptiles including gecko and goanna species. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/world-first-mining-standard-must-protect-people-and-hold-powerful-companies-to-account-144285">World-first mining standard must protect people and hold powerful companies to account</a>
</strong>
</em>
</p>
<hr>
<p>Australia is also <a href="https://www.ga.gov.au/scientific-topics/minerals/mineral-resources-and-advice/australian-resource-reviews/rare-earth-elements#heading-6">ranked sixth</a> in the world for deposits of rare earth elements, many of which are needed to produce magnets for wind turbines. We also have large resources of other renewables materials such as cobalt, manganese, tantalum, tungsten and zirconium. </p>
<p>It’s critical that mining doesn’t damage Australia’s already vulnerable biodiversity, and harm the natural places valued by <a href="https://theconversation.com/rio-tinto-just-blasted-away-an-ancient-aboriginal-site-heres-why-that-was-allowed-139466">Indigenous</a> people and other communities.</p>
<p>In many cases, renewables minerals are found in countries where the resource sector is not strongly regulated, posing an even greater environmental threat. For example, the world’s <a href="https://www.bloomberg.com/news/features/2018-12-03/bolivia-s-almost-impossible-lithium-dream">second-largest</a> untouched lithium reserve exists in Bolivia’s Salar de Uyuni salt pan. This naturally diverse area is mostly <a href="https://conbio.onlinelibrary.wiley.com/doi/full/10.1111/j.1755-263X.2011.00166.x">untouched</a> by mining. </p>
<p>The renewables expansion will also require iron and steel. To date, mining for iron in Brazil has almost wiped out an entire <a href="https://link.springer.com/article/10.1007/s10531-007-9156-8">plant community</a>, and recent <a href="https://theconversation.com/dam-collapse-at-brazilian-mine-exposes-grave-safety-problems-110666">dam failures</a> devastated the environment and communities.</p>
<figure class="align-center ">
<img alt="A little red antechinus" src="https://images.theconversation.com/files/355700/original/file-20200901-22-17nnyi7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/355700/original/file-20200901-22-17nnyi7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=415&fit=crop&dpr=1 600w, https://images.theconversation.com/files/355700/original/file-20200901-22-17nnyi7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=415&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/355700/original/file-20200901-22-17nnyi7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=415&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/355700/original/file-20200901-22-17nnyi7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=522&fit=crop&dpr=1 754w, https://images.theconversation.com/files/355700/original/file-20200901-22-17nnyi7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=522&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/355700/original/file-20200901-22-17nnyi7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=522&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Pilbara has large lithium deposits and is also home to the little red antechinus.</span>
<span class="attribution"><span class="source">Needpix</span></span>
</figcaption>
</figure>
<h2>We need proactive planning</h2>
<p>Strong planning and conservation action is needed to avoid, manage and prevent the harm mining causes to the environment. However global conservation efforts are often naive to the threats posed by significant growth in renewable energies. </p>
<p>Some protected areas around the world prevent mining, but more than 14% contain metal mines in or near their boundaries. Consequences for biodiversity may extend many kilometres from mining sites.</p>
<p>Meanwhile, other areas increasingly important for conservation are focused on the needs of biodiversity, and don’t consider the distribution of mineral resources and pressures to extract them. Conservation plans for these sites must involve strategies to manage the mining threat.</p>
<p>There is some good news. <a href="https://www.nature.com/articles/s41467-020-17928-5">Our analyses</a> suggest many required materials occur outside protected areas and other conservation priorities. The challenge now is to identify which species are most at risk from current and future mining development, and develop strong policies to avoid their loss. </p>
<p><em>The map in this article has been updated, because due to a technical issue the previous version omitted some information.</em></p><img src="https://counter.theconversation.com/content/145166/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Laura Sonter receives funding from the Australian Research Council and The University of Queensland. </span></em></p><p class="fine-print"><em><span>James Watson receives funding from National Environmental Science Program, the Australian Research Council and The University of Queensland. He is Director of the Science and Research Initiative at the Wildlife Conservation Society and serves as a volunteer on Bush Heritage Australia and BirdLife Australia science committees. </span></em></p><p class="fine-print"><em><span>Richard K Valenta receives funding from the Queensland State Government, The Northern Territory Government and the University of Queensland. He is chair of the research working group of the Queensland Exploration Council.</span></em></p>
Building renewable energy infrastructure involves mining for materials such as lithium, graphite and cobalt. If not done responsibly, that could cause huge environmental damage.
Laura Sonter, Lecturer in Environmental Management, The University of Queensland
James Watson, Professor, The University of Queensland
Richard K Valenta, Director - WH Bryan Mining and Geology Research Centre - The Sustainable Minerals Institute, The University of Queensland
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/133356
2020-03-16T19:01:05Z
2020-03-16T19:01:05Z
5 ways nutrition could help your immune system fight off the coronavirus
<figure><img src="https://images.theconversation.com/files/320678/original/file-20200316-18043-1rg6ra8.jpg?ixlib=rb-1.1.0&rect=0%2C6%2C4500%2C2977&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The coronavirus presents many uncertainties, and none of us can completely eliminate our risk of getting COVID-19. But one thing we can do is eat as healthily as possible.</p>
<p>If we do catch COVID-19, our immune system is responsible for fighting it. Research shows improving nutrition helps <a href="https://www.ncbi.nlm.nih.gov/pubmed/15337163">support optimal immune function</a>. </p>
<p>Micronutrients essential to fight infection include vitamins A, B, C, D, and E, and the minerals iron, selenium, and zinc. </p>
<p>Here’s what we know about <a href="https://www.ncbi.nlm.nih.gov/pubmed/30336639">how these nutrients support our immune system</a> and the foods we can eat to get them. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-a-balanced-diet-anyway-72432">What is a balanced diet anyway?</a>
</strong>
</em>
</p>
<hr>
<h2>1. Vitamin A</h2>
<p><a href="https://www.healthdirect.gov.au/vitamin-a">Vitamin A</a> maintains the structure of the cells in the skin, respiratory tract and gut. This forms a barrier and is your body’s first line of defence. If fighting infection was like a football game, vitamin A would be your forward line. </p>
<p>We also need vitamin A to help make <a href="https://en.wikipedia.org/wiki/Antibody">antibodies</a> which neutralise the pathogens that cause infection. This is like assigning more of your team to target an opposition player who has the ball, to prevent them scoring. </p>
<p>Vitamin A is found in oily fish, egg yolks, cheese, tofu, nuts, seeds, whole grains and legumes. </p>
<p>Further, vegetables contain <a href="https://en.wikipedia.org/wiki/Beta-Carotene">beta-carotene</a>, which your body can convert into vitamin A. Beta-carotene is found in leafy green vegetables and yellow and orange vegetables like pumpkin and carrots.</p>
<h2>2. B vitamins</h2>
<p><a href="https://www.betterhealth.vic.gov.au/health/HealthyLiving/vitamin-b">B vitamins</a>, particularly B6, B9 and B12, contribute to your body’s first response once it has recognised a pathogen. </p>
<p>They do this by influencing the production and activity of “<a href="https://en.wikipedia.org/wiki/Natural_killer_cell">natural killer</a>” cells. Natural killer cells work by causing infected cells to “implode”, a process called <a href="https://en.wikipedia.org/wiki/Apoptosis">apoptosis</a>. </p>
<p>At a football match, this role would be like security guards intercepting wayward spectators trying to run onto the field and disrupt play.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/320685/original/file-20200316-18086-1i9edys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/320685/original/file-20200316-18086-1i9edys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/320685/original/file-20200316-18086-1i9edys.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/320685/original/file-20200316-18086-1i9edys.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/320685/original/file-20200316-18086-1i9edys.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/320685/original/file-20200316-18086-1i9edys.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/320685/original/file-20200316-18086-1i9edys.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Fish is a good source of vitamin B6.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>B6 is found in cereals, legumes, green leafy vegetables, fruit, nuts, fish, chicken and meat. </p>
<p>B9 (<a href="https://en.wikipedia.org/wiki/Folate">folate</a>) is abundant in green leafy vegetables, legumes, nuts and seeds and is added to commercial bread-making flour.</p>
<p><a href="https://theconversation.com/have-you-gone-vegan-keep-an-eye-on-these-4-nutrients-107708">B12</a> (cyanocobalamin) is found in animal products, including eggs, meat and dairy, and also in fortified soy milk (check the nutrition information panel). </p>
<h2>3. Vitamins C and E</h2>
<p>When your body is fighting an infection, it experiences what’s called oxidative stress. Oxidative stress leads to the production of <a href="https://en.wikipedia.org/wiki/Reactive_oxygen_species">free radicals</a> which can pierce cell walls, causing the contents to leak into tissues and exacerbating inflammation.</p>
<p><a href="https://ods.od.nih.gov/factsheets/VitaminC-HealthProfessional/">Vitamin C</a> and <a href="https://www.healthdirect.gov.au/vitamin-e">vitamin E</a> help protect cells from oxidative stress. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/coronavirus-its-time-to-debunk-claims-that-vitamin-c-could-cure-it-132803">Coronavirus: it's time to debunk claims that vitamin C could cure it</a>
</strong>
</em>
</p>
<hr>
<p>Vitamin C also helps clean up this cellular mess by producing specialised cells to mount an immune response, including <a href="https://en.wikipedia.org/wiki/Neutrophil">neutrophils</a>, lymphocytes and <a href="https://en.wikipedia.org/wiki/Phagocyte">phagocytes</a>. </p>
<p>So the role of vitamin C here is a bit like cleaning up the football ground after the game.</p>
<p>Good sources of vitamin C include oranges, lemons, limes, berries, kiwifruit, broccoli, tomatoes and capsicum. </p>
<p>Vitamin E is found in nuts, green leafy vegetables and vegetables oils.</p>
<h2>4. Vitamin D</h2>
<p>Some immune cells need <a href="https://www.betterhealth.vic.gov.au/health/HealthyLiving/vitamin-d">vitamin D</a> to help destroy pathogens that cause infection. </p>
<p>Although sun exposure allows the body to produce vitamin D, food sources including eggs, fish and some milks and margarine brands may be fortified with Vitamin D (meaning extra has been added).</p>
<p>Most people need just <a href="https://www.cancer.org.au/preventing-cancer/sun-protection/vitamin-d/">a few minutes outdoors</a> most days.</p>
<p>People with vitamin D deficiency may need supplements. A <a href="https://www.ncbi.nlm.nih.gov/pubmed/30675873">review of 25 studies</a> found vitamin D supplements can help protect against <a href="https://www.healthline.com/health/acute-respiratory-disease">acute respiratory infections</a>, particularly among people who are deficient.</p>
<h2>5. Iron, zinc, selenium</h2>
<p>We need iron, zinc and selenium for immune cell growth, among other functions.</p>
<p><a href="https://www.betterhealth.vic.gov.au/health/ConditionsAndTreatments/iron">Iron</a> helps kill pathogens by <a href="https://www.ncbi.nlm.nih.gov/pubmed/30336639">increasing the number of free radicals</a> that can destroy them. It also regulates enzyme reactions essential for immune cells to recognise and target pathogens. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/320686/original/file-20200316-18079-my91st.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/320686/original/file-20200316-18079-my91st.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/320686/original/file-20200316-18079-my91st.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/320686/original/file-20200316-18079-my91st.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/320686/original/file-20200316-18079-my91st.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/320686/original/file-20200316-18079-my91st.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/320686/original/file-20200316-18079-my91st.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Whole grain foods contain a variety of important nutrients.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p><a href="https://www.healthdirect.gov.au/zinc">Zinc</a> helps maintain the integrity of the skin and mucous membranes. Zinc and <a href="https://en.wikipedia.org/wiki/Selenium">selenium</a> also act as an antioxidant, helping mop up some of the damage caused by oxidative stress. </p>
<p>Iron is found in meat, chicken and fish. Vegetarian sources include legumes, whole grains and iron-fortified breakfast cereals. </p>
<p>Zinc is found in oysters and other seafood, meat, chicken, dried beans and nuts. </p>
<p>Nuts (especially Brazil nuts), meat, cereals and mushrooms are good food sources of selenium.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-should-i-take-vitamin-c-or-other-supplements-for-my-cold-98309">Health Check: should I take vitamin C or other supplements for my cold?</a>
</strong>
</em>
</p>
<hr>
<h2>Putting it all together</h2>
<p>It’s true some supermarkets are out of certain products at the moment. But as much as possible, focus on eating a variety of foods <a href="https://www.eatforhealth.gov.au/guidelines/australian-guide-healthy-eating">within each of the basic food groups</a> to <a href="https://www.ncbi.nlm.nih.gov/pubmed/25625814">boost your intake</a> of vitamins and minerals.</p>
<p>While vitamin and mineral supplements are <a href="https://theconversation.com/mondays-medical-myth-take-a-vitamin-a-day-for-better-health-8482">not recommended for the general population</a>, there are some exceptions. </p>
<p>Pregnant women, some people with chronic health conditions, and people with conditions that mean they can’t eat properly or are on very restrictive diets, may need specific supplements. Talk to your doctor, Accredited Practising Dietitian or pharmacist.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/social-distancing-what-it-is-and-why-its-the-best-tool-we-have-to-fight-the-coronavirus-133581">Social distancing: What it is and why it's the best tool we have to fight the coronavirus</a>
</strong>
</em>
</p>
<hr>
<p>And beyond diet, there are other measures you can take to stay as healthy as possible in the face of coronavirus.</p>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/30789425">Stop smoking</a> to improve your lung’s ability to fight infection, perform <a href="https://www.ncbi.nlm.nih.gov/pubmed/32139352">moderate intensity exercise</a> like brisk walking, <a href="https://www.ncbi.nlm.nih.gov/pubmed/31941836">get enough sleep</a>, practise social distancing and wash your hands with soap regularly.</p><img src="https://counter.theconversation.com/content/133356/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Clare Collins is affiliated with the Priority Research Centre for Physical Activity and Nutrition, the University of Newcastle, NSW. She is an NHMRC Senior Research and Gladys M Brawn Research Fellow. She has received research grants from NHMRC, ARC, Hunter Medical Research Institute, Meat and Livestock Australia, Diabetes Australia, Heart Foundation, Bill and Melinda Gates Foundation, nib foundation, Rijk Zwaan Australia and Greater Charitable Foundation. She has consulted to SHINE Australia, Novo Nordisk, Quality Bakers, the Sax Institute and the ABC. She was a team member conducting systematic reviews to inform the Australian Dietary Guidelines update and the Heart Foundation evidence reviews on meat and dietary patterns.</span></em></p>
The food we eat influences our bodies’ immune responses to infection. So focusing on nutrition is one thing we can do to help protect ourselves in the face of the coronavirus threat.
Clare Collins, Professor in Nutrition and Dietetics, University of Newcastle
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/107708
2019-04-30T20:13:26Z
2019-04-30T20:13:26Z
Have you gone vegan? Keep an eye on these 4 nutrients
<figure><img src="https://images.theconversation.com/files/271649/original/file-20190430-194630-1afyvj1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Legumes are a good source of calcium.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/healthy-homemade-chickpea-veggies-salad-jar-535446037?src=vLw9oCI1nLotsXy-87sbEw-1-34">Saschanti17/Shutterstock</a></span></figcaption></figure><p>There are <a href="https://veganuary.com/au/why/">many reasons</a> people go vegan, from wanting to be healthier, to reducing their environmental footprint, to concerns about animal welfare.</p>
<p>No matter what the reason, many people find it difficult to meet the <a href="https://www.nrv.gov.au/nutrients">nutrient intake targets</a> for specific vitamins and minerals while on a vegan diet. These include vitamin B12, iron, calcium, and iodine. </p>
<p>Here’s how to make sure you’re getting enough of these vitamins and minerals while following a vegan diet.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/vegan-diet-how-your-body-changes-from-day-one-100413">Vegan diet: how your body changes from day one</a>
</strong>
</em>
</p>
<hr>
<h2>1. Vitamin B12</h2>
<p><a href="https://www.nrv.gov.au/nutrients/vitamin-b12">Vitamin B12</a>, or cobalamin, is essential for making red blood cells, DNA (your genetic code), fatty acids located in <a href="https://en.wikipedia.org/wiki/Myelin">myelin</a> (which insulate nerves), and some neurotransmitters needed for brain function. </p>
<p>Vitamin B12 is stored in the liver, so a deficiency probably won’t happen in adults in the short term.</p>
<p><strong>Symptoms of B12 deficiency</strong></p>
<p>Symptoms of vitamin B12 <a href="https://www.healthline.com/health/vitamin-b12-level">deficiency</a> include tiredness, lethargy, low exercise tolerance, light-headedness, rapid heart rate or palpitations, bruising and bleeding easily, weight loss, impotence, bowel or bladder changes, a sore tongue, and bleeding gums. </p>
<p>Other <a href="https://www.nrv.gov.au/nutrients/vitamin-b12">symptoms related to the nervous system</a> include a loss of sensation in the hands or feet, problems related to movement, brain changes ranging from memory loss to mood changes or dementia, visual disturbances, and impaired bowel and bladder control. </p>
<p><strong>Testing for B12 deficiency</strong> </p>
<p>Your doctor may request a <a href="https://www.healthdirect.gov.au/vitamin-b12-test">blood test</a> to check your vitamin B12 status and determine whether indicators are in the <a href="https://www.labtestsonline.org.au/learning/test-index/vitamin-b12">healthy range</a>.</p>
<p><strong>Vegan food sources of B12</strong></p>
<p>Vitamin B12 is <a href="https://www.nrv.gov.au/nutrients/vitamin-b12">abundant in animal foods</a> including meat, milk and dairy products. </p>
<p>For vegans, plant sources of vitamin B12 include some algae and plants exposed to bacterial action or contaminated by soil or insects. While traces of vitamin B12 analogues can be found in some mushrooms, nori or fermented soy beans, more reliable sources include vitamin B12-supplemented soy or nut “milks”, or meat substitutes. Check the nutrition information panel on the label for the the B12 content. </p>
<p><a href="https://www.nrv.gov.au/nutrients/vitamin-b12">Crystalline vitamin B12</a> added to these products can boost the B12’s absorption rate to a level similar to that from animal products. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/271660/original/file-20190430-194609-1dzhtrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/271660/original/file-20190430-194609-1dzhtrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/271660/original/file-20190430-194609-1dzhtrz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/271660/original/file-20190430-194609-1dzhtrz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/271660/original/file-20190430-194609-1dzhtrz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/271660/original/file-20190430-194609-1dzhtrz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/271660/original/file-20190430-194609-1dzhtrz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Meat substitutes are often supplemented with B12.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/407288122?src=7DIfZxJLmk1QUWRMkz3hPA-1-14&size=huge_jpg">Stephanie Frey/Shutterstock</a></span>
</figcaption>
</figure>
<h2>2. Calcium</h2>
<p><a href="https://www.healthdirect.gov.au/calcium">Calcium</a> is needed to develop and maintain the skeleton bones, and is stored in the teeth and bones. It is also essential for heart, muscle and nerve function. </p>
<p><strong>Testing for calcium deficiency</strong> </p>
<p>Low calcium intakes are associated with <a href="https://www.osteoporosis.org.au/what-it">osteoporosis</a> or “brittle bones” and a higher risk of bone fractures. </p>
<p>A <a href="https://www.osteoporosis.org.au/diagnosis">bone scan is used</a> to measure bone density, with <a href="https://www.healthdirect.gov.au/osteoporosis-diagnosis">osteoporosis diagnosed</a> when bone density is low. </p>
<p>Both low calcium intakes and low vitamin D levels increase the risk of osteoporosis. Check your bone health using the <a href="https://www.knowyourbones.org.au/">Know Your Bones online quiz</a>. </p>
<p><strong>Vegan food sources of calcium</strong></p>
<p>Although the richest sources of calcium are milk and milk-based foods, vegans can get calcium from tofu or bean curd, some fortified soy or nut beverages, nuts, seeds, legumes, and breakfast cereals. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/271650/original/file-20190430-194603-e1fvju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/271650/original/file-20190430-194603-e1fvju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/271650/original/file-20190430-194603-e1fvju.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/271650/original/file-20190430-194603-e1fvju.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/271650/original/file-20190430-194603-e1fvju.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/271650/original/file-20190430-194603-e1fvju.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/271650/original/file-20190430-194603-e1fvju.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Nut and soy milks are a good source of calcium.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/soymilk-may-be-used-substitute-dairy-1294096993?src=Z28w0wPZMiLq6Rg4mQv3vA-1-9">Rodica Ciorba/Shutterstock</a></span>
</figcaption>
</figure>
<p>Calcium needs can be higher for vegans and vegetarians due to the relatively high <a href="https://en.wikipedia.org/wiki/Oxalic_acid">oxalic acid</a> content of foods such as spinach, rhubarb, beans, and the high <a href="https://en.wikipedia.org/wiki/Phytic_acid">phytic acid</a> content of seeds, nuts, grains, some raw beans, and soy products. These specific acids can lower the calcium absorption from these foods by 10-50%.</p>
<p>In a <a href="https://www.ncbi.nlm.nih.gov/pubmed/24667136">study of calcium intakes of 1,475 adults </a>, vegans were below national recommendations and had lower calcium intakes compared with vegetarians, semi-vegetarians, pesco-vegetarians, and omnivores.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-how-do-our-bones-get-calcium-and-why-do-they-need-it-75227">Explainer: how do our bones get calcium and why do they need it?</a>
</strong>
</em>
</p>
<hr>
<h2>3. Iodine</h2>
<p><a href="https://www.nrv.gov.au/nutrients/iodine">Iodine</a> is needed to make thyroxine, a thyroid hormone used in normal growth, regulation of metabolic rate, and development of the central nervous system. <a href="https://www.healthdirect.gov.au/iodine">Iodine</a> is concentrated in the thyroid gland.</p>
<p><strong>Symptoms of iodine deficiency</strong></p>
<p><a href="https://www.thyroidfoundation.org.au/Iodine-Deficiency">Iodine deficiency</a> can lead to the enlargement of the thyroid gland, a <a href="https://www.healthdirect.gov.au/goitre">goitre</a>, or hypothyroidism. </p>
<p><a href="https://www.thyroidfoundation.org.au/Iodine-Deficiency">Symptoms of hypothyroidism</a> include lethargy, tiredness, muscular weakness, feeling cold, difficulty concentrating, poor memory, weight gain, depression, facial puffiness, hair loss, dry skin, constipation, and slower heartbeat. </p>
<p>In women, iodine deficiency can increase risk of miscarriage and stillbirth, and congenital anomalies, including mental retardation and <a href="https://en.wikipedia.org/wiki/Congenital_iodine_deficiency_syndrome">cretinism</a>. </p>
<p><strong>Testing for iodine deficiency</strong> </p>
<p>Your iodine status can be assessed by a range of tests, including thyroid hormones in your blood, the size of your thyroid gland, or the presence of a goitre. Talk to your doctor about these tests. </p>
<p><strong>Vegan food sources of iodine</strong></p>
<p>The <a href="https://www.betterhealth.vic.gov.au/health/healthyliving/iodine">iodine content of food</a> depends on the iodine content of plants, which in turn depends on soil iodine content. When soil content is low, iodine may need to be supplemented. </p>
<p>Major sources of iodine are seafood, dairy products, and eggs. </p>
<p>For vegans, iodised salt, commercial bread made using iodised salt, fortified soy or nut milks (check the product label) and seaweed are important. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/271663/original/file-20190430-194609-1c673kh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/271663/original/file-20190430-194609-1c673kh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/271663/original/file-20190430-194609-1c673kh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/271663/original/file-20190430-194609-1c673kh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/271663/original/file-20190430-194609-1c673kh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/271663/original/file-20190430-194609-1c673kh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/271663/original/file-20190430-194609-1c673kh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Iodine is added to some salts.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/266034749?src=a3U1zoGU9rYfErdHsdPCoA-1-22&size=huge_jpg">IlzeTheBeast/Shutterstock</a></span>
</figcaption>
</figure>
<p>Substances called goitrogens, which are found in <a href="https://en.wikipedia.org/wiki/Brassica">brassica vegetables</a> – including cabbage, broccoli and Brussels sprouts, sweet potato and maize – can interfere with the production of thyroid hormones. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/lack-of-dietary-iodine-threatens-brain-development-in-children-14996">Lack of dietary iodine threatens brain development in children</a>
</strong>
</em>
</p>
<hr>
<h2>4. Iron</h2>
<p><a href="https://www.nrv.gov.au/nutrients/iron">Iron</a> is needed to make <a href="https://en.wikipedia.org/wiki/Hemoglobin">haemoglobin</a> in red blood cells, which carries oxygen around your body. </p>
<p>Iron is <a href="https://www.healthshare.com.au/factsheets/12147-iron-deficiency/">also needed for the production of energy</a> in your muscles, and for concentration and a healthy immune system. </p>
<p><strong>Symptoms and testing for iron deficiency and anaemia</strong></p>
<p>Not having enough iron leads to <a href="https://www.healthdirect.gov.au/iron-deficiency">iron deficiency</a>, and is associated with reduced work capacity, impaired brain function, lower immunity, and delayed development in infants. </p>
<p>The first stage of iron deficiency is referred to as <a href="https://www.betterhealth.vic.gov.au/health/ConditionsAndTreatments/iron-deficiency-adults">low iron stores</a> and your doctor may refer you for a <a href="https://www.healthdirect.gov.au/iron-studies">blood test</a> to check your iron status. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ive-been-diagnosed-with-iron-deficiency-now-what-87670">I've been diagnosed with iron deficiency, now what?</a>
</strong>
</em>
</p>
<hr>
<p><strong>Vegan food sources of iron</strong></p>
<p>In Australia and New Zealand, the biggest contributors to iron intake are wholegrain cereals, meats, chicken, and fish. </p>
<p>The amount of iron absorbed from food depends on a person’s iron status (with those who are iron-deficient absorbing more), as well as the iron content of the entire meal, and whether iron is haem (from animal foods) or non-haem iron from plant sources such as grains and vegetables. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/271657/original/file-20190430-194633-1sxme7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/271657/original/file-20190430-194633-1sxme7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/271657/original/file-20190430-194633-1sxme7g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/271657/original/file-20190430-194633-1sxme7g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/271657/original/file-20190430-194633-1sxme7g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/271657/original/file-20190430-194633-1sxme7g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/271657/original/file-20190430-194633-1sxme7g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Whole grains are rich in iron.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/1135582598?src=K3o6CoVyDdqRkgkQLKBNpw-1-0&size=huge_jpg">Photka/Shutterstock</a></span>
</figcaption>
</figure>
<p>Although iron from plant sources is less able to enter the body, you can boost your absorption by adding lemon or lime juice (citric acid) or other vitamin C-rich vegetables and fruits, which convert non-haem iron to a form than is better absorbed. </p>
<p>Take care with food components that inhibit absorption of both haem and non-haem iron, including calcium, zinc and phytates in legumes, rice and other grains, and <a href="https://foodwatch.com.au/blog/super-foods/item/top-100-polyphenols-what-are-they-and-why-are-they-important.html">polyphenols</a> and vegetable proteins that can inhibit absorption of non-haem iron. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-iron-is-such-an-important-part-of-your-diet-69974">Why iron is such an important part of your diet</a>
</strong>
</em>
</p>
<hr>
<p>Long-term vegans will also need to keep an eye on levels of <a href="https://www.betterhealth.vic.gov.au/health/healthyliving/vitamin-d">vitamin D</a>, <a href="https://www.heartfoundation.org.au/news/omega-3-fatty-acid-the-importance-of-fat-in-a-healthy-diet">omega-3 fat</a> and <a href="https://www.betterhealth.vic.gov.au/health/HealthyLiving/protein">protein</a>.</p>
<p>A good strategy is to check in with your GP periodically to review your health and well-being, and an <a href="https://daa.asn.au/find-an-apd/">accredited practising dietitian</a> can check whether you’re getting all the nutrients you need.</p><img src="https://counter.theconversation.com/content/107708/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Clare Collins is affiliated with the Priority Research Centre for Physical Activity and Nutrition, the University of Newcastle, NSW. She is an NHMRC Senior Research and Gladys M Brawn Research Fellow. She has received research grants from NHMRC, ARC, Hunter Medical Research Institute, Meat and Livestock Australia, Diabetes Australia, Heart Foundation, Bill and Melinda Gates Foundation, nib foundation, Rijk Zwaan Australia and Greater Charitable Foundation. She has consulted to SHINE Australia, Novo Nordisk, Quality Bakers, the Sax Institute and the ABC. She was a team member conducting systematic reviews to inform the Australian Dietary Guidelines update and 2017 evidence review on dietary patterns for the Heart Foundation.</span></em></p>
Are you getting enough vitamin B12, calcium, iodine and iron? Here’s what can happen if you don’t get enough – and how to ensure you do.
Clare Collins, Professor in Nutrition and Dietetics, University of Newcastle
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/101337
2018-08-15T10:27:56Z
2018-08-15T10:27:56Z
Anaemia: why is it still affecting women?
<figure><img src="https://images.theconversation.com/files/232058/original/file-20180815-2915-s5i88i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/1006210684?src=Fn7Ie1UTmPGG3ic5xELJqg-1-11&size=medium_jpg">MIA Studio/Shutterstock.com</a></span></figcaption></figure><p>Iron deficiency is the <a href="http://apps.who.int/iris/bitstream/handle/10665/43894/9789241596657_eng.pdf?sequence=1">most common nutritional deficiency</a> in the world, affecting both low- and high-income countries. Although it is an easy problem to fix, it remains unfixed. </p>
<p>Our bodies need iron to function. Too little leads to anaemia, limiting the body’s ability to carry and deliver oxygen. Well-known symptoms of iron deficiency include <a href="https://www.ncbi.nlm.nih.gov/pubmed/12188461">poor concentration, fatigue and mood changes</a>.</p>
<p>Women are more affected by iron deficiency anaemia than men because they lose iron during their periods and need more when pregnant or breastfeeding. In the UK, <a href="https://www.ncbi.nlm.nih.gov/pubmed/21890259">one in four women</a> becomes anaemic in pregnancy. In low-income countries, it’s <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4547326/">one in two</a>.</p>
<p>The consequences of iron deficiency anaemia in pregnancy are alarming. In cases of severe anaemia, our research found that the condition can <a href="https://www.qmul.ac.uk/media/news/2018/smd/risk-of-maternal-death-doubled-in-pregnant-women-with-anaemia.html">double the risk of death for the mother</a>. In less severe cases, iron deficiency anaemia can lead to <a href="https://www.ncbi.nlm.nih.gov/pubmed/26256281">low birth weight</a>, <a href="https://www.ncbi.nlm.nih.gov/pubmed/29986785">early delivery</a> and <a href="https://www.ncbi.nlm.nih.gov/pubmed/24065908">poor brain development</a> in babies. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/232064/original/file-20180815-2894-17ym47d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/232064/original/file-20180815-2894-17ym47d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/232064/original/file-20180815-2894-17ym47d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/232064/original/file-20180815-2894-17ym47d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/232064/original/file-20180815-2894-17ym47d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/232064/original/file-20180815-2894-17ym47d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/232064/original/file-20180815-2894-17ym47d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Iron deficiency in pregnancy can have serious consequences for mother and baby.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/526489342?src=-8KnL4Jy8tLOZAkAgIWO7A-1-37&size=medium_jpg">Pressmaster/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Simple treatment</h2>
<p>The treatment for iron deficiency is simple: give iron. Iron tablets are often the first-line treatment as they are cheap and readily available. </p>
<p>Many doctors prescribe iron tablets for anaemic women, especially those who are pregnant. Many national and international guidelines suggest that iron should be given prophylactically. In countries where iron deficiency is widespread, iron supplements are given to all pregnant women, irrespective of whether they are anaemic. But still, anaemia persists. </p>
<p>There’s a range of ways to give iron – <a href="https://bnf.nice.org.uk/drug/ferrous-sulfate.html">pills</a>, <a href="https://www.healthline.com/health/iron-infusion">intravenous drip</a>, <a href="https://www.spatone.com/en">fortified water</a> and <a href="https://luckyironfish.com/">cooking with iron</a> – but we still don’t know which type is right for different situations. For example, what is the most appropriate type of iron for women who are pregnant versus for women who experience anaemia because of heavy menstrual bleeding? These questions remain unanswered. </p>
<p>Pregnant women and menstruating women are biologically different. These subtleties need attention, not just because they can affect the efficacy of iron treatments, but because <a href="https://www.ncbi.nlm.nih.gov/pubmed/26482110">side effects and tolerance</a> to treatments can also vary.</p>
<p>There are over 100 published clinical trials of iron interventions both for <a href="https://www.cochrane.org/CD004736/PREG_effects-and-safety-preventive-oral-iron-or-iron-folic-acid-supplementation-women-during-pregnancy">pregnant</a> women and for women <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010861.pub2/abstract">who have just had a baby</a>. Newer preparations of iron <a href="https://www.chemistryworld.com/business/solving-irons-solubility-problem/8066.article">are constantly under development</a>. So the question remains: why hasn’t this solved the problem?</p>
<p>Access to care and awareness of the problem is just half the story. It is common for women with heavy periods to endure the effects of anaemia <a href="https://www.ncbi.nlm.nih.gov/pubmed/25627706">for years before they seek treatment</a>. These women then enter pregnancy already deficient in iron, which only worsens as their pregnancy progresses, putting themselves and <a href="https://www.ncbi.nlm.nih.gov/pubmed/29986785">their babies under unnecessary risk</a>. </p>
<h2>Gaps in our knowledge</h2>
<p>While studies have compared iron preparations, it has not been possible to find out which type of iron is the most effective for women with iron deficiency anaemia depending on their stage of life. This gap in our knowledge needs attention. </p>
<p>New statistical methods now allow us to compare all treatments against one another and build a network of comparisons. Such a comprehensive comparison of all available iron treatments will help to <a href="https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=100822">provide better guidance</a> on which type of iron works best and for whom. But this alone cannot solve the problem. </p>
<p>Increasing the awareness of the problem among healthcare professionals, women and their friends and family, so that women seek advice and help early, will help to eradicate iron deficiency anaemia, which remains an under-recognised condition affecting women, globally.</p><img src="https://counter.theconversation.com/content/101337/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jahnavi Daru has previously received funding from the National Institute for Health Research and has acted as an advisory board member for Pharmacosmos. </span></em></p><p class="fine-print"><em><span>Ewelina Rogozinska is affiliated with WHO Collaborating Centre for Women's Health at the Queen Mary University of London. </span></em></p>
Iron deficiency anaemia is an under-recognised condition, but one that can have serious health consequences.
Jahnavi Daru, Specialist Registrar in Obstetrics and Gyanecology, Doctoral Research Fellow, Queen Mary University of London
Ewelina Rogozinska, Lecturer in Evidence Synthesis, Queen Mary University of London
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/87670
2018-02-08T05:37:00Z
2018-02-08T05:37:00Z
I’ve been diagnosed with iron deficiency, now what?
<figure><img src="https://images.theconversation.com/files/201604/original/file-20180111-60724-4qcun6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Iron deficiency causes weakness, fatigue, poor concentration, headaches, and intolerance to exercise.</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/TGBGd4mAvhg">Toa Heftiba</a></span></figcaption></figure><p>Iron deficiency is the <a href="http://apps.who.int/iris/bitstream/10665/259425/1/9789241513067-eng.pdf?ua=1">most common nutrient deficiency</a> in the developed world, affecting around <a href="https://www.rcpa.edu.au/Library/College-Policies/Position-Statements/The-Use-of-Iron-Studies,-Ferritin-and-Other-Tests">one in three women of reproductive age</a>. </p>
<p>It can develop when iron intakes or iron absorption rates are unable to meet the iron demands of the body, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2754511/">causing</a> weakness, fatigue, poor concentration, headaches, and intolerance to exercise.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-iron-is-such-an-important-part-of-your-diet-69974">Why iron is such an important part of your diet</a>
</strong>
</em>
</p>
<hr>
<p>Iron deficiency has several stages of severity and is <a href="https://www.rcpa.edu.au/Library/College-Policies/Position-Statements/The-Use-of-Iron-Studies,-Ferritin-and-Other-Tests">diagnosed</a> by a blood test showing the level of serum ferritin (a protein that stores iron in the body) and/or haemoglobin (a protein responsible for transporting oxygen in the blood). </p>
<p>If serum ferritin falls below 30µg/L (micrograms per litre), then iron stores are depleted (stage one or iron depletion). </p>
<p>At serum ferritin levels less than about 20µg/L, the tissues and cells are not receiving the iron they need to function correctly (stage two or latent iron deficiency). </p>
<p>The final and most severe stage is iron-deficiency anaemia. At this stage, red blood cells can no longer carry adequate amounts of oxygen around the body, causing extreme weakness and fatigue. </p>
<h2>Causes</h2>
<p>It’s important for doctors and health professionals to try and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2754511/">identify the cause</a> of iron deficiency, as it may be a side effect of a serious underlying disease. This can be difficult, as there are many possible causes, such as:</p>
<ol>
<li><p>Blood loss, often from heavy or prolonged menstruation, haemorrhage or <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4072018/">frequent blood donation</a></p></li>
<li><p>Being vegetarian, vegan, or having a diet where iron is not well absorbed</p></li>
<li><p>Malabsorption of nutrients from the gut, due to conditions such as coeliac disease or irritable bowel syndrome</p></li>
<li><p>Red blood cell damage due to extreme training practices, common in elite athletes</p></li>
<li><p>Genetic predisposition.</p></li>
</ol>
<h2>Supplementation</h2>
<p>Despite the cause, the initial treatment should always involve an <a href="https://tgldcdp.tg.org.au/viewTopic?topicfile=iron-deficency#toc_d1e234">iron supplement</a> to help improve iron status quickly and prevent progression to iron-deficient anaemia.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/205439/original/file-20180208-74473-1rgvg1m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/205439/original/file-20180208-74473-1rgvg1m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205439/original/file-20180208-74473-1rgvg1m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205439/original/file-20180208-74473-1rgvg1m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205439/original/file-20180208-74473-1rgvg1m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205439/original/file-20180208-74473-1rgvg1m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205439/original/file-20180208-74473-1rgvg1m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">High-dose supplements can cause gastrointestinal side effects.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-girl-holding-red-pill-glass-1019054167?src=thBW8XU_M12ScaNrOjoC0Q-1-73">MIA Studio/Shutterstock</a></span>
</figcaption>
</figure>
<p>Current <a href="https://tgldcdp.tg.org.au/viewTopic?topicfile=iron-deficency#toc_d1e234">clinical guidelines</a> recommend a high-dose supplement of 80-105 mg of elemental iron. But <a href="https://www.ncbi.nlm.nih.gov/pubmed/24714351">clinical trials</a> have also found 60 mg may be enough to effectively treat women with iron deficiency. </p>
<p>Doctors frequently recommend over-the-counter iron treatment in the form of ferrous sulphate, such as <a href="https://www.healthdirect.gov.au/medicines/brand/amt,53178011000036104/ferro-gradumet">Ferro-Gradumet</a>. Some formulations contain vitamin C, which can improve the absorption of supplemental iron. </p>
<p>High-dose iron supplements are generally only recommended until the person’s iron stores are replenished and this is confirmed with a blood test, three to six months after starting supplementation. </p>
<p>High-dose iron supplements can have side effects including nausea, constipation and bloating. These may make taking supplements difficult, so treatment should be a short-term option only. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-can-vitamins-supplement-a-poor-diet-62291">Health Check: can vitamins supplement a poor diet?</a>
</strong>
</em>
</p>
<hr>
<p>Side effects may be reduced by taking the supplement with meals rather than on an empty stomach, or by counteracting constipation with a fibre supplement. But both of these will likely reduce the absorption of the iron from the supplement. If you’re really having trouble tolerating high-dose iron supplements, talk to your doctor or pharmacist about lower-dose options or alternative formulations. </p>
<h2>How much iron do you need?</h2>
<p>In the longer term, it’s important to address the cause of iron deficiency, which may mean increasing your iron intake and absorption. </p>
<p>Menstruating women (aged 19-50 years) <a href="https://www.nrv.gov.au/nutrients/iron">need around</a> 18 mg of iron a day, more than double the recommended amount for Australian men (8 mg). This can be difficult for many women to achieve from diet alone, but it <a href="https://www.ncbi.nlm.nih.gov/pubmed/11506061">can be done</a>, with the right dietary advice.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/205436/original/file-20180208-74497-1oqb2b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/205436/original/file-20180208-74497-1oqb2b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205436/original/file-20180208-74497-1oqb2b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205436/original/file-20180208-74497-1oqb2b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205436/original/file-20180208-74497-1oqb2b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205436/original/file-20180208-74497-1oqb2b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205436/original/file-20180208-74497-1oqb2b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Women need more than double the amount of iron as men.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/pV_ixbLn4QU">Stacey Rozells</a></span>
</figcaption>
</figure>
<p>This was shown in a trial where women with iron deficiency were randomised to receive either a high-dose iron supplement (105 mg per day) or dietary counselling to achieve a high-iron diet. Although the iron supplement led to a quicker restoration of iron stores compared with the diet group, the high-iron diet group continued to improve their iron status for a sustained period of time. </p>
<p>As a bonus, the high-iron diet group saw <a href="https://www.ncbi.nlm.nih.gov/pubmed/11506061">greater improvements</a> in health and well-being outcomes, such as mental health and vitality. </p>
<h2>What is a high-iron diet?</h2>
<p>High total dietary iron intakes <a href="https://www.ncbi.nlm.nih.gov/pubmed/17982706">do not guarantee</a> good iron status. This is because the absorption of dietary iron is complex, and influenced by many dietary factors. </p>
<p>The most important of these is the type of <a href="https://www.ncbi.nlm.nih.gov/pubmed/23719560">dietary iron</a>, of which there are two. <a href="https://www.ncbi.nlm.nih.gov/pubmed/11506061">Haem iron</a> is found in meat, fish and poultry. Non-haem iron comes from breads and cereals, vegetables and fruit. </p>
<p>Between <a href="https://www.ncbi.nlm.nih.gov/pubmed/619599">25-35% of haem iron</a> is absorbed from the gut, compared with only 2-15% of non-haem iron, so you need to eat considerably more non-haem iron to absorb the same amount. Therefore, eating red meat (which contains the most haem iron), or fish or poultry, can really boost iron absorption.</p>
<p>It is important to eat a <a href="https://www.ncbi.nlm.nih.gov/pubmed/11506061">variety of non-haem</a> iron-containing foods as well for good long-term iron status. <a href="https://www.ncbi.nlm.nih.gov/pubmed/11506061">Good sources</a> include beans, lentils, tofu, pasta, breakfast cereals (many of which are iron-fortified), breads, rice, eggs, dried fruit, nuts and vegetables such as broccoli, cauliflower, cabbage, peas and beans. In fact, a majority of our dietary iron is from non-haem sources such as breads and cereals.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-you-should-eat-a-plant-based-diet-but-that-doesnt-mean-being-a-vegetarian-78470">Why you should eat a plant-based diet, but that doesn't mean being a vegetarian</a>
</strong>
</em>
</p>
<hr>
<p>The <a href="https://www.eatforhealth.gov.au/guidelines/australian-guide-healthy-eating">Australian Guide to Healthy Eating</a> recommends women consume five serves of vegetables, two serves of fruit, six serves of breads and cereals, 2.5 serves of meats and alternatives, and 2.5 serves of dairy per day. You’re likely to achieve the recommended 18 mg of iron if you stick to these guidelines, and you include: an iron-fortified breakfast cereal as one serve of the breads/cereals; one serve of green leafy veg such as spinach; and one serve of meat, chicken or fish in the meats/alternatives category. </p>
<p>Another key strategy is to <a href="https://www.ncbi.nlm.nih.gov/pubmed/11506061">boost your ability to absorb iron</a>. Vitamin C-rich foods are well known for boosting iron absorption, so include these at each meal in the form of fresh fruit, vegetables and salad. Other iron absorption boosters include lemon juice, vinegar and alcohol. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/205437/original/file-20180208-74470-1y854wc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/205437/original/file-20180208-74470-1y854wc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/205437/original/file-20180208-74470-1y854wc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/205437/original/file-20180208-74470-1y854wc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/205437/original/file-20180208-74470-1y854wc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/205437/original/file-20180208-74470-1y854wc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/205437/original/file-20180208-74470-1y854wc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Vitamin C-rich foods help you absorb iron.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/1cWZgnBhZRs">Luke Michael</a></span>
</figcaption>
</figure>
<p>In addition to being a good source of haem iron, red meat, fish and poultry also contain a special compound that enhances non-haem iron absorption. So an ideal meal for good iron absorption is a small piece of lean meat, chicken or fish with a dressed salad and glass of wine, finished with some fresh fruit. </p>
<h2>What to avoid</h2>
<p>There are also some substances in foods and drinks that inhibit iron absorption, binding iron in the gut so it passes through the gastrointestinal tract unabsorbed. These include: tannins and polyphenols, found in tea and coffee; oxalates found in spinach; and phytates found in high-fibre foods and legumes. </p>
<p>While many of these are very beneficial for other reasons, those following a vegetarian diet in particular need to be aware of their effects. You can combat these by including plenty of iron absorption-enhancers with meals and holding off on the tea or coffee for at least an hour after a meal.</p>
<p>One final thing to consider is that other minerals – specifically, calcium and zinc – can compete with iron for absorption. While this is not a big issue in the context of a balanced diet, taking another mineral supplement will interfere with your iron absorption. So seek advice from you doctor or a <a href="https://daa.asn.au/what-dietitans-do/choosing-your-nutrition-expert/">dietitian</a> about any supplements you take.</p><img src="https://counter.theconversation.com/content/87670/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Amanda Patterson has previously received funding from the Hunter Medical Research Institute, the University of Newcastle and Meat and Livestock Australia for research into Iron Deficiency. </span></em></p><p class="fine-print"><em><span>Jacklyn Jackson does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The first step is to take an iron supplement to give your iron stores an immediate boost, then you want to investigate the cause and possibly work on your diet.
Amanda Patterson, Senior Lecturer in the School of Health Sciences, University of Newcastle
Jacklyn Jackson, PhD candidate in nutrition and dietetics, University of Newcastle
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/79353
2017-06-15T20:06:03Z
2017-06-15T20:06:03Z
Volcanoes under the ice: melting Antarctic ice could fight climate change
<figure><img src="https://images.theconversation.com/files/173930/original/file-20170615-24988-wlh6r4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Furious winds keep the McMurdo Dry Valleys in Anarctica free of snow and ice. Calcites found in the valleys have revealed the secrets of ancient subglacial volcanoes. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/24354425@N03/15974778779/">Stuart Rankin/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span></figcaption></figure><p>Iron is not commonly famous for its role as a micronutrient for tiny organisms dwelling in the cold waters of polar oceans. But iron feeds plankton, which in turn hold carbon dioxide in their bodies. When they die, the creatures sink to the bottom of the sea, safely storing that carbon.</p>
<p>How exactly the iron gets to the Southern Ocean is hotly debated, but we do know that during the last ice age huge amounts of carbon were stored at the <a href="https://phys.org/news/2016-02-southern-ocean-carbon-dioxide-mystery.html">bottom of the Southern Ocean</a>. Understanding how carbon comes to be stored in the depth of the oceans could help abate CO<sub>2</sub> in the atmosphere, and Antarctica has a powerful role.</p>
<p>Icebergs and atmospheric dust are believed to have been the major sources of this micronutrient in the past. However, in research published in <a href="https://www.nature.com/articles/ncomms15425.epdf?author_access_token=q_njgY8kpm9uOzHBOzIjStRgN0jAjWel9jnR3ZoTv0NDijqdEtnSa_-cRAA3I9D3guB7Wt4waDbHdtXGPg1cnTcvt5ruEU3njHse_z94Ybx16w8amxBJz7ivo8fvlEG_">Nature Communications</a>, my colleagues and I examined calcite crusts from Antarctica, and found that volcanoes under its glaciers were vital in delivering iron to the ocean during the last ice age. </p>
<p>Today, glacial meltwaters from Greenland and the Antarctic peninsula supply iron both in solution and as tiny particles (less than 0.0001mm in diameter), which are readily consumed by plankton. Where glaciers meet bedrock, minute organisms can live in pockets of relatively warm water. They are able to extract “food” from the rock, and in doing so release iron, which then can be carried by underwater rivers to the sea. </p>
<p>Volcanic eruptions under the ice can create underwater subglacial lakes, which, at times, discharge downstream large masses of water that travel to the ice margin and beyond, carrying with them iron in particle and in solution.</p>
<p>The role of melting ice in climate change is as yet poorly understood. It’s particularly pertinent as scientists predict the imminent collapse of part of the <a href="https://www.theguardian.com/environment/climate-consensus-97-per-cent/2017/jun/12/the-larsen-c-ice-shelf-collapse-hammers-home-the-reality-of-climate-change">Larsen C ice shelf</a>.</p>
<p>Researchers are also investigating how to <a href="http://www.gc.noaa.gov/documents/2010_climate_fert_rept_Congress_final.pdf">reproduce natural iron fertilisation in the Southern Ocean</a> and induce algal blooms. By interrogating the volcanic archive, we learn more about the effect that iron fertilisation from meltwater has on global temperatures. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=557&fit=crop&dpr=1 600w, https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=557&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=557&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=700&fit=crop&dpr=1 754w, https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=700&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/173932/original/file-20170615-24948-1il876v.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=700&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A polished wafer of the subglacial calcites. The translucent, crystalline layers formed while in pockets of water, providing nourishment to microbes. The opaque calcite with rock fragments documents a period when waters discharged from a subglacial lake formed by a volcanic eruption, carrying away both iron in solution and particles of iron.</span>
<span class="attribution"><span class="source">Supplied</span></span>
</figcaption>
</figure>
<h2>The Last Glacial Maximum</h2>
<p>During the <a href="https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch6s6-4-1-2.html">Last Glacial Maximum</a>, a period 27,000 to 17,000 years ago when glaciers were at their greatest extent worldwide, the amount of CO<sub>2</sub> in the atmosphere was lowered to 180 parts per million (ppm) relative to pre-industrial levels (280 ppm). </p>
<p>Today we are at <a href="https://theconversation.com/february-carbon-dioxide-levels-average-400ppm-for-first-time-38417">400 ppm</a> and, if current warming trends continue, a <a href="https://theconversation.com/teetering-on-a-tipping-point-dangerous-climate-change-in-the-arctic-5156">point of no return</a> will be reached. The global temperature system will return to the age of the dinosaurs, when there was little difference in temperature from the equator to the poles.</p>
<p>If we are interested in providing a habitable planet for our descendants, we need to mitigate the quantity of carbon in the atmosphere. Blooms of plankton in the Southern Ocean boosted by iron fertilisation were one important ingredient in lowering CO<sub>2</sub> in the Last Glacial Maximum, and they could help us today.</p>
<p>The Last Glacial Maximum had winds that spread dust from deserts and icebergs carrying small particles into the Southern Ocean, providing the necessary iron for algal blooms. These extreme conditions don’t exist today. </p>
<h2>Hidden volcanoes</h2>
<p>Neither dust nor icebergs alone, however, explain bursts of productivity recorded in ocean sediments in the Last Glacial Maximum. There was another ingredient, only discovered in rare archives of subglacial processes that could be precisely dated to the Last Glacial Maximum.</p>
<p>Loss of ice in Antartica’s <a href="http://icestories.exploratorium.edu/dispatches/big-ideas/dry-valleys/index.html">Dry Valleys</a> uncovered rusty-red crusts of calcite plastered on glacially polished rocks. The calcites have tiny layers that can be precisely dated by radiometric techniques.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=926&fit=crop&dpr=1 600w, https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=926&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=926&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1164&fit=crop&dpr=1 754w, https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1164&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/173933/original/file-20170615-24955-itzkks.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1164&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A piece of subglacial calcite coating pebbles. This suggests that the current transporting the pebbles was quite fast, like a mountain stream. The pebbles were deposited at the same time as the opaque layer in the calcite formed.</span>
<span class="attribution"><span class="source">Supplied</span></span>
</figcaption>
</figure>
<p>Each layer preserves in its chemistry and DNA a record of processes that contributed to delivering iron to the Southern Ocean. For example, fluorine-rich spherules indicate that underwater vents created by volcanic activity injected a rich mixture of minerals into the subglacial environment. This was confirmed by DNA data, revealing a thriving community of <a href="https://serc.carleton.edu/microbelife/extreme/extremeheat/index.html">thermophiles</a> – microorganisms that live in very hot water only.</p>
<p>Then, it became plausible to hypothesise that volcanic eruptions occurred subglacially and formed a subglacial lake, whose waters ran into an interconnected system of channels, ultimately reaching the ice margin. Meltwater drained iron from pockets created where ice met bedrock, which then reached the ocean – thus inducing algal blooms. </p>
<p>We dated this drainage activity to a period when dust flux does not match ocean productivity. Thus, our study indicates that volcanoes in Antarctica had a role in delivering iron to the Southern Ocean, and potentially contributed to lowering CO<sub>2</sub> levels in the atmosphere.</p>
<p>Our research helps explain how volcanoes act on climate change. But it also uncovers more about iron fertilisation as a possible way to mitigate global warming.</p><img src="https://counter.theconversation.com/content/79353/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Silvia Frisia receives funding from ARC.</span></em></p>
Melting ice from Antartica could feed vast plankton blooms, trapping carbon in the ocean. To understand this complex mechanism, researchers looked at volcanoes deep under glaciers.
Silvia Frisia, Associate Professor, School of Environmental and Life Sciences , University of Newcastle
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/76981
2017-05-02T22:01:37Z
2017-05-02T22:01:37Z
Feeling worn out? You could have iron overload
<figure><img src="https://images.theconversation.com/files/167448/original/file-20170502-26313-zixla5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">No, not that type of iron overload – haemochromatosis, when your body absorbs too much iron.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/442118806?src=_STvjoIZMwVdZZezu0Copw-1-5&size=medium_jpg">from www.shutterstock.com</a></span></figcaption></figure><p>Feeling a bit tired and worn out? Vague symptoms like these are common in iron deficiency and <a href="https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/anaemia">anaemia</a>. But before you reach for the iron supplements or chow down on steak, these symptoms are common in another condition related to iron. This time the trouble is <em>too much</em> iron, not too little, because of the iron overload disorder called <a href="http://haemochromatosis.org.au/explanation/">haemochromatosis</a>.</p>
<h2>What is haemochromatosis?</h2>
<p>Haemochromatosis is the most common iron storage disease in Australia, the US and most European countries and occurs in about <a href="https://www.ncbi.nlm.nih.gov/pubmed/9138148">one person in 200</a>. It is <a href="https://www.ncbi.nlm.nih.gov/pubmed/23577916">rare in people of Asian descent</a>. </p>
<p>It is a recessive genetic condition, meaning you have to <a href="https://www.niddk.nih.gov/health-information/liver-disease/hemochromatosis">inherited two copies of the haemochromatosis gene</a> (one from each parent). The defect is in the gene that regulates how much iron you absorb from food and supplements. This means that more iron gets into your system than you <a href="https://en.wikipedia.org/wiki/Human_iron_metabolism">need to make red blood cells or to perform other functions</a>. The excess iron ends up in your organs and <a href="https://www.niddk.nih.gov/health-information/liver-disease/hemochromatosis">can damage your heart, liver, pancreas, joint and glands that make hormones</a>. If left untreated, you are at a higher <a href="http://haemochromatosis.org.au/">risk of heart and liver disease, diabetes and arthritis</a>. </p>
<h2>Signs and symptoms</h2>
<p>Symptoms commonly appear in men aged 40-60 years, but appear later in women due to blood loss from menstruation and childbirth.</p>
<p>The most common symptoms are fatigue and joint pain. More advanced symptoms include osteoarthritis, hormonal changes with loss of libido, skin that has a bronze or slate grey colour, heart problems, diabetes (including <a href="http://www.diabetes.co.uk/hemochromatotis-bronze-diabetes.html">bronze diabetes</a>) and liver diseases such as cirrhosis and liver cancer.</p>
<p>It seems confusing that absorbing <em>more iron</em> could lead to fatigue. Iron is needed to make red blood cells that carry oxygen around the body. However, <em>too much</em> iron is toxic. <a href="http://www.mayoclinic.org/diseases-conditions/hemochromatosis/symptoms-causes/dxc-20167290">Excess iron gets deposited in your organs, and this then interferes with normal body functions</a>, as well as the production of hormones that regulate your metabolism and sex drive. Not surprisingly, you don’t feel well. </p>
<h2>Diagnosis and treatment</h2>
<p>Your GP can order a simple blood test to check your iron status. This includes <a href="https://en.wikipedia.org/wiki/Transferrin_saturation">transferrin saturation</a> and <a href="https://en.wikipedia.org/wiki/Ferritin">serum ferritin</a>. If these suggest you could have an iron overload disorder then a gene test will confirm the diagnosis. Once diagnosed, close relatives would also need to be checked for the condition. </p>
<p>The good news is that treatment for haemochromatosis is straight forward and effective. The <a href="https://en.wikipedia.org/wiki/Venipuncture">venipuncture</a> process (similar to becoming a regular blood donor) removes excess iron from the body.</p>
<h2>What do I need to avoid eating and drinking?</h2>
<p>Avoiding eating meat, chicken and fish or becoming a <a href="https://daa.asn.au/smart-eating-for-you/smart-eating-fast-facts/healthy-eating/vegetarian-diets-the-basics/">vegetarian</a> will help reduce the amount of iron you eat and can therefore potentially reduce what your body absorbs.</p>
<p>Other things to avoid are vitamin C supplements and juices high in, or supplemented with, vitamin C. Vitamin C converts the iron from legumes, eggs, nuts, seeds, grains and breakfast cereals into a form that is more easily absorbed, increasing your iron load.</p>
<p>There are many reasons why you could feel fatigued. If you have a lethargy that just won’t lift, see your GP for a check up.</p><img src="https://counter.theconversation.com/content/76981/count.gif" alt="The Conversation" width="1" height="1" />
<h4 class="border">Disclosure</h4><p class="fine-print"><em><span>Clare Collins is affiliated with the Priority Research Centre for Physical Activity and Nutrition, the University of Newcastle, NSW. She is an NHMRC Senior Research fellow. She has received a range of research grants including NHMRC, ARC, Hunter Medical Research Institute, Meat and Livestock Australia, Diabetes Australia, the Heart Foundation. She has consulted to SHINE Australia, Novo Nordisk, Quality Bakers and the Sax Institute. She is a spokesperson for the Dietitians Association of Australia on some specific nutrition issues, including Australia's Healthy Weight Week.</span></em></p>
Feeling tired and out of energy? Talk to your GP about checking your iron level.
Clare Collins, Professor in Nutrition and Dietetics, University of Newcastle
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/70970
2017-01-09T12:12:27Z
2017-01-09T12:12:27Z
What happens to your gut if you eat the $2,000 New York pizza topped with gold?
<figure><img src="https://images.theconversation.com/files/152114/original/image-20170109-23468-xjv5yg.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cock and bullion: the $2,000 pizza. </span> <span class="attribution"><span class="source">Industry Kitchen</span></span></figcaption></figure><p>A restaurant in the New York financial district <a href="http://www.maxim.com/entertainment/2000-dollar-gold-pizza-2017-1">is offering customers a pizza</a> priced at US$2,000 (£1,623). It is topped with caviar, stilton cheese and gold leaf, with each bite costing around US$50. </p>
<p>New York is usually the kind of place that sets trends, but pizzerias elsewhere have actually been making pizzas sparkle for a while. A takeaway pizza chain in London <a href="http://www.mirror.co.uk/news/weird-news/worlds-most-expensive-pizza-500-7395670">started offering</a> £500 pizzas a year ago, this time with added lobster, caviar and truffle oil; while a Glasgow restaurant <a href="http://www.dailyrecord.co.uk/business/business-news/savour-pleasures-classic-italian-food-3081571">attracted attention</a> by selling a gold leaf pizza on eBay. </p>
<p>Gold on food goes back a good deal further than that, however. The renowned Italian chef, Gualtiero Marchesi, <a href="https://www.finedininglovers.com/blog/food-drinks/marchesi-milanese-gold-risotto/">has been</a> topping his signature dish, risotto alla milanese, with a single leaf of gold for decades. And that too is recent when you reflect that the kitchens of the wealthy were <a href="https://books.google.co.uk/books?id=HectxYEZg0oC&pg=PA110&lpg=PA110&dq=%22gold+leaf%22+food+medieval&source=bl&ots=mB3ymFLK31&sig=YBWFZOikAbP__r2nmgGwbsWTKSc&hl=en&sa=X&ved=0ahUKEwj4lJ-i863RAhXCORoKHbaRDggQ6AEIUjAO#v=onepage&q=%22gold%20leaf%22%20food%20medieval&f=false">sprinkling</a> the precious metal on feast cuisine <a href="https://cornucaupia.com/deiaurum/wiki-gold-and-silver-leaf-edible-html/">during</a> medieval times. </p>
<p>There is a medieval liqueur still consumed today with gold flakes in it known as <a href="http://www.local-life.com/gdansk/articles/goldwasser">Goldwasser</a>. Gold leaf is <a href="http://www.ediblegold.co.uk">also used</a> on chocolates and even has an E number (<a href="http://www.ukfoodguide.net/e175.htm">E175</a>). Whatever else has changed over the years, swallowing gold has always been considered the highest form of decadence. But what happens when we put gold into the body? And are there any other metals we’d be better off shaving on to pizzas instead?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/152017/original/image-20170106-18662-hzyla2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/152017/original/image-20170106-18662-hzyla2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/152017/original/image-20170106-18662-hzyla2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=460&fit=crop&dpr=1 600w, https://images.theconversation.com/files/152017/original/image-20170106-18662-hzyla2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=460&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/152017/original/image-20170106-18662-hzyla2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=460&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/152017/original/image-20170106-18662-hzyla2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=578&fit=crop&dpr=1 754w, https://images.theconversation.com/files/152017/original/image-20170106-18662-hzyla2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=578&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/152017/original/image-20170106-18662-hzyla2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=578&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Better than chicken nuggets.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/pic-340054991/stock-photo-superhero-pizza-man.html?src=ZSpgSF_i8bp_bygQHn3pYw-1-49">Luis Molinero</a></span>
</figcaption>
</figure>
<h2>Eat your carats</h2>
<p>Gold is an inert metal and is therefore not degraded by the acid in our stomachs. It will travel the length of the intestinal system unchanged, passing out in your poo. Depending on the sewage treatment system, it will eventually be returned to the land or washed out to sea ready to be recycled again. It casts panning for gold in an entirely new light. </p>
<p>Other metals are generally not used for ostentatious displays of edible wealth, but one exception is silver. Silver can be beaten into a leaf similar to gold and is also approved for use as an additive (<a href="http://www.ukfoodguide.net/e174.htm">E174</a>) – so long as it is pure and in its non-ionic form, which is the one that can’t be absorbed by the body. </p>
<p>Even then it is easier to add other metals to silver than gold, so there is still the risk it can be contaminated with the likes of aluminium. This can reduce the body’s ability to absorb essential minerals such as zinc, calcium and iron (aluminium is not essential). This will cause deficiency symptoms as diverse as soft bones (calcium), tiredness (iron) and lack of smell (zinc). </p>
<p>You might think these minerals might therefore be just the thing for a pizza, so long as they are in the ionic form that the body needs. We tend not to notice them in our diet but they are ubiquitous in grains, fruit and vegetables as they are essential for plant growth, too. Meat and dairy products are particularly rich sources and we have a very efficient system of absorbing the minerals they contain. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/152016/original/image-20170106-18641-1v1lceu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/152016/original/image-20170106-18641-1v1lceu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/152016/original/image-20170106-18641-1v1lceu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=626&fit=crop&dpr=1 600w, https://images.theconversation.com/files/152016/original/image-20170106-18641-1v1lceu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=626&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/152016/original/image-20170106-18641-1v1lceu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=626&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/152016/original/image-20170106-18641-1v1lceu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=787&fit=crop&dpr=1 754w, https://images.theconversation.com/files/152016/original/image-20170106-18641-1v1lceu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=787&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/152016/original/image-20170106-18641-1v1lceu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=787&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chewy sandwich filling.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/pic-466277147/stock-photo-iron-nails-on-a-wooden-yellow-backgroundselective-focusvintage-tone.html?src=5bMDe08D-GqUYB0m8CN9YA-1-44">mansong suttakam</a></span>
</figcaption>
</figure>
<p>One reason we don’t see minerals grated on our foods, of course, is that they don’t give the same bling value. But they will also react with the acid in our stomachs and get absorbed, since they are not inert. Excessive amounts of minerals in the body can be toxic, since they get laid down in soft tissues such as the brain and kidneys. This causes severe pain and eventually death. </p>
<p>In normal circumstances the body avoids such horrors by only absorbing a percentage of the minerals in the foods we eat. But if you flood the system with a mineral by taking large quantities, it can cause an excessive intake. As well as the toxicity risk, excessive intake of one essential mineral can make the body struggle to properly absorb other essential minerals – the same risk as when you ingest non-essential minerals like aluminium. </p>
<p>The bottom line is about balance, as with most of nutrition. Since there’s plenty of these minerals in the foods we eat, there’s absolutely no need and much potential harm to be had from adding any extra to our meals – or from taking supplements we don’t need. </p>
<p>Better to stick to gold, which does nothing good or bad for health except perhaps a feeling of satisfaction – or regret if you see it twinkling as it disappears down the drain. And if you’ve more money than sense and you’re still hungry for more after that gold pizza, you could always ask your willing chef to throw in a few diamonds next time. They’re inert, too, albeit a little crunchy.</p><img src="https://counter.theconversation.com/content/70970/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marie-Ann Ha does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
On sale in New York for US$2,000. Don’t all rush at once.
Marie-Ann Ha, Senior Lecturer in Nutrition, Anglia Ruskin University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/60408
2016-06-03T11:22:29Z
2016-06-03T11:22:29Z
Why did Tutankhamun have a dagger made from a meteorite?
<figure><img src="https://images.theconversation.com/files/125109/original/image-20160603-11598-1l0h6qq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fallen star sword</span> <span class="attribution"><span class="source">Daniella Comelli/University of Pisa</span></span></figcaption></figure><p>Scientists have long speculated that the ancient Egyptians used metal from meteorites to make iron objects. Now an <a href="http://edition.cnn.com/2016/06/02/africa/king-tut-dagger-meteorite/">analysis of a dagger</a> found in Tutankhamun’s tomb has given us <a href="http://onlinelibrary.wiley.com/doi/10.1111/maps.12664/full">strong evidence</a> that this was the case – and that the Egyptians knew the iron had come from the sky. But why did they use such an unusual source for the metal when there’s plenty of iron here on Earth?</p>
<p>Until recently, we didn’t think that the ancient Egyptians were particularly good at producing iron objects until late in their history, around <a href="http://www.ucl.ac.uk/museums-static/digitalegypt/metal/metalinegypt.html">500 BC</a>. There’s no archaeological evidence for significant iron working anywhere in the Nile Valley. Even the large amounts of iron-rich smelting waste products found in the Delta region could actually have been produced by attempts to make copper. When Tutankhamun died – 800 years earlier – iron was a rarer material than gold.</p>
<p>The most common natural source of metal iron on Earth is iron ores – rocks that contain iron chemically bonded to other elements. These <a href="https://www.jstor.org/stable/499136?seq=1#page_scan_tab_contents">need to be processed</a> by heating them with other materials (smelting) to extract a low-quality form of iron, which is then beaten with hammers to remove impurities. This requires considerable know-how, effort and tools that we have no evidence for in ancient Egypt.</p>
<p>There were <a href="https://books.google.co.uk/books?id=Vj7A9jJrZP0C&pg=PA166&lpg=PA166&dq=ancient+egyptian+iron+ore+pigments&source=bl&ots=zt20tivJJy&sig=Q9o-4ArxAbGaKW8scfMLybideqc&hl=en&sa=X&ved=0ahUKEwim-aC-uYvNAhWI8RQKHXlLC3wQ6AEIIzAB#v=onepage&q=ancient%20egyptian%20iron%20ore%20pigments&f=false">abundant supplies</a> of iron ore in both Egypt and the Sinai peninsula and textual sources indicate that Egyptians were aware of the metal from early in their history. But the ore was mostly used to create pigments for art and make up. One explanation for this may be that the readily accessible iron ores were of poor quality so couldn’t be worked into more useful metal.</p>
<h2>Interstellar source</h2>
<p>But iron doesn’t just come from iron ore. We have evidence that numerous prehistoric societies worldwide which did not have access to ores or knowledge of smelting made use of metallic iron found in <a href="http://www.open.edu/openlearn/science-maths-technology/science/geology/iron-the-sky-meteors-meteorites-and-ancient-culture">occasional meteorites</a>. This precious gift from nature still required shaping into a useful form, often resulting in very basic iron objects, such as small thin metal pieces that could be used as blades or bent into shapes.</p>
<p>If ancient Egyptians knew that iron could be found in meteorites that came from the sky – the place of the gods – it may have been symbolically important to them. As a result, they could have seen all iron as a divine material that wasn’t appropriate to work into a practical, everyday form and that should be reserved only for high-status people.</p>
<p>Meteorites may have even played a more direct role in state religion. For example, the “Benben” stone worshipped in the sun temple of the god Ra at Heliopolis is thought to have possibly <a href="http://www.theguardian.com/world/2001/may/14/humanities.highereducation">been a meteorite</a>. The word “benben” is derived from the verb “weben”, meaning “<a href="http://www.touregypt.net/featurestories/benu.htm">to shine</a>”.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/125110/original/image-20160603-11593-5g0a8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/125110/original/image-20160603-11593-5g0a8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=463&fit=crop&dpr=1 600w, https://images.theconversation.com/files/125110/original/image-20160603-11593-5g0a8k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=463&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/125110/original/image-20160603-11593-5g0a8k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=463&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/125110/original/image-20160603-11593-5g0a8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=582&fit=crop&dpr=1 754w, https://images.theconversation.com/files/125110/original/image-20160603-11593-5g0a8k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=582&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/125110/original/image-20160603-11593-5g0a8k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=582&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The earliest known ancient Egypt iron object: a meteorite iron bead from a prehistoric cemetery.</span>
<span class="attribution"><span class="source">Diane Johnson/The Manchester Museum</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The ancient language also offers clues as to how how iron was perceived by Egyptians – and that they knew meteorites were a source of the metal. The earliest hieroglyphic word for iron was greatly debated by translators, who frequently confused the words for copper and iron. The word “bi-A” was eventually translated as “iron”, but could easily have referred a range of hard, dense, <a href="http://adsabs.harvard.edu/full/1973Metic...8...91B">iron-like materials</a>.</p>
<p>The word was used in many texts including the funerary Pyramid Texts, early religious writings dating from approximately 2375 BC but likely to have been composed far earlier, carved on the internal walls of <a href="http://www.pyramidtextsonline.com">some pyramids</a>. These textual references to iron connect it with aspects of the sky and with the bones of the dead king who will live for ever as an undying star in the sky.</p>
<p>From the beginning of the 19th Dynasty (approximately 1295 BC) a new hieroglyphic word for iron appeared: “bi-A-n-pt”, which literally translates as “<a href="http://www.ironfromthesky.org/?p=366">iron from the sky</a>”. Why this new word appears in this exact form at this time is unknown but it was later applied to all metallic iron. An obvious explanation for the sudden emergence of the word would be a major impact event or large shower of meteorites.</p>
<p>This would have been witnessed by much of the ancient Egyptian population, leaving little uncertainty as to where exactly the mysterious iron came from. One possible candidate event is the Gebel Kamil meteorite impact in southern Egypt. Although its exact date remains unknown, based upon nearby archaeology we know it occurred within the past <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.1945-5100.2011.01222.x/abstract">5000 years</a>.</p>
<h2>Ritual significance</h2>
<p>Iron is also connected to ritual artefacts such as those used in the <a href="http://www.ucl.ac.uk/museums-static/digitalegypt//religion/wpr.html">Opening of the Mouth ceremony</a>, a ritual performed at the entrance of a tomb designed to transform the mummy into a latent being with the potential for life. Later texts, including temple inventories, that reference the equipment used in this ceremony refer to the iron blades used as “<a href="http://anees.as.nyu.edu/docs/IO/2596/RothFingersStars.pdf">the two stars</a>”. It may be that iron was allowed an important role in this ceremony because of the association of iron with meteorites, powerful natural phenomena whose own inherent power might increase the potency of the ritual.</p>
<p>We also know that iron dagger blades were important enough to be mentioned in diplomatic correspondence. The <a href="http://www.reshafim.org.il/ad/egypt/amarnaletters.htm">best-known example</a> is a letter from King Tushratta of Mitanni (today in northern Iraq and Syria) detailing a dowry of his daughter who was to be sent as a bride to Tutankhamun’s grandfather, king Amenhotep III. This letter intriguingly refers to a dagger blade of “habalkinu”, a poorly documented word derived from the ancient Hittite language which some linguists have translated as “steel”.</p>
<p>Only further detailed analysis of the chemistry and microstructure of other artefacts will tell us if meteorites were a common source of the iron that the ancient Egyptians produced. We also need to determine when where and how the smelting of terrestrial iron ores started in Egypt to further guide us in our knowledge on the origins, evolution and specific techniques of ancient Egyptian metalworking technology. By combining this with our knowledge of the cultural importance of iron, we can start to develop a realistic understanding of the true value of this metal in ancient Egypt.</p><img src="https://counter.theconversation.com/content/60408/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Diane Johnson works for the Open University. She receives funding from STFC and is affiliated with the Egypt Exploration Society. She has recently collaborated with Prof PT Nicholson, Cardiff University, Dr J Tyldesley, University of Manchester and Prof MM Grady, Open University, studying the presence and perception of iron in ancient Egypt.</span></em></p>
Research has confirmed a knife found in the ancient Egyptian pharaoh’s tomb was made with metal from the heavens.
Diane Johnson, Post Doctoral Research Associate, Department of Physical Sciences, The Open University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/39160
2016-03-09T11:13:56Z
2016-03-09T11:13:56Z
Microwave repairs might annihilate zombie potholes once and for all
<figure><img src="https://images.theconversation.com/files/114165/original/image-20160307-31263-7thqpu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The vehicle-based microwave system, making the streets safe again.</span> <span class="attribution"><span class="source">Zanko et al., 2016</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Some potholes are like zombies – they never die. Or at least that’s the perception of much of the driving public, especially as we enter <a href="http://www.startribune.com/warmer-weather-brings-potholes-or-not/370439201/">peak pothole season</a>: late winter and early spring.</p>
<p>At a minimum, potholes create rough roads and poor driving conditions. Too often they degenerate into <a href="http://newsroom.aaa.com/2016/02/pothole-damage-costs-u-s-drivers-3-billion-annually/">vehicle-damaging safety hazards</a> that incur the wrath of drivers, attract <a href="http://www.smithsonianmag.com/innovation/tweeting-potholes-panama-180955507/?no-ist">negative attention from the news media</a> and adversely affect commerce by disrupting or slowing traffic. Our nation’s deteriorating roads – of which potholes are an obvious manifestation – are a
<a href="http://www.infrastructurereportcard.org/economic-impact/">drag on our economy</a>.</p>
<p>That’s why transportation department maintenance crews and pavement engineers continue to stress the need for more effective and efficient <a href="http://cait.rutgers.edu/files/FHWA-NJ-2001-002.pdf">pavement repair and maintenance</a>. From their perspective, the ideal repair would last at least a year, could be performed in all seasons, and could be installed easily and relatively quickly – all while keeping traffic delays to a minimum and repair costs down.</p>
<p>Recurring “zombie” potholes are too often a reflection of the type of method that’s <a href="http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_syn_463.pdf">used to patch or “fix” them</a> – many of which are short-lived and only marginally effective. Researchers around the world, including <a href="http://www.cts.umn.edu/Research/ProjectDetail.html?id=2016007">my colleagues and me</a>, are working to develop better and longer lasting repair alternatives. At the same time, researchers and pavement engineers in academia and in the private and public sectors are developing improved construction techniques and innovative pavement formulations – <a href="http://www.citg.tudelft.nl/studeren/masterclasses/masterclasses-2013-2014/self-healing-materials/">such as “self healing” materials</a> – that will help prevent potholes from forming in the first place.</p>
<p>But we still have to deal with the millions of miles of roads – and their potholes – we already have.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/RW4BmHsjwS0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Animation describing the birth of a pothole.</span></figcaption>
</figure>
<h2>Pothole repair is patchy</h2>
<p>Potholes are symptomatic of underlying structural and/or pavement problems.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/114156/original/image-20160307-31283-1li2lvz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114156/original/image-20160307-31283-1li2lvz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/114156/original/image-20160307-31283-1li2lvz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114156/original/image-20160307-31283-1li2lvz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114156/original/image-20160307-31283-1li2lvz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114156/original/image-20160307-31283-1li2lvz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114156/original/image-20160307-31283-1li2lvz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114156/original/image-20160307-31283-1li2lvz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Potholes occur in all climates. Here’s a nasty one on Kauai, where a temporary ‘fix’ was putting large rocks in the hole.</span>
<span class="attribution"><span class="source">Larry Zanko</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>They form when water penetrates a crack. In cold climates, that water freezes and expands, pushing up on the overlying pavement. Repeated freezing and thawing is a great way to create a pothole. Water also softens and weakens the base material below a pavement, making it susceptible to deformation by passing traffic loads. As the base material deforms, the pavement loses structural support and breaks up. And another pothole is born!</p>
<p>Bottom line: a roadway marred by multiple potholes means the pavement is probably failing and should be replaced. But before that can happen, potholes still need to be repaired.</p>
<p>Traditional repair techniques are, at best, temporary fixes. Take “throw-and-go” cold patching methods, for example. These use repair mixtures that are worked when cold. Some cold patch repairs don’t bond well to the edges of the hole, a shortcoming made worse when attempting a repair under challenging wintertime conditions. The same pothole repaired with cold mix patches may have to be <a href="http://www.oregon.gov/ODOT/COMM/CRO/pages/answer_team.aspx#Road_conditions/_travel_information_questions">redone several times a winter</a>.</p>
<p>Without a good interface bond, the freezing and thawing cycles of late winter and early spring can further weaken the repair and enlarge the crack between the patch and the surrounding pavement. </p>
<p>Another way a repair gets weakened is analogous to hydraulic fracturing, or “fracking.” The tires of vehicles passing over the repair forcefully push liquid water and fine aggregate particles down into the crack, progressively widening any cracks. Road salt further enhances the latter effect by keeping water in liquid form in subfreezing conditions. </p>
<p>Together, it’s all a prescription for a repair’s early demise – hello again, zombie pothole.</p>
<h2>Search for better repairs heats up</h2>
<p>In an effort to address the ongoing need for better repair mechanisms, my colleagues at the Natural Resources Research Institute - University of Minnesota Duluth, outside project collaborators, and I recently completed a study to <a href="http://www.dot.state.mn.us/research/TS/2016/201603.pdf">evaluate promising innovative pothole repair tactics</a>. Our emphasis is on all-season approaches that use the iron oxide mineral magnetite (Fe3O4).</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/114322/original/image-20160308-22129-qwlk05.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114322/original/image-20160308-22129-qwlk05.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/114322/original/image-20160308-22129-qwlk05.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=438&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114322/original/image-20160308-22129-qwlk05.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=438&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114322/original/image-20160308-22129-qwlk05.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=438&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114322/original/image-20160308-22129-qwlk05.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=550&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114322/original/image-20160308-22129-qwlk05.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=550&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114322/original/image-20160308-22129-qwlk05.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=550&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Magnetite content enhances microwave heating rates.</span>
<span class="attribution"><span class="source">Hopstock, 2009</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>More than 10 years ago, we showed that magnetite and magnetite-containing rock were <a href="http://www.cts.umn.edu/Publications/ResearchReports/reportdetail.html?id=1017">excellent microwave energy absorbers</a>. The mineral is contained in iron ore rock mined and processed on Minnesota’s Mesabi Iron Range, and has the ability to readily absorb microwaves and heat very quickly. We started thinking: when combined with portable microwave technology, could magnetite-containing materials be an effective solution to cold-weather pothole repair? </p>
<p>We mixed small amounts (1 to 2 percent) of magnetite into patching compound, typically made of recycled asphalt pavement (RAP) augmented with ground-up recycled asphalt shingles (RAS); the RAS adds a little more asphaltic binder to the overall mix. Then we pack the mixture into a pothole and microwave until the binder softens and is compactible, thanks to the magnetite.</p>
<p>Here’s our cookbook recipe (emphasis on cook) for the microwave repairs we performed.</p>
<ul>
<li>First, find a pothole (easy).</li>
<li>Clean loose debris and/or blow water from pothole.</li>
<li>In subfreezing temperatures, preheat pothole and pavement adjacent to hole with microwave unit to melt or debond any ice or snow in the hole, and to soften the surrounding pavement. This warming contributes to a good bond since the edges of the pothole are able to plasticly intermix – that is, smush together – and meld with the patch material.</li>
<li>Remove or blow out loosened/melted ice/snow.</li>
<li>Place mixture of RAP, microwave-absorbing taconite materials, and RAS into the pothole. Overfill the hole by about two inches to allow for final compaction.</li>
<li>Heat mixture until temperature reaches at least 100°C (212°F) at base of mixture in the hole. Sufficient heating takes place in about 8 to 12 minutes at a 40kW power level.</li>
<li>Tamp down heated mixture with portable gasoline-powered compactor.</li>
</ul>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/114155/original/image-20160307-31277-1hm6o4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/114155/original/image-20160307-31277-1hm6o4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/114155/original/image-20160307-31277-1hm6o4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=425&fit=crop&dpr=1 600w, https://images.theconversation.com/files/114155/original/image-20160307-31277-1hm6o4u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=425&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/114155/original/image-20160307-31277-1hm6o4u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=425&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/114155/original/image-20160307-31277-1hm6o4u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=534&fit=crop&dpr=1 754w, https://images.theconversation.com/files/114155/original/image-20160307-31277-1hm6o4u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=534&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/114155/original/image-20160307-31277-1hm6o4u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=534&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Steps to an effective microwave pothole repair.</span>
<span class="attribution"><span class="source">Zanko et al., 2016</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>The existing pavement essentially becomes part of the repair itself – a unique and key benefit of this technique. And our repairs showed excellent longevity, with some performing well more than two years after their installation.</p>
<p>Obviously, we’re not just opening the door of a kitchen microwave oven and pointing it down at the road. In the pilot test, we worked with a small company which had previously developed a truck-mounted microwave system to thaw frozen ground to access buried utilities. They adapted their high-power (50kW), vehicle-based microwave system for the project.</p>
<p>And it wouldn’t be much of a stretch for Minnesota’s taconite industry to supply the relatively small quantities of magnetite a repair compound would consume. The industry typically produces about 40 million tons of magnetite concentrate annually, and generates tens of millions of tons of additional byproduct rock that also contains magnetite. The <a href="http://www.nrri.umn.edu/egg/REPORTS/TSR201001/TSR201001.html">byproduct taconite rock</a> actually represents a potential source of hard and durable high quality aggregate for our nation’s roads and highways.</p>
<h2>Benefits of the pilot pothole patch system</h2>
<p>One welcome side effect of the in-place heating mechanism is that it drives off moisture, letting the patch more readily adhere to the surrounding pavement. Patch material can be premixed and stockpiled or mixed on site. And you don’t need to keep material hot during transport, making this patching system well-suited for cold weather situations. </p>
<p>Importantly, our project also demonstrated that an effective microwave pothole repair compound can be made almost entirely from inexpensive and abundant recycled materials (such as RAP and RAS) that many maintenance departments have on hand, as opposed to repair compounds that rely on specialized asphalt formulations, virgin asphalt and/or specialty binders.</p>
<p>Microwave technology is not yet a routine method of repair, and it’s best-suited for potholes in asphalt rather than concrete. But this approach merits further consideration, and we are working to advance the technology.</p>
<p>After all, given our nation’s aging network of roads, zombie potholes will continue to flourish. Microwave repair could be an effective method for keeping them at bay.</p><img src="https://counter.theconversation.com/content/39160/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Larry Zanko has received grant funding from the Minnesota Department of Transportation, as well as the Economic Development Administration of the U.S. Department of Commerce. This funding has helped support some of the research related to this topic.</span></em></p>
Crews patch them, just to see these recurrent potholes come back again. New research focuses on microwaves zapping patches to make a more permanent pothole fix.
Larry Zanko, Senior Research Fellow in Economic Geology at the Natural Resources Research Institute, University of Minnesota Duluth
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/48933
2015-10-28T10:07:44Z
2015-10-28T10:07:44Z
In the fight against anemia, iron fortification is a clutch player
<p>If nutrition had a World Series, iron would never make the playoffs. <a href="http://www.hki.org/our-impact/reaching-millions/saving-sight-lives-vitamin#.Vi5MEtJdGM8">Vitamin A</a> scores home runs for preventing childhood blindness. <a href="http://www.ffinetwork.org/why_fortify/PreventNTDs.html">Folic acid</a> knocks it out of the park by preventing devastating birth defects. <a href="http://ign.org/index.cfm">Iodine</a> throws a shut-out by protecting a child’s IQ.</p>
<p>On the other hand, iron <a href="http://www.ffinetwork.org/why_fortify/productivity.html">gives people energy</a> and protects a <a href="http://www.ingentaconnect.com/content/els/03069192/2003/00000028/00000001/art00070">child’s cognitive capacity</a> with very little fanfare. When iron deficiency is severe enough, people can develop anemia. With anemia, there are insufficient red blood cells to carry oxygen from the lungs to the rest of the body. Any woman who has had anemia from iron deficiency will tell you it causes <a href="https://www.flickr.com/photos/ffinetwork/sets/72157650071655464/">debilitating fatigue</a>. But fatigue is hard to picture, and it can be difficult to raise funds and recruit public health leaders to defeat an invisible problem.</p>
<p>Another reason iron doesn’t make the big leagues is that people think iron deficiency is a problem only in developing countries. Yet the World Health Organization (WHO) says <a href="http://www.who.int/nutrition/topics/ida/en/">iron deficiency</a> is the “most common and widespread nutritional disorder in the world… It is the only nutrient deficiency which is also significantly prevalent in Industrialized Countries.” For example, the United Kingdom’s latest <a href="https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/310995/NDNS_Y1_to_4_UK_report.pdf">National Diet and Nutrition Survey</a> shows low iron intakes among 23% of women aged 19 to 64 years and 46% of girls aged 11 to 18 years.</p>
<p>The magnitude of the global problem can be overwhelming. The WHO’s <a href="http://www.who.int/nutrition/publications/micronutrients/global_prevalence_anaemia_2011/en/">Global Prevalence of Anemia in 2011</a> estimates that 243.2 million nonpregnant women of child-bearing age and 16.2 million pregnant women have anemia related to iron deficiency.</p>
<p>And those figures do not include the estimated 114.7 million children who have anemia from iron deficiency worldwide. Men are less likely than women to have iron deficiency, so they’re not typically included in anemia surveys.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/99881/original/image-20151027-4985-1pj0ldt.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/99881/original/image-20151027-4985-1pj0ldt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/99881/original/image-20151027-4985-1pj0ldt.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/99881/original/image-20151027-4985-1pj0ldt.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/99881/original/image-20151027-4985-1pj0ldt.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/99881/original/image-20151027-4985-1pj0ldt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/99881/original/image-20151027-4985-1pj0ldt.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/99881/original/image-20151027-4985-1pj0ldt.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Words people with anemia use to describe how they feel.</span>
<span class="attribution"><span class="source">Food Fortification Initiative</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Flour fortified, results unquantified</h2>
<p>How do you go to bat against a health concern that is globally pervasive yet generally invisible? One solution is to add iron to commonly consumed foods. <a href="http://doi.org/10.1086/345361">Flour has been iron-fortified</a> in some <a href="http://www.researchgate.net/profile/Max_Kamien/publication/6982150_The_repeating_history_of_objections_to_the_fortification_of_bread_and_alcohol_from_iron_filings_to_folic_acid/links/02e7e5182251090fd5000000.pdf">countries for decades</a>, yet most of these programs have not been evaluated. That’s like fielding a team of professional players but not keeping score.</p>
<p>To address this, my colleagues and I at the Food Fortification Initiative began looking at anemia prevalence in nonpregnant women. We found anemia reports in national surveys, such as the <a href="http://dhsprogram.com/">Demographic and Health Surveys</a>, <a href="http://mics.unicef.org/">Multiple Indicator Cluster Surveys</a>, and <a href="http://www.who.int/vmnis/en/">Vitamin and Mineral Nutrition Information System</a> from the WHO. In countries with fortification programs, we compared anemia before and after fortification began; in countries without fortification, we compared anemia from two different surveys as a kind of control group for our analysis.</p>
<p>We looked for countries that fortified wheat flour alone or in combination with maize flour. Fortification had to include at least iron, folic acid, vitamin A or vitamin B12 since deficiencies in any of these nutrients can cause anemia. We included countries in our study if they had anemia data from before and after fortification began. Twelve “fortification countries” met this criterion. For comparison, we found 20 countries with at least two national surveys on anemia but no flour fortification program.</p>
<p>Iron deficiency is the single most common cause of anemia, but not the only cause. To account for other variables that affect anemia prevalence, we factored in a country’s social and economic development (as captured by the Human Development Index) and whether malaria was endemic. We concluded that in the 12 “fortification countries,” each year of fortification was associated with a 2.4% decline in anemia prevalence. In comparison, the nonfortification countries had a 0.1% decline in anemia prevalence over time.</p>
<h2>Just any old iron won’t do</h2>
<p>After this study was published in the <a href="http://dx.doi.org/10.1017/S0007114515001646">British Journal of Nutrition</a> earlier this year, Richard Hurrell, professor emeritus for human nutrition, ETH Zurich, made an important observation in response. In an <a href="http://doi.org/10.1017/S0007114515002147">invited commentary</a>, he noted that most of the 12 “fortification countries” used iron compounds <a href="http://www.who.int/nutrition/publications/micronutrients/wheat_maize_fortification/en/">recommended by the WHO</a>.</p>
<p>Iron compounds vary greatly in their bioavailability; that’s the extent to which they can be absorbed by the human body. Using a nonbioavailable compound, or using inadequate amounts of a recommended iron compound, will prevent fortification from having a significant impact on iron deficiency anemia.</p>
<p>People don’t need to worry about getting too much iron from fortification, even when a <a href="http://www.ncbi.nlm.nih.gov/pubmed/9460807">highly bioavailable form</a> is used. The human body is designed to <a href="http://www.cdc.gov/ncbddd/hemochromatosis/training/pathophysiology/iron_cycle_popup.htm">absorb the iron it needs</a> and discard the rest. Only people with diseases associated with iron absorption have to manage their iron intake to avoid excess levels.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/99892/original/image-20151027-4974-1wyhot0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/99892/original/image-20151027-4974-1wyhot0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/99892/original/image-20151027-4974-1wyhot0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/99892/original/image-20151027-4974-1wyhot0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/99892/original/image-20151027-4974-1wyhot0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/99892/original/image-20151027-4974-1wyhot0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/99892/original/image-20151027-4974-1wyhot0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/99892/original/image-20151027-4974-1wyhot0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sparse red blood cells in a case of iron deficiency anemia.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/euthman/4422704616">Ed Uthman</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>The dosage counts</h2>
<p>In a second project, I worked with colleagues at the Global Alliance for Improved Nutrition (<a href="http://www.gainhealth.org">GAIN</a>) and the US Centers for Disease Control and Prevention’s International Micronutrient Malnutrition Prevention and Control (<a href="http://www.cdc.gov/immpact/">IMMPaCt</a>) program. We conducted the first systematic review of the effectiveness of flour fortification on iron and anemia outcomes.</p>
<p>We used in-depth evaluations (published and unpublished) of national and subnational programs that fortify flour with iron. The reviewed reports all compared data collected before fortification with data collected at least 12 months after fortification began. We didn’t include studies without both a pre- and post-fortification evaluation. Fortification was for wheat flour alone or in combination with maize flour.</p>
<p>Our review, just published in <a href="http://dx.doi.org/10.1093/nutrit/nuv037">Nutrition Reviews</a>, showed that fortification consistently improved the iron status of women. But we found limited evidence for fortification reducing the prevalence of anemia. A key point is that the type of iron used followed WHO recommendations in eight of the 13 studies reviewed. But only two of the studies added the minimum recommended level of iron. Women were getting more iron than they would have without fortification, but evidently it wasn’t enough to boost them out of anemia.</p>
<p>For a grand slam in nutrition, any food fortification program needs to reach the majority of the population and be monitored to ensure quality and impact. To get a hit against iron deficiency anemia, fortifying with iron must also meet these two basic requirements: use a bioavailable form of iron and use it at recommended concentrations.</p><img src="https://counter.theconversation.com/content/48933/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Helena Pachón works for the Food Fortification Initiative. She receives funding from the US Centers for Disease Control and Prevention. </span></em></p>
In a World Series of nutrition, don’t leave iron on the bench. Fortifying flour can prevent the iron deficiency anemia that affects hundreds of millions of women and children globally.
Helena Pachón, Research Associate Professor of Global Health, Emory University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/37170
2015-10-12T03:51:41Z
2015-10-12T03:51:41Z
Health Check: seven nutrients important for mental health – and where to find them
<figure><img src="https://images.theconversation.com/files/98007/original/image-20151012-23288-t3ve32.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">While nutrient supplementation can have a role in treating certain psychiatric disorders, all kinds of nutrients should, in the first instance, be consumed as part of a balanced wholefood diet.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/nakrnsm/3815441846/">PROPatrick Feller/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Dietary nutrients are critical for brain structure and function, so they have a potentially profound impact on mental health. An increasingly <a href="http://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(14)00051-0/abstract">robust body of research</a> points to the detrimental effect of unhealthy diets and nutrient deficiencies, and to the protective value of healthy diets – along with select nutritional supplements as required – for maintaining and promoting mental health. </p>
<p>Research literature suggests dietary improvement and nutritional interventions may help reduce the risk, or even arrest the progression, of certain psychiatric disorders. <a href="http://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(14)00051-0/abstract">Clinical studies</a> support the use of certain nutrients, which influence a range of neurochemical activities beneficial for treating mental disorders, as medicinal supplements.</p>
<p>Evidence from clinical research supports the use of several nutritional medicines for certain psychiatric disorders: omega-3 fatty acids; N-acetyl cysteine (NAC); S-adenosyl methionine (SAMe); zinc; magnesium; vitamin D; and B vitamins (including folic acid). Other natural compounds such as amino acids, plant-based antioxidants and microbiotics (derived from fermented food or laboratory synthesis) are also known to influence brain health. </p>
<p>But while some evidence supports these natural compounds as having brain chemical-modulating effects, or having a role in treating certain mental disorders, we cannot currently name particular foods as being effective for the treatment of mental illness. The best nutritional advice at this point is to cultivate an unprocessed wholefood diet, with judicious prescriptive use of nutrients (if required) based on advice from a qualified health professional. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/98010/original/image-20151012-23309-1jxpwuh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/98010/original/image-20151012-23309-1jxpwuh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=353&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98010/original/image-20151012-23309-1jxpwuh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=353&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98010/original/image-20151012-23309-1jxpwuh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=353&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98010/original/image-20151012-23309-1jxpwuh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=444&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98010/original/image-20151012-23309-1jxpwuh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=444&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98010/original/image-20151012-23309-1jxpwuh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=444&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Oily fish such as sardines are the best source of omega-3 fats.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/jmenj/9434507959/">Jeanne Menj/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>In the meanwhile, here are seven key nutrients that may positively influence brain health, and the foods they appear in.</p>
<p><strong>1. Omega-3</strong> </p>
<p>Polyunsaturated fats (in particular omega-3 fatty acids) <a href="http://www.ncbi.nlm.nih.gov/pubmed/23538073">have a vital role</a> in maintaining proper neuronal structure and function, as well as in modulating critical aspects of the inflammatory pathway in the body. Taking omega-3 supplements appears beneficial for addressing symptoms of depression, bipolar depression and post-traumatic stress disorder. And it may potentially help <a href="http://www.ncbi.nlm.nih.gov/pubmed/20124114">prevent psychosis</a>.</p>
<p>Omega-3 fats can be found in nuts, seeds and oysters, although the highest amounts exist in oily fish such as sardines, salmon (especially King salmon), anchovies and mackerel. Due to higher levels of mercury, larger fish, such as mackerel, should be consumed in moderation.</p>
<p><strong>2. B vitamins and folate</strong></p>
<p>We need B vitamins for a range of cellular and metabolic processes, and they have a critical role in the production of a range of brain chemicals. Folate (B9) deficiency <a href="http://www.psychiatrist.com/JCP/article/Pages/2009/v70s05/v70s0503.aspx">has been reported</a> in depressed populations and among people who respond poorly to antidepressants.</p>
<p>Several studies have assessed the antidepressant effect of folic acid (the synthetic form of folate) with antidepressant medication. <a href="http://www.psychiatrist.com/JCP/article/Pages/2009/v70s05/v70s0503.aspx">Some show positive results</a> in enhancing either antidepressant response rates or the onset of response to these medications. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/98012/original/image-20151012-23319-13i4uq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/98012/original/image-20151012-23319-13i4uq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98012/original/image-20151012-23319-13i4uq6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98012/original/image-20151012-23319-13i4uq6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98012/original/image-20151012-23319-13i4uq6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98012/original/image-20151012-23319-13i4uq6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98012/original/image-20151012-23319-13i4uq6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Nuts are a good source of folate, amino acids and minerals.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/addiction/62824084/">Ahmed Al Masaood/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Folate is found in abundance in leafy green vegetables, legumes, whole grains, brewer’s yeast and nuts. Unprocessed meats, eggs, cheese, dairy, whole grains and nuts are, in general, richest in B vitamins. If you’re going to take supplements, it’s advisable to take B vitamins together as <a href="http://www.ncbi.nlm.nih.gov/pubmed/23253391">they have a synergistic effect</a>.</p>
<p><strong>3. Amino acids</strong></p>
<p>Amino acids are the building blocks for creating proteins, from which brain circuitry and brain chemicals are formed. Some amino acids are precursors of mood-modulating chemicals; tryptophan, for instance, is needed to create serotonin. Another example is cysteine, a sulphur-based amino acid that can convert into glutathione – the body’s most powerful antioxidant. </p>
<p>When given as a supplement, an amino acid form known as N-acetyl cysteine (NAC) converts into <a href="https://en.wikipedia.org/wiki/Glutathione">glutathione</a> in the body. We have <a href="http://www.ncbi.nlm.nih.gov/pubmed/23369637">evidence that it’s helpful</a> in bipolar depression, schizophrenia, trichotillomania and other compulsive and addictive behaviours. Another amino acid-based nutrient known as S-adenosyl methionine (SAMe) <a href="http://www.ncbi.nlm.nih.gov/pubmed/24856557">has antidepressant qualities</a>. </p>
<p>Amino acids are found in any source of protein, most notably meats, seafood, eggs, nuts and legumes.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/98013/original/image-20151012-23319-wauedl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/98013/original/image-20151012-23319-wauedl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98013/original/image-20151012-23319-wauedl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98013/original/image-20151012-23319-wauedl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98013/original/image-20151012-23319-wauedl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98013/original/image-20151012-23319-wauedl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98013/original/image-20151012-23319-wauedl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Amino acids are found in sources of protein such as meat.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/wurzeltod/357151207/">Suzanne Gerber/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p><strong>4. Minerals</strong> </p>
<p>Minerals, especially zinc, magnesium and iron, have important roles in neurological function. </p>
<p>Zinc is an abundant trace element, being involved in many brain chemistry reactions. It’s also a key element supporting proper immune function. <a href="http://www.ncbi.nlm.nih.gov/pubmed/25012438">Deficiency has been linked</a> to increased depressive symptoms and there’s emerging evidence for zinc supplementation in <a href="http://www.ncbi.nlm.nih.gov/pubmed/21798601">improving depressed mood</a>, primarily alongside antidepressants. </p>
<p>Magnesium is also involved in many brain chemistry reactions and <a href="http://www.ncbi.nlm.nih.gov/pubmed/19085527">deficiency has been linked</a> to depressive and anxiety symptoms. Iron is involved in many neurological activities and <a href="http://www.biomedcentral.com/1471-244X/13/161">deficiency is associated with</a> anxiety and depressive symptoms as well as developmental problems. This is, in part, due to its role in transporting oxygen to the brain.</p>
<p>Zinc is abundant in lean meats, oysters, whole grains, pumpkin seeds and nuts, while magnesium is richest in nuts, legumes, whole grains, leafy greens and soy. Iron occurs in higher amounts in unprocessed meats and organ meats, such as liver, and in modest amounts in grains, nuts and leafy greens, such as spinach. </p>
<p><strong>5. Vitamin D</strong></p>
<p>Vitamin D is a fat-soluble compound that’s important as much for brain development as it is for bone development. Data suggests low maternal levels of vitamin D are <a href="http://www.ncbi.nlm.nih.gov/pubmed/22796576">implicated in schizophrenia risk</a>, and deficiency is linked to <a href="http://www.ncbi.nlm.nih.gov/pubmed/23377209">increased depressive symptoms</a>. But there’s little evidence to support the use of <a href="http://www.ncbi.nlm.nih.gov/pubmed/24423304">vitamin D supplements for preventing depression</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/98015/original/image-20151012-23300-uz3k8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/98015/original/image-20151012-23300-uz3k8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=362&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98015/original/image-20151012-23300-uz3k8j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=362&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98015/original/image-20151012-23300-uz3k8j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=362&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98015/original/image-20151012-23300-uz3k8j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=456&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98015/original/image-20151012-23300-uz3k8j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=456&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98015/original/image-20151012-23300-uz3k8j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=456&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Vitamin D can be synthesised via sunlight.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/naturesdawn/4299041739/">Dawn Ellner/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Vitamin D can be synthesised via sunlight: 15 minutes a day on the skin between 10am and 3pm during summer, although be sure to seek professional health advice regarding skin cancer concerns. Aside from sunlight, vitamin D can also be found in oily fish, UVB-exposed mushrooms and fortified milk.</p>
<p><strong>6. Plant-based antioxidants</strong></p>
<p>An increase in oxidative stress and damage to brain cells has been <a href="http://www.ncbi.nlm.nih.gov/pubmed/22271002">implicated in a range of mental disorders</a>, including depression and dementia. Antioxidant compounds (such as “polyphenols”, which are found in fruits and certain herbs) may “mop up” free radicals that damage cells to <a href="http://www.ncbi.nlm.nih.gov/pubmed/22334236">provide a natural way</a> to combat excessive oxidation.</p>
<p>Consuming natural antioxidant compounds through your diet is better than taking supplements of high doses of synthetic vitamin A, C or E, as the oxidative system is finely tuned and excess may actually be harmful. </p>
<p>Fruits and vegetables contain these antioxidant compounds in relative abundance, especially blackberries, blueberries, raspberries and goji berries; grapes; mangoes and mangosteen; onions; garlic; kale; as well as green and black tea; various herbal teas; and coffee.</p>
<p><strong>7. Microbiotics</strong></p>
<p><a href="http://www.ncbi.nlm.nih.gov/pubmed/23384445">Research</a> shows a connection between the bacteria in our guts and brain health, which may affect mental health. When the composition of the gut microbiota is less than optimal, it can result in inflammatory responses that <a href="http://www.ncbi.nlm.nih.gov/pubmed/21135322">may negatively affect</a> the nervous system and brain function. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/98009/original/image-20151012-23283-125i0an.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/98009/original/image-20151012-23283-125i0an.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/98009/original/image-20151012-23283-125i0an.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/98009/original/image-20151012-23283-125i0an.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/98009/original/image-20151012-23283-125i0an.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/98009/original/image-20151012-23283-125i0an.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/98009/original/image-20151012-23283-125i0an.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Diets high in sugary, fatty and processed foods are associated with depression and poor brain health.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/brizzlebornandbred/9375507295/">Paul Townsend/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>A balanced microfloral environment is supported by a diet rich in the foods that nourish beneficial bacteria and reduce harmful microbial species, such as <em>Helicobacter pylori</em>. Beneficial microflora can be supported by eating fermented foods such as tempeh, sauerkraut, kefir and yoghurt, and also by pectin-rich foods such as fruit skin. </p>
<h2>What now?</h2>
<p>Diets high in sugary, fatty and processed foods <a href="https://theconversation.com/you-are-what-you-eat-how-diet-affects-mental-well-being-27115">are associated</a> with depression and poor brain health. While nutrient supplementation can have a role in maintaining proper brain function and treating certain psychiatric disorders, nutrients should, in the first instance, be consumed as part of a balanced wholefood diet.</p>
<p>There is now enough research evidence to show the importance of nutrients for mental as well as physical well-being. A <a href="http://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(14)00051-0/abstract">discussion about diet and nutrition</a> should be the starting point in conversations about mental health, just as it is for physical health.</p>
<p><em>If you’re interested in participating in a clinical trial prescribing nutrients for treating depression (SE Queensland and Victoria only), visit <a href="http://nutrientsdepressionstudy.com/">nutrientsdepressionstudy</a>.</em> </p>
<p><strong>Acknowledgement</strong>: Dr Drew Ramsey contributed to this article.</p><img src="https://counter.theconversation.com/content/37170/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jerome Sarris has received funding from Integria Health, Blackmores, Bioceuticals, Pepsico, HealthEd, Soho-Flordis, Pfizer, Elsevier, the Society for Medicinal Plant and Natural Product Research, CR Roper Fellowship, and The National Health and Medical Research Council. He is affiliated with The International Society for Nutritional Psychiatry Research. </span></em></p>
A growing body of research points to the detrimental effect of unhealthy diets and the protective value of healthy diets – along with select nutritional supplements as required – for maintaining and promoting mental health.
Jerome Sarris, Senior Research Fellow, The University of Melbourne
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/41339
2015-05-11T05:44:48Z
2015-05-11T05:44:48Z
Bleed me: why excess iron can be dangerous
<figure><img src="https://images.theconversation.com/files/80691/original/image-20150506-10953-e13tkj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">It's good for you.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-152567954/stock-photo-blood-donor-at-donation-with-a-bouncy-ball-holding-in-hand.html?src=3_mXm_4Szh-PBk_fsHAVgw-2-15">Blood donation via www.shutterstock.com.</a></span></figcaption></figure><p>Iron is a most versatile element. It is essential to many of the enzymes that are the engines for life, and in mammals is also used to carry oxygen on hemoglobin in blood. Remember <a href="http://www.thekitchn.com/why-did-popeye-eat-so-much-spinach-the-surprising-answer-191802">Popeye and his spinach</a>: all that iron made him strong. </p>
<p>But the very quality that makes iron so useful also makes it dangerous. Iron can easily lose or gain one electron going from the ferrous (Fe++) to the ferric (Fe+++) state, back and forth indefinitely. This is how it carries oxygen, for example. </p>
<p>It also means it can be a potent pro-oxidant – it catalyzes the production of free radicals which can destroy cells and tissue, and thereby contribute to <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1567854/">cancer and heart disease</a>. </p>
<p>Life forms like us have developed extensive defense mechanisms that allow us to use iron for life’s work while keeping it away from anywhere it is not immediately needed within cells and in the body in general.</p>
<h2>Iron fortification sweeps the world</h2>
<p>Severe iron deficiency is a health problem in much of the world, but in the US it is uncommon. </p>
<p>The recommended daily allowance for adult men is about <a href="http://ods.od.nih.gov/factsheets/Iron-HealthProfessional/#h2">8mg per day</a>, and for adult women under 50 it is about 18mg per day (for pregnant women 27mg per day is recommended). Recommended daily allowances are higher for vegetarians. Most Americans get all the iron they need from their diet. And some foods are supplemented with iron. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/80722/original/image-20150506-10922-pqu74a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/80722/original/image-20150506-10922-pqu74a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/80722/original/image-20150506-10922-pqu74a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/80722/original/image-20150506-10922-pqu74a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/80722/original/image-20150506-10922-pqu74a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/80722/original/image-20150506-10922-pqu74a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/80722/original/image-20150506-10922-pqu74a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/80722/original/image-20150506-10922-pqu74a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Many foods, including bread, are enriched with iron.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-166231535/stock-photo-sliced-bread-in-plastic-bag-isolated-on-white.html?src=dFLUzBjrwEEQW09pwJgtJA-1-12">Loaf via www.shutterstock.com.</a></span>
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</figure>
<p>During the first half of the 20th century, both medical and public health forces began to aggressively promote iron fortification of food to fight iron-deficiency anemia, particularly in the developing world where the problem was most acute and as much as <a href="http://whqlibdoc.who.int/publications/2008/9789241596657_eng.pdf">half the population</a> of some areas fit the definition of anemia. </p>
<p>Of the many harmful effects of severe iron deficiency perhaps of greatest concern are the <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3266848/">developmental problems in children</a>. </p>
<p>Severe iron deficiency is harmful, but that isn’t the whole story.</p>
<p>Researchers found that Somali nomads who ate iron restricted diets (very low in meat, but rich in dairy) had lower prevalence of infectious diseases than those <a href="http://www.ncbi.nlm.nih.gov/pubmed/7445536">that ate more meat</a>. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/80728/original/image-20150506-10947-1gnwtcr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/80728/original/image-20150506-10947-1gnwtcr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/80728/original/image-20150506-10947-1gnwtcr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=776&fit=crop&dpr=1 600w, https://images.theconversation.com/files/80728/original/image-20150506-10947-1gnwtcr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=776&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/80728/original/image-20150506-10947-1gnwtcr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=776&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/80728/original/image-20150506-10947-1gnwtcr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=975&fit=crop&dpr=1 754w, https://images.theconversation.com/files/80728/original/image-20150506-10947-1gnwtcr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=975&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/80728/original/image-20150506-10947-1gnwtcr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=975&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A source of non-heme iron.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-151636469/stock-photo-fresh-harvested-spinach-on-a-old-grungy-table.html?src=YpPIxoYSCqGeboThtbohDw-1-59">Spinach via www.shutterstock.com</a></span>
</figcaption>
</figure>
<p>Dietary iron falls into two categories: heme iron which is easily absorbed from our gut, and non-heme iron which is not absorbed nearly as well. Iron from plants and dairy products is almost entirely non-heme, whereas, of course, red meat contains a lot of heme iron. </p>
<p>Almost all infectious agents including bacteria, fungi, and protozoa that cause disease require iron for their growth. They have developed proteins called siderophores that scavenge iron from their human hosts so they can <a href="http://www.sciencedirect.com/science/article/pii/S0304416508001451">thrive and multiply</a>. One defense mechanism we have against a bacterial infection is to develop a fever; this is because siderophores don’t work at temperatures above 104 F, whereas they work very well at our normal body temperature of 98.6 F. </p>
<h2>‘Fortification’ or adulteration?</h2>
<p>For a long time iron was sacrosanct as a nutrient: if a little is good, then more must be better. </p>
<p>This was the worldwide mantra to fight iron-deficiency anemia. Food was iron “fortified” as much as possible. For example, widespread fortification of flour in the United States <a href="http://web1.sph.emory.edu/users/hpacho2/PartnershipsMaize/Bishai_2002.pdf">began in the 1930s</a>.</p>
<p>The tipping point for the iron fortification debate came in 1978 when an eminent physician and scientist named William Crosby published a paper in the Journal of the American Medical Association called <a href="http://jama.jamanetwork.com/article.aspx?articleid=1722212">The Safety of Iron-Fortified Food</a>. </p>
<p>He argued that although there are some groups at risk of anemia such as pregnant women, adding iron to the food supply in general exposes many who are not at risk of iron deficiency, and who might therefore be harmed.</p>
<p>It was a provocative idea at the time. And it was taken seriously because of who he was: a World War II veteran who received a Bronze Star, a scientist with over 300 scientific publications to his name who had established hematology and oncology specialties at Walter Reed Army Hospital in the early 1950s. </p>
<p>Evidence of potential harm came the same year Crosby’s paper came out. In 1978 Researchers in Sweden found increasing rates of <a href="http://www.ncbi.nlm.nih.gov/pubmed/642130">early-stage hemochromatosis among men</a>. </p>
<p>Hemochromatosis is an iron overload condition that in its later stages kills by heart attack or cancer. Further studies in Sweden suggested that iron fortification <a href="http://onlinelibrary.wiley.com/doi/10.1111/j.0954-6820.1983.tb03706.x/abstract;jsessionid=7B3494D6ECAD1746509488B14102FD66.f03t04?deniedAccessCustomisedMessage=&userIsAuthenticated=false%20genetic%20hemechromoatosis">was harmful</a> for people with genetic hemochromatosis. Iron fortification of food in Sweden was the highest in the world until it was <a href="http://www.nature.com/ejcn/journal/v51/n11/pdf/1600488a.pdf">withdrawn in 1995</a>.</p>
<h2>Cancer and the battle over iron</h2>
<p>My PhD advisor was a Nobel prize winner named <a href="http://www.nobelprize.org/nobel_prizes/medicine/laureates/1976/blumberg-bio.html">Barry Blumberg</a>. He was interested in whether body iron level interacted with hepatitis B virus in causing liver cancer. </p>
<p>So he sent me all over the world to conduct studies of this possibility, and we found <a href="http://www.ncbi.nlm.nih.gov/pubmed/3007843">some support</a>. </p>
<p>Later, after obtaining a PhD, I took it a little further and published a paper in 1988 in New England Journal of Medicine that <a href="http://www.ncbi.nlm.nih.gov/pubmed/3173433">became a turning point</a> in how the medical and public health communities viewed iron. </p>
<p>Unbeknownst to me – a young researcher at the time – the battle over iron had been brewing for some time, and my paper provided the first hard evidence in humans that elevated body iron level was linked to increased cancer risk in general (not just liver). It became very highly cited by other scientists, and the battle was on. </p>
<p>Iron may help cause cancer as a pro-oxidant, but it may also play an important role in progression as a <a href="http://www.ncbi.nlm.nih.gov/pubmed/21875943">nutrient for existing cancer cells</a>.</p>
<p>Now, these many years later, it has become clear from work by molecular biologists that <a href="http://www.nature.com/nsmb/journal/v14/n12/full/nsmb1344.html">heme is the ligand for rev-erb alpha</a>. Translation into English: body iron level helps regulate our circadian rhythms and <a href="https://theconversation.com/a-dark-night-is-good-for-your-health-39161">their link to metabolism</a>. The implications of this exciting finding for our health are not yet clear.</p>
<h2>Too much iron is bad, but so is too little – what’s just right?</h2>
<p>After all these years of conflicting research and often extreme opinions on iron, it turns out that like anything else that is a benefit in moderation, in excess it is a detriment.</p>
<p>Severe iron deficiency anemia is still a real problem in the developing world and requires treatment, particularly for children and pregnant women. However, we must avoid over-treatment because too much iron is dangerous. There needs to be a balance. </p>
<p>Mild iron deficiency for non-pregnant adults may have some benefits such as lower risk of cancer and heart disease, and lower susceptibility to infectious disease.</p>
<p>The best way to attain mild deficiency is to <a href="http://www.redcrossblood.org/">donate blood</a> at the Red Cross with some regularity. Not that bloodletting is a cure-all, but maybe doctors back in the ancient days of medicine had inadvertently stumbled <a href="http://www.sciencedaily.com/releases/2012/05/120529211645.htm">onto something</a>.</p><img src="https://counter.theconversation.com/content/41339/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard G. "Bugs" Stevens does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
After years of conflicting research and often extreme opinions on iron, it turns out that like anything else that is a benefit in moderation, in excess it is a detriment.
Richard G. "Bugs" Stevens, Professor, School of Medicine, University of Connecticut
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/15557
2014-01-15T03:32:43Z
2014-01-15T03:32:43Z
Explainer: can the body have too much iron?
<figure><img src="https://images.theconversation.com/files/38260/original/8qh87r9s-1387424819.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Campaigns tell us to eat red meat to keep our iron levels up – but what if we have too much?</span> <span class="attribution"><span class="source">tarale</span></span></figcaption></figure><p>Many people are aware that low levels of iron in their body can lead anaemia, with symptoms such as fatigue. But few realise that too much iron can result in a potentially fatal condition.</p>
<p>Normally, if we have enough iron in our body, then no further iron is absorbed from the diet, and our iron levels remain relatively constant.</p>
<p>But the body also has no way of excreting excess iron. In a condition called hereditary haemochromatosis, the most common cause of iron overload, the mechanism to detect sufficient iron in the body is impaired and people can go on absorbing iron beyond the normal required amount.</p>
<p>Untreated, haemochromatosis can result in scarring to the liver (cirrhosis), liver cancer, damage to the heart and diabetes. These problems are the result of excess iron being deposited in the liver, heart and pancreas. Haemochromatosis can also cause non-specific symptoms such as fatigue, loss of libido and arthritis. In some, it results in a shortened lifespan. </p>
<p>The most common cause of hereditary haemochromatosis is a mutation received from both parents, in a gene called HFE. </p>
<p>Around one in every 200 Australians of European heritage have a double dose of this gene fault and are at risk of developing the disorder. Haemochromatosis is much less common among people who aren’t of European ancestry.</p>
<p>Approximately <a href="http://www.nejm.org/doi/full/10.1056/NEJMoa073286">80% of men</a> and 60% of women who have inherited this gene fault from both parents develop high iron levels. And of those who do, up to 40% of men and 10% of women will develop health problems.</p>
<h2>Diagnosis</h2>
<p>Actual blood iron levels are generally normal in those with haemochromatosis, as excess iron in the body is stored in tissues like the liver. So haemochromatosis is diagnosed by testing blood iron indices called transferrin saturation and serum ferritin levels.</p>
<p>Transferrin is a protein that transports iron around the body; ferritin is a protein that stores iron. The more iron in the body, the more ferritin that is made. Those with the haemochromatosis generally have high transferrin saturation and serum ferritin levels. </p>
<p>These proteins are very important in minimising tissue damage from iron, as iron that is not stored in ferritin or bound to transferrin is very toxic to cells.</p>
<p>If abnormal iron indices are identified, then genetic testing is usually the next step. Sometimes a liver biopsy is also required, to assess the degree of excess iron and whether there is permanent scarring of the liver.</p>
<p>There is <a href="http://www.ncbi.nlm.nih.gov/pubmed/22198253">debate among experts</a> over whether everybody should undergo genetic testing for the disorder, even if they don’t display symptoms.</p>
<p>Those who argue for blanket screening claim that if a person is at risk, knowledge of their condition will allow them to have their ferritin levels monitored, and they can seek treatment to prevent severe problems.</p>
<p>Arguments against the practice include the high cost of genetic screening, and the fact that many people who have the genetic risk don’t go on to develop the disorder.</p>
<h2>Treatment</h2>
<p>Donating blood is the primary form of treatment for haemochromitosis. Red blood cells contain haemoglobin, which is very high in iron – removing red blood cells therefore removes iron. </p>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/38263/original/89r8by23-1387425574.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/38263/original/89r8by23-1387425574.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/38263/original/89r8by23-1387425574.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/38263/original/89r8by23-1387425574.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/38263/original/89r8by23-1387425574.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/38263/original/89r8by23-1387425574.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/38263/original/89r8by23-1387425574.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Donating blood is the most common treatment for haemochromatosis.</span>
<span class="attribution"><span class="source">Canadian Blood Services</span></span>
</figcaption>
</figure>
<p>Once iron levels are normalised, a person generally needs to make two to four blood donations per year to maintain normal iron levels. Blood donated by people with haemochromitosis can generally be used in transfusions with no problems.</p>
<p>While there’s no doubt that people with very high iron levels due to haemochromatosis require treatment through donating blood, the evidence is less clear for those with only slightly elevated iron levels.</p>
<p>A research study call <a href="http://www.mi-iron.com.au">Mi-iron</a> is underway in Melbourne, Brisbane and Perth to examine whether there are benefits to treatment when there is only moderate iron excess. </p>
<p>In this study, individuals will either have their iron levels normalised or left untreated without the person knowing which is the case (there’s more information <a href="http://www.mi-iron.com.au">here</a> about how this is achieved). Various symptoms are being assessed before and after the intervention to see if people with haemochromatosis who don’t have severely elevated iron levels benefit from treatment.</p>
<p>Media campaigns may encourage us to eat more red meat, in part to make sure that we get enough iron. But with haemochromatosis, there can be too much of a good thing.</p><img src="https://counter.theconversation.com/content/15557/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Martin Delatycki receives funding from National Health and Medical Research Council, Friedreich Ataxia Research Alliance, Friedreich Ataxia Research Association</span></em></p>
Many people are aware that low levels of iron in their body can lead anaemia, with symptoms such as fatigue. But few realise that too much iron can result in a potentially fatal condition. Normally, if…
Martin Delatycki, Director of Bruce Lefroy Centre for Genetic Health Research, Murdoch Children's Research Institute
Licensed as Creative Commons – attribution, no derivatives.