tag:theconversation.com,2011:/us/topics/glucose-6382/articles
Glucose – The Conversation
2024-03-28T12:18:54Z
tag:theconversation.com,2011:article/223239
2024-03-28T12:18:54Z
2024-03-28T12:18:54Z
What is sugar and what would happen if I stopped eating it? A scientist explains
<p>The world has declared a time-out on sugar consumption. The harmful link between disease and dietary sugar was recently outlined in a <a href="https://pubmed.ncbi.nlm.nih.gov/37019448/">comprehensive assessment</a> of published studies. </p>
<p>Recognising this link between widely consumed food and disease is essential in marshalling forces to <a href="https://www.who.int/tools/elena/interventions/free-sugars-adults-ncds">change harmful outcomes</a>. These include coronary heart disease, obesity, type 2 diabetes, tooth decay and some cancers. For over a decade, <a href="https://www.researchgate.net/profile/Grace-Jones-10#publications">my research</a> has focused on the mechanisms by which fructose intake plays into disease. </p>
<p>A growing number of African countries have joined the worldwide efforts to reduce sugar intake. For instance, in an attempt to address obesity, diabetes and other non-communicable diseases, South Africa introduced a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9597050/#:%7E:text=South%20Africa%20became%20the%20first,implemented%20on%201%20April%202018.&text=Referred%20to%20as%20the%20Health,billions%20of%20rands%20in%20revenues.">tax on sugar-sweetened drinks</a> in 2018. </p>
<p>It’s hard to avoid sugar when it’s become a normal part of diets and when we celebrate special times with sweet treats. But being more aware of what sugar is and how it can affect our health is the first step.</p>
<h2>What is sugar?</h2>
<p>Sugar is a class of naturally occurring sweet-tasting molecules found in fruits, vegetables, plants and the milk of mammals. It can be extracted from these natural sources and concentrated in processed foods. </p>
<p>The sweet-tasting molecules in sucrose (table sugar) are glucose and fructose. </p>
<p>Sucrose is a disaccharide. This is a molecule made of two simple sugars – glucose and fructose – in a 1:1 ratio and chemically bound. Sucrose is used in many processed foods.</p>
<p>High fructose corn syrup, also used in processed foods, is a mixture of the monosaccharides glucose and fructose. Usually the combination is 45% glucose and 55% fructose. </p>
<p>Sucrose and high fructose corn syrup are more concentrated in processed foods than in fruits and vegetables. </p>
<p>Both are considered added sugars when they are <a href="https://ift.onlinelibrary.wiley.com/doi/abs/10.1111/1541-4337.12151">added to foods and drinks</a>. Besides the sweet taste, they may be <a href="https://www.sciencedaily.com/releases/2015/08/150818131807.htm#:%7E:text=Sugar%20aids%20in%20the%20fermentation,reducing%20water%20activity%20in%20foods">added</a> for colour and texture, as a preservative or to aid fermentation. </p>
<p>There are other natural sugars found in the foods we eat. Lactose, or milk sugar, is a disaccharide made of two simple sugars – glucose and galactose – in a 1:1 ratio. It’s found in mammals’ milk and produced naturally to provide nutrition to offspring, and in other dairy products, such as cheese and ice cream. </p>
<p>Honey, made from nectar by honeybees, is primarily a mixture of glucose and fructose monosaccharides with some maltose, sucrose and other carbohydrates. Maltose, which is found in breakfast cereals and breads, is a disaccharide of two glucose molecules. </p>
<p>Naturally occurring sugars are made by plants, bees or mammals based on their needs. </p>
<p>The human body needs glucose as a fuel for every cell, especially brain cells. That’s one of the reasons why we need a stable blood glucose level throughout the day and night.</p>
<p>The way our bodies use fructose is different. It can be turned into glucose, used as fuel, or processed into fats, called triglycerides. Excessive fructose in our diets can lead to <a href="https://pubmed.ncbi.nlm.nih.gov/29408694/">increases</a> in blood triglycerides, liver fat, blood glucose, body mass index and insulin resistance (where the body cannot easily remove glucose from the bloodstream). </p>
<p>Increases in these markers can lead to an increased risk for metabolic dysfunction, type 2 diabetes and non-alcoholic fatty liver disease (or metabolic dysfunction-associated steatotic liver disease). </p>
<p>Because of the difference in how the body uses glucose and fructose, and evidence that a higher consumption of sugar leads to worse health outcomes, we must be mindful of the added sugar we eat.</p>
<h2>What would happen if we quit eating sugar?</h2>
<p>A group of scientists performed a study and published a set of research papers that detailed <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/oby.21371">exactly what happened</a> when over 40 children (aged eight to 18) stopped eating sugar and fructose for 10 days. The participants didn’t stop eating bread, hotdogs or snacks. They stopped eating fructose. These studies found <a href="https://pubmed.ncbi.nlm.nih.gov/28579536/">significant reductions</a> in:</p>
<ul>
<li><p>newly made triglycerides (or fats)</p></li>
<li><p>fasting blood glucose</p></li>
<li><p>blood pressure</p></li>
<li><p>fat stored on organs, including the liver</p></li>
<li><p>AST, which is a marker of liver function</p></li>
<li><p>insulin resistance, as their cells were better able to remove glucose from the bloodstream</p></li>
<li><p>body mass index.</p></li>
</ul>
<p>The participants also reported feeling better and were better behaved.</p>
<p>The World Health Organization has made <a href="https://iris.who.int/bitstream/handle/10665/149782/9789241549028_eng.pdf?sequence=1">recommendations</a> for adults and children to reduce their sugar intake to about 58 grams, or 14 teaspoons, per day or between 5% and 10% of total caloric intake. </p>
<p>This is not a lot of sugar. </p>
<p>Consider that a 300ml bottle of Coca-Cola or 240ml cup of sugarcane juice contain about <a href="https://www.coca-cola.com/ke/en/brands/brand-coca-cola/product-coca-cola-original#accordion-d588759a1d-item-8b5bb499cf">30 grams</a> of sugar. One piece of mandazi, a popular deep-fried Kenyan wheat snack, has about <a href="https://www.nutritionix.com/i/nutritionix/mandazi-1-small-piece-3-diameter/5c4f552f21b2c9e80f1748f2">4 grams</a> of sugar, or about 6% of the WHO’s recommended intake contained in each small piece.</p>
<h2>What can I do to lower my sugar intake to recommended levels?</h2>
<p>First, keep track of everything you eat during a typical day, what you eat, when you eat and how much you eat. Secondly, give yourself a star for the fresh vegetables and whole fruits you eat, and identify the foods that have added sugars. </p>
<p>Now, set an attainable goal that details one thing you can change to either:</p>
<p>1) increase the whole fruits or vegetables you eat or </p>
<p>2) decrease the amount of added sugar that you eat each day. </p>
<p>This way, you can be mindful of the added sugar you consume and adjust what you eat accordingly.</p><img src="https://counter.theconversation.com/content/223239/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Grace Marie Jones receives funding from The National Institutes of Health (US). </span></em></p>
A higher consumption of sugar leads to worse health outcomes, so we need to be mindful of the added sugar we eat.
Grace Marie Jones, Associate Professor, College of Osteopathic Medicine, Touro University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/222972
2024-03-11T12:25:42Z
2024-03-11T12:25:42Z
Why do trees need sunlight? An environmental scientist explains photosynthesis
<figure><img src="https://images.theconversation.com/files/578432/original/file-20240227-20-s7p24d.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2048%2C1364&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The reason trees need sunlight is the same reason their leaves are green.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/scottb211/10108377914/"> Scottb211/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
<hr>
<blockquote>
<p><strong>Why do trees need sunlight? – Tillman, age 9, Asheville, North Carolina</strong></p>
</blockquote>
<hr>
<p>Trees need sunlight for the same reason you need food. The energy from the Sun’s rays is a crucial ingredient in how plants make their own food that helps them power all their cells. Since trees don’t harvest or hunt food, they have to produce their own. The way they make their food is a unique and important chemical process called photosynthesis.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/574698/original/file-20240209-30-3fr5f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="honey-comb pattern of rings each containing many small green spheres" src="https://images.theconversation.com/files/574698/original/file-20240209-30-3fr5f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/574698/original/file-20240209-30-3fr5f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=406&fit=crop&dpr=1 600w, https://images.theconversation.com/files/574698/original/file-20240209-30-3fr5f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=406&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/574698/original/file-20240209-30-3fr5f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=406&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/574698/original/file-20240209-30-3fr5f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=510&fit=crop&dpr=1 754w, https://images.theconversation.com/files/574698/original/file-20240209-30-3fr5f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=510&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/574698/original/file-20240209-30-3fr5f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=510&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 is what makes leaves green.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Plagiomnium_affine_laminazellen.jpeg">Kristian Peters-Fabelfroh/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>What is photosynthesis?</h2>
<p>The cells in plants and all other living things have microscopic components called <a href="https://www.genome.gov/genetics-glossary/Organelle">organelles</a>. One type of organelle in plant cells is the chloroplast, and it contains the <a href="https://www.kidzone.ws/science/lessons/pigments.html">pigment</a> chlorophyll, which is what makes leaves green. When chlorophyll receives sunlight, it starts the <a href="https://education.nationalgeographic.org/resource/photosynthesis">photosynthesis</a> reaction.</p>
<p>The name photosynthesis comes from the ancient Greek words “photo,” which means light, and “synthesis,” which means to make. During this food-making process, plants take carbon dioxide from the air and water from the ground, and with the energy from sunlight, make glucose. Glucose is a very simple type of sugar. Because it is a simple compound, it is simple to make.</p>
<p>Most of the time, photosynthesis occurs in leaves, and leaves take in sunlight to make food. There are some special plants, though, that actually absorb sunlight on their stems. Some of these include cactuses like the balloon-shaped <a href="https://www.gardenia.net/plant/echinocactus-grusonii-golden-barrel-cactus">golden barrel cactus</a>, the spiky <a href="https://huntington.org/educators/learning-resources/spotlight/cylindropuntia-munzii">Munz’s Cholla</a> and the paddle-shaped <a href="https://huntington.org/educators/learning-resources/spotlight/opuntia-ficus-indica">prickly pear</a>. Some plants even have roots that can photosynthesize, like the rare palm <em><a href="https://huntington.org/educators/learning-resources/spotlight/cryosophila-albida">Cryosophila albida</a></em>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/579708/original/file-20240304-28-wxa438.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A graphic diagram of a plant showing sun, soil, roots, leaves and a flower" src="https://images.theconversation.com/files/579708/original/file-20240304-28-wxa438.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579708/original/file-20240304-28-wxa438.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=601&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579708/original/file-20240304-28-wxa438.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=601&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579708/original/file-20240304-28-wxa438.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=601&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579708/original/file-20240304-28-wxa438.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=755&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579708/original/file-20240304-28-wxa438.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=755&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579708/original/file-20240304-28-wxa438.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=755&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sunlight gives plants the energy to turn water and carbon dioxide into carbohydrates – the food their cells need to live and grow.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Photosynthesis_en.svg">At09kg/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
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<h2>Photosynthesis is billions of years old</h2>
<p>Photosynthesis evolved more than <a href="https://doi.org/10.1104%2Fpp.110.161687">3.5 billion years ago</a>. Initially, only single-celled organisms, kind of like today’s algae, could make sugar this way. Oxygen is a waste product from the photosynthesis process, and over time, these single-celled organisms released enough oxygen to change the Earth’s atmosphere. Ultimately, we and all other animals needed this to happen to be able to live and breathe. </p>
<p>Over time, aquatic plants developed, and gradually plants <a href="https://doi.org/10.1126/science.aat3642">moved to land</a> around 500 million years ago to better access their most vital resource: sunlight. Plants eventually got taller by around <a href="https://doi.org/10.1126/science.aar2986">350 million years ago</a>. This is when the first tree evolved, which grew up to 150 feet tall. These trees looked like the evergreen trees we see today – sort of like pines, firs and spruce. And about 125 million years ago, trees that looked like the maples, oaks and beech trees we see today shared the landscape when <a href="https://new.nsf.gov/news/dinosaur-age-fossils-provide-new-insights-origin">dinosaurs ruled the Earth</a>.</p>
<h2>Not just good for plants</h2>
<p>The Sun provides energy for the Earth. However, we humans are not capable of taking in the sun directly and using it to power our bodies. So how do we make use of the Sun’s energy? Plants do it for us.</p>
<p>Plants take in that energy and make food for us and other animals to eat and oxygen for us to breathe. We wouldn’t exist without plants and photosynthesis.</p>
<p>Like the ancient tiny single-celled organisms from 3.5 billion years ago, some microorganisms today use photosynthesis. Specifically, the algae that you might see living on top of lakes and the ocean do. Chlorophyll is why algae is green. </p>
<p>There are <a href="https://news.asu.edu/20191114-asu-study-shows-some-aquatic-plants-depend-landscape-photosynthesis">aquatic plants</a> that use sunlight to grow. They typically make use of less sunlight because sunlight does not travel well through water.</p>
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<a href="https://images.theconversation.com/files/578425/original/file-20240227-30-2rnnkd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="yellowish green grass-like plants underwater" src="https://images.theconversation.com/files/578425/original/file-20240227-30-2rnnkd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/578425/original/file-20240227-30-2rnnkd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/578425/original/file-20240227-30-2rnnkd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/578425/original/file-20240227-30-2rnnkd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/578425/original/file-20240227-30-2rnnkd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/578425/original/file-20240227-30-2rnnkd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/578425/original/file-20240227-30-2rnnkd.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">Some plants can do photosynthesis underwater, where there is less sunlight.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/chesbayprogram/32446887586/">Chesapeake Bay Program/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
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<p>In addition, there are a very few animals that can photosynthesize. The <a href="https://doi.org/10.1038/nature.2012.11214">pea aphid</a> uses pigment to harvest sunlight to make energy. The <a href="https://phys.org/news/2011-01-physicists-outer-shell-hornet-harvest.html">Oriental hornet</a> uses a pigment in its exoskeleton to make energy from sunlight. The <a href="https://www.nationalgeographic.com/animals/article/solar-powered-photosynthetic-sea-slugs-in-decline-news">emerald-green sea slug</a> eats algae and then incorporates chlorophyll from the algae into its body to photosynthesize. Because of this strategy, the sea slug can go nine months without eating. </p>
<p>So the answer to this question – why do trees need sunlight – is to make their food. And thanks to trees and other plants turning sunlight into their food, most of the rest of the living things on Earth get to eat, too!</p>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/222972/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rebekah Stein 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>
Trees – and all plants – harvest sunlight to gain the energy they need to live and grow.
Rebekah Stein, Assistant Professor of Environmental Science, Quinnipiac University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/220756
2024-01-09T20:18:23Z
2024-01-09T20:18:23Z
Why don’t fruit bats get diabetes? New understanding of how they’ve adapted to a high-sugar diet could lead to treatments for people
<figure><img src="https://images.theconversation.com/files/568452/original/file-20240109-23-jjo6l0.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2376%2C1442&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fruit bats have honed their sweet tooth through adaptive evolution.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/fruit-bat-feeding-in-a-tree-royalty-free-image/1293525000">Keith Rose/iStock via Getty Images Plus</a></span></figcaption></figure><p>People around the world eat too much sugar. When the body is unable to process sugar effectively, leading to excess glucose in the blood, this can result in diabetes. According to the World Health Organization, diabetes became the <a href="https://www.who.int/news-room/fact-sheets/detail/the-top-10-causes-of-death">ninth leading cause of death</a> in 2019.</p>
<p>Humans are not the only mammals that love sugar. Fruit bats do, too, eating up to <a href="https://dem.ri.gov/sites/g/files/xkgbur861/files/programs/bnatres/fishwild/outreach/critter-kits/bat-ex-benefits.pdf">twice their body weight</a> in sugary fruit a day. However, unlike humans, fruit bats thrive on a sugar-rich diet. They can <a href="https://doi.org/10.1007/s00360-019-01242-8">lower their blood sugar faster</a> than bats that rely on insects as their main food source.</p>
<p>We are a team of <a href="https://www.menlo.edu/about/find-an-expert/wei-gordon/">biologists</a> and <a href="https://scholar.google.com/citations?user=kkrPGvcAAAAJ&hl=en">bioengineers</a>. Determining how fruit bats evolved to specialize on a high-sugar diet sent us on a quest to approach diabetes therapy from an unusual angle – one that sent us all the way to Lamanai, Belize, for the <a href="https://www.batcon.org/belize-bat-a-thon/">Belize Bat-a-thon</a>, an annual gathering where researchers collect and study bats.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/568470/original/file-20240109-29-2hgb6j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two people wearing face masks, one with a headlamp and one holding a small bat up to the camera" src="https://images.theconversation.com/files/568470/original/file-20240109-29-2hgb6j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/568470/original/file-20240109-29-2hgb6j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568470/original/file-20240109-29-2hgb6j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568470/original/file-20240109-29-2hgb6j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568470/original/file-20240109-29-2hgb6j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568470/original/file-20240109-29-2hgb6j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568470/original/file-20240109-29-2hgb6j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Authors Nadav Ahituv, left, and Wei Gordon.</span>
<span class="attribution"><span class="source">Wei Gordon</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>In our <a href="https://doi.org/10.1038/s41467-023-44186-y">newly published research</a> in Nature Communications, we and colleagues <a href="https://netbiolab.org/w/People:SB_Baek">Seungbyn Baek</a> and <a href="https://scholar.google.com/citations?user=H4jO_DQAAAAJ&hl=en">Martin Hemberg</a> used a technology that analyzes the DNA of individual cells to compare the unique metabolic instructions encoded in the genome of the Jamaican fruit bat, <em>Artibeus jamaicensis</em>, with those in the genome of the insect-eating big brown bat, <em>Eptesicus fuscus</em>. </p>
<p><a href="https://doi.org/10.1038/nature11247">Approximately 2% of DNA</a> is composed of genes, which are segments of DNA that contain the instructions cells use to create certain traits, such as a <a href="https://doi.org/10.1016/j.acthis.2020.151503">longer tongue in fruit bats</a>. The other 98% are segments of DNA that regulate genes and determine the presence and absence of the traits they encode.</p>
<p>To understand how fruit bats evolved to consume so much sugar, we wanted to identify the genetic and cellular differences between bats that eat fruit and bats that eat insects. Specifically, we looked at the genes, regulatory DNA and cell types in two significant organs involved in metabolic disease: the pancreas and the kidney. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568363/original/file-20240109-25-d0snov.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Four male *Artibeus jamaicensis* and four male *Eptesicus fuscus* bats were put in a fast then fed fruit or worms, respectively, or no meal before analyzing the cells and genes of their kidney and pancreas." src="https://images.theconversation.com/files/568363/original/file-20240109-25-d0snov.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568363/original/file-20240109-25-d0snov.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=244&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568363/original/file-20240109-25-d0snov.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=244&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568363/original/file-20240109-25-d0snov.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=244&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568363/original/file-20240109-25-d0snov.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=306&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568363/original/file-20240109-25-d0snov.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=306&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568363/original/file-20240109-25-d0snov.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=306&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 flowchart outlines the authors’ study methodology.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1038/s41467-023-44186-y">Wei Gordon, created with BioRender.com/Nature Communications</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><a href="https://doi.org/10.1038/s41580-020-00317-7">The pancreas</a> regulates blood sugar and appetite by secreting hormones like insulin, which lowers your blood sugar, and glucagon, which raises your blood sugar. We found Jamaican fruit bats have <a href="https://doi.org/10.1038/s41467-023-44186-y">more insulin-producing and glucagon-producing cells</a> than big brown bats, along with regulatory DNA that primes fruit bat pancreatic cells to initiate production of insulin and glucagon. Together these two hormones work to keep blood sugar levels balanced even when the fruit bats are eating large amounts of sugar.</p>
<p><a href="https://doi.org/10.1093%2Fndt%2Fgfx027">The kidney</a> filters metabolic waste from the blood, maintains water and salt balance and regulates blood pressure. Fruit bat kidneys need to be equipped to remove from their bloodstreams the large amounts of water that come from fruit while retaining the low amounts of salt in fruit. We found Jamaican fruit bats have adjusted the compositions of their kidney cells in accordance with their diet, <a href="https://doi.org/10.1038/s41467-023-44186-y">reducing the number of urine-concentrating cells</a> so their urine is more diluted with water compared with big brown bats.</p>
<h2>Why it matters</h2>
<p>Diabetes is one of the most expensive chronic conditions in the world. The <a href="https://doi.org/10.2337/dci23-0085">U.S. spent US$412.9 billion</a> in 2022 on direct medical costs and indirect costs related to diabetes.</p>
<p>Most approaches to developing new treatments for diabetes are based on traditional laboratory animals such as mice because they are easy to reproduce and study in a lab. But outside the lab, there exist mammals like fruit bats that have actually evolved to withstand high sugar loads. Figuring out how these mammals deal with high sugar loads can help researchers identify new approaches to treat diabetes.</p>
<p>By applying new cell characterization technologies on these <a href="https://theconversation.com/e-coli-is-one-of-the-most-widely-studied-organisms-and-that-may-be-a-problem-for-both-science-and-medicine-206045">nonmodel organisms</a>, or organisms researchers don’t usually use for research in the lab, we and a growing body of researchers show that nature could be leveraged to develop novel treatment approaches for disease. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/QIBMyj8ebRU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The authors disentangle a fruit bat from a net during the Belize Bat-a-thon.</span></figcaption>
</figure>
<h2>What still isn’t known</h2>
<p>While our study revealed many potential therapeutic targets for diabetes, more research needs to be done to demonstrate whether our fruit bat DNA sequences can help understand, manage or cure diabetes in humans.</p>
<p>Some of our fruit bat findings may be unrelated to metabolism or are specific only to Jamaican fruit bats. There are <a href="https://www.britannica.com/animal/Old-World-fruit-bat">close to 200 species</a> of fruit bats. Studying more bats will help researchers clarify which fruit bat DNA sequences are relevant for diabetes treatment. </p>
<p>Our study also focused only on bat pancreases and kidneys. Analyzing other organs involved in metabolism, such as the liver and small intestine, will help researchers more comprehensively understand fruit bat metabolism and design appropriate treatments.</p>
<h2>What’s next</h2>
<p>Our team is now testing the regulatory DNA sequences that allow fruit bats to eat so much sugar and checking whether we can use them to better regulate how people respond to glucose.</p>
<p>We are doing this by <a href="https://www.youtube.com/watch?v=Cv59sjupd1Y&t=77s">swapping the regulatory DNA sequences</a> in mice with those of fruit bats and testing their effects on how well these mice manage their glucose levels.</p>
<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><img src="https://counter.theconversation.com/content/220756/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Wei Gordon receives funding from NSF. </span></em></p><p class="fine-print"><em><span>Nadav Ahituv is a cofounder and on the scientific advisory board of Regel Therapeutics and also received funding from BioMarin Pharmaceutical Incorporate.
Funding for this research was supported by the National Human Genome Research Institute grant R01HG012396.
</span></em></p>
Fruit bats can eat up to twice their body weight in fruit a day. But their genes and cells evolved to process all that sugar without any health consequences − a feat drug developers can learn from.
Wei Gordon, Assistant Professor of Biology, Menlo College
Nadav Ahituv, Professor, Department of Bioengineering and Therapeutic Sciences; Director, Institute for Human Genetics, University of California, San Francisco
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/215166
2023-10-09T12:17:28Z
2023-10-09T12:17:28Z
Centenarian blood tests give hints of the secrets to longevity
<figure><img src="https://images.theconversation.com/files/552718/original/file-20231009-28-ftpqy8.jpg?ixlib=rb-1.1.0&rect=103%2C17%2C3725%2C2132&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/portrait-hundred-years-old-woman-centenarian-1022974105">Dan Negureanu/Shutterstock</a></span></figcaption></figure><p>Centenarians, once considered rare, have become commonplace. Indeed, they are the <a href="https://www.weforum.org/agenda/2021/02/living-to-one-hundred-life-expectancy/">fastest-growing demographic group</a> of the world’s population, with numbers roughly doubling every ten years since the 1970s.</p>
<p>How long humans can live, and what determines a long and healthy life, have been of interest for as long as we know. Plato and Aristotle discussed and <a href="https://pubmed.ncbi.nlm.nih.gov/12092789/">wrote about the ageing process</a> over 2,300 years ago. </p>
<p>The pursuit of understanding the secrets behind exceptional longevity isn’t easy, however. It involves <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7105197/">unravelling the complex interplay</a> of genetic predisposition and lifestyle factors and how they interact throughout a person’s life. Now our recent study, <a href="https://link.springer.com/article/10.1007/s11357-023-00936-w">published in GeroScience</a>, has unveiled some common biomarkers, including levels of cholesterol and glucose, in people who live past 90.</p>
<p>Nonagenarians and centenarians have long been of intense interest to scientists as they may help us understand how to live longer, and perhaps also how to age in better health. So far, studies of centenarians have often been small scale and focused on a selected group, for example, excluding centenarians who live in care homes. </p>
<h2>Huge dataset</h2>
<p>Ours is the largest study comparing biomarker profiles measured throughout life among exceptionally long-lived people and their shorter-lived peers to date. </p>
<p>We compared the biomarker profiles of people who went on to live past the age of 100, and their shorter-lived peers, and investigated the link between the profiles and the chance of becoming a centenarian. </p>
<p>Our research included data from 44,000 Swedes who underwent health assessments at ages 64-99 - they were a sample of <a href="https://pubmed.ncbi.nlm.nih.gov/28158674/">the so-called Amoris cohort</a>. These participants were then followed through Swedish register data for up to 35 years. Of these people, 1,224, or 2.7%, lived to be 100 years old. The vast majority (85%) of the centenarians were female. </p>
<p>Twelve blood-based biomarkers related to inflammation, metabolism, liver and kidney function, as well as potential malnutrition and anaemia, were included. All of these <a href="https://www.nature.com/articles/s41591-019-0719-5">have been associated</a> with ageing or mortality in previous studies.</p>
<p>The biomarker related to inflammation was uric acid – a waste product in the body caused by the digestion of certain foods. We also looked at markers linked to metabolic status and function including total cholesterol and glucose, and ones related to liver function, such as alanine aminotransferase (Alat), aspartate aminotransferase (Asat), albumin, gamma-glutamyl transferase (GGT), alkaline phosphatase (Alp) and lactate dehydrogenase (LD). </p>
<p>We also looked at creatinine, which is linked to kidney function, and iron and total iron-binding capacity (TIBC), which is linked to anaemia. Finally, we also investigated albumin, a biomarker associated with nutrition. </p>
<h2>Findings</h2>
<p>We found that, on the whole, those who made it to their hundredth birthday tended to have lower levels of glucose, creatinine and uric acid from their sixties onwards. Although the median values didn’t differ significantly between centenarians and non-centenarians for most biomarkers, centenarians seldom displayed extremely high or low values.</p>
<p>For example, very few of the centenarians had a glucose level above 6.5 earlier in life, or a creatinine level above 125.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Image of Villagrande Strisaili in the Ogliastra Province of Sardinia, Italy, which has the world's highest population of centenarian men." src="https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552719/original/file-20231009-27-cn0vqz.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">Villagrande Strisaili in the Ogliastra Province of Sardinia, Italy, has the world’s highest population of centenarian men.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/villagrande-strisaili-italy-october-2019-scenic-1543489556">Sabino Parente/Shutterstock</a></span>
</figcaption>
</figure>
<p>For many of the biomarkers, both centenarians and non-centenarians had values outside of the range considered normal in clinical guidelines. This is probably because these guidelines are set based on a younger and healthier population. </p>
<p>When exploring which biomarkers were linked to the likelihood of reaching 100, we found that all but two (alat and albumin) of the 12 biomarkers showed a connection to the likelihood of turning 100. This was even after accounting for age, sex and disease burden. </p>
<p>The people in the lowest out of five groups for levels of total cholesterol and iron had a lower chance of reaching 100 years as compared to those with higher levels. Meanwhile, people with higher levels of glucose, creatinine, uric acid and markers for liver function also decreased the chance of becoming a centenarian. </p>
<p>In absolute terms, the differences were rather small for some of the biomarkers, while for others the differences were somewhat more substantial.</p>
<p>For uric acid, for instance, the absolute difference was 2.5 percentage points. This means that people in the group with the lowest uric acid had a 4% chance of turning 100 while in the group with the highest uric acid levels only 1.5% made it to age 100.</p>
<p>Even if the differences we discovered were overall rather small, they suggest a potential link between metabolic health, nutrition and exceptional longevity. </p>
<p>The study, however, does not allow any conclusions about which lifestyle factors or genes are responsible for the biomarker values. However, it is reasonable to think that factors such as nutrition and alcohol intake play a role. Keeping track of your kidney and liver values, as well as glucose and uric acid as you get older, is probably not a bad idea.</p>
<p>That said, chance probably plays a role at some point in reaching an exceptional age. But the fact that differences in biomarkers could be observed a long time before death suggests that genes and lifestyle may also play a role.</p><img src="https://counter.theconversation.com/content/215166/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Karin Modig receives funding from The Swedish Research Council and Swedish Research Council for Health, Working Life, and Welfare.</span></em></p>
Centenarians tend to have lower levels of glucose, creatinine and uric acid from their sixties onwards.
Karin Modig, Associate Professor, Epidemiology, Karolinska Institutet
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/194502
2022-11-14T10:44:38Z
2022-11-14T10:44:38Z
Over 12% of South African adults have diabetes - education is critical to achieve good outcomes
<figure><img src="https://images.theconversation.com/files/494927/original/file-20221112-29604-1ypgsq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Type 2 diabetes mostly affects adults of a certain age.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p><em>Over <a href="https://www.up.ac.za/tshwane-insulin-project-tip/news/post_2937261-world-diabetes-day-up-insulin-project-acknowledges-crucial-role-of-nurses-in-managing-the-disease">12%</a> of adults in South Africa have diabetes. Since 2019, researchers at the University of Pretoria have been working on the <a href="https://www.up.ac.za/diabetes-research-centre/article/3107624/tshwane-insulin-programme-tip">Tshwane Insulin Project</a>. The project consists of delivering training workshops on comprehensive diabetes and hypertension management in primary care. The researchers also provide technical assistance to healthcare professionals to improve diabetes care. The Conversation Africa spoke to project manager Dr Patrick Ngassa Piotie about what diabetes is and why it’s so difficult to manage.</em></p>
<hr>
<h2>What is diabetes?</h2>
<p>Diabetes mellitus, or <a href="https://www.who.int/news-room/fact-sheets/detail/diabetes">diabetes</a>, refers to a group of conditions that affect how the body uses blood glucose (sugar). Diabetes occurs when the pancreas is no longer <a href="https://www.idf.org/aboutdiabetes/what-is-diabetes.html">able to make insulin</a>, or when the body cannot make good use of the insulin it produces. This leads to elevated glucose levels in the blood. Over time, high blood glucose levels cause damage to the body and the failure of various organs.</p>
<p>There are different types of diabetes. Type 2 is the most common. It accounts for 90% of all cases. With type 2, the body is still able to produce insulin but can’t use it correctly. Type 2 diabetes mostly affects adults of a certain age, who are overweight, don’t exercise, and have a family history of diabetes.</p>
<p>Type 1 diabetes can develop at any age, but it occurs most frequently in children and adolescents. With type 1 diabetes, the pancreas produces very little to no insulin. This means people who have type 1 diabetes need insulin daily to maintain blood glucose levels. </p>
<p>Lastly, there’s diabetes that occurs during pregnancy – gestational diabetes. It affects both mother and child, but usually disappears after pregnancy.</p>
<p>Pre-diabetes is a reversible condition. It happens when blood glucose levels are higher than normal, but <a href="https://www.mayoclinic.org/diseases-conditions/diabetes/symptoms-causes/syc-20371444">not high enough to be called diabetes</a>. It can lead to diabetes unless measures such as lifestyle modifications are taken to prevent it.</p>
<p>The symptoms of diabetes are linked to the high levels of sugar in the blood. They include feeling tired and weak, feeling more thirsty than usual, urinating often, or losing weight without trying. Other symptoms such as blurry vision, recurring infections or slow-healing sores are signs of an advanced stage of the disease.</p>
<h2>How is it managed?</h2>
<p>This depends on the type of diabetes. For example, people with type 1 diabetes need daily insulin injections. The management of type 2 diabetes consists of adopting a healthy lifestyle including increased physical activity and healthy diet. However, type 2 diabetes is a progressive disease. This means that, as the condition progresses, people with type 2 diabetes will need oral drugs and/or insulin to keep their blood glucose levels under control.</p>
<p>Managing diabetes is not just about keeping the blood glucose levels within normal ranges. Often, people with diabetes and healthcare professionals must control the blood pressure and cholesterol levels as well. In addition, a key aspect of managing diabetes is to prevent complications by protecting target organs such as the kidneys and the heart, or the feet.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/technology-and-home-visits-can-help-south-africans-with-diabetes-cope-with-insulin-186000">Technology and home visits can help South Africans with diabetes cope with insulin</a>
</strong>
</em>
</p>
<hr>
<p>At the <a href="http://www.diabetes.up.ac.za">University of Pretoria Diabetes Research Centre</a>, we have developed an acronym that summarises our approach to good diabetes care: the <a href="https://www.up.ac.za/media/shared/856/ZP_Resources/living-with-diabetes_starting-insulin.zp225902.pdf">four “Bs” and four “Cs”</a> or 4Bs 4Cs.</p>
<p>The 4Bs are critical elements to control diabetes:</p>
<ul>
<li><p>Blood pressure control</p></li>
<li><p>Blood glucose control</p></li>
<li><p>Blood cholesterol control</p></li>
<li><p>Breathe air, don’t smoke</p></li>
</ul>
<p>The 4Cs are important tests that people with diabetes should receive every year:</p>
<ul>
<li><p>Check eyes, with a diabetic eye screening – a specific test to check for eye problems caused by diabetes</p></li>
<li><p>Check mouth, by going to the dentist</p></li>
<li><p>Check kidneys, with a laboratory test</p></li>
<li><p>Check feet, with a simple easy-to-do foot exam.</p></li>
</ul>
<p>To manage diabetes, healthcare professionals need the full participation of people with diabetes and their families. That is why it’s important that people with diabetes and their families receive <a href="https://www.semdsa.org.za/">diabetes education</a>. People with diabetes must be <a href="https://worlddiabetesday.org/about/theme/">equipped</a> with the skills to navigate self-management decisions and activities. </p>
<h2>What are the main challenges in managing the condition?</h2>
<p>In South Africa, most people with diabetes rely on the public health system for care. This system is overburdened, overstretched and under-resourced. These systemic challenges have an impact on the delivery of diabetes care, despite the availability of diabetes medication – including insulin – free of charge at primary care clinics.</p>
<p>Healthcare professionals often don’t have time for diabetes education because of long queues and congested health facilities. As a result, people with diabetes <a href="https://pubmed.ncbi.nlm.nih.gov/28156143/">don’t receive the education they need</a>. This, in turn, means people don’t have a good understanding of their condition, which affects their ability to adopt appropriate self-management behaviours, and to adhere to their medication.</p>
<p>Research conducted in South Africa has consistently shown that healthcare workers <a href="https://pubmed.ncbi.nlm.nih.gov/32242428/">don’t comply with diabetes management guidelines</a>. They also fail to implement the recommended processes of care such as measurements of body mass index, waist circumference or weight.</p>
<p>Having paper-based medical records instead of electronic medical records is an additional barrier. The medical records are often lost or misplaced. In a context where healthcare professionals rotate often between departments, it becomes difficult to preserve patient history and to ensure continuity of care. A paper-based system makes it difficult to implement structured diabetes care.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/our-research-shows-gaps-in-south-africas-diabetes-management-programme-160275">Our research shows gaps in South Africa's diabetes management programme</a>
</strong>
</em>
</p>
<hr>
<p>South African <a href="https://pubmed.ncbi.nlm.nih.gov/35532128/">studies</a> have found that screening for diabetes-related complications is lacking. For example, healthcare professionals are <a href="https://www.diabetessa.org.za/challenges-facing-sa-in-the-fight-against-diabetic-retinopathy/">not able to screen patients for eye problems</a> caused by diabetes. Diabetic eye screening requires a specific camera that is not available in most clinics and community health centres. </p>
<h2>How can these be addressed?</h2>
<p><a href="https://guidelines.diabetes.ca/cpg">Diabetes care</a> should be structured, evidence-based and facilitated by a multidisciplinary team trained in diabetes management.</p>
<p>South Africa’s health system should be strengthened. Investments are needed to improve the delivery of diabetes care. There is a pressing need for the continuous training of healthcare professionals in diabetes management.</p>
<p>Because of the heavy workload on primary care nurses and doctors, allied healthcare workers, community health workers and health promoters should be trained to carry out non-clinical duties like diabetes education and support.</p>
<p>The recognition and integration of diabetes educators within the public healthcare system should be a priority. This will ensure that diabetes education becomes systematic and consistent. It should be repeated at regular intervals. Families of people living with diabetes should also be involved and receive diabetes education because their support is crucial.</p>
<p>Technology, digital health solutions and telehealth can improve the delivery of quality diabetes care. Clinical information systems such as electronic medical records and electronic patient registries can have a positive impact on evidence-based diabetes care. Those systems should be introduced as a matter of urgency.</p>
<h2>What are some of the key lessons from the Tshwane Insulin Project so far?</h2>
<p>The use of digital health, enhancing the role played by community health workers and following patients proactively are some of the <a href="https://pubmed.ncbi.nlm.nih.gov/34733467/">innovations that were introduced</a>.</p>
<p>Most healthcare professionals are eager to embrace change and new knowledge. And people with diabetes and their families were appreciative of the education they were receiving. They qualified it as life changing.</p>
<p>Improving diabetes care and outcomes in South Africa will require a strong will and unwavering support from the health authorities, the introduction of clinical information systems, the use of technology and digital solutions, advocacy and accountability.</p><img src="https://counter.theconversation.com/content/194502/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Patrick Ngassa Piotie 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>
Improving diabetes care in South Africa requires strong will and support from health authorities, introduction of clinical information systems, the use of technology and digital solutions.
Patrick Ngassa Piotie, Project Manager, University of Pretoria Diabetes Research Centre, University of Pretoria
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/184128
2022-08-22T12:26:15Z
2022-08-22T12:26:15Z
Two surprising reasons behind the obesity epidemic: Too much salt, not enough water
<figure><img src="https://images.theconversation.com/files/471724/original/file-20220629-12-h11vd4.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3600%2C2398&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Salty french fries may taste good, but they just contribute to dehydration and obesity.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/cropped-image-of-tempted-boy-holding-french-fries-royalty-free-image/660559557?adppopup=true">William Voon/EyeEm via Getty Images</a></span></figcaption></figure><p>Scientific studies and <a href="https://www.washingtonpost.com/health/what-percent-young-adults-obese/2021/12/03/b6010f98-5387-11ec-9267-17ae3bde2f26_story.html">media coverage</a> are rife <a href="https://doi.org/10.1002/oby.22073">with warnings</a> on how <a href="https://doi.org/10.31883/pjfns/110735">sugar</a>, <a href="https://doi.org/10.1111/jhn.12559">carbohydrates</a>, <a href="https://doi.org/10.3945/jn.111.153460">saturated fat</a> and <a href="https://www.hsph.harvard.edu/obesity-prevention-source/obesity-causes/physical-activity-and-obesity/">lack of exercise</a> contribute to obesity. And <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7721435/">tens of millions of Americans are still overweight or obese</a> in large part because of the classic Western diet and lifestyle. </p>
<p>As an <a href="https://drrichardjohnson.com/about/#">educator, researcher and professor of medicine</a>, I have <a href="https://drrichardjohnson.com/books/">spent more than 20 years</a> <a href="https://scholar.google.com/citations?user=dTgECeMAAAAJ&hl=en">investigating the causes of obesity</a>, as well as related conditions such as diabetes, high blood pressure and chronic kidney disease. </p>
<p>Throughout my many years of studying obesity and related health conditions, I’ve observed that relatively little is said about two significant pieces of this very complex puzzle: lack of hydration and excessive salt intake. Both are known to contribute to obesity. </p>
<h2>Lessons learned from a desert sand rat</h2>
<p>Nature provides a clue to the role these factors play with the desert sand rat <em>Psammomys obesus</em>, a half-pound rodent with a high-pitched squeak that lives in the salty marshes and deserts of Northern Africa. It survives, barely, by eating the stems of <em>Salicornia</em> – the glasswort – a plant that looks a bit like asparagus. </p>
<p>Although low in nutrients, the glasswort’s fleshy, succulent sap is filled with water that’s rich in salt, at concentrations as high as what’s found in seawater.</p>
<p>Recent studies <a href="https://doi.org/10.1073/pnas.1713837115">have provided new insights</a> into why the desert sand rat might crave the salty sap of glasswort. Although this has not yet been proven specifically in the sand rat, it is likely that a high-salt diet helps the sand rat convert the relatively low amount of carbohydrates it’s ingesting into fructose, a type of sugar that occurs naturally in fruits, honey and some vegetables.</p>
<p>This <a href="https://doi.org/10.1111/joim.12993">helps the animal survive</a> when food and fresh water are sparse. This is because fructose activates a “survival switch” that stimulates foraging, food intake and the storage of fat and carbohydrates that protect the animal from starvation.</p>
<p>However, when the rat is brought into captivity and given the common rodent diet of about 50% carbohydrates, it <a href="https://doi.org/10.1152/ajplegacy.1965.208.2.297">rapidly develops obesity and diabetes</a>. But if given fresh vegetables low in starchy carbohydrates, the rodent remains lean. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A desert sand rat, with prominent whiskers and a brown and white coat, takes a look outside its burrow." src="https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=433&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=433&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=433&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=544&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=544&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=544&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The desert sand rat, also known as the fat sand rat, is actually a gerbil. It’s found in Asia as well as Africa.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/fat-sand-rat-emerging-from-burrow-in-coastal-royalty-free-image/617548398?adppopup=true">Kristian Bell/Moment via Getty Images</a></span>
</figcaption>
</figure>
<p><a href="https://drrichardjohnson.com/books/">My research</a>, and the research of many other scientists over the decades, shows that many Americans unwittingly behave much like a captive desert sand rat, although few are in settings where food and water are limited. They are constantly activating the survival switch. </p>
<h2>Fructose and our diets</h2>
<p>As mentioned, fructose, a simple sugar, appears to have a key role in activating this survival switch that leads to fat production.</p>
<p>Small amounts of fructose, like that found in an individual fruit, are not the problem – rather it is excessive amounts of fructose that are problematic for human health. Most of us get our fructose from table sugar and high-fructose corn syrup. Intake of these two sugars <a href="https://www.usatoday.com/story/news/world/2014/03/05/five-percent-of-calories-should-be-from-sugar/6097623/">totals approximately 15% of calories</a> in the average American diet. </p>
<p>These sugars encourage people to eat more, which can lead to <a href="https://doi.org/10.1038/s41574-021-00627-6">weight gain, fat accumulation and prediabetes</a>. </p>
<p>Our bodies also make fructose on their own – and experimental studies suggest it may be enough to <a href="https://doi.org/10.1074/jbc.RA118.006158">trigger the development of obesity</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A spoonful of sugar, surrounded by sugar cubes, on a wooden table." src="https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=461&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=461&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=461&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=579&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=579&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=579&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Table sugar and high-fructose corn syrup are two of the culprits that can cause weight gain and obesity.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/sugar-spoon-on-wood-royalty-free-image/681197933?adppopup=true">ATU Images/The Image Bank via Getty Images</a></span>
</figcaption>
</figure>
<p>Since fructose is made from glucose, production of fructose increases when blood glucose levels are high. This process happens when we eat a lot of rice, cereal, potatoes and white bread; those are carbs that rapidly release glucose into the blood rapidly.</p>
<p>And notably, fructose production can also <a href="https://doi.org/10.1074/jbc.RA118.006158">be stimulated by dehydration</a>, which drives fat production. </p>
<h2>Fat provides water</h2>
<p>Fat has two major functions. The first one, which is well known, is to store calories for a later time when food is unavailable. </p>
<p>The other major but lesser-known function of fat <a href="https://doi.org/10.1681/ASN.2015121314">is to provide water</a>. </p>
<p>To be clear, fat does not contain water. But when fat breaks down, it generates water in the body. The amount produced is substantial, and roughly equivalent to the amount of fat burned. It’s so significant that some animals <a href="https://doi.org/10.1681/ASN.2015121314">rely on fat to provide water</a> during times when it’s not available. </p>
<p>Whales are but one example. While they drink some seawater, they get most of their water from the foods they eat. And when they go for extended periods without food, they get their water <a href="https://doi.org/10.1242/jeb.204.11.1831">primarily by metabolizing fat</a>. </p>
<h2>Hold the fries</h2>
<p>The role of dehydration as a contributor to obesity should not be underestimated. It commonly occurs after eating salty foods. Both dehydration and salt consumption lead to <a href="https://doi.org/10.1073/pnas.1713837115">the production of fructose and fat</a>. </p>
<p>This is why salty french fries are especially fattening. The salt causes a dehydration-like state that encourages the conversion of the starch in the french fry to fructose.</p>
<p>What’s more, studies show most people who are overweight or obese <a href="https://doi.org/10.1038/sj.ejcn.1602521">don’t drink enough water</a>. They are far more likely to be dehydrated than those who are lean. Their salt intake is also very high compared with lean people’s. </p>
<p>Research shows that people with obesity frequently <a href="https://doi.org/10.1038/ijo.2012.88">have high levels of vasopressin</a>, a hormone that helps the kidneys hold water to regulate urine volume. </p>
<p>But recent studies suggest vasopressin has another purpose, which is <a href="https://doi.org/10.1172/jci.insight.140848">to stimulate fat production</a>. </p>
<p>For someone at risk of dehydration or starvation, vasopressin may have a real survival benefit. But for those not at risk, vasopressin could drive most of the metabolic effects of excess fructose, like weight gain, fat accumulation, fatty liver and prediabetes. </p>
<h2>Drinking more water</h2>
<p>So does this mean drinking more water can help us lose weight? The medical community has <a href="https://www.nytimes.com/2021/09/17/well/live/how-much-water-should-I-drink.html">often scoffed at the assertion</a>. However, our research team found that giving mice more water slowed <a href="https://doi.org/10.1172/jci.insight.140848">weight gain and the development of prediabetes</a>, even when the mice had diets rich in sugar and fat. </p>
<p>There is also increasing evidence that <a href="https://doi.org/10.3390/nu14102070">most people drink too little water</a> in general, and increasing water intake may help people who are obese <a href="https://doi.org/10.1038/oby.2008.409">lose weight</a>. </p>
<p>That’s why I encourage drinking eight tall glasses of water a day. And eight is likely enough; don’t assume more is better. There have been cases of people drinking so much that “water intoxication” occurs. This is particularly a problem with people who have heart, kidney or liver conditions, as well as those who have had recent surgery or <a href="https://doi.org/10.1056/NEJMoa043901">are long-distance runners</a>. It’s always good to first check with your doctor about water intake. </p>
<p>For the desert sand rat, and for our ancestors who scavenged for food, a high-salt and limited-water diet made sense. But human beings no longer live that way. These simple measures – drinking more water and reducing salt intake – offer cheap, easy and healthy strategies that may prevent or treat obesity.</p><img src="https://counter.theconversation.com/content/184128/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Johnson is a Professor of Medicine at the University of Colorado Anschutz Medical Campus who has received funding from the National Institutes of Health, Veteran's Health Administration, and Department of Defense to understand the role of fructose metabolism in a variety of metabolic disorders. He also has equity with Colorado Research Partners LLC that is developing inhibitors of fructose metabolism. He is also author of Nature Wants Us to Be Fat (Benbella books, 2022) that discusses the science of fructose and its role in obesity and metabolic disorders.</span></em></p>
Studies show that most people who are overweight or obese are also chronically dehydrated.
Richard Johnson, Professor of Medicine, University of Colorado Anschutz Medical Campus
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/181263
2022-06-08T20:20:46Z
2022-06-08T20:20:46Z
‘Food sequencing’ really can help your glucose levels. Here’s what science says about eating salad before carbs
<figure><img src="https://images.theconversation.com/files/462659/original/file-20220512-24-a8w7cx.jpg?ixlib=rb-1.1.0&rect=0%2C4%2C1000%2C661&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/healthy-vegan-lunch-bowl-avocado-quinoa-604314275">Shutterstock</a></span></figcaption></figure><p>Biochemist and author of the <a href="https://www.glucose-revolution.com">Glucose Revolution</a> Jessie Inchauspé says tweaking your diet can change your life.</p>
<p>Among her recommendations in the <a href="https://www.abc.net.au/radionational/programs/lifematters/talkback:-could-changing-your-glucose-intake-change-your-life/13791024">mainstream media</a> and <a href="https://www.instagram.com/glucosegoddess/?hl=en">on Instagram</a>, the founder of the “<a href="https://www.glucose-revolution.com">Glucose Goddess movement</a>” says eating your food in a particular order is the key. </p>
<p>By eating salads first, before proteins, and finishing the meal with starchy carbohydrates, she says blood glucose spikes will be flattened, which is better for you.</p>
<p>Scientifically speaking, does this make sense? It turns out, yes, partially.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/lemon-water-wont-detox-or-energise-you-but-it-may-affect-your-body-in-other-ways-180035">Lemon water won't detox or energise you. But it may affect your body in other ways</a>
</strong>
</em>
</p>
<hr>
<h2>What is a glucose spike?</h2>
<p>A glucose spike occurs in your bloodstream <a href="https://www.sciencedirect.com/science/article/pii/S0261561419301542">about 30-60 minutes</a> after you eat carbohydrate. Many things determine how high and how long the peak lasts. These include what you ate with or before the carbohydrate, how much fibre is in the carbohydrate, and your body’s ability to secrete, and use, the hormone insulin.</p>
<p>For people with certain medical conditions, any tactic to flatten the glucose peak is incredibly important. These conditions include: </p>
<ul>
<li><p>diabetes</p></li>
<li><p>reactive hypoglycaemia (a particular type of recurring sugar crash)</p></li>
<li><p>postprandial hypotension (low blood pressure after eating) or </p></li>
<li><p>if you’ve had bariatric surgery. </p></li>
</ul>
<p>That’s because high and prolonged glucose spikes have lasting and detrimental impacts on many hormones and proteins, including those that trigger inflammation. Inflammation is linked with a range of conditions including diabetes and heart disease.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/got-pre-diabetes-heres-five-things-to-eat-or-avoid-to-prevent-type-2-diabetes-80838">Got pre-diabetes? Here's five things to eat or avoid to prevent type 2 diabetes</a>
</strong>
</em>
</p>
<hr>
<h2>Different foods, different spikes</h2>
<p>Does eating different food types before carbs affect glucose spikes? Turns out, yes. This isn’t new evidence either. </p>
<p>Scientists have known for a long time that high-fibre foods, such as salads, slow gastric emptying (the rate at which food exits the stomach). So high-fibre foods <a href="https://link.springer.com/article/10.1186/1475-2891-9-58">slow the delivery</a> of glucose and other nutrients to the small intestine for absorption into the blood.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/462675/original/file-20220512-21-exx33b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Stomach and small intestines" src="https://images.theconversation.com/files/462675/original/file-20220512-21-exx33b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/462675/original/file-20220512-21-exx33b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/462675/original/file-20220512-21-exx33b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/462675/original/file-20220512-21-exx33b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/462675/original/file-20220512-21-exx33b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/462675/original/file-20220512-21-exx33b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/462675/original/file-20220512-21-exx33b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Salads slow down the movement of food from your stomach into your small intestine.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/3d-illustration-human-digestive-system-anatomy-1898319229">Shutterstock</a></span>
</figcaption>
</figure>
<p>Proteins and fats <a href="https://diabetesjournals.org/care/article/32/9/1600/28666/Effects-of-a-Protein-Preload-on-Gastric-Emptying">also slow</a> gastric emptying. Protein has the extra advantage of stimulating a hormone called glucagon-like-peptide 1 (or GLP1). When protein from your food hits the cells in your intestines, this hormone is secreted, slowing gastric emptying even further. The hormone also affects the pancreas where it helps secretion of the hormone insulin that mops up the glucose in your blood. </p>
<p>In fact, drugs that mimic how GLP1 works (known as <a href="https://www.diabetesaustralia.com.au/living-with-diabetes/medicine/injectables/">GLP1 receptor agonists</a>) are a new and very effective class of medication for people with type 2 diabetes. They’re making a real difference to improve their blood sugar control.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/these-4-diets-are-trending-we-looked-at-the-science-or-lack-of-it-behind-each-one-136045">These 4 diets are trending. We looked at the science (or lack of it) behind each one</a>
</strong>
</em>
</p>
<hr>
<h2>What about eating food in sequence?</h2>
<p>Most of the scientific research on whether eating food in a particular order makes a difference to glucose spikes involves giving a fibre, fat or protein “preload” before the meal. Typically, the preload is a liquid and given around 30 minutes before the carbohydrate.</p>
<p>In <a href="https://diabetesjournals.org/care/article/32/9/1600/28666/Effects-of-a-Protein-Preload-on-Gastric-Emptying">one study</a>, drinking a whey protein shake 30 minutes before (rather than with) a mashed potato meal was better at slowing gastric emptying. Either option was better at reducing the glucose spike than drinking water before the meal.</p>
<p>While this evidence shows eating protein before carbohydrates helps reduce glucose spikes, the evidence for eating other food groups separately, and in sequence, during an average meal is not so strong.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/462678/original/file-20220512-18-odqy2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Steak on flame-grill barbecue" src="https://images.theconversation.com/files/462678/original/file-20220512-18-odqy2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/462678/original/file-20220512-18-odqy2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/462678/original/file-20220512-18-odqy2g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/462678/original/file-20220512-18-odqy2g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/462678/original/file-20220512-18-odqy2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/462678/original/file-20220512-18-odqy2g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/462678/original/file-20220512-18-odqy2g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&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 steak takes longer than mash to churn into a size ready for the small intestine.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/grilling-steaks-on-flaming-grill-shot-397498693">Shutterstock</a></span>
</figcaption>
</figure>
<p>Inchauspé <a href="https://www.abc.net.au/radionational/programs/lifematters/talkback:-could-changing-your-glucose-intake-change-your-life/13791024">says</a> fibre, fats, and proteins don’t mix in the stomach – they do. But nutrients don’t exit the stomach until they have been churned into a fine particle size.</p>
<p>Steak takes longer than mash to be churned into a fine particle. Given the additional fact that liquids empty faster than solids, and people tend to complete their entire dinner in around 15 minutes, is there any real evidence that eating a meal within a particular sequence will be more beneficial than eating the foods, as you like, and all mixed up on the plate?</p>
<p>Yes, but it is not very strong. </p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S0261561419301542">One small study</a> tested five different meal sequences in 16 people without diabetes. Participants had to eat their meal within 15 minutes. </p>
<p>There was no overall difference in glucose spikes between groups that ate their vegetables before meat and rice versus the other sequences.</p>
<h2>What’s the take-home message?</h2>
<p>Watching those glucose spikes is particularly important if you have
diabetes or a handful of other medical conditions. If that’s the case, your treating doctor or dietitian will advise how to modify your meals or food intake to avoid glucose spikes. Food ordering may be part of that advice.</p>
<p>For the rest of us, don’t tie yourself up in knots trying to eat your meal in a particular order. But do consider removing sugary beverages, and adding fibre, proteins or fats to carbohydrates to slow gastric emptying and flatten glucose spikes.</p><img src="https://counter.theconversation.com/content/181263/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Leonie Heilbronn currently receives funding from Medical Research Futures Fund and National Health and Medical Research Council, and Isagenix LLT. </span></em></p>
It sounds too good to be true. But the science on how different types of foods affect your glucose levels has been known for a long time.
Leonie Heilbronn, Professor and Group Leader, Obesity & Metabolism, University of Adelaide
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/179454
2022-05-19T12:23:24Z
2022-05-19T12:23:24Z
Is intermittent fasting the diet for you? Here’s what the science says
<figure><img src="https://images.theconversation.com/files/453968/original/file-20220323-23-zm8qqm.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6000%2C3997&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Intermittent fasting could have an array of health benefits, but as of yet there are no long-term studies into its effects.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/intermitted-farsting-diet-concept-royalty-free-image/1361961784?adppopup=true">neirfy/iStock via Getty Images Plus</a></span></figcaption></figure><p>What if I told you all you need to do to lose weight is read a calendar and tell time? These are the basics for successfully following an intermittent fasting diet. </p>
<p>Can it be that simple, though? Does it work? And what is the scientific basis for fasting? As a registered dietitian and <a href="https://experts.okstate.edu/mckale.montgomery">expert in human nutrition and metabolism</a>, I am frequently asked such questions.</p>
<p>Simply stated, intermittent fasting is defined by alternating set periods of fasting with periods in which eating is permitted. One method is <a href="https://doi.org/10.1093/ajcn/86.1.7">alternate-day fasting</a>. On “fast days,” followers of this form of fasting are restricted to consuming no more than 500 calories per day; on “feast days,” which occur every other day, they can eat freely, with no restrictions on the types or quantities of foods eaten. </p>
<p>Other methods include the increasingly popular <a href="https://doi.org/10.1038/s41574-022-00638-x">5:2 method</a>. This form of fasting involves five days of feasting and two days of fasting per week. </p>
<p>Another variation relies on time-restricted eating. That means followers should fast for a specified number of hours – typically 16 to 20 per day – while freely consuming foods within a designated four- to eight-hour period.</p>
<p>But what about eating breakfast and <a href="https://doi.org/10.1056/NEJM198910053211403">then small meals throughout</a> the day to keep the body’s metabolism running? After all, that’s the <a href="https://doi.org/10.1093/ajcn/81.1.16">conventional wisdom</a> that many of us grew up with. </p>
<p>To answer these questions, it helps to understand the basics of human metabolism. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/QNJ3fJT2qY8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A TV host went on a two-month intermittent fast to lose weight. Did it work?</span></figcaption>
</figure>
<h2>Human metabolism 101</h2>
<p>The human body requires a continual supply of energy to sustain life, and the foods we eat provide us with this energy. But because eating is often followed by periods of time without eating, an intricate set of biological pathways is in place to meet the body’s energy demands between meals. </p>
<p>Most of the pathways function at some level all the time, but they fluctuate following a meal in a predictable pattern called the <a href="https://doi.org/10.1007/s13679-018-0308-9">fed-fast cycle</a>. The time frames of the cycle can vary, depending on the food types eaten, the size of the meal and the person’s activity level.</p>
<p>So what happens, metabolically speaking, after we eat? Consuming carbohydrates and fats leads to a rise in blood glucose and also <a href="https://doi.org/10.1001/jama.2013.280593">lipid levels</a>, which include cholesterol and triglycerides. </p>
<p>This triggers the release of insulin from the pancreas. The insulin helps tissues throughout the body take up the glucose and lipids, which supplies the tissues with energy. </p>
<p>Once energy needs are met, leftover glucose is stored in the liver and skeletal muscle in a condensed form called glycogen. When glycogen stores are full, excess glucose converts to fatty acids and is stored in fat tissue. </p>
<p><a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/absorptive-state">About three to 18 hours</a> after a meal – again, depending upon a person’s activity level and size the of the meal – the amount of circulating blood glucose and lipids returns to baseline levels. So tissues then must rely on fuel sources already in the body, which are the glycogen and fat. A hormone called glucagon, secreted by the pancreas, helps facilitate the breakdown of glycogen and fat to provide energy for the body between meals. </p>
<p>Glucagon also initiates a process known as <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/gluconeogenesis">gluconeogenesis</a>, which is the synthesis of glucose from nondietary sources. This helps maintain the right level of blood glucose levels.</p>
<p>When the body reaches a true fasting state – about 18 hours to two days without additional food intake – the body’s stores of glycogen are depleted, and tissues like the heart and skeletal muscle start to rely heavily on fats for energy. That means an increase in the breakdown of the stored fats. </p>
<p>“Aha!” you might say. “So intermittent fasting is the key to ultimate fat burning?” Well, it’s not that simple. Let’s go through what happens next.</p>
<h2>The starvation state</h2>
<p>Though many tissues adapt to using fats for energy, the brain and red blood cells need a continual supply of glucose. But when glucose is not available because of fasting, the body starts to break down its own proteins and <a href="https://doi.org/10.1152/ajpendo.1997.273.6.E1209">converts them to glucose instead</a>. However, because proteins are also critical for supporting essential bodily functions, this is not a sustainable process.</p>
<p>When the body enters the starvation state, the body goes into self-preservation mode, and a metabolic shift occurs in an effort to spare body protein. The body continues to synthesize glucose for those cells and tissue that absolutely need it, but the breakdown of stored fats increases as well to provide energy for tissues such as the skeletal muscle, heart, liver and kidneys. </p>
<p>This also <a href="https://www.ncbi.nlm.nih.gov/books/NBK493179/#">promotes ketogenesis</a>, or the formation of ketone bodies – molecules produced in the liver as an energy source when glucose is not available. In the starvation state, ketone bodies are important energy sources, because the body is not capable of solely utilizing fat for energy. This is why it is inaccurate when some proponents of intermittent fasting claim that fasting is a way of burning “just fat” - it’s not biologically possible.</p>
<p>What happens when you break the fast? The cycle starts over. Blood glucose and lipids return to basal levels, and energy levels in the body are seamlessly maintained by transitioning between the metabolic pathways described earlier. The neat thing is, we don’t even have to think about it. The body is well-equipped to adapt between periods of feasting and fasting. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/G5J6BfFMZPM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Intermittent fasting – fact or fiction? What the science actually says.</span></figcaption>
</figure>
<h2>Possible downsides</h2>
<p>If an “all-or-nothing” dietary approach to weight loss sounds appealing to you, chances are it just might work. Indeed, intermittent fasting diets have produced <a href="https://doi.org/10.1001/jamainternmed.2017.0936">clinically significant</a> amounts of weight loss. Intermittent fasting may also <a href="https://doi.org/10.1038/s41574-022-00638-x">reduce disease risk</a> by lowering blood pressure and blood lipid levels.</p>
<p>On the flip side, numerous studies have shown that the weight reduction from intermittent fasting diets is <a href="https://doi.org/10.1001/jamainternmed.2017.0936">no greater than</a> the weight loss on a standard calorie-restricted diet.</p>
<p>In fact, the weight loss caused by intermittent fasting is due not to spending time in some sort of magic metabolic window, but rather to reduced overall calorie consumption. On feast days, dieters do not typically <a href="https://doi.org/10.1186/1475-2891-9-35">fully compensate</a> for lack of food on fasted days. This is what results in mild to moderate weight loss. Approximately 75% of the weight is fat mass; the rest is lean mass. That’s about the <a href="https://doi.org/10.1038/s41574-022-00638-x">same ratio as a standard low-calorie diet</a>.</p>
<p>Should you still want to go forward with intermittent fasting, keep a few things to keep in mind. First, there are no studies on the long-term safety and efficacy of following this type of diet. Second, studies show that intermittent fasters don’t get enough of <a href="https://doi.org/10.1016/j.clnu.2020.02.022">certain nutrients</a>. </p>
<p>Exercise is something else to consider. It helps preserve lean muscle mass and may also contribute to increased weight loss and long-term weight maintenance. This is important, because nearly a quarter of the weight lost on any diet is muscle tissue, and the efficacy of intermittent fasting for weight loss has been demonstrated <a href="https://doi.org/10.1038/s41574-022-00638-x">for only short durations</a>.</p>
<p>Also, once you stop following an intermittent-fasting diet, you will very likely gain the weight back. This is a critical consideration, because many people find the diet difficult to follow long-term. Imagine the challenge of planning six months’ worth of feasting and fasting around family dinners, holidays and parties. Then imagine doing it for a lifetime. </p>
<p>Ultimately, the best approach is to follow an eating plan that meets current dietary recommendations and fits into your lifestyle.</p><img src="https://counter.theconversation.com/content/179454/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>McKale Montgomery receives funding from the National Institutes of Health.</span></em></p>
Proponents of intermittent fasting say the clock can help you win the battle of the bulge. But the science behind it is a little more complicated.
McKale Montgomery, Assistant Professor of Nutritional Sciences, Oklahoma State University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/174770
2022-01-31T15:49:59Z
2022-01-31T15:49:59Z
How sweat sensors could play a critical role in monitoring our health
<figure><img src="https://images.theconversation.com/files/443001/original/file-20220127-22-9eyjrs.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6000%2C3988&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sweat contains information on the condition of our bodies.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Sweat is a biological fluid — like blood, saliva and urine — that contains metabolites, electrolytes, proteins and hormones. The levels of these vary depending on a person’s health. Wearable sweat sensors have been developed to <a href="https://doi.org/10.1007/s42242-021-00171-2">track users’ health condition and monitor the levels of these substances (known as analytes) in sweat</a>. </p>
<p>Lactate is considered an important biomarker thanks to its involvement in anaerobic metabolism. The undesired accumulation of lactate in muscles can result in fatigue, so changes in the concentration of lactate in sweat can be used to monitor fatigue. At Simon Fraser University’s Additive Manufacturing Laboratory, we have developed <a href="https://doi.org/10.1038/srep30565">a flexible sensor for sweat lactate</a>. </p>
<p>The benefit of using wearable sweat sensors is the capability for real-time, non-invasive and continuous monitoring of sweat. However, there are still challenges that must be overcome for practical biomedical applications such as diagnosis of health conditions.</p>
<h2>Sweat challenges</h2>
<p>One of the first hurdles in developing a reliable sweat sensor is the difficulty of collecting and routing of sweat. There are various methods for sampling sweat for sensing. One of the most representative approaches for collecting sweat is using <a href="https://doi.org/10.1021/acssensors.0c02446">microfluidic systems with channels that deliver sweat</a>. </p>
<p>Absorbent materials like cloth can also be <a href="https://doi.org/10.1007/s10570-019-02396-y">used for sweat sampling for sensing</a>. However, sampling sweat takes time, and how to handle the sweat sample and supply it in the sensing region in a continuous and stable manner remains a challenge for real-time measurement through continuous sensing of freshly generated sweat. </p>
<p>One of the most recent demonstrations used an <a href="https://doi.org/10.1038/s41467-020-18238-6">integrated microfluidic system with thermo-responsive hydrogels</a>. This system demonstrated significant potential for programmable control of sweat routing and sensing, which will improve the sweat handling for future sweat sensors.</p>
<p>Secondly, there is no single representative analyte in sweat. <a href="https://doi.org/10.1039/c9lc00103d">Sweat sensors can detect analytes</a> such as <a href="https://doi.org/10.1039/c9lc01045a">ammonia, ethanol</a>, ions, glucose, lactate, sweat chloride, pH, urea and creatinine, but there isn’t a single analyte that can independently provide a significant picture of an individual’s health. This means that sweat sensors must be able to measure many different substances in sweat to provide a useful report.</p>
<p>There are several sweat sensor products coming to market <a href="https://newsroom.ucla.edu/releases/adhesive-turns-smartwatch-into-biomedical-system">that measure analytes like the protein cytokine</a> and <a href="https://www.epicorebiosystems.com/">glucose and lactate</a>. </p>
<p>A third challenge is the reliability and accuracy of sweat sensors. If we measure the level of a target analyte from sweat, can we determine how reliable the result is in terms of judging the level of the same analyte in subject’s blood?</p>
<p>We still need to determine the relationship between <a href="https://doi.org/10.1039/c8lc01082j">levels of analyte in sweat and blood</a>, and <a href="https://doi.org/10.1126/sciadv.aaw9906">the relationship between sweats from different parts of body</a>. This recent study demonstrated that sweat bio-sensing can provide blood-correlated ethanol concentration data, which gives us hope that it may be possible to find blood-correlated concentrations for other analytes as well.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A woman wearing a red t-shirt checks her blood glucose level" src="https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=409&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=409&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=409&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=514&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=514&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443009/original/file-20220127-4399-1jj7vig.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=514&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">People living with diseases like diabetes can benefit from non-invasive and real-time monitoring.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Powerful solutions</h2>
<p>Users can specifically monitor targeted analytes in real-time by non-invasive sweat sensing. This can save time, energy and resources by helping people avoid painful and inconvenient invasive tests, improving health and living standards, and receiving medical assistance in a timely manner. </p>
<p>Wearable sweat sensors are a powerful solution for monitoring daily health, and could support the prevention, diagnosis, treatment and prognosis of diseases. Technological applications may come earlier than we expected through close collaboration between clinical doctors, scientists and engineers.</p><img src="https://counter.theconversation.com/content/174770/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr. Woo Soo Kim at Simon Fraser University received funding from Natural Sciences and Engineering Research Council of Canada (NSERC). </span></em></p><p class="fine-print"><em><span>Taeil Kim 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>
Sensors that measure sweat could be coming to the market soon, but for them to be useful, we’ll need to understand more about this fluid that our body produces.
Woo Soo Kim, Associate Professor, Mechatronic Systems Engineering, Simon Fraser University
Taeil Kim, Postdoctoral fellow, Applied Sciences, Simon Fraser University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/173992
2022-01-14T13:35:45Z
2022-01-14T13:35:45Z
Sugar detox? Cutting carbs? A doctor explains why you should keep fruit on the menu
<figure><img src="https://images.theconversation.com/files/440471/original/file-20220112-25-egh65j.jpg?ixlib=rb-1.1.0&rect=270%2C457%2C4193%2C2828&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Ripe berries and sugar crystals are both sweet, but one offers much more than just calories.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/sugar-sprinkling-down-onto-a-spoonful-of-strawberries-taken-news-photo/138203565">Chris George/PhotoPlus Magazine/Future via Getty Images</a></span></figcaption></figure><p>One of my patients – who had been struggling with obesity, uncontrolled diabetes and the cost of her medications – agreed in June 2019 to adopt a more whole-food plant-based diet.</p>
<p>Excited by the challenge, she did a remarkable job. She increased her fresh fruit and vegetable intake, stopped eating candy, cookies and cakes and cut down on foods from animal sources. Over six months, she lost 19 pounds and her HbA1c – a measure of her <a href="https://www.cdc.gov/diabetes/managing/managing-blood-sugar/a1c.html">average blood sugar</a> – dropped from 11.5% to 7.6%.</p>
<p>She was doing so well, I expected that her HbA1c would continue to drop and she would be one of our plant-based successes who had reversed diabetes.</p>
<p>Her three-month follow-up visit in March 2020 was canceled because of COVID-19 lockdowns. When I eventually saw her again in May 2021, she’d regained some of the weight and her HbA1c had climbed to 10.4%. She explained that her diabetes doctor and a diabetes nurse educator had told her that she was eating too much “sugar” on the plant-based diet.</p>
<p>She’d been advised to limit carbohydrates by cutting back on fruits and starchy vegetables and eating more fish and chicken. Sugar-free candy, cakes, cookies and artificial sweeteners were encouraged. In the face of conflicting medical advice, she fell back on conventional wisdom that “sugar” is bad and should be avoided whenever possible, especially if you have diabetes. </p>
<p>I’m a physician, board certified in preventive medicine with a <a href="https://lifestylemedicine.org/What-is-Lifestyle-Medicine">lifestyle medicine</a> clinic at Morehouse Healthcare in Atlanta. This emerging medical specialty focuses on helping patients make healthy lifestyle behavior modifications. Patients who adopt whole-food plant-based diets increase carbohydrate intake and often see reversal of chronic diseases including diabetes and hypertension. In my clinical experience, myths about “sugar” and carbohydrates are common among patients and health professionals. </p>
<h2>Fruit vs. sugar</h2>
<p>Your body runs on glucose. It is the simple sugar that cells use for energy.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/440472/original/file-20220112-19-1a13b8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="molecular diagrams for glucose, fructose and galactose" src="https://images.theconversation.com/files/440472/original/file-20220112-19-1a13b8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440472/original/file-20220112-19-1a13b8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=140&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440472/original/file-20220112-19-1a13b8z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=140&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440472/original/file-20220112-19-1a13b8z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=140&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440472/original/file-20220112-19-1a13b8z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=176&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440472/original/file-20220112-19-1a13b8z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=176&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440472/original/file-20220112-19-1a13b8z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=176&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">These molecules are the three kinds of simple sugars, found in starches, fruit and milk.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/biology-diagram-show-structure-and-formation-royalty-free-illustration/1247905133">Trinset/ iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Glucose is a molecular building block of <a href="https://open.oregonstate.education/animalnutrition/chapter/chapter-3/">carbohydrates</a>, one of the three essential <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7468865/">macronutrients</a>. The other two are fat and protein. Starches are long, branching chains of glucose.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/440473/original/file-20220112-21-k525qd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="molecular diagram of chain of glucoses together" src="https://images.theconversation.com/files/440473/original/file-20220112-21-k525qd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440473/original/file-20220112-21-k525qd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=78&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440473/original/file-20220112-21-k525qd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=78&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440473/original/file-20220112-21-k525qd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=78&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440473/original/file-20220112-21-k525qd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=98&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440473/original/file-20220112-21-k525qd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=98&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440473/original/file-20220112-21-k525qd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=98&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chains of simple sugar molecules linked together form starches and other carbohydrates.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/biology-diagram-show-structure-and-formation-royalty-free-illustration/1247905133">Trinset/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Naturally occurring carbohydrates travel in nutrient-dense packages such as fruits, vegetables, whole grains, nuts and seeds. </p>
<p>Humans <a href="https://theconversation.com/a-taste-for-sweet-an-anthropologist-explains-the-evolutionary-origins-of-why-youre-programmed-to-love-sugar-173197">evolved to crave sweet tastes</a> to get the nutrients needed to survive. A daily supply of vitamins, minerals and fiber is needed because our bodies cannot make them. The best source of these substances for our ancient ancestors was sweet, ripe, delicious fruit. In addition, fruits contain <a href="https://fruitsandveggies.org/stories/what-are-phytochemicals/">phytonutrients</a> and <a href="https://www.nccih.nih.gov/health/antioxidants-in-depth">antioxidants</a>, chemicals produced only by plants. Phytonutrients such as <a href="https://doi.org/10.1093/fqsafe/fyx023">ellagic acid in strawberries</a> have cancer-fighting properties and promote heart health. </p>
<p>Refined sugars, on the other hand, are highly processed and stripped of all nutrients except calories. They’re a concentrated form of carbohydrates. The food industry produces refined sugars in many forms. The most common are sucrose crystals, which you’d recognize as table sugar, and high-fructose corn syrup, which is found in many processed foods and sweetened beverages. </p>
<p>If you continually satisfy your taste for sweet with foods that contain refined sugar – rather than the nutrient-rich fruits at the core of this craving passed on by evolution – you <a href="https://doi.org/10.1136/openhrt-2016-000469">may not get all the nutrients you need</a>. Over time, this deficit may create a vicious cycle of overeating that leads to obesity and obesity-related health problems. Women who eat the most fruit <a href="https://doi.org/10.3945/jn.114.199158">tend to have lower rates of obesity</a>.</p>
<h2>Sugar toxicity</h2>
<p>Refined sugars are not directly toxic to cells, but they can combine with proteins and fats in food and in the bloodstream to produce toxic substances such as <a href="https://doi.org/10.3945/an.115.008433">advanced glycation end products</a> (AGEs). High blood glucose levels may produce <a href="https://doi.org/10.1046/j.1432-1033.2002.03017.x">glycated low-density lipoproteins</a>. High levels of these and other glucose-related toxic substances are associated with an increased risk of a wide range of chronic health problems, including <a href="https://doi.org/10.2337/dc17-1740">cardiovascular disease and diabetes</a>.</p>
<p>[<em>You’re smart and curious about the world. So are The Conversation’s authors and editors.</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-youresmart">You can read us daily by subscribing to our newsletter</a>.]</p>
<p>The disease most commonly associated with sugar is Type 2 diabetes. A surprising number of people, including health professionals, incorrectly believe that eating sugar causes Type 2 diabetes. This myth leads to a focus on lowering blood sugar and “counting carbs” while ignoring the real cause: progressive <a href="https://doi.org/10.2337/dcS13-2008">loss of pancreatic beta cell function</a>. At diagnosis, a patient may have lost between <a href="https://doi.org/10.1016/S2213-8587(20)30022-X">40% and 60%</a> of their beta cells, which are responsible for producing insulin. </p>
<p>Insulin is a hormone that controls how much glucose is in the bloodstream by blocking glucose production in the liver and driving it into fat and muscle cells. Loss of beta cell function means not enough insulin gets produced, resulting in the high blood glucose levels characteristic of Type 2 diabetes.</p>
<p>Beta cells have <a href="https://doi.org/10.1007/s00424-010-0862-9">low levels of antioxidants and are susceptible to attack</a> by metabolic and dietary oxidized free radicals and AGEs. Antioxidants in fruit can protect beta cells. Researchers have found that eating <a href="https://www.bmj.com/content/347/bmj.f5001">whole fruit decreases the risk of Type 2 diabetes</a>, with those who <a href="https://doi.org/10.1210/clinem/dgab335">eat the most fruit having the lowest risk</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/440475/original/file-20220112-19-1uy72hg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="hands pouring sugar into a bowl with strawberries in the background" src="https://images.theconversation.com/files/440475/original/file-20220112-19-1uy72hg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440475/original/file-20220112-19-1uy72hg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440475/original/file-20220112-19-1uy72hg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440475/original/file-20220112-19-1uy72hg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440475/original/file-20220112-19-1uy72hg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440475/original/file-20220112-19-1uy72hg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440475/original/file-20220112-19-1uy72hg.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">As you consume less refined sugar, you may notice more nuance in fruits’ flavors.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/christine-burns-rudalevige-pours-sugar-into-the-strawberry-news-photo/806582004">Brianna Soukup/Portland Portland Press Herald via Getty Images</a></span>
</figcaption>
</figure>
<h2>Detoxing from sugar</h2>
<p>People interested in losing weight and improving health often ask if they should do a “sugar detox.” In my opinion this is a waste of time, because it is not possible to eliminate sugar from the body. For instance, if you ate only baked chicken breasts, your liver would convert protein to glucose in a process called <a href="https://www.ncbi.nlm.nih.gov/books/NBK541119/">gluconeogenesis</a>.</p>
<p>Low-carb diets may lead to weight loss, but at the expense of health. Diets that significantly reduce carbohydrates are associated with <a href="https://doi.org/10.1186/1550-2783-7-24">nutrient deficiencies</a> and higher <a href="https://doi.org/10.1371/journal.pone.0055030">risk of death from any cause</a>. On low-carbohydrate <a href="https://www.ncbi.nlm.nih.gov/books/NBK499830/">ketogenic</a> diets the <a href="https://doi.org/10.3390/nu13020374">body will break down muscles</a> and turn their protein into glucose. The lack of fiber causes constipation.</p>
<p>Eliminating foods sweetened with refined sugar is a worthy goal. But don’t think of it as a “detox” – it should be a permanent lifestyle change. The safest way to go on a refined sugar “detox” is to increase your intake of nutrient-dense fruits and vegetables. Once you eliminate refined sugar, you’ll likely find that your taste buds become more sensitive to – and appreciative of – the natural sweetness of fruits.</p>
<p></p><hr> <p></p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?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"></span>
</figcaption>
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<p><em>This article is part of a series examining sugar’s effects on human health and culture. <a href="https://theconversation.com/us/topics/sugar-2022-114641">You can read the articles on theconversation.com.</a></em></p><img src="https://counter.theconversation.com/content/173992/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jennifer Rooke works for Morehouse School of Medicine. This is stated in the article.</span></em></p>
Sugar gets a bad rap, but exactly which sugar is meant? Nutrient-dense sweet ripe fruits are a far cry from refined table sugar – and their differences can have big health implications.
Jennifer Rooke, Assistant Professor of Community Health & Preventive Medicine, Morehouse School of Medicine
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/173214
2022-01-11T13:34:07Z
2022-01-11T13:34:07Z
How does excess sugar affect the developing brain throughout childhood and adolescence? A neuroscientist who studies nutrition explains
<figure><img src="https://images.theconversation.com/files/436595/original/file-20211209-15-n5wcwm.jpg?ixlib=rb-1.1.0&rect=0%2C37%2C6230%2C4091&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A diet high in sugary foods can affect brain development in children.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/assortment-of-products-with-high-sugar-level-royalty-free-image/1137312526?adppopup=true">carlosgaw/iStock via Getty Images Plus</a></span></figcaption></figure><p>Parents often stress about their kids’ sugar intake, but it can be hard to know <a href="https://theconversation.com/how-much-candy-do-americans-eat-in-a-whole-year-173956">how much is too much</a> – or what to do about it. </p>
<p>Glucose – a simple sugar that <a href="https://theconversation.com/whats-the-difference-between-sugar-other-natural-sweeteners-and-artificial-sweeteners-a-food-chemist-explains-sweet-science-172571">forms the basis of most carbohydrate-rich food</a> – is the primary source of energy for the brain. Healthy brains require a continuous source of energy and nutrients to fuel growth, learning and development. </p>
<p>However, that doesn’t mean extra consumption of sugar is good for the developing brain. In fact, too much sugar can actually be detrimental to the normal growth of the brain. </p>
<p><a href="https://www.binghamton.edu/decker/health-wellness-studies/profile.html?id=lina">I am a clinical nutritionist and a nutrition scientist with a neuroscience focus</a> whose <a href="https://scholar.google.com/citations?user=sOMbzQ0AAAAJ&hl=en">research revolves around</a> understanding the impact of diet and lifestyle on brain function and mental well-being. Preliminary results from my research indicate that consumption of sugary food is associated with mental distress – such as anxiety and depression – and disrupted sleep. </p>
<figure class="align-center ">
<img alt="A young girl eats a pink-glazed donut." src="https://images.theconversation.com/files/436767/original/file-20211209-13-8rbzw3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/436767/original/file-20211209-13-8rbzw3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/436767/original/file-20211209-13-8rbzw3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/436767/original/file-20211209-13-8rbzw3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/436767/original/file-20211209-13-8rbzw3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/436767/original/file-20211209-13-8rbzw3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/436767/original/file-20211209-13-8rbzw3.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">Eating too many sugary foods can overstimulate the brain, leading to hyperactivity and mood swings.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/portrait-of-girl-eating-doughnut-jersey-city-new-royalty-free-image/492644977?adppopup=true">Jamie Grill via Getty Images</a></span>
</figcaption>
</figure>
<h2>Sources of sugar in kids’ diet</h2>
<p>Processed foods, such as donuts, sodas and sweetened cereals, often contain added sugars. Unfortunately, these foods tend to be easily accessible to children and teenagers – whether it be after sports games or at birthday parties. </p>
<p>Chemically <a href="https://www.hsph.harvard.edu/nutritionsource/processed-foods/">processed foods</a> are those that have been altered by adding components not naturally found in them. These foods often contain added sugars, preservatives, salts and trans fats – all aimed at increasing taste, texture or shelf life. </p>
<p>As a result, processed foods have a lower nutritional value than whole foods, such as fruits, vegetables and whole grains. One of the most common sweeteners in U.S. food products is high-fructose corn syrup, which contains not only glucose but another simple sugar called fructose. Too much fructose has been <a href="https://doi.org/10.1038/srep09589">associated with increased body fat</a>. High-fructose corn syrup is found in sodas and baked goods like muffins and donuts. </p>
<h2>Diet, brain and function</h2>
<p>Certain dietary components such as amino acids, which form the basis of proteins, act as precursors for brain chemicals. Amino acids also play important roles in mood, learning and cognitive functions.</p>
<p>Like car engines that require the proper fuel to run efficiently, brains also require an <a href="https://www.ncbi.nlm.nih.gov/books/NBK20414/">adequate diet for optimal functioning</a>. The <a href="https://www.livescience.com/29365-human-brain.html">brain is made up of</a> nerve cells, or neurons, and housekeeping cells, called glial cells. Although these two types of brain cells have different metabolic needs, glucose is the primary source of energy for both. </p>
<p>Despite the fact that the brain accounts for only 2% of human body weight, it requires <a href="https://doi.org/10.1073/pnas.172399499">about 20% of the human body’s energy needs</a> to perform all of its functions, including learning, memory and cognitive processes. Research suggests that this number is even higher in children <a href="https://doi.org/10.1097/MPG.0000000000001875">whose brains and bodies are developing rapidly</a>.</p>
<p>Brain function and growth are regulated by brain chemicals known as <a href="https://www.medicalnewstoday.com/articles/326649#key-types-of-neurotransmitters">neurotransmitters</a>, which should dictate <a href="https://doi.org/10.1016/S0166-2236(96)01028-4">the architecture of brain development</a>. Depending on the stage of brain growth, an <a href="https://www.verywellhealth.com/chemical-imbalance-5191365">imbalance of critical neurotransmitters</a> may cause a myriad of ailments, affecting learning, mood and behaviors. </p>
<p>Similarly, a low-quality or imbalanced diet, such as one high in processed sugar, can throw off the brain’s chemical equilibrium. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/lEXBxijQREo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Why are sugary foods so hard to resist? One reason is that sweets activate the brain’s reward system.</span></figcaption>
</figure>
<h2>Excess sugar puts the brain in overdrive</h2>
<p>Because glucose is the primary source of energy to the brain, too much sugar can put it into an overdrive mode. When the brain is overstimulated, it can lead to hyperactivity and mood swings. However, these behavioral changes are only the short-term consequences. Some evidence suggests that this brain hyperactivity in adolescents is linked to <a href="https://doi.org/10.3389/fnins.2021.670430">cognitive deficits in adulthood</a>. </p>
<p>Sugar also <a href="https://doi.org/10.1016/j.neubiorev.2007.04.019">has an addictive effect</a> because it stimulates neurons in the brain’s reward system, known as the limbic system. When activated, the limbic system generates high emotions such as pleasure, which <a href="https://www.healthline.com/nutrition/how-food-addiction-works">reinforces further sugar consumption</a>.</p>
<p>In addition, within the limbic system there is a tiny structure called the <a href="https://doi.org/10.1016/j.neuron.2017.09.013">amygdala</a>, which processes emotional information. Overactivation of the amygdala is associated with exaggerated emotions such as fear and anxiety. </p>
<p>[<em>Over 140,000 readers rely on The Conversation’s newsletters to understand the world.</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-140ksignup">Sign up today</a>.]</p>
<p>Research suggests that there is <a href="https://doi.org/10.1016/j.neubiorev.2019.05.021">a strong relationship</a> between high sugar consumption, altered behaviors and poor emotional regulation. Although sugar intake may boost mood momentarily, chronic sugar consumption has been linked with <a href="https://doi.org/10.1038/s41598-017-05649-7">increased risk of mental health problems</a>. </p>
<p>Studies in lab animals also suggest that <a href="https://doi.org/10.1038/s41398-021-01309-7">high consumption of sugar</a> hinders learning and memory. Interestingly, daily intake of <a href="https://doi.org/10.1038/s41398-021-01309-7">sugar-sweetened beverages</a> during teenage years is associated with worsening of performance on a learning and memory task during adulthood. The researchers of that study suggest that this impairment could be due to alterations in gut bacteria. </p>
<p>Considering the mounting body of evidence, the seemingly <a href="https://theconversation.com/a-taste-for-sweet-an-anthropologist-explains-the-evolutionary-origins-of-why-youre-programmed-to-love-sugar-173197">irresistible sweetness of sugar</a> can translate into a bitter outcome for the developing brain. </p>
<p></p><hr> <p></p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/439239/original/file-20220103-48418-1p7tcpi.png?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"></span>
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<p><em>This article is part of a series examining sugar’s effects on human health and culture. <a href="https://theconversation.com/us/topics/sugar-2022-114641">Read the series at theconversation.com</a>.</em></p><img src="https://counter.theconversation.com/content/173214/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lina Begdache 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>
Kids often crave processed sugary foods. But research shows that consuming too many treats during childhood and adolescence may lead to behavioral and emotional problems.
Lina Begdache, Assistant Professor of Nutrition, Binghamton University, State University of New York
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/159349
2021-04-22T07:34:51Z
2021-04-22T07:34:51Z
Alexei Navalny has been on a hunger strike for over 3 weeks. How long can humans survive without food?
<p>From time to time, generally when there’s a public case of a hunger strike, people ask me how long a person can survive without food.</p>
<p>The hunger strike <a href="https://www.bloomberg.com/news/articles/2021-04-20/kremlin-foe-navalny-extends-hunger-strike-seeks-own-doctors">generating attention</a> at the moment is that of Russian opposition leader Alexei Navalny. Navalny, who was arrested in January after returning to Russia, began refusing food <a href="https://www.washingtonpost.com/world/europe/russia-navalny-hunger-strike-prison/2021/03/31/750214fc-9234-11eb-aadc-af78701a30ca_story.html">on March 31</a> in protest at not being able to access medical care in prison. This means he’s been fasting now for more than three weeks.</p>
<p>Based on the science of long-term fasting, Navalny could theoretically continue his hunger strike for another number of weeks. But reports suggest he’s experiencing problems with his <a href="https://www.reuters.com/world/europe/jailed-kremlin-critic-navalny-growing-risk-kidney-failure-medics-union-2021-04-17/">kidneys</a>, which may be caused by underlying health issues. He’s now <a href="https://www.theguardian.com/world/2021/apr/19/alexei-navalny-moved-to-hospital-as-fears-grow-for-life-of-putin-critic">in a prison hospital</a>, with concerns circulating he is very ill.</p>
<p>To put the specifics of Navalny’s situation aside, a normal adult human can actually survive a surprisingly long time without food, provided they have an adequate intake of water, which contains some minerals. </p>
<h2>Starvation is a long process</h2>
<p>I advise my undergraduate students to avoid hunger strikes to generate public pressure, because generally it takes too long for health risks to become severe enough to garner the expected attention. </p>
<p>Evolution has prepared us well to starve. It’s conceivable early hunter-gatherers and early farmers endured extended periods without adequate food. We’re also aware of pictures of prisoners of war with a skeletal appearance who were undernourished for months, if not years. </p>
<p>The science is pretty well understood, thanks to a pioneer in this field, <a href="https://thehealthsciencesacademy.org/wp-content/uploads/2015/07/Fuel-Metabolism-in-Starvation_ReviewArticleTIMM2008-9Lazar-1.pdf">George F. Cahill</a>, and his colleagues. In the 1960s Cahill worked with volunteers in fasting experiments of up to 40 days, and established many of the ways our bodies seem to adapt to long periods without food. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/by-jailing-alexei-navalny-the-kremlin-may-turn-him-into-an-even-more-potent-opposition-symbol-154258">By jailing Alexei Navalny, the Kremlin may turn him into an even more potent opposition symbol</a>
</strong>
</em>
</p>
<hr>
<p>The main challenge to long-term fasting is our brain. It consumes <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6107421/">20% of our total energy</a>, regardless of mental activity. It also loves glucose, our preferred energy provider when we’re eating normally.</p>
<p>The body’s stores of glucose are fairly limited and run out in less than <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6566767/">one day</a> when we stop eating. But your body knows what to do. While you’re sleeping or fasting, your body starts to convert muscle mass into glucose, thereby keeping glucose levels up. </p>
<p>Producing glucose <a href="https://thehealthsciencesacademy.org/wp-content/uploads/2015/07/Fuel-Metabolism-in-Starvation_ReviewArticleTIMM2008-9Lazar-1.pdf">from muscle protein</a> is a good way to keep up glucose in the short term, but you don’t want to lose muscle mass in case you need to be active again.</p>
<figure class="align-center ">
<img alt="An empty plate with a fork." src="https://images.theconversation.com/files/396476/original/file-20210422-23-1hnfn93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/396476/original/file-20210422-23-1hnfn93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/396476/original/file-20210422-23-1hnfn93.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/396476/original/file-20210422-23-1hnfn93.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/396476/original/file-20210422-23-1hnfn93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/396476/original/file-20210422-23-1hnfn93.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/396476/original/file-20210422-23-1hnfn93.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">When we don’t eat, our body’s stores of glucose — an important energy provider — run out. So our body draws on other reserves for energy.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Enter fat. Fat is our best energy store. In contrast to glycogen (our stores of glucose in the body), fat doesn’t need water to be stored with it, meaning it gives you far more energy for an equivalent amount. Per gram, fat has more than <a href="https://www1.health.gov.au/internet/publications/publishing.nsf/Content/canteen-mgr-tr1%7Enutrition-energy#">twice the energy content</a> of carbohydrates and protein.</p>
<p>Even a person at a normal weight has about <a href="https://en.wikipedia.org/wiki/Body_fat_percentage">15kg of fat</a> and 6kg of protein in the form of muscle. Almost all the fat is dispensable, but only part of the muscles can be wasted to avoid damage to vital organs. </p>
<p>So fat stores are mobilised during fasting to sustain the body. But they provide limited capacity to generate glucose. To keep your brain happy, your body has two tricks up its sleeve. First, fat is converted into <a href="https://en.wikipedia.org/wiki/Ketone_bodies">ketone bodies</a> — an alternative energy supply to glucose — through a process called ketogenesis.</p>
<p>You can push your body to make ketone bodies by eating a lot of fat and minimal glucose (think ketogenic diets), or by starving. The <a href="https://thehealthsciencesacademy.org/wp-content/uploads/2015/07/Fuel-Metabolism-in-Starvation_ReviewArticleTIMM2008-9Lazar-1.pdf">levels of ketone bodies</a> in blood rise after a couple of hours of fasting, and skyrocket over the next couple of days of fasting. Importantly, your organs prefer them over glucose to generate energy. </p>
<p>The second trick is that your brain starts using ketone bodies as an energy source as well. This is an important trick to minimise the loss of muscle mass, by reducing the demand for glucose. The brain works very well on ketone bodies and there’s no reduction of intellectual capacity.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/chemical-messengers-how-hormones-make-us-feel-hungry-and-full-35545">Chemical messengers: how hormones make us feel hungry and full</a>
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</em>
</p>
<hr>
<p>In summary, the body has some nifty ways of using muscle mass and fat to produce the energy we need, when it’s not coming directly from glucose. And we can usually survive until these alternate supplies are depleted. </p>
<h2>So, how long?</h2>
<p>A normal person might last for almost three months without eating if resting; <a href="https://thehealthsciencesacademy.org/wp-content/uploads/2015/07/Fuel-Metabolism-in-Starvation_ReviewArticleTIMM2008-9Lazar-1.pdf">two months</a> is considered a safe bet. </p>
<p>An obese person could take much longer to starve, perhaps 6-12 months, because of the considerably larger fat mass their body can draw on for energy supplies. However, loss of muscle mass could impair mobility, heart and kidney function.</p>
<p>For a person on a hunger strike, the feeling of hunger first increases but then subsides. In response to <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/obr.13191">starvation and malnutrition</a>, a person is likely to experience chronic fatigue, and a range of negative effects on their mood.</p>
<p>However, not drinking any <a href="https://pubmed.ncbi.nlm.nih.gov/32575998/">water</a> is much more dangerous than abstaining from food. It will cause serious health problems and death a lot more quickly.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-the-chemical-agent-that-was-reportedly-used-to-poison-russian-politician-alexei-navalny-145013">What is the chemical agent that was reportedly used to poison Russian politician Alexei Navalny?</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/159349/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stefan Broer has received funding from the Australian Research Council (ARC), the National Health and Medical Research Council (NHMRC) for his work on nutrition and proteins. </span></em></p>
The average person is likely to be able to survive on a hunger strike for two months, provided they are drinking water. Here’s how the human body can manage for so long without food.
Stefan Broer, Head of molecular nutrition group, College of Medicine, Biology and Environment, Australian National University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/129629
2020-01-15T14:08:14Z
2020-01-15T14:08:14Z
How we deduced that our ancestors liked roast vegetables too
<figure><img src="https://images.theconversation.com/files/309461/original/file-20200110-97145-fxrle.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The rhizomes of this flowering plant, Hypoxis angustifolia, were cooked by early humans.</span> <span class="attribution"><span class="source">© Lyn Wadley</span></span></figcaption></figure><p>Archaeological work at the <a href="https://www.tandfonline.com/doi/full/10.1080/00934690.2018.1504544">Border Cave site</a> has revealed the earliest evidence for cooked root vegetables. Border Cave lies between South Africa and <a href="https://www.bbc.com/news/world-africa-43821512">eSwatini</a> and has a remarkable record of human habitation. </p>
<p>Hot, roasted root vegetables are comfort food, and a plateful of <a href="https://www.hsph.harvard.edu/nutritionsource/carbohydrates/">carbohydrate</a> is both satisfying and nutritious. Archaeologists have found that our ancestors thought so, too. A team working at the site has <a href="https://www.sciencedaily.com/releases/2020/01/200102143424.htm">discovered and documented</a> the remains of starchy underground plant stems (called rhizomes) cooked 170,000 years ago. </p>
<p>Border Cave’s roasted rhizomes were identified as <a href="http://pza.sanbi.org/hypoxis"><em>Hypoxis angustifolia</em></a> (yellow stars). This was done by comparing their shape and internal anatomy to those of modern rhizomes which today grow in countries along the eastern flank of Africa. The distribution extends much further too, for example into Yemen. </p>
<p>If, as seems likely, <em>Hypoxis</em> had a similar distribution in the past, it would have provided a secure staple food for people travelling within and out of Africa.</p>
<p>Our findings suggest that the food was transported to the cave and then cooked. The food could easily have been consumed directly in the field by the collectors, but our findings suggest this wasn’t the case, adding extra information about social behaviour and sharing – and a glimpse into ancient communal behaviour – 170,000 years ago. Food was the focus for satisfying physical and social hunger.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/309452/original/file-20200110-97140-1ynour.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/309452/original/file-20200110-97140-1ynour.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/309452/original/file-20200110-97140-1ynour.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/309452/original/file-20200110-97140-1ynour.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/309452/original/file-20200110-97140-1ynour.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/309452/original/file-20200110-97140-1ynour.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/309452/original/file-20200110-97140-1ynour.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/309452/original/file-20200110-97140-1ynour.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">A drone image of Border Cave, a rich source of knowledge about the past because of well documented human habitation in the cave.</span>
<span class="attribution"><span class="source">© Ashley Kruger</span></span>
</figcaption>
</figure>
<h2>Eating habits of our ancestors</h2>
<p><em>Hypoxis angustifolia</em> plants are gregarious so many can be harvested at once. Wooden digging sticks or sharpened bones may have been used to dig rhizomes from the ground. </p>
<p>The food was carried home to the cave, perhaps as a hide-wrapped parcel or a simple bunch tied with leaves. </p>
<p>Wood was also collected for the cooking fire that probably burned to small coals and hot ash before the rhizomes were added directly to the ashes for roasting. Some South Africans are familiar with this cooking technique: as children we made <a href="https://anthrochef.blog/2017/08/11/ash-bread/">“askoek” (ash cakes)</a> directly on coals and tapped them on rocks to dislodge the ash before garnishing our culinary treasures with apricot jam. </p>
<p>Some of the thumb-sized Border Cave rhizomes were lost in the ashes where they were burned and thus preserved for archaeologists. We know that they were burned while still fresh and “green” because the charred rhizomes have split surfaces. This was caused by shrinkage when moisture was rapidly expelled. Many starchy root vegetables can be eaten raw, but their nutritional content is much greater when cooked (the human gut can then access the glucose better and absorb much more of it). </p>
<p>Cooking made <em>Hypoxis</em> rhizomes easy to peel, and rendered them digestible by releasing glucose and breaking down the fibre. Such treatment was particularly important for the aged members of the group and small children that might otherwise have had difficulty chewing the rhizomes. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/309460/original/file-20200110-97158-11crlf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/309460/original/file-20200110-97158-11crlf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/309460/original/file-20200110-97158-11crlf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/309460/original/file-20200110-97158-11crlf5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/309460/original/file-20200110-97158-11crlf5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/309460/original/file-20200110-97158-11crlf5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/309460/original/file-20200110-97158-11crlf5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/309460/original/file-20200110-97158-11crlf5.png?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">Some Border Cave <em>Hypoxis</em> rhizomes. Each rhizome is about 1.2cm wide. Top left is a diagram of the internal structure of <em>Hypoxis</em>, showing splits in the charcoal, mucilage cavities in black, and white ovals representing xylem bundles. On the right is a bundle of xylem vessels magnified 2,000 times.</span>
<span class="attribution"><span class="source">Lyn Wadley</span></span>
</figcaption>
</figure>
<p>The Border Cave occupants were modern humans (<a href="http://humanorigins.si.edu/evidence/human-fossils/species/homo-sapiens"><em>Homo sapiens</em></a>) with the same nutritional needs as people today. To enable our large brains to function we need to consume about 100g of <a href="https://www.dietdoctor.com/low-carb/does-the-brain-need-carbs">carbohydrate per day</a>. <em>Hypoxis</em> rhizomes may have fulfilled that need in the past. </p>
<p>We know, too, that Border Cave dwellers also ate meat because we have recovered the cooked bones of wild animals that were eaten in the cave. In Africa, game meat is lean, especially in the dry season when animals lose weight. Lean meat protein cannot be metabolised by humans in the absence of either carbohydrates or fat. </p>
<p>The addition of some carbohydrate to their diet would then have enabled early humans to process protein effectively. A balanced, healthy diet with a combination of cooked carbohydrate and protein – the “real” palaeo-diet - increased human fitness and longevity.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/309451/original/file-20200110-97126-1cpn7uc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/309451/original/file-20200110-97126-1cpn7uc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/309451/original/file-20200110-97126-1cpn7uc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/309451/original/file-20200110-97126-1cpn7uc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/309451/original/file-20200110-97126-1cpn7uc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/309451/original/file-20200110-97126-1cpn7uc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/309451/original/file-20200110-97126-1cpn7uc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/309451/original/file-20200110-97126-1cpn7uc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The excavation work underway at Border Cave.</span>
<span class="attribution"><span class="source">© Lucinda Backwell</span></span>
</figcaption>
</figure>
<h2>The discovery</h2>
<p>We discovered the first of the rhizomes in 2016 while digging in Border Cave’s ashy sediments. The sediments date between 170,000 and 100,000 years ago. </p>
<p>In total, 55 whole charred rhizomes were recovered, all from the same species. We worked together in the field over a period of four years, collecting modern plants with rhizomes so that we could compare these with the Border Cave ones in order to identify them. </p>
<p>With a permit from local wildlife authorities, we surveyed the Lebombo Mountain hillside near the cave for interesting plants with appropriate rhizomes. When a plant could not immediately be identified it was planted in a vegetable garden to await flowering. When each plant was securely identified, its rhizome was charred, examined microscopically, and compared with Border Cave specimens. </p>
<p>Eventually patience was rewarded, and a combination of morphological and anatomical evidence showed that the Border Cave rhizome was a <em>Hypoxis</em>.</p><img src="https://counter.theconversation.com/content/129629/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lyn Wadley received funding from the Centre of Excellence, University of the Witwatersrand.</span></em></p><p class="fine-print"><em><span>Christine Sievers has received funding from the National Research Foundation</span></em></p>
The charred remains of root vegetables found at Border Cave help us understand how early humans survived and thrived.
Lyn Wadley, Honorary Professor, School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand
Christine Sievers, Senior lecturer, Archaeobotany, University of the Witwatersrand
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/126581
2019-11-14T23:44:14Z
2019-11-14T23:44:14Z
Your brain on sugar: What the science actually says
<figure><img src="https://images.theconversation.com/files/301668/original/file-20191113-77305-17ucjtz.jpg?ixlib=rb-1.1.0&rect=345%2C581%2C3453%2C2123&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The average Canadian adult consumes more than triple the daily limit of 25g added sugar recommended by the World Health Organization.</span> <span class="attribution"><span class="source">(Unsplash/muhammad ruqiyaddin)</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>We love sweet treats. But too much sugar in our diets can lead to <a href="https://www.healthline.com/nutrition/does-sugar-make-you-fat">weight gain and obesity</a>, <a href="https://www.diabetes.ca/recently-diagnosed/type-2-toolkit">Type 2 diabetes</a> and <a href="http://www.actiononsugar.org/sugar-and-health/sugars-and-tooth-decay/">dental decay</a>. We know we shouldn’t be eating candy, ice cream, cookies, cakes and drinking sugary sodas, but sometimes they are so hard to resist. </p>
<p>It’s as if our brain is hardwired to want these foods.</p>
<p>As a neuroscientist my research centres on how <a href="https://theconversation.com/is-the-food-industry-conspiring-to-make-you-fat-81537">modern day “obesogenic,” or obesity-promoting, diets</a> change the brain. I want to understand how what we eat alters our behaviour and whether brain changes can be mitigated by other lifestyle factors.</p>
<p>Your body runs on sugar — glucose to be precise. Glucose comes from the Greek word <em>glukos</em> which means sweet. Glucose fuels the cells that make up our body — <a href="https://www.verywellmind.com/what-is-a-neuron-2794890">including brain cells (neurons)</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/301665/original/file-20191113-77338-10uj0dy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301665/original/file-20191113-77338-10uj0dy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301665/original/file-20191113-77338-10uj0dy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301665/original/file-20191113-77338-10uj0dy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301665/original/file-20191113-77338-10uj0dy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301665/original/file-20191113-77338-10uj0dy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301665/original/file-20191113-77338-10uj0dy.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">3D illustration of neurons in human brain.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Dopamine “hits” from eating sugar</h2>
<p>On an evolutionary basis, our primitive ancestors were scavengers. Sugary foods are excellent sources of energy, so we have evolved to find sweet foods particularly pleasurable. Foods with unpleasant, bitter and sour tastes can be unripe, poisonous or rotting — causing sickness. </p>
<p>So to maximize our survival as a species, we have an innate brain system that makes us like sweet foods since they’re a great source of energy to fuel our bodies. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/forget-toast-and-oatmeal-low-carb-breakfasts-reduce-sugar-spikes-in-those-with-type-2-diabetes-115621">Forget toast and oatmeal, low-carb breakfasts reduce sugar spikes in those with Type 2 diabetes</a>
</strong>
</em>
</p>
<hr>
<p>When we eat sweet foods the brain’s reward system — called the <a href="https://www.neuroscientificallychallenged.com/glossary/mesolimbic-pathway">mesolimbic dopamine system</a> — gets activated. <a href="https://www.sciencenewsforstudents.org/article/explainer-what-dopamine">Dopamine</a> is a brain chemical released by neurons and can signal that an event was positive. When the reward system fires, it reinforces behaviours — making it more likely for us to carry out these actions again. </p>
<p>Dopamine “hits” from eating sugar promote rapid learning to preferentially find more of these foods. </p>
<p>Our environment today is abundant with sweet, energy rich foods. We no longer have to forage for these special sugary foods — they are available everywhere. Unfortunately, our brain is still functionally very similar to our ancestors, and it really likes sugar. So what happens in the brain when we excessively consume sugar?</p>
<h2>Can sugar rewire the brain?</h2>
<p>The brain continuously <a href="https://brainworksneurotherapy.com/what-neuroplasticity">remodels and rewires itself through a process called neuroplasticity</a>. This rewiring can happen in the reward system. Repeated activation of the reward pathway by drugs or by eating lots of sugary foods causes the brain to adapt to frequent stimulation, leading to a sort of tolerance. </p>
<p>In the case of sweet foods, this means we need to eat more to get the same rewarding feeling — a classic feature of addiction. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/301664/original/file-20191113-77320-o9qil1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301664/original/file-20191113-77320-o9qil1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301664/original/file-20191113-77320-o9qil1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301664/original/file-20191113-77320-o9qil1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301664/original/file-20191113-77320-o9qil1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301664/original/file-20191113-77320-o9qil1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301664/original/file-20191113-77320-o9qil1.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">Regularly eating high-sugar foods can amplify cravings.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p><a href="https://theconversation.com/fact-or-fiction-is-sugar-addictive-73340">Food addiction</a> is a controversial subject among scientists and clinicians. While it is true that you can become physically dependent on certain drugs, it is debated whether you can be <a href="https://doi.org/10.1016/j.neubiorev.2014.08.016">addicted to food</a> when you need it for basic survival.</p>
<h2>The brain wants sugar, then more sugar</h2>
<p>Regardless of our need for food to power our bodies, many people experience food cravings, particularly when stressed, hungry or just faced with an alluring display of cakes in a coffee shop. </p>
<p>To resist cravings, we need to inhibit our natural response to indulge in these tasty foods. A network of inhibitory neurons is critical for controlling behaviour. These <a href="https://www.neuroscientificallychallenged.com/blog/2014/5/16/know-your-brain-prefrontal-cortex">neurons are concentrated in the prefrontal cortex</a> — a key area of the brain involved in decision-making, impulse control and delaying gratification.</p>
<p>Inhibitory neurons are like the brain’s brakes and <a href="https://www.healthline.com/health/gamma-aminobutyric-acid">release the chemical GABA</a>. Research in rats has shown that <a href="http://www.learnmem.org/cgi/doi/10.1101/lm.038000.114">eating high-sugar diets can alter the inhibitory neurons</a>. The sugar-fed rats were also less able to control their behaviour and make decisions. </p>
<p>Importantly, this shows that what we eat can influence our ability to resist temptations and may underlie why diet changes are so difficult for people.</p>
<p>A recent study asked people to rate <a href="https://doi.org/10.1016/j.physbeh.2017.10.007">how much they wanted to eat high-calorie snack foods when they were feeling hungry</a> versus when they had recently eaten. The people who regularly ate a high-fat, high-sugar diet rated their cravings for snack foods higher even when they weren’t hungry. </p>
<p>This suggests that regularly eating high-sugar foods could amplify cravings — creating a vicious circle of wanting more and more of these foods.</p>
<h2>Sugar can disrupt memory formation</h2>
<p>Another brain area affected by high sugar diets is the <a href="https://www.medicalnewstoday.com/articles/313295.php">hippocampus</a> — a key memory centre. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/301666/original/file-20191113-77363-1tjadl1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301666/original/file-20191113-77363-1tjadl1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301666/original/file-20191113-77363-1tjadl1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301666/original/file-20191113-77363-1tjadl1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301666/original/file-20191113-77363-1tjadl1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301666/original/file-20191113-77363-1tjadl1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301666/original/file-20191113-77363-1tjadl1.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">Is your breakfast affecting your memory?</span>
<span class="attribution"><span class="source">(Unsplash/ashwin vaswani)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Research shows that rats eating high-sugar diets were <a href="http://learnmem.cshlp.org/content/23/7/386.full.html">less able to remember</a> whether they had previously seen objects in specific locations before. </p>
<p>The sugar-induced changes in the hippocampus were both a <a href="https://qbi.uq.edu.au/brain-basics/brain-physiology/what-neurogenesis">reduction of newborn neurons</a>, which are vital for encoding memories, and an <a href="https://doi.org/10.1016/j.bbi.2013.11.016">increase in chemicals linked to inflammation</a>. </p>
<h2>How to protect your brain from sugar?</h2>
<p>The World Health Organization advises that we limit our intake of added sugars to <a href="https://www.ages.at/en/topics/nutrition/who-sugar-recommendations/">five per cent of our daily calorie intake</a>, which is 25g (six teaspoons). </p>
<p>Considering the average Canadian adult consumes <a href="https://sugar.ca/Sugars-Consumption-and-Dietary-Guidelines/Consumption-of-Sugars-in-Canada.aspx">85g (20 teaspoons) of sugar per day</a>, this is a big diet change for many.</p>
<p>Importantly, the brain’s neuroplasticity capabilities allow it to reset to an extent following cutting down on dietary sugar, and <a href="https://doi.org/10.1016/j.nlm.2016.03.002">physical exercise can augment this process</a>. Foods rich in omaga-3 fats (found in fish oil, nuts and seeds) are also neuroprotective and can boost brain chemicals needed to form new neurons. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/young-adults-need-to-eat-more-omega-3-fats-95508">Young adults need to eat more omega-3 fats</a>
</strong>
</em>
</p>
<hr>
<p>While it’s not easy to break habits like always eating dessert or making your coffee a double-double, your brain will thank you for making positive steps. </p>
<p>The first step is often the hardest. These diet changes can often get easier along the way.</p>
<p>[ <em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/ca/newsletters?utm_source=TCCA&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/126581/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Amy Reichelt receives funding from the Australian Research Council and Canada First Research Excellence Fund (BrainsCAN, Western University). </span></em></p>
Sugar triggers dopamine “hits” in the brain, making us crave more of it. Sugar also disrupts memory formation.
Amy Reichelt, BrainsCAN Research Associate, Western University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/113455
2019-04-23T20:13:23Z
2019-04-23T20:13:23Z
Sickly sweet or just right? How genes control your taste for sugar
<figure><img src="https://images.theconversation.com/files/270320/original/file-20190423-15218-9to8i9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Genes not only influence how sweet you think something is, but also how much sugary food you eat.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/123816682?src=AXenF6GhIp4jrizZ5_Awdg-1-14&size=medium_jpg">from www.shutterstock.com</a></span></figcaption></figure><p>You might love sugary doughnuts, but your friends find them too sweet and only take small nibbles. That’s partly because your genes influence how you perceive sweetness and how much sugary food and drink you consume.</p>
<p>Now our <a href="https://academic.oup.com/ajcn/advance-article-abstract/doi/10.1093/ajcn/nqz043/5475742?redirectedFrom=fulltext">recently published study</a> shows a wider range of genes at play than anyone thought. In particular, we suggest how these genes might work with the brain to influence your sugar habit.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/fact-or-fiction-is-sugar-addictive-73340">Fact or fiction – is sugar addictive?</a>
</strong>
</em>
</p>
<hr>
<h2>What we know</h2>
<p>When food touches our taste buds, taste receptors produce a signal that travels along taste nerves to the brain. This generates a sensation of flavour and helps us decide if we like the food.</p>
<p>Genetic research in the past decade has largely focused on genes for sweet taste receptors and whether variation in these genes influences how sensitive we are to sweetness and how much sugar we eat and drink. </p>
<p><a href="https://doi.org/10.1017/thg.2015.42">Our previous study</a> showed genetics accounts for 30% of how sweet we think sugars or artificial sweeteners are. However, at the time, we didn’t know the exact genes involved.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-do-tongues-taste-food-103744">Curious Kids: how do tongues taste food?</a>
</strong>
</em>
</p>
<hr>
<h2>What our latest study found</h2>
<p>Our new study looked at data from 176,867 people of European ancestry from Australia, the US and UK.</p>
<p>We measured how sweet 1,757 Australians thought sugars (glucose and fructose) and artificial sweeteners (aspartame and <a href="https://pubchem.ncbi.nlm.nih.gov/compound/neohesperidin_dihydrochalcone">neohesperidin dihydrochalcone</a>) were. We also looked at how sweet 686 Americans thought sucrose was and whether they liked its taste. </p>
<p>We also calculated the daily intake of dietary sugars (monosaccharide and disaccharide sugars found in foods such as fruit, vegetables, milk and cheese) and sweets (lollies and chocolates) from 174,424 British people of European descent in the <a href="https://www.ukbiobank.ac.uk/">UK Biobank</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/270326/original/file-20190423-15221-1hw5opp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/270326/original/file-20190423-15221-1hw5opp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/270326/original/file-20190423-15221-1hw5opp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/270326/original/file-20190423-15221-1hw5opp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/270326/original/file-20190423-15221-1hw5opp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/270326/original/file-20190423-15221-1hw5opp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/270326/original/file-20190423-15221-1hw5opp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/270326/original/file-20190423-15221-1hw5opp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">How many lollies do you eat a day? The researchers combined these types of questions with genome analysis to find links between sugar intake and people’s genes.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/1092965624?src=cL9zC9-ie-rJm9Emlw2ZFw-1-29&size=medium_jpg">from shutterstock.com</a></span>
</figcaption>
</figure>
<p>Then we looked at the associations between millions of genetic markers across the whole genome and the perception of sweet taste and sugar intake, using a technique known as <a href="https://doi.org/10.1371/journal.pcbi.1002822">genome-wide association analysis</a>.</p>
<p>After a 15-year study, we showed that several genes (other than those related to sweet taste receptors) have a stronger impact on how we perceive sweetness and how much sugar we eat and drink.</p>
<p>These included an association between the <a href="https://ghr.nlm.nih.gov/gene/FTO">FTO gene</a> and sugar intake. Until now, this gene has been associated with obesity and related health risks. However, the effect is possibly driven <a href="https://www.cell.com/cell-metabolism/fulltext/S1550-4131(15)00475-1?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1550413115004751%3Fshowall%3Dtrue">not by FTO but nearby genes</a> whose protein products act in the brain to regulate appetite and how much energy we use.</p>
<p>We believe a similar situation may be influencing our sugar habit; genes near the FTO gene may be acting in the brain to regulate how much sugar we eat.</p>
<p>Our study suggests the important role the brain plays in how sweet we think something is and how much sugar we consume. That’s in addition to what we already know about the role of taste receptors in our mouth.</p>
<h2>Why we love sweet foods</h2>
<p>Our natural enjoyment of sweet foods could be an evolutionary hangover. Scientists believe being able to taste sweetness might have helped our ancestors identify energy-rich food, which played a critical part in their survival.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/our-ancient-obsession-with-food-humans-as-evolutionary-master-chefs-42899">Our ancient obsession with food: humans as evolutionary Master Chefs</a>
</strong>
</em>
</p>
<hr>
<p>However, being able to taste sweetness doesn’t always mean you prefer to eat lots of sweet-tasting food. </p>
<p>So it looks like there are genes associated with the consumption of sweet foods, but not how sweet we think they are, such as FTO. There might also be genes that influence our perception of sweetness but not how likely we are to eat sweet food.</p>
<h2>Regional differences</h2>
<p>We were surprised to find genes for sweet taste receptors had no effect on either the ability to taste sweetness or on the amount of sugar consumed in our study, which looked only at large populations of European descent.</p>
<p>But by comparing people of different ancestries in the UK Biobank, we showed there was some variation between different populations that variations in genes for sweet taste receptors might explain. For instance, we found people of African descent tended to eat more sugar than people of European and Asian descent.</p>
<h2>So, how can we use this?</h2>
<p>Just like genetics can help explain <a href="https://theconversation.com/why-you-like-coffee-and-i-choose-tea-its-in-the-genes-106854">why some people choose tea over coffee</a>, our latest study helps explain why some people prefer sweet food. That could lead to personalised diets to improve people’s eating habits based on their genetics.</p>
<p>However, genetics is not the only factor to influence your taste for sugary foods and how much of these you eat or drink. So you can’t always blame your genes if you’ve ever tried to quit sugary drinks or snacks and failed.</p><img src="https://counter.theconversation.com/content/113455/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Daniel Liang-Dar Hwang is affiliated with The University of Queensland and QIMR Berghfoer Medical Research Institute. </span></em></p>
People with a sweet tooth can (partly) blame their genes for their sugar habit. New research shows how the brain also gets involved.
Daniel Liang-Dar Hwang, Postdoctoral Researcher, The University of Queensland
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/79413
2017-07-27T02:10:09Z
2017-07-27T02:10:09Z
Could too much sitting be bad for our brains?
<figure><img src="https://images.theconversation.com/files/177821/original/file-20170712-14421-1sum807.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sitting affects our glucose levels, which affects our brain. </span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/8WgCEagMfTk">Unsplash/Andrew Branch</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>In many aspects of life where we need to use our brain power, we also tend to sit down: at school, at work, sitting exams or concentrating on a crossword. In a <a href="http://www.trci.alzdem.com/article/S2352-8737(17)30025-2/fulltext">new paper</a>, we explore how prolonged sitting may affect the brain’s fuel supply and have a negative impact on brain health.</p>
<p>The brain is a glucose hungry organ. It weighs about 2% of body mass but demands about 20% of our resting energy requirements, which is mostly in the form of glucose, the primary brain fuel. If this energy supply is disrupted it can impair and even <a href="https://www.ncbi.nlm.nih.gov/pubmed/22233811">damage brain cells</a>. Therefore, the availability of glucose to brain cells may have implications for brain health.</p>
<p>Exposure of the brain to both <a href="http://www.nejm.org/doi/10.1056/NEJMoa1215740">high glucose levels</a> and <a href="http://jamanetwork.com/journals/jama/fullarticle/183750">low glucose levels</a> can increase the risk of developing dementia. Also, switching between a high and low glucose level, known as glucose variability, is important, as higher <a href="http://care.diabetesjournals.org/content/33/10/2169">glucose variability</a> has been associated with lower cognitive function. This indicates that tight control of glucose is essential for brain health.</p>
<h2>The problem with too much sitting</h2>
<p>Too much sitting can increase the risk of early death. It’s estimated that 60-75 minutes a day of moderate to vigorous intensity exercise is required to offset the <a href="http://thelancet.com/journals/lancet/article/PIIS0140-6736(16)30370-1/fulltext">increased risk</a> of death associated with more than eight hours a day of sitting.</p>
<p>This is a lot of exercise. At least twice as much as the current minimum <a href="http://www.who.int/dietphysicalactivity/factsheet_recommendations/en/">recommended amount</a> for adults. So reducing sitting may be an additional health-enhancing strategy.</p>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/26378942">Multiple studies</a> have demonstrated that reducing and replacing sitting with light intensity walking improves glucose control after food consumption. That means glucose levels that do not spike too high, or dip too low. This may be explained by the way <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4995429/">working muscles</a> can use up some of the glucose in our system, helping to keep glucose in the optimal range.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/179732/original/file-20170726-30108-1fegglk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/179732/original/file-20170726-30108-1fegglk.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/179732/original/file-20170726-30108-1fegglk.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/179732/original/file-20170726-30108-1fegglk.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/179732/original/file-20170726-30108-1fegglk.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/179732/original/file-20170726-30108-1fegglk.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/179732/original/file-20170726-30108-1fegglk.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hypothetical data illustrating the effects of sitting versus intermittent walking on glucose control in response to a meal.</span>
<span class="attribution"><span class="source">Author provided/The Conversation</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p><a href="https://link.springer.com/article/10.1007%2Fs00125-016-4161-7">Evidence suggests</a> that when it comes to glucose control, light intensity physical activity spread across the day can be superior to a day in which a single bout of moderate to vigorous exercise is performed in the morning. Even when the total energy expenditure of the light intensity activity is equal to the energy expenditure of the single bout of higher intensity activity. </p>
<p>Improved glucose control may explain some of the health benefits of reducing sitting time, but what about effects on brain function?</p>
<h2>High sitting time and brain function</h2>
<p>Studies investigating the effects of excessive sitting on brain function have had mixed results. Laboratory studies both <a href="https://www.ncbi.nlm.nih.gov/pubmed/27777038">support</a> and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4769400/">fail to support</a>, the idea that a day of sitting can impair performance on memory related tasks, relative to a day where sitting is interrupted by regular activity breaks.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/177822/original/file-20170712-14233-4i43fl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/177822/original/file-20170712-14233-4i43fl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/177822/original/file-20170712-14233-4i43fl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/177822/original/file-20170712-14233-4i43fl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/177822/original/file-20170712-14233-4i43fl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/177822/original/file-20170712-14233-4i43fl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/177822/original/file-20170712-14233-4i43fl.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">We need to get into the habit of sitting less anyway.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/search/standing-desk?photo=RvPDe41lYBA">Unsplash/Grovemade</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Other types of studies that track a large number of people over a number of years <a href="http://bjsm.bmj.com/content/early/2016/05/06/bjsports-2015-095551">suggest an association</a> between higher sitting time and impaired brain function. But drawing conclusions from these studies is made difficult by the multitude of different measurements used. Generally, methods that do not rely on the self-reporting of participants are preferred, because self-reporting isn’t always accurate. This isn’t always practical though. </p>
<p>Apart from directly measuring performance on cognitively demanding tasks, another approach is to measure something that would theoretically support improved brain function. For example, researchers at New Mexico Highlands University <a href="http://www.fasebj.org/content/31/1_Supplement/840.23">demonstrated</a> that foot impact during walking sends pressure waves through blood vessels to increase brain blood flow. </p>
<p>Brain blood flow is involved in regulating supply of glucose to the brain, and this likely has implications for brain health over time. For example, we know <a href="https://www.ncbi.nlm.nih.gov/pubmed/19931870">decreases in brain blood flow</a> are associated with a more rapid decline in brain function in those with Alzheimer’s disease. </p>
<h2>What can we do?</h2>
<p>For scientists, the way in which sitting is likely to affect brain function poses a research challenge. Based on the available evidence, it’s more likely that reducing sitting would slow cognitive decline, rather than improve cognitive function. </p>
<p>For everyone else, despite a current lack of conclusive studies linking brain health and sitting, reducing sitting time is <a href="http://care.diabetesjournals.org/content/39/11/2065">already advised</a> to prevent other adverse health outcomes linked to poor glucose control. With improved glucose control in mind, reducing sitting is especially important after meals. </p>
<p>So take a walk after lunch, wash the dishes by hand after dinner and take an active commute to and from work if possible. There is much opportunity to reduce sitting time throughout the day, and therefore much potential to have a positive impact on health.</p><img src="https://counter.theconversation.com/content/79413/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Wheeler is supported by The University of Western Australia and The Baker Heart and Diabetes Institute.</span></em></p><p class="fine-print"><em><span>Daniel Green receives funding from the NHMRC, ARC and NHF.</span></em></p><p class="fine-print"><em><span>David Dunstan receives funding from National Health and Medical Research Council, VicHealth, National Heart Foundation of Australia. </span></em></p><p class="fine-print"><em><span>Paul Gardiner receives funding from NHMRC, ARC and DCRC. </span></em></p>
The brain is a glucose-hungry organ. If this energy supply is disrupted, it can impair and even damage brain cells.
Michael Wheeler, PhD Candidate in Exercise Physiology, The University of Western Australia
Daniel Green, Winthrop Professor, The University of Western Australia
David Dunstan, Professor and Laboratory Head of Physical Activity, Baker Heart and Diabetes Institute
Paul Gardiner, Postdoctoral Research Fellow in Healthy Ageing, The University of Queensland
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/78921
2017-06-09T05:01:06Z
2017-06-09T05:01:06Z
We know too much sugar is bad for us, but do different sugars have different health effects?
<figure><img src="https://images.theconversation.com/files/172880/original/file-20170608-29563-1dmhqa8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The type of sugar in popular soft drinks varies from country to country even if the brand name is the same.</span> <span class="attribution"><span class="source">from shutterstock.com</span></span></figcaption></figure><p>Our recent article published in the <a href="https://www.mja.com.au/journal/2017/206/10/sugar-content-soft-drinks-australia-europe-and-united-states">Medical Journal of Australia</a> found that Australian and European soft drinks contained higher concentrations of glucose, and less fructose, than soft drinks in the United States. The total glucose concentration of Australian soft drinks was on average 22% higher than in US formulations.</p>
<p>We compared the composition of sugars in four popular, globally marketed brands – Coca-Cola, Fanta, Sprite and Pepsi – using samples from Australia, Europe and the US. While the total sugar concentration did not differ significantly between brands or geographical location, there were differences between countries in the concentrations of particular sugars, even when drinks were marketed under the same trade name.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/172874/original/file-20170608-29563-pnrhx8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/172874/original/file-20170608-29563-pnrhx8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/172874/original/file-20170608-29563-pnrhx8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=913&fit=crop&dpr=1 600w, https://images.theconversation.com/files/172874/original/file-20170608-29563-pnrhx8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=913&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/172874/original/file-20170608-29563-pnrhx8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=913&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/172874/original/file-20170608-29563-pnrhx8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1148&fit=crop&dpr=1 754w, https://images.theconversation.com/files/172874/original/file-20170608-29563-pnrhx8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1148&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/172874/original/file-20170608-29563-pnrhx8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1148&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sucrose is made up of one glucose molecule and one fructose molecule.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>Whether these differences have distinct effects on long-term health is currently unclear. Certainly, over-consumption of either glucose or fructose will contribute to <a href="http://ajcn.nutrition.org/content/98/4/1084.full.pdf">weight gain</a>, which is associated with a host of health conditions such as <a href="https://www.ncbi.nlm.nih.gov/pubmed/15328324">type 2 diabetes</a> and <a href="http://circ.ahajournals.org/content/121/11/1356">heart disease</a>. And because the body metabolises glucose and fructose in different ways, their effects may differ.</p>
<h2>Sucrose, glucose and fructose</h2>
<p>Soft drinks, as they are referred to in Australia, or “sodas” in the US and “fizzy drinks” in the UK, are non-alcoholic, carbonated, sugar-sweetened beverages. <a href="http://www.coca-colacompany.com/cs/tccc-yir2012/operating_groups.html">Australia ranks seventh out of the top ten countries</a> for soft drink sales per capita.</p>
<p>Sugars are the chief ingredient in soft drinks and include glucose, fructose and sucrose. The source of sugars in popular soft drinks varies between global regions. This is because sugars are sourced from different crops in different areas of the world. </p>
<p>Soft drinks in Australia are primarily sweetened with sucrose from sugar cane. Sucrose, often referred to as “table sugar”, is composed of one glucose molecule and one fructose molecule joined by chemical bonds. This means equal amounts of glucose and fructose are released into the bloodstream when sucrose is digested.</p>
<p>Overseas, soft drinks are sweetened with sucrose-rich sugar beet (Europe) or high-fructose corn syrup (US). High-fructose corn syrup is also made up of glucose and fructose, but contains a higher fructose-to-glucose ratio than sucrose.</p>
<h2>Do they have different health impacts?</h2>
<p>Fructose over-consumption is <a href="https://www.ncbi.nlm.nih.gov/pubmed/26055949">known to contribute</a> to <a href="http://christinecronau.com/wp-content/uploads/2011/10/nrgastro.2010.41.pdf">fatty liver disease</a>. Fatty liver disease affects <a href="https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/liver-fatty-liver-disease">about one in ten people</a> in the West. Non-alcoholic fatty liver disease is the leading cause of liver disease.</p>
<p>Some researchers have suggested too much fructose in the diet can harm the liver in a similar fashion to alcohol. However, this concern is related to <em>added</em> fructose in the diet, not natural sources. Natural sources of fructose, such as fruit, honey and some vegetables, are not generally over-consumed and provide other important nutrients, such as dietary fibre and vitamins. So, fruit does not generally pose a risk for fatty liver disease.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/173054/original/file-20170609-1721-1lht3p3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/173054/original/file-20170609-1721-1lht3p3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/173054/original/file-20170609-1721-1lht3p3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=406&fit=crop&dpr=1 600w, https://images.theconversation.com/files/173054/original/file-20170609-1721-1lht3p3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=406&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/173054/original/file-20170609-1721-1lht3p3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=406&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/173054/original/file-20170609-1721-1lht3p3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=510&fit=crop&dpr=1 754w, https://images.theconversation.com/files/173054/original/file-20170609-1721-1lht3p3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=510&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/173054/original/file-20170609-1721-1lht3p3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=510&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Natural sources of fructose, such as fruit, are generally not over-consumed.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>High glucose consumption rapidly elevates blood glucose and insulin. This may affect <a href="https://www.ncbi.nlm.nih.gov/pubmed/15451897">brain function</a>, including <a href="https://lipidworld.biomedcentral.com/articles/10.1186/1476-511X-13-195">mood and fatigue</a>. Because high blood glucose is <a href="https://www.ncbi.nlm.nih.gov/pubmed/16919548">linked to diabetes</a>, consumption of high-glucose drinks may also raise the risk of diabetes and cardiovascular (heart) disease. </p>
<p>All soft drinks are considered energy-dense, nutrient-poor and bad for health. However, one of the inherent challenges in the field has been an inability to determine the actual dose of glucose or fructose in these drinks. </p>
<p>Studies that follow people over time, and link soft drink consumption to adverse health effects, are complicated by not knowing whether individuals in these studies are simply eating too many energy-rich foods, and whether soft drink consumption coincides with other poor health behaviours. So, further research is required to determine whether soft drinks containing different concentrations of fructose and glucose are associated with differing health risks. </p>
<h2>Soft drink policies</h2>
<p>There is still much to learn about the differences in composition of sugars and patterns of soft drink intake between countries. A small number of countries, including <a href="https://www.theguardian.com/society/2017/feb/22/mexico-sugar-tax-lower-consumption-second-year-running">Mexico</a> and <a href="http://www.bbc.com/news/world-europe-38767941">France</a>, have already implemented taxation on soft drinks. It remains to be determined whether these actions reduce the incidence of obesity, diabetes and heart diseases.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/173056/original/file-20170609-32402-pssvkt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/173056/original/file-20170609-32402-pssvkt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/173056/original/file-20170609-32402-pssvkt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/173056/original/file-20170609-32402-pssvkt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/173056/original/file-20170609-32402-pssvkt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/173056/original/file-20170609-32402-pssvkt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/173056/original/file-20170609-32402-pssvkt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/173056/original/file-20170609-32402-pssvkt.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">Over-consumption of any kind of sugar leads to weight gain.</span>
<span class="attribution"><span class="source">from shutterstock.com</span></span>
</figcaption>
</figure>
<p>Australian policymakers are yet to take action to reduce soft drink consumption. A range of intervention strategies have been considered, including banning sugary soft drinks in schools and hospitals, taxation, and regulating beverage marketing. </p>
<p>The <a href="http://www.abc.net.au/news/2017-06-08/sugary-drinks-to-be-phased-out-of-nsw-health-facilities/8599820">New South Wales Health Department</a> has just announced sugary drinks will be phased out of vending machines, cafes and catering services in the state’s health facilities by December. This is a great move. Importantly, we must continue to increase public awareness of the adverse health effects of sugary soft drinks.</p><img src="https://counter.theconversation.com/content/78921/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bronwyn Kingwell receives funding from the National Health and Medical Research Council of Australia.</span></em></p><p class="fine-print"><em><span>Pia Varsamis and Robyn Larsen 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>
A recent study found Australian soft drinks had higher concentrations of glucose than US soft drinks, which had more fructose. Does this mean Australian drinks are worse for health than US drinks?
Bronwyn Kingwell, Head, Metabolic and Vascular Physiology NHMRC, Senior Principal Research Fellow, Baker Heart and Diabetes Institute
Pia Varsamis, PhD Student, Metabolic and Vascular Physiology, Baker Heart and Diabetes Institute
Robyn Larsen, Postdoctural Research Fellow in Nutritional Biochemistry, Baker Heart and Diabetes Institute
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/73258
2017-02-23T14:03:24Z
2017-02-23T14:03:24Z
The human brain makes fructose, researchers discover – here’s why that might be a big deal
<figure><img src="https://images.theconversation.com/files/157539/original/image-20170220-15892-1cxna2m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Fructose factory.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/425709700?src=aPSVg551_PmaSrRc4TFqPA-1-49&size=medium_jpg">Jezper/Shutterstock.com</a></span></figcaption></figure><p>Researchers at Yale University have <a href="http://insight.jci.org/articles/view/90508">discovered</a> that the brain is capable of making fructose – a simple sugar, usually found in fruit, vegetables and honey.</p>
<p>Not all sugars are equal. Glucose is a simple sugar that provides energy for the cells in your body. Fructose has a less important physiological role and has been repeatedly linked to the development of <a href="http://ajcn.nutrition.org/content/86/4/899.short">obesity and type 2 diabetes</a>. When there is excess glucose the processes that break it down can become saturated, so the body converts glucose into fructose instead, using a process known as the “polyol pathway”, a chemical reaction involved in <a href="https://www.ncbi.nlm.nih.gov/pubmed/18224243">diabetic complications</a>. The researchers at Yale reported in the journal, JCI Insight, that the brain uses the polyol pathway to produce fructose in the brain. </p>
<p>Unlike glucose, which can be metabolised throughout the body, fructose is normally metabolised almost completely <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3533803/">in the liver</a> and also in semen where it <a href="http://onlinelibrary.wiley.com/doi/10.1002/j.1939-4640.1980.tb00035.x/abstract">produces energy for sperm</a>. Most fructose produced by this pathway is thought to stay inside the cells that make it, as fructose levels in the blood are usually extremely low. These low circulating levels make it unlikely that fructose made in this way reaches the brain in significant amounts, and yet some studies have previously identified very <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0128582">high levels of fructose</a> in the central nervous system (the brain and spinal cord). </p>
<p>Importantly, research has shown that exposure to fructose can significantly <a href="http://www.ebiomedicine.com/article/S2352-3964%2816%2930143-8/abstract">alter the expression</a> of hundreds of genes in the brain, including genes that control metabolism, cell communication, inflammation and brain function. This suggests that fructose is likely to alter brain function.</p>
<h2>What it means</h2>
<p>The brain relies heavily on glucose to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3900881/">fuel its activities</a>. There is evidence that those with diabetes have a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2797942/">higher risk of dementia or cognitive decline</a>, suggesting that exposure to excess glucose is also bad for the brain. Until now, the mechanism for this has been poorly understood. </p>
<p>The team at Yale, which published this most recent research, used a brain scanning technology known as as magnetic resonance spectroscopy to measure the levels of glucose and fructose in the brains of eight healthy participants. What they showed was that after just 20 minutes of a glucose infusion into the blood, fructose levels in the brain markedly increased, and at much higher levels than in the blood. </p>
<p>All eight volunteers included in the study saw similar effects, but those that had the highest levels of glucose in the brain also had the highest levels of fructose. This provides the first ever conclusive evidence that the human brain is able to take excess glucose and rapidly convert it into fructose. Production of fructose in the human brain may therefore actually be a mechanism by which high levels of glucose alter brain function. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/157561/original/image-20170220-15914-ws8uuu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/157561/original/image-20170220-15914-ws8uuu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=493&fit=crop&dpr=1 600w, https://images.theconversation.com/files/157561/original/image-20170220-15914-ws8uuu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=493&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/157561/original/image-20170220-15914-ws8uuu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=493&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/157561/original/image-20170220-15914-ws8uuu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=619&fit=crop&dpr=1 754w, https://images.theconversation.com/files/157561/original/image-20170220-15914-ws8uuu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=619&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/157561/original/image-20170220-15914-ws8uuu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=619&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">High-fructose corn syrup is increasingly used in junk food.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/116741284?src=B75GxXz5urHySa3V77fpGQ-1-4&size=medium_jpg">Nitr/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>The findings of this study are very important. The consumption of fructose has greatly increased over the last five decades, due largely to the development of high-fructose corn syrup, a commercial sweetening agent that contains high amounts of free fructose. Consumption of fructose-rich diets have rightly come under attack as the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4429636/">health implications become more clear</a>, but little focus on how glucose can be converted to fructose exists. </p>
<p>We currently have epidemic levels of <a href="https://www.diabetes.org.uk/Type-2-diabetes/">type 2 diabetes</a> in many parts of the world, a disease in which elevated blood glucose levels are seen. The data presented by the team at Yale suggest that in poorly controlled diabetics, whose blood glucose can rise and stay elevated for hours at a time, fructose will likely be rapidly produced in significant amounts in the brain and this could provide a mechanism for <a href="https://www.sciencedaily.com/releases/2015/07/150708160528.htm">changes in the brain</a> seen in type 2 diabetes. The population of poorly controlled diabetics is <a href="http://www.ajmc.com/journals/issue/2013/2013-1-vol19-n6/population-health-approach-for-diabetic-patients-with-poor-a1c-control">growing annually</a> making this an urgent problem.</p>
<p>This data is very exciting but does need to be approached with some caution. As only eight subjects were included in the study, it is difficult to apply the findings to larger populations. It would be interesting to repeat the experiment in people who have diabetes, to show if this effect also occurs due to normal fluctuations in blood-glucose levels. Regardless, this study changes the way we think about how the brain uses sugar and may lead to changes in how we target neurological complications of diabetes.</p><img src="https://counter.theconversation.com/content/73258/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Brown 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 discovery by researchers at Yale University that the brain is capable of converting glucose into fructose may lead to changes in how we target neurological complications in diabetes.
James Brown, Lecturer in Biology and Biomedical Science, Aston University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/57003
2016-04-01T11:47:35Z
2016-04-01T11:47:35Z
Why finding a real alternative to sugar is so difficult
<figure><img src="https://images.theconversation.com/files/116777/original/image-20160330-28455-1j1phef.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sweets for my sweets ...</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=spoonful%20of%20sugar&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=237309733">Kozlenko</a></span></figcaption></figure><p>So much for the decades in which fats and oils were public enemy number one on our dinner plates. There is <a href="http://www.actiononsugar.org/index.html">more and more evidence</a> that sugar – or more precisely, carbohydrate – is behind our increasing rates of <a href="http://www.healthdata.org/news-release/nearly-one-third-world%E2%80%99s-population-obese-or-overweight-new-data-show">obesity</a> and <a href="https://www.sciencedaily.com/releases/2015/04/150402101410.htm">heart disease</a>. Even if the mechanisms by which this occurs are still not well defined, there are endless <a href="http://www.who.int/mediacentre/news/releases/2015/sugar-guideline/en/">calls for</a> reducing its quantities in the foods we eat. Most recently in the UK this led to the chancellor, George Osborne, <a href="https://theconversation.com/sorry-jamie-oliver-id-be-surprised-if-sugar-tax-helped-cut-obesity-56471">announcing</a> a tax on sugary soft drinks. </p>
<p>Had we ever come up with a proper substitute for sugar, of course, we wouldn’t need to have this debate. In <a href="https://theconversation.com/heres-what-happens-to-your-brain-when-you-give-up-sugar-for-lent-37745">our sweetness-addicted era</a>, it is one of science’s greatest challenges. So why has it eluded us for so long, and are we any closer to a solution?</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/116984/original/image-20160331-31093-1gmtfqu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/116984/original/image-20160331-31093-1gmtfqu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/116984/original/image-20160331-31093-1gmtfqu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=587&fit=crop&dpr=1 600w, https://images.theconversation.com/files/116984/original/image-20160331-31093-1gmtfqu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=587&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/116984/original/image-20160331-31093-1gmtfqu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=587&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/116984/original/image-20160331-31093-1gmtfqu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=738&fit=crop&dpr=1 754w, https://images.theconversation.com/files/116984/original/image-20160331-31093-1gmtfqu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=738&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/116984/original/image-20160331-31093-1gmtfqu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=738&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Saccharine on sale.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=saccharine&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=240640765">Lunasee Studios</a></span>
</figcaption>
</figure>
<p>Replacing the sweetness of sugar in foods is actually relatively straightforward. The first synthetic sweetener, saccharine, was <a href="http://www.todayifoundout.com/index.php/2014/05/saccharin-discovered-accident/">discovered accidentally</a> by a young Russian chemist named Constantin Fahlberg in 1879 while studying coal-tar derivatives, when he unknowingly got it on his hands and licked his fingers. Saccharine became widely used around World War I, when natural sugar was in short supply. In the 1960s scientists discovered several more artificial sweeteners in similarly serendipitous ways, including aspartame and acesulfame K.</p>
<p>As well as these discoveries, there are naturally occurring sweeteners that we have actually known about for much longer (see table below). The <a href="http://linguistics.byu.edu/classes/ling450ch/reports/Guarani1.html">Guarani</a> peoples of modern-day Brazil and Paraguay have been using the leaves of the <a href="https://theconversation.com/a-rose-by-any-other-name-the-low-down-on-healthy-coke-33552">stevia</a> plant as a sweetener for about 1,500 years. And the seeds of the West African katemfe fruit, which contain a sweet chemical called thaumatin, have been on our radar since the 19th century. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/116771/original/image-20160330-9712-1frvkxu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/116771/original/image-20160330-9712-1frvkxu.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=185&fit=crop&dpr=1 600w, https://images.theconversation.com/files/116771/original/image-20160330-9712-1frvkxu.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=185&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/116771/original/image-20160330-9712-1frvkxu.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=185&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/116771/original/image-20160330-9712-1frvkxu.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=233&fit=crop&dpr=1 754w, https://images.theconversation.com/files/116771/original/image-20160330-9712-1frvkxu.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=233&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/116771/original/image-20160330-9712-1frvkxu.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=233&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">‘Sweetness’ is relative to sugar – stevia is 275 times as sweet.</span>
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</figure>
<h2>Sweet but sour</h2>
<p>Yet while we have plenty of options for sweetness, there are several difficulties associated with using non-sugar sweeteners in foods. There have been various cancer scares over the years, which have affected <a href="http://drrichswier.com/2015/05/25/fda-generated-stevia-myth/">stevia</a>, <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1637197/">saccharine</a> and <a href="http://www.mercola.com/article/aspartame/hidden_dangers.htm">aspartame</a>, among others. Some artificial sweeteners have <a href="http://www.nhs.uk/news/2014/09September/Pages/Do-artificial-sweeteners-raise-diabetes-risk.aspx">also been</a> linked to type 2 diabetes. </p>
<p>To compound this, governments class all non-sugar sweeteners as additives, which means they are assigned an E-number – even stevia and thaumatin. In an era where consumers have become increasingly wary of these numbers even when there aren’t specific health risks, manufacturers have been moving towards so-called “clean-label” products that are free of them. This puts these sweeteners at a disadvantage. </p>
<p>Aside from health and labelling, sugars have chemical functions in foods that make them difficult to replace. Sugar solutions freeze at a lower temperature than pure water, for instance. In products like ice cream, this is critical to maintaining a soft texture at freezer temperatures. </p>
<p>Sugars play an important role in giving products like bread, cakes and even wine their darker colour, through what chemists call <a href="http://www.scienceofcooking.com/browning_of_foods.htm">non-enzymatic browning reactions</a>. Artificial
sweeteners are not good at reproducing either of these. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/116781/original/image-20160330-28472-616nos.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/116781/original/image-20160330-28472-616nos.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/116781/original/image-20160330-28472-616nos.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/116781/original/image-20160330-28472-616nos.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/116781/original/image-20160330-28472-616nos.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/116781/original/image-20160330-28472-616nos.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/116781/original/image-20160330-28472-616nos.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/116781/original/image-20160330-28472-616nos.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">‘Mmmm aspartame.’</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-12164185/stock-photo-man-checking-food-labelling-on-supermarket-products.html?src=csl_recent_image-1">Monkey Business Images</a></span>
</figcaption>
</figure>
<p>Then there is aftertaste. This arises from the mechanism by which sweetness is detected in the taste buds. One problem is that the structural features of any sweet molecule that allow them to bind to the sweetness receptors on the tongue are <a href="http://www.sciencedirect.com/science/article/pii/S0092867403000710">similar to</a> the ones that bind to our bitterness receptors. This is why some sweeteners leave a bitter aftertaste, which is of course undesirable to some consumers. </p>
<p>But looking at the previous table again, for sweeteners that don’t have a bitter aftertaste there is another issue. Artificial sweeteners bind more strongly to the sweetness receptors and have a different and longer-lasting taste profile to sugar, and so are perceived as tasting different by consumers. </p>
<p>All in all, although non-sugar sweeteners are a multi-billion-pound industry, these drawbacks help to explain why they are nowhere near eclipsing sugar. In 2014 sugar (sucrose) <a href="http://www.preparedfoods.com/articles/114720-alternative-sweeteners-gain-12-share-of-734-billion-market">accounted for</a> 78% of all sweetener sales. Artificial sweeteners made up 8%, with acesulfame k the market leader. Natural alternatives like stevia, which was <a href="https://www.acefitness.org/certifiednewsarticle/1644/the-truth-about-stevia-the-so-called-quot-healthy/">banned</a> in the US and EU until fairly recently, made up 1%. (The rest of the market comprises everything from glucose to syrups). </p>
<h2>Where sweeteners go from here</h2>
<p>The cancer evidence against non-sugar sweeteners has turned out to be thinner than feared. <a href="http://www.cancerresearchuk.org/about-cancer/causes-of-cancer/diet-and-cancer/food-controversies#food_controversies1">Cancer Research UK</a> and the US <a href="http://www.cancer.gov/about-cancer/causes-prevention/risk/diet/artificial-sweeteners-fact-sheet">National Cancer Institute</a> both say there is no increased risk regarding artificial sweeteners. Stevia’s years in the wilderness were the result of an anonymous complaint about the cancer risks to the US authorities <a href="https://health.thefuntimesguide.com/2014/08/what-is-stevia.php">commonly thought</a> to have come from artificial-sweetener producers, but it has since been rehabilitated. As for type 2 diabetes, the <a href="http://www.nature.com/nature/journal/v514/n7521/full/nature13793.html">evidence linking it</a> to artificial sweeteners is <a href="http://nutritionreviews.oxfordjournals.org/content/71/7/433">inconclusive</a> and we need more research – so far it has all been done on animals. </p>
<p>On the physical issues, food scientists have had to think creatively. When it comes to texture, for instance, manufacturers add protein texturisers instead – <a href="http://www.clextral.com/food-feed-2/food/extured-protein/">soy</a>, for example. Or you can turn to other substances that have a similar effect as sugar on the freezing properties of water – the sugar alcohol erythritol is one option. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/116779/original/image-20160330-28443-133low5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/116779/original/image-20160330-28443-133low5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/116779/original/image-20160330-28443-133low5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=792&fit=crop&dpr=1 600w, https://images.theconversation.com/files/116779/original/image-20160330-28443-133low5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=792&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/116779/original/image-20160330-28443-133low5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=792&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/116779/original/image-20160330-28443-133low5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=995&fit=crop&dpr=1 754w, https://images.theconversation.com/files/116779/original/image-20160330-28443-133low5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=995&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/116779/original/image-20160330-28443-133low5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=995&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Stevia wonder?</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=stevia&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=99968267">Olivier le Moal</a></span>
</figcaption>
</figure>
<p>Manufacturers seek to overcome the aftertaste issue by mixing sweeteners. We perceive the aftertaste of different sweeteners over differing timescales, so one sweetener can be used to mask the aftertaste of a second. It is common to use stevia in combination with acesulfame K, for instance. </p>
<p>Another increasingly common ploy is to mix sugar and other sweeteners together. This helps explain why the use of non-sugar sweeteners in new product launches <a href="http://www.mintel.com/press-centre/food-and-drink/stevia-set-to-steal-intense-sweetener-market-share-by-2017-reports-mintel-and-leatherhead-food-research">rose from</a> 3.5% in 2009 to 5.5% in 2012. It also explains why stevia is rocketing. Food analysts Mintel and Leatherhead forecast it will have become the most widely used non-sugar sweetener by as early as next year. </p>
<p>In the absence of a Holy Grail for sugar replacement, this could be as good as it gets any time soon. No wonder the authorities are beginning to intervene to save us from our sweet tooth instead.</p><img src="https://counter.theconversation.com/content/57003/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephen Euston has received research funding from BBSRC, EPSRC, Innovate UK and EC Horizon2020, though the views in this piece are entirely his own. He is also a committee member of the Agri-Food group of the Society of Chemical Industry. </span></em></p>
If only it were as simple as sweetness.
Stephen Euston, Professor, Heriot-Watt University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/51635
2015-12-07T10:33:32Z
2015-12-07T10:33:32Z
Explainer: why can’t humans photosynthesise?
<figure><img src="https://images.theconversation.com/files/103931/original/image-20151201-21714-1ijonx5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">You know what, I think we looked better before.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/clement127/13895046579/in/photolist-naRKfB-9VW2PP-9VYLNQ-ch971m-9VRLJ4-9VX1SF-9VYN9m-9VW5ai-8c4wFn-9VVuvZ-9VYf7E-4Z9LDh-9VYmSw-9VVthg-7Qs1qq-7QoEUR-7Qs21J-7Qs1As-7QoEGZ-9VYmbL-ob2U1T-8VYPoe-9VYV3J-9VWLiM-9VVU6t-8pkrsz-9VYjcU-9VYgwb-9VXyQV-8Eq1tL-9VYKDm-8bxfm9-bu5NTC-aVm9QR-8oZMaM-dLnsCW-9cDJYF-6ui9Tc-dJG9va-4CMAw9-7xSYYM-6L4Rtq-9VYfPo-8Evamu-4VPsdq-6ZbqbA-bUYESJ-itsuF3-hus7Vu-8rDw4L">clement127/flickr</a></span></figcaption></figure><p>Little green men feature heavily in movies about aliens. But why aren’t humans green? And why can’t we photosynthesise like plants? It would, after all, save us a whole lot of bother.</p>
<p>The most familiar green organisms are, of course, plants. Plants are green because their cells are packed with internal organelles – organs within cells – called chloroplasts, which are the centres of <a href="http://www.rsc.org/Education/Teachers/Resources/cfb/Photosynthesis.htm">photosynthesis</a>. These chloroplasts have a rather interesting evolutionary history, as they were once free-living <a href="http://www.ucmp.berkeley.edu/bacteria/cyanointro.html">cyanobacteria</a>, independent of plants. </p>
<p>Cyanobacteria are famous for inventing photosynthesis, a process that harnesses the energy in sunlight to make sugar from water and carbon dioxide. But as any inventor can tell you, if you have a great idea then pretty soon everyone else will want a piece of it. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/atUUjSLMSiM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>In an astonishing piece of insight, <a href="http://www.sciencedirect.com/science/article/pii/0022519367900793">Lynne Margulis</a> realised that the chloroplasts inside plants were domesticated cyanobacteria that had been captured early in the evolution of the plant lineage. It appears that a unicellular ancestor of the land plant engulfed a cyanobacteria, but rather than digesting it, realised that it was a useful acquisition. </p>
<p>But even more fundamental to the functioning of all higher organisms is a second organelle called the <a href="http://www.britannica.com/science/mitochondrion">mitochondrion</a>. Margulis realised that this too was once a free-living bacterium – in this case one that could harness the chemical energy locked up in sugary substrates such as <a href="hyperphysics.phy-astr.gsu.edu/hbase/organic/sugar.html">glucose</a>. So the cells of plants are really <a href="http://www.britannica.com/topic/chimera-genetics">chimeras</a> – a single organism made up of the original host plus two captured bacteria. This theory is known as the endosymbiotic theory.</p>
<h2>The joy of chloroplasts</h2>
<p>Ownership of a chloroplast brings an enormous and immediate benefit. Animals only have mitochondria, which allow them to oxidise glucose and harness the resulting chemical energy to fuel their metabolism. But they have to find a source of glucose. And that means dedicating a substantial part of their day to locating, subduing and consuming food. Plants on the other hand don’t have to bother. They can simply use their chloroplasts to make their own glucose, which they can then pass to the mitochondria to release chemical energy as and when it is required.</p>
<p>So surely everyone else is missing a trick. If plants can bypass finding glucose, then surely animals could too. In fact, many animals have done exactly this. The chloroplast was just too good an invention and many other organisms managed to beg, borrow or steal a chloroplast, mainly from free-living unicellular algae that already had one. This process is known as secondary endosymbiosis to distinguish it from the primary <a href="http://www.dummies.com/how-to/content/endosymbiotic-theory.html">endosymbiotic event</a>, in which the original plant ancestor engulfed a free-living cyanobacterium.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/103932/original/image-20151201-9279-dnlhzq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/103932/original/image-20151201-9279-dnlhzq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/103932/original/image-20151201-9279-dnlhzq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/103932/original/image-20151201-9279-dnlhzq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/103932/original/image-20151201-9279-dnlhzq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/103932/original/image-20151201-9279-dnlhzq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/103932/original/image-20151201-9279-dnlhzq.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">Why can’t I photosynthesise?</span>
<span class="attribution"><span class="source">R~P~M/flickr</span></span>
</figcaption>
</figure>
<p>It’s not entirely clear why <a href="https://endosymbiotichypothesis.wordpress.com/primary-versus-secondary-endosymbiosis/">secondary endosymbiosis</a> appears to have occurred many times, while the primary endosymbiosis occurred only once; although recently scientists have discovered a second example of a primary endosymbiosis in the making. In this case the host is a strange amoeba called <em><a href="http://www.ncbi.nlm.nih.gov/pubmed/16310747">Paulinella</a></em>, which appears to be domesticating a cyanobacteria from the new and hence recreating the ancient event that gave rise to the land plants. </p>
<p>The transfer of the chloroplast around the tree of life by secondary endosymbiosis has given rise to a whole host of ecologically important organisms, most of which are unicellular. These organisms, for example, <a href="http://www.ucl.ac.uk/GeolSci/micropal/diatom.html">diatoms</a>, <a href="http://www.ucmp.berkeley.edu/protista/dinoflagellata.html">dinoflagellates</a> and <a href="http://tolweb.org/Euglenida/97461">euglenids</a>, are unknown to most of us and arise from independent acquisitions of a chloroplast from an alga. </p>
<p>Perhaps most interesting of all for our story, these unicellular photosynthesising organisms have themselves been taken up by multicellular animals. These symbioses have evolved independently many times and the relationship between the host and the photosymbiont can take many forms. </p>
<h2>Sea slugs can do it – so why can’t we?</h2>
<p>For example, there are incredible green sea slugs that <a href="http://www.plantphysiol.org/content/123/1/29.full">steal chloroplasts</a> from the algae on which they graze. The slugs can’t maintain the chloroplasts in working order for long, so they need a constant supply and there’s still debate about whether the chloroplasts are really essential for the <a href="http://rspb.royalsocietypublishing.org/content/281/1774/20132493">slug’s existence</a>. At the other end of the spectrum, many marine organisms such as corals, giant clams and sea squirts are totally dependent on their symbionts and will perish without them.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/104518/original/image-20151205-11669-m63iay.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/104518/original/image-20151205-11669-m63iay.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/104518/original/image-20151205-11669-m63iay.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/104518/original/image-20151205-11669-m63iay.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/104518/original/image-20151205-11669-m63iay.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/104518/original/image-20151205-11669-m63iay.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/104518/original/image-20151205-11669-m63iay.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"><em>Elysia grandifolia</em> eating algae.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/87895263@N06/17111551869/in/photolist-s56bdn-ecSLoL-cn1NUw-qU5PRF-4YAn1-feuQmZ-auC8FH-8SnFeb-7FMag3-7FMzNy-7FHg1r-oqCkGu-669bWq-83bzZB-vRpfLY-oxBc3i-qr9qGM-9Yxf9s-bGEzCB-9KkSZU-8TJvnJ-73C5oJ-67VySV-9vkrfm-8rTq6q-Kvuph-oaWoPa-63yVf2-nTJCEK-ob5H6s-nTJ8rz-83eJth-9NE3Cc-83bzYP-ax8uqp-n5QnVk-ypdYmV-bXdhNu-83bzZg-feuRvF-feK84Y-feK7Rs-9vkrfo-feKdiU-feKa3q-feK8s5-feK897-feK7w1-feuQsc-feK7iw">Sylke Rohrlach/flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>So, if slugs and sea squirts can all benefit from photosynthesis, why can’t we?</p>
<p>The answer lies in considering the energy budget of a large active multicellular animal such as a human being. Every day an adult human requires its own body weight in a molecule called <a href="http://bionumbers.hms.harvard.edu/bionumber.aspx?&id=105606&ver=4&trm=atp">ATP</a>, which stores the chemical energy released from the oxidation of glucose. </p>
<h2>We need more skin</h2>
<p>To produce roughly 60kg of ATP, a typical adult woman therefore requires around 700g of glucose per day. Given the maximum known rates of photosynthesis in higher <a href="http://bionumbers.hms.harvard.edu/">plants</a> and assuming that the surface area of an adult woman’s skin is around 1.6 m2, a woman with green skin could produce a highly disappointing 1% of her daily demand for glucose through photosynthesis. So to meet her energy demands, a photosynthesising woman would have to have a lot more skin. Indeed, roughly a tennis court’s worth. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/104517/original/image-20151205-30590-4taqmq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/104517/original/image-20151205-30590-4taqmq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/104517/original/image-20151205-30590-4taqmq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/104517/original/image-20151205-30590-4taqmq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/104517/original/image-20151205-30590-4taqmq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/104517/original/image-20151205-30590-4taqmq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/104517/original/image-20151205-30590-4taqmq.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">To photosynthesise she’d need enough skin to cover a tennis court.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/su-may/19204611418/in/photolist-vg3DTY-vx56Yu-vviLF9-uAMiAg-vviUoJ-vgaNEH-uALKbM-7GQXUj-7pMceS-6rkM1h-8mDnv-86rdEE-J1G5J-vg2WAQ-uALWBH-nRk3nW-71cN4v-jgn17J-7zJ3nC-7pHmRn-asPYhM-rXkjLH-8BxXaQ-ar5KkT-6mYR7p-vx5UFN-vg4rdY-vgbchg-vg419s-uAC3EU-uABZR7-uABSXh-dYRgqu-vg3PH7-a5rXGt-8xQSvW-cYeCGw-bXPx5y-bXPwZU-bXPx3N-cYeDo5-bXMhJG-7g8TXm-AsjUM9-cSQUaq-cSQUkh-dMSaNn-o9jDwc-6rkME7-8BuQPg">Su--May/flicker</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>We must therefore reluctantly conclude that either aliens look substantially weirder than they are currently portrayed in movies or that the photosynthesis that has potentially evolved on other planets colonised by little green men is seriously more efficient than the one that evolved here.</p><img src="https://counter.theconversation.com/content/51635/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lindsay Turnbull 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>
There are solar-power sea slugs, so why haven’t humans mastered the art of photosynthesis?
Lindsay Turnbull, Associate Professor, Department of Plant Sciences, University of Oxford
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/47906
2015-09-23T16:36:52Z
2015-09-23T16:36:52Z
Starving cancer cells of sugar could be the key to future treatment
<figure><img src="https://images.theconversation.com/files/95882/original/image-20150923-2617-1frwddr.jpg?ixlib=rb-1.1.0&rect=0%2C1%2C736%2C547&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Is sugar the answer for tackling cancer cells?</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/wellcomeimages/5814247339/">Flickr/Wellcome Images</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>All the cells in our bodies are programmed to die. As they get older, our cells accumulate toxic molecules that make them sick. In response, they eventually break down, clearing the way for new, healthy cells to grow. This “<a href="http://www.ncbi.nlm.nih.gov/books/NBK26873/">programmed cell death</a>” is a natural and essential part of our wellbeing. Every day, billions of cells die like this in order for the whole organism to continue functioning as it is supposed to.</p>
<p>But as with any programme, errors can occur and injured cells that are supposed to die continue to grow and divide. These damaged cells can eventually become malignant and generate tumours. In order to <a href="http://www.ncbi.nlm.nih.gov/pubmed/19351640">avoid their programmed cell death</a> in this way, cancer cells reorganise their metabolism so they can cheat death and proliferate indefinitely.</p>
<p>Cancer researchers have <a href="http://www.ncbi.nlm.nih.gov/pubmed/19460998">known for decades</a> that tumours use a faster metabolism than normal cells in our body. <a href="http://www.ncbi.nlm.nih.gov/pubmed/19029908">One classic example</a> of this is that cancer cells increase their consumption of glucose to fuel their rapid growth and strike against programmed cell death. This means that limiting glucose consumption in cancer cells is becoming an <a href="http://www.ncbi.nlm.nih.gov/pubmed/16892078">attractive tool</a> for cancer treatments.</p>
<h2>A new hope?</h2>
<p>You may have seen <a href="http://www.dailymail.co.uk/home/you/article-1025497/The-anti-cancer-diet--introducing-healthy-new-way-life.html">articles</a> or <a href="http://www.canceractive.com/cancer-active-page-link.aspx?n=3087">websites advocating</a> that starving patients of sugar is crucial for getting rid of tumours or that eating less sugar reduces the risk of cancer. The story is not that simple. Cancer cells always <a href="http://www.ncbi.nlm.nih.gov/pubmed/23177934">find alternatives</a> to fuel their tank of glucose, no matter how little sugar we ingest. There is not a direct connection between eating sugar and getting cancer and it is always advisable to talk to your doctor if you have doubt about your diet. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/95887/original/image-20150923-2648-1vrhcpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/95887/original/image-20150923-2648-1vrhcpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/95887/original/image-20150923-2648-1vrhcpm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/95887/original/image-20150923-2648-1vrhcpm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/95887/original/image-20150923-2648-1vrhcpm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/95887/original/image-20150923-2648-1vrhcpm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/95887/original/image-20150923-2648-1vrhcpm.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">Chemotherapy – the most common cancer treatment.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=iewo8m4xx7g4rclor3&searchterm=chemotherapy&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=218458957">www.shutterstock.com</a></span>
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</figure>
<p>Researchers <a href="http://www.ncbi.nlm.nih.gov/pubmed/19270154">have demonstrated</a> that cancer cells use glucose to generate the building blocks of the cellular compounds needed for rapid tumour growth. They also use it to <a href="http://www.ncbi.nlm.nih.gov/pubmed/19029908">generate molecules</a> that guard against the toxic accumulation of reactive oxygen species, the cell-damaging molecules that activate programmed cell death. This means that glucose serves as a master protector against cell death.</p>
<p>If the amount of sugar we eat doesn’t affect this process, the question we need to answer is how the cancer cells are instructed to consume more glucose. Who is filling the fuel tank? We have discovered that what allows tumours to evade their natural cause of death in this way is a protein that is overproduced in virtually every human cancer but not in normal cells.</p>
<h2>Turbocharged growth</h2>
<p>In a <a href="http://www.nature.com/ncomms/2015/150810/ncomms8882/full/ncomms8882.html">recent study</a> published in Nature Communications we showed that cancer cells stimulate the over-production of the protein known as PARP14, enabling them to use glucose to turbocharge their growth and override the natural check of cell death. Using a combination of genetic and molecular biology approaches, we have also demonstrated that inhibiting or reducing levels of PARP14 in cancer cells starves them to death.</p>
<p>The best news is that by comparing cancer tissues (biopsies) from patients that has survived cancer and those that have died, we have found that levels of PARP14 were significantly higher in those patients that have died. This means that levels of PARP14 in cancer tissues could also predict how aggressive the cancer would be and what the chances are of a patient’s survival.</p>
<p>This means that a treatment which could block the protein could represent a significant revolution in the future of cancer treatment. What’s more, unlike traditional chemotherapy and radiotherapy, the use of PARP14 inhibitors would only kill cancer cells and not healthy ones. The next step is to design and generate new drugs that can block this protein and work out how to use them safely in patients.</p><img src="https://counter.theconversation.com/content/47906/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Concetta Bubici receives funding from Key Kendall Leukaemia Fund. </span></em></p><p class="fine-print"><em><span>Salvatore Papa receives funding from Foundation for Liver Research and AMMF-Cholangiocarcinoma Charity</span></em></p>
Eating less sugar isn’t enough to stop glucose-hungry cancer cells but new research points the way to how we might starve them to death.
Concetta Bubici, Lecturer in biomedical science, Brunel University London
Salvatore Papa, Senior scientist, Institute of Hepatology, Birkbeck, University of London
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/37229
2015-07-20T03:14:58Z
2015-07-20T03:14:58Z
Health Check: the science of ‘hangry’, or why some people get grumpy when they’re hungry
<figure><img src="https://images.theconversation.com/files/88622/original/image-20150716-32652-1yvhwwp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There are many reasons why some people get very grumpy when they haven't eaten for a while.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/katiekills/3819235832/">Katie Inglis/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>Have you ever snapped angrily at someone when you were hungry? Or has someone snapped angrily at <em>you</em> when <em>they</em> were hungry? If so, you’ve experienced “hangry” (an amalgam of hungry and angry) – the phenomenon whereby some people get grumpy and short-tempered when they’re overdue for a feed. </p>
<p>But where does hanger come from? And why is it that only some people seem to get hangry? The answer lies in some of the processes that happen inside your body when it needs food. </p>
<h2>The physiology of hanger</h2>
<p>The carbohydrates, proteins and fats in everything you eat are digested into simple sugars (such as glucose), amino acids and free fatty acids. These nutrients pass into your bloodstream from where they are distributed to your organs and tissues and used for energy. </p>
<p>As time passes after your last meal, the amount of these nutrients circulating in your bloodstream starts to drop. If your blood-glucose levels fall far enough, your brain will perceive it as a life-threatening situation. You see, unlike most other organs and tissues in your body which can use a variety of nutrients to keep functioning, your brain is critically dependent on glucose to do its job. </p>
<p>You’ve probably already noticed this dependence your brain has on glucose; simple things can become difficult when you’re hungry and your <a href="http://m.diabetes.diabetesjournals.org/content/50/7/1618.full">blood glucose levels drop</a>. You may find it hard to concentrate, for instance, or you may make silly mistakes. Or you might have noticed that your words become muddled or slurred. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/89141/original/image-20150721-24295-b4eb5u.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/89141/original/image-20150721-24295-b4eb5u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/89141/original/image-20150721-24295-b4eb5u.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=792&fit=crop&dpr=1 600w, https://images.theconversation.com/files/89141/original/image-20150721-24295-b4eb5u.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=792&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/89141/original/image-20150721-24295-b4eb5u.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=792&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/89141/original/image-20150721-24295-b4eb5u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=995&fit=crop&dpr=1 754w, https://images.theconversation.com/files/89141/original/image-20150721-24295-b4eb5u.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=995&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/89141/original/image-20150721-24295-b4eb5u.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=995&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
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<p>Another thing that can become more difficult when you’re hungry is behaving within socially acceptable norms, such as not snapping at people. So while you may be able to conjure up enough brain power to avoid being grumpy with important colleagues, you may let your guard down and inadvertently <a href="http://www.ncbi.nlm.nih.gov/pubmed/24733932">snap at the people you are most relaxed with or care most about</a>, such as partners and friends. Sound familiar?</p>
<h2>Another bodily response</h2>
<p>Besides a drop in blood-glucose concentrations, another reason people can become hangry is the glucose counter-regulatory response. Let me explain.</p>
<p>When blood-glucose levels drop to a certain threshold, your brain sends instructions to several organs in your body to synthesise and release hormones that increase the amount of glucose in your bloodstream. </p>
<p>The four main glucose counter-regulatory hormones are: growth hormone from the pituitary gland situated deep in the brain; glucagon from the pancreas; and adrenaline, which is sometimes called epinephrine, and cortisol, which are both from the adrenal glands. These latter two glucose counter-regulatory hormones are stress hormones that are released into your bloodstream in all sorts of stressful situations, not just when you experience the physical stress of low blood-glucose levels. </p>
<p>In fact, adrenaline is one of the major hormones released into your bloodstream with the “fight or flight” response to a sudden scare, such as when you see, hear or even think something that threatens your safety. Just as you might easily shout out in anger at someone during the “fight or flight” response, the flood of adrenaline you get during the glucose counter-regulatory response can promote a similar response. </p>
<h2>Nature and nurture</h2>
<p>Another reason hunger is linked to anger is that both are controlled by common genes. The product of one such gene is <a href="http://www.ncbi.nlm.nih.gov/pubmed/19822185">neuropeptide Y</a>, a natural brain chemical released into the brain when you are hungry. It stimulates voracious feeding behaviours by acting on a variety of receptors in the brain, including one called the Y1 receptor. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/89142/original/image-20150721-24261-1i4fvd9.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/89142/original/image-20150721-24261-1i4fvd9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/89142/original/image-20150721-24261-1i4fvd9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=681&fit=crop&dpr=1 600w, https://images.theconversation.com/files/89142/original/image-20150721-24261-1i4fvd9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=681&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/89142/original/image-20150721-24261-1i4fvd9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=681&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/89142/original/image-20150721-24261-1i4fvd9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=856&fit=crop&dpr=1 754w, https://images.theconversation.com/files/89142/original/image-20150721-24261-1i4fvd9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=856&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/89142/original/image-20150721-24261-1i4fvd9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=856&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<p>Besides acting in the brain to <a href="http://www.ncbi.nlm.nih.gov/pubmed/22768253">control hunger</a>, neuropeptide Y and the Y1 receptor also regulate <a href="http://www.ncbi.nlm.nih.gov/pubmed/15314215">anger or aggression</a>. In keeping with this, people with high <a href="http://www.ncbi.nlm.nih.gov/pubmed/22985695">levels of neuropeptide Y in their cerebrospinal fluid</a> also tend to show high levels of impulse aggression. </p>
<p>As you can see, there are several pathways that can make you prone to anger when you’re hungry. Hanger is undoubtedly <a href="http://www.sciencedirect.com/science/article/pii/S0031938415001316">a survival mechanism</a> that has served humans and other animals well. Think about it like this: if hungry organisms stood back and graciously let others eat before them, their species could die out.</p>
<p>While many physical factors contribute to hanger, psychosocial factors also have a role. Culture influences <a href="http://onlinelibrary.wiley.com/doi/10.1002/%28SICI%291098-2337%281999%2925:3%3C185::AID-AB3%3E3.0.CO;2-K/abstract">whether you express verbal aggression</a> directly or indirectly, for instance. </p>
<p>And as we are all different across all of these factors, it’s little wonder there are differences in how angry people seem to get when they’re hungry. </p>
<h2>Dealing with hanger</h2>
<p>The easiest way to handle hanger is to eat something before you get too hungry. While you may hanker for quick-fix foods, such as chocolate and potato chips, when you’re in the throes of hanger, junk foods generally induce large rises in blood-glucose levels that come crashing down fast. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/89140/original/image-20150721-24304-be3mpa.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/89140/original/image-20150721-24304-be3mpa.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/89140/original/image-20150721-24304-be3mpa.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/89140/original/image-20150721-24304-be3mpa.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/89140/original/image-20150721-24304-be3mpa.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/89140/original/image-20150721-24304-be3mpa.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/89140/original/image-20150721-24304-be3mpa.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/89140/original/image-20150721-24304-be3mpa.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<p>Ultimately, they may leave you feeling hangrier. So think nutrient-rich, natural foods that help satisfy hunger for as long as possible, without excess kilojoules. </p>
<p>Eating as soon as you are hungry may not always be possible. This may be the case during long shifts at work, for instance, or through religious fasts such as Ramadan, or during weight-loss diets that involve severe energy restriction (such as intermittent fasting diets). All of these should only be done if your doctor has given you the all-clear.</p>
<p>In these cases, it can help to remember that, with time, your glucose counter-regulatory response will kick in and your blood-glucose levels will stabilise. Also, when you go without food, your body starts breaking down its own fat stores for energy, some of which are converted by your body into ketones, a product of fat metabolism. <a href="http://onlinelibrary.wiley.com/doi/10.1111/obr.12230/abstract">Ketones are thought to help keep your hunger under control</a> because your brain can use ketones in place of glucose for fuel. </p>
<p>A final – and very civilised – way of handling hanger is to suggest that difficult situations be dealt with <em>after</em> food, not before!</p>
<hr>
<p><em>If you live in the Sydney metropolitan area and would like to find out about participating in clinical trials aimed at reducing hunger during weight loss, <a href="mailto:tempo.diet@sydney.edu.au">please email us</a>.</em></p><img src="https://counter.theconversation.com/content/37229/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Amanda Salis (publishing as Sainsbury) receives funding from the National Health & Medical Research Council (NHMRC) of Australia, in the form of research project grants and a Senior Research Fellowship. She is the author of The Don’t Go Hungry Diet (Bantam, Australia and New Zealand, 2007) and Don’t Go Hungry for Life (Bantam, Australia and New Zealand, 2011) and owns shares in a company (Zuman International Pty Ltd) that sells these books</span></em></p>
“Hangry” is an amalgam of hungry and angry that describes the distinct grumpiness that some people experience when they haven’t eaten for a while. Ring a bell?
Amanda Salis, NHMRC Senior Research Fellow in the Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders, University of Sydney
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/42910
2015-07-14T20:21:11Z
2015-07-14T20:21:11Z
How the right diet can control diabetes and reduce its massive economic costs
<figure><img src="https://images.theconversation.com/files/88301/original/image-20150714-11821-w8jl7r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Studies based on Mediterranean diet, combined with exercise, have proved groundbreaking in managing type 2 diabetes.</span> <span class="attribution"><span class="source">from shutterstock.com</span></span></figcaption></figure><p>More than <a href="http://www.who.int/features/factfiles/diabetes/facts/en/">350 million people worldwide</a> suffer from type 2 diabetes. The condition is already rampant in several Western countries and numbers are now rising fast in emerging economies, such as India and China. But the right kind of dietary changes could dramatically reduce the impact of the illness on both patients and economies. </p>
<p>Alongside the impact of the disease and its associated complications on the lives of patients and their families, diabetes’ cost to health-care systems is huge. In Australia, for example, the total economic impact of type 2 diabetes is estimated at A$10.3 billion, while <a href="http://www.ncbi.nlm.nih.gov/pubmed/18308683">in the United States</a> it is likely to exceed US$174 billion.</p>
<p>There are many ways to beat diabetes or reduce its impact; the key is <a href="http://www.professional.diabetes.org/admin/UserFiles/0%20-%20Sean/dc132042%20FINAL.pdf?utm_source=Offline&utm_medium=Print&utm_content=nutritionguidelines&utm_campaign=DP&s_src=vanity&s_subsrc=nutritionguidelines">making changes to your diet</a> and lifestyle that you then follow for life. Indeed, lifestyle modification – eating a healthy diet and exercising regularly – is the cornerstone of any effective diabetes-management plan. </p>
<h2>More than sugar</h2>
<p>For decades now, the general recommendation has been for everyone to cultivate a high-unrefined-carbohydrate, low-fat diet. More recently, reducing sugar intake, even though it is one of the most popular carbohydrates, has been receiving a lot of attention. But a healthy eating plan for diabetes is <em>not</em> just about cutting out sugar. And scientific opinion is now turning in favour of lower carbohydrate diets – for everyone.</p>
<p>While excessive sugar will no doubt increase blood sugar levels, especially if you’re having sweetened drinks, any source of carbohydrate will have the same effect. This includes anything that contains flour, rice or pasta, as well as fruit and potato. </p>
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<img alt="" src="https://images.theconversation.com/files/88304/original/image-20150714-11795-deksmr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/88304/original/image-20150714-11795-deksmr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=435&fit=crop&dpr=1 600w, https://images.theconversation.com/files/88304/original/image-20150714-11795-deksmr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=435&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/88304/original/image-20150714-11795-deksmr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=435&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/88304/original/image-20150714-11795-deksmr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=546&fit=crop&dpr=1 754w, https://images.theconversation.com/files/88304/original/image-20150714-11795-deksmr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=546&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/88304/original/image-20150714-11795-deksmr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=546&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Eating foods like this will only increase the risks of diabetes and its associated complications.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/72616463@N00/11341949626/in/photolist-ihfstC-efUekQ-ozQENt-6JA1sY-H9Sz7-8vkHN1-2cucG-4y6LAP-nQJaNM-3cjANW-9f5vxm-ebbeWS-4uCoUZ-fDwCUh-7dSSE1-7uR8v2-6jpVcr-6s7rPB-8iQcTE-83wjDC-4V4u3t-8fBwG4-8iLYdr-4Wz92E-8jaH5z-baHZt8-8iQcmQ-8hufw8-cMS3G-9L2pHH-8iQbJW-8iQd9w-8iLXkn-8iLXVT-8hxvBQ-6JA1tW-4Y5emW-8iQbY3-pEmtyQ-57NKNJ-HBTmE-by5WU-6UV6RF-73YGqH-76VDem-6QihAq-6FLerX-8an1gD-66fMrZ-4TqSS9">Josephine Stenudd/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Carbohydrate foods with a low glycaemic index (GI), such as oats and legumes, on the other hand, will dampen down the blood sugar response. That’s why careful carbohydrate selection is now recommended for everyone, especially people who have type 2 diabetes.</p>
<p><a href="http://www.ncbi.nlm.nih.gov/pubmed/25287761">New data</a> from <a href="http://www.ncbi.nlm.nih.gov/pubmed/25071075">high-quality nutrition research</a> now strongly suggests that restricting carbohydrates even further, while moderately increasing protein and unsaturated fat intake, may have further benefits for controlling type 2 diabetes and reducing the risk of complications.</p>
<h2>What we did and found</h2>
<p>Based on these ideas, our research teams have been studying the effects of a “Mediterranean” diet – which has low carbohydrate, high protein and includes a lot of vegetables, nuts, lean meats and healthy fats – in combination with an exercise plan. We wanted to see how much we could improve the health of people with type 2 diabetes.</p>
<p>We assigned 115 adults with type 2 diabetes to one of two weight-loss programs. One group followed a very low-carbohydrate and high-protein diet for 24 weeks. The other had a higher carbohydrate, but still low GI, diet.</p>
<p>Early results have been ground-breaking; <a href="http://www.ncbi.nlm.nih.gov/pubmed/25071075">our diet is better</a> at improving diabetes control compared to traditional weight-loss diets. But its most striking benefit is that it reduces the amount of medication someone with diabetes has to take by half. This reduction was three times greater than for people who followed the lifestyle program that incorporates a traditional high-carbohydrate diet plan. </p>
<p>Our very low-carbohydrate diet also improved blood cholesterol profile by increasing the levels of good (HDL) cholesterol and decreasing triglyceride (blood fat) levels to a greater extent than the traditional high-carbohydrate, low-fat diet. Both diets achieved similar reductions in bad (LDL) cholesterol levels – often a concern with some low-carbohydrate diets.</p>
<h2>There’s more</h2>
<p>Variation of blood glucose levels through the day is <a href="http://www.ncbi.nlm.nih.gov/pubmed/25974701">emerging as a strong independent risk factor</a> for diabetes complications. In our study, the very low-carbohydrate diet was also more effective in reducing the number and levels of blood glucose variations over a 24-hour period.</p>
<p>In 2008-09, of the estimated A$1,507 million spent on the health care of diabetes in Australia, <a href="http://www.aihw.gov.au/WorkArea/DownloadAsset.aspx?id=60129543916">A$490 million was spent on diabetes-related medications</a>. Our findings suggest that, by implementing a lifestyle program incorporating a healthy low-carbohydrate, high-protein, high-unsaturated-fat diet at a national level, the country could save up to A$250 million annually through reductions in diabetes-related medication alone. </p>
<p>This does not even account for any additional cost savings that could be generated from the marked improvements in diabetes control and patients’ well-being. It is these costs – related to the complications of diabetes and patients’ ability to contribute to the economy – that account for most of the economic impact of type 2 diabetes.</p>
<p>Our research shows evidence from the latest nutrition science can guide dietary approaches to tackling one of the most serious global health challenges of this century.</p><img src="https://counter.theconversation.com/content/42910/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Grant Brinkworth receives funding from the National Health and Medical Research Council.</span></em></p><p class="fine-print"><em><span>Manny Noakes receives funding from National Health and Medical Research Council, SP Health, Probiotec, Meat and Livestock Australia, Horticulture Australia, Unilever. Manny Noakes is co-author of the CSIRO Total Wellbeing Diet and co-developed the Impromy Program.</span></em></p><p class="fine-print"><em><span>Chris Proud 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>
For decades, a low fat and sugar free diet were key to controlling type 2 diabetes. Now, new data shows a diet high in protein and healthy fats has better outcomes for the disease.
Chris Proud, Theme Leader, Nutrition and Metabolism, South Australian Health & Medical Research Institute
Grant Brinkworth, Senior Research Scientist in Human Nutrition, CSIRO
Manny Noakes, Professor of Nutrition & Research Director for the Food and Nutrition Flagship , CSIRO
Licensed as Creative Commons – attribution, no derivatives.