tag:theconversation.com,2011:/us/topics/sodium-28299/articlesSodium – The Conversation2024-03-12T12:29:23Ztag:theconversation.com,2011:article/2245912024-03-12T12:29:23Z2024-03-12T12:29:23ZSalty foods are making people sick − in part by poisoning their microbiomes<figure><img src="https://images.theconversation.com/files/580543/original/file-20240307-30-s3d9jw.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1729%2C1732&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Salt has taken over many diets worldwide -- some more than others.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/salt-on-pile-royalty-free-image/115788609">ATU Images/The Image Bank via Getty Images</a></span></figcaption></figure><p>People have been using salt since the <a href="https://doi.org/10.1007/978-1-349-21841-7">dawn of civilization</a> to process, preserve and enhance foods. In <a href="https://www.sidestone.com/books/archaeology-of-salt">ancient Rome</a>, salt was so central to commerce that soldiers were paid their “salarium,” or salaries, in salt, for instance. </p>
<p>Salt’s value was in part as a food preservative, keeping unwanted microbes at bay while <a href="https://doi.org/10.1002/bit.260090302">allowing desired ones to grow</a>. It was this remarkable ability to regulate bacterial growth that likely helped spark the <a href="https://www.jstor.org/stable/26017985">development of fermented foods</a> ranging from sauerkraut to salami, olives to bread, cheese to kimchi.</p>
<p>Today, salt has become ubiquitous and highly concentrated in <a href="https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/sodium/sodium-sources">increasingly processed diets</a>. The evidence has mounted that too much salt – specifically the sodium chloride added to preserve and enhance the flavor of many highly processed foods – is <a href="https://www.npr.org/sections/health-shots/2021/10/13/1045651839/eating-too-much-salt-is-making-americans-sick-even-a-12-reduction-can-save-lives">making people sick</a>. It can cause <a href="https://doi.org/10.1016/j.jacc.2019.11.055">high blood pressure</a> and contribute to <a href="https://doi.org/10.1056/NEJMoa2105675">heart attacks and stroke</a>. It is also associated with an increased risk of developing <a href="https://doi.org/10.3390%2Fnu14204260">stomach</a> and <a href="https://doi.org/10.1093%2Fcdn%2Fnzz030.P05-039-19">colon cancer</a>, <a href="https://doi.org/10.1080/00016489.2024.2315302">Ménière’s disease</a>, <a href="https://doi.org/10.1038/s41598-022-18830-4">osteoporosis</a> and <a href="https://doi.org/10.1038/nrneph.2018.23">obesity</a>.</p>
<p>How might a substance previously thought <a href="https://www.worldhistory.org/article/1342/the-salt-trade-of-ancient-west-africa/">worth its weight in gold</a> have transformed into something <a href="https://doi.org/10.1038%2Fs41371-022-00690-0">many medical institutions</a> consider a <a href="https://doi.org/10.1001/jama.2017.0947">key predictor of disease</a>?</p>
<p>Salt lobbyists may be one answer to this question. And as <a href="https://gastro.uw.edu/people/faculty/damman-c">a gastroenterologist</a> and research scientist at the University of Washington, I want to share the mounting evidence that microbes from the shadows of your gut might also shed some light on how salt contributes to disease.</p>
<h2>Blood pressure cookers</h2>
<p>Sodium’s role in blood pressure and heart disease results largely from its regulating the <a href="https://doi.org/10.1161/01.CIR.53.4.589">amount of water inside your blood vessels</a>. In simple terms, the more sodium in your blood, the more water it pulls into your blood vessels. This leads to higher blood pressure and subsequently an increased risk for heart attack and stroke. Some people may be <a href="https://doi.org/10.1038/s41371-020-00407-1">more or less sensitive</a> to the effects salt has on blood pressure.</p>
<p>Recent research suggests an additional way salt may <a href="https://doi.org/10.1038/s44161-022-00204-8">raise blood pressure</a> – by altering your gut microbiome. Salt leads to a decrease in <a href="https://doi.org/10.3390%2Fnu14061171">healthy microbes</a> and the <a href="https://doi.org/10.3390%2Fnu10091154">key metabolites</a> they produce from fiber. These metabolites <a href="https://doi.org/10.1038/s44161-022-00204-8">decrease inflammation</a> in blood vessels and <a href="https://doi.org/10.1161/HYPERTENSIONAHA.122.18558">keep them relaxed</a>, contributing to reduced blood pressure.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580552/original/file-20240307-18-c1oq15.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Salt shaker next to a blood pressure cuff" src="https://images.theconversation.com/files/580552/original/file-20240307-18-c1oq15.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580552/original/file-20240307-18-c1oq15.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580552/original/file-20240307-18-c1oq15.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580552/original/file-20240307-18-c1oq15.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580552/original/file-20240307-18-c1oq15.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580552/original/file-20240307-18-c1oq15.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580552/original/file-20240307-18-c1oq15.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">Extra salt may contribute to high blood pressure.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/blood-pressure-cuff-and-salt-royalty-free-image/86495796">Jupiterimages/Stockbyte via Getty Images</a></span>
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</figure>
<p>With the exception of certain organisms that thrive in salt <a href="https://doi.org/10.1038/s41366-018-0201-3">called halophiles</a>, high levels of salt can <a href="https://www.sciencefocus.com/nature/why-does-salt-have-antibacterial-properties">poison just about any microbe</a>, even ones your body wants to keep around. This is why people have been using salt for a long time to <a href="https://www.ncbi.nlm.nih.gov/books/NBK50952/">preserve food</a> and keep unwanted bacteria away.</p>
<p>But modern diets often have too much sodium. According to the World Health Organization, healthy consumption amounts to less than <a href="https://www.who.int/news-room/fact-sheets/detail/salt-reduction">2,000 milligrams</a> per day for the average adult. The global mean intake of <a href="https://www.who.int/news-room/fact-sheets/detail/salt-reduction">4,310 milligrams</a> of sodium has likely increased the amount of <a href="https://doi.org/10.1038/ki.1985.38">salt in the gut</a> over healthy levels.</p>
<h2>Salt of the girth</h2>
<p>Sodium is connected to health outcomes <a href="https://doi.org/10.1016%2Fj.jacc.2014.12.039">other than blood pressure</a>, and your microbiome may be playing a role here, too.</p>
<p>High sodium diets and higher <a href="https://doi.org/10.1038/s41366-018-0201-3">sodium levels in stool</a> are significantly linked to <a href="https://doi.org/10.1111/dom.14980">metabolic disorders</a>, including elevated <a href="https://doi.org/10.2147/DMSO.S338915">blood sugar</a>, <a href="https://doi.org/10.1002%2Ffsn3.2781">fatty liver disease</a> and <a href="https://doi.org/10.4162%2Fnrp.2023.17.2.175">weight gain</a>. In fact, one study estimated that for every one gram per day increase in dietary sodium, there is a 15% <a href="https://doi.org/10.1016/j.nutres.2018.04.008">increased risk of obesity</a>. </p>
<p>A gold-standard dietary study from the National Institutes of Health found that those on a diet of ultraprocessed foods over two weeks ate about <a href="https://doi.org/10.1016/j.cmet.2019.05.008">500 more calories and weighed about 2 pounds more</a> compared with those on a minimally processed diet. One of the biggest differences between the two diets was the extra 1.2 grams of sodium consumed with the ultraprocessed diets.</p>
<p>A leading explanation for why increased salt may lead to weight gain despite having no calories is that <a href="https://doi.org/10.1016/j.physbeh.2008.04.008">sodium increases cravings</a>. When sodium is combined with simple sugars and unhealthy fats, these so-called <a href="https://doi.org/10.1002/oby.22639">hyperpalatable foods</a> may be linked to <a href="https://doi.org/10.1016/j.appet.2021.105592">fat gain</a>, as they are particularly good at stimulating the <a href="https://doi.org/10.1155%2F2016%2F7238679">reward centers</a> in the brain and <a href="https://doi.org/10.3945/ajcn.111.020164">addictionlike</a> eating behaviors.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580540/original/file-20240307-28-lr4cr3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up of a chef's hand dispensing a pinch of salt" src="https://images.theconversation.com/files/580540/original/file-20240307-28-lr4cr3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580540/original/file-20240307-28-lr4cr3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580540/original/file-20240307-28-lr4cr3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580540/original/file-20240307-28-lr4cr3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580540/original/file-20240307-28-lr4cr3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580540/original/file-20240307-28-lr4cr3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580540/original/file-20240307-28-lr4cr3.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>
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<span class="caption">Many people could do with a pinch less of salt.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/close-up-of-a-chef-adding-salt-into-his-recipe-royalty-free-image/1339981307">skynesher/E+ via Getty Images</a></span>
</figcaption>
</figure>
<p>Salt may also connect to cravings via a short circuit in the gut microbiome. Microbiome metabolites stimulate the release of a <a href="https://theconversation.com/your-body-already-has-a-built-in-weight-loss-system-that-works-like-wegovy-ozempic-and-mounjaro-food-and-your-gut-microbiome-220272">natural version</a> of weight loss drugs Wegovy and Ozempic, the gut hormone GLP-1. Through GLP-1, a healthy microbiome can control your appetite, blood sugar levels and your body’s decision to burn or store energy as fat. Too much salt may interfere with its release.</p>
<p>Other explanations for salt’s effect on metabolic disease, with varying amounts of evidence, include increased <a href="https://doi.org/10.1097%2FMNH.0000000000000152">sugar absorption</a>, increased <a href="https://doi.org/10.1093/cvr/cvac160">gut-derived corticosteroids</a> and a <a href="https://doi.org/10.1073/pnas.1713837115">sugar called fructose</a> that can lead to fat accumulation and decreases in <a href="https://doi.org/10.3390%2Fnu14020253">energy use for heat production</a>.</p>
<h2>Desalin-nations</h2>
<p>While many countries are implementing <a href="https://doi.org/10.1093/advances/nmab008">national salt reduction initiatives</a>, sodium consumption in most <a href="https://www.hsph.harvard.edu/magazine/magazine_article/wheres-the-salt/">parts of the world</a> remains on the rise. Dietary salt reduction in the <a href="http://dx.doi.org/10.15585/mmwr.mm7042a4">United States</a> in particular remains behind the curve, while many <a href="https://doi.org/10.1016/j.nfs.2015.03.001">European countries</a> have started to <a href="https://doi.org/10.1093/eurheartj/ehab274">see benefits</a> such as lower blood pressure and fewer deaths from heart disease through initiatives like improved <a href="https://www.iarc.who.int/wp-content/uploads/2021/09/IARC_Evidence_Summary_Brief_2.pdf">package labeling</a> of salt content, reformulating foods to limit salt and even salt taxes. </p>
<p>Comparing the nutrition facts of fast-food items <a href="https://doi.org/10.1503/cmaj.111895">between countries</a> reveals considerable variability. For instance, <a href="https://www.npr.org/sections/thesalt/2012/04/16/150728142/fast-food-in-the-u-s-has-way-more-salt-than-in-other-countries">McDonald’s chicken nuggets</a> are saltiest in the U.S. and even <a href="https://www.coca-cola.com/us/en/brands/coca-cola/products/original#accordion-c55f229edc-item-93131ee8b3">American Coke</a> contains salt, an ingredient it <a href="https://world.openfoodfacts.org/cgi/search.pl?search_terms=coca+cola&search_simple=1&action=process">lacks in other countries</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580549/original/file-20240307-24-bxdz7t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Hand shaking salt on a packet of fries beside a soft drink" src="https://images.theconversation.com/files/580549/original/file-20240307-24-bxdz7t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580549/original/file-20240307-24-bxdz7t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=421&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580549/original/file-20240307-24-bxdz7t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=421&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580549/original/file-20240307-24-bxdz7t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=421&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580549/original/file-20240307-24-bxdz7t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=529&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580549/original/file-20240307-24-bxdz7t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=529&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580549/original/file-20240307-24-bxdz7t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=529&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Some fast foods have more salt than others.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/excess-salt-being-added-to-chips-french-fires-royalty-free-image/1069612086">Peter Dazeley/The Image Bank via Getty Images</a></span>
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<p>The <a href="https://www.npr.org/sections/thesalt/2019/03/30/707747077/after-a-century-a-voice-for-the-u-s-salt-industry-goes-quiet">salt industry</a> in the U.S may have a role here. It lobbied to prevent government regulations on salt in the 2010s, not dissimilar from what the <a href="https://doi.org/10.1111%2Fj.1468-0009.2009.00555.x">tobacco industry did with cigarettes</a> in the 1980s. Salty foods sell well. One of the key voices of the salt industry for many years, the now-defunct <a href="https://thehill.com/regulation/healthcare/281914-salt-lobby-warns-sodium-reduction-will-endanger-public-health/">Salt Institute</a>, may have confused public health messaging around the importance of salt reduction by emphasizing the <a href="https://www.acc.org/About-ACC/Press-Releases/2023/02/22/20/42/Too-Little-Sodium-Can-be-Harmful-to-Heart-Failure-Patients">less common</a> instances where restriction can be dangerous.</p>
<p>But the evidence for reducing salt in the general diet is mounting, and institutions are responding. In 2021, the U.S. Department of Agriculture issued <a href="https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-industry-voluntary-sodium-reduction-goals">new industry guidance</a> calling for a <a href="https://www.fda.gov/food/food-additives-petitions/sodium-reduction#">voluntary gradual reduction of salt</a> in commercially processed and prepared foods. The <a href="https://www.npr.org/sections/thesalt/2019/03/30/707747077/after-a-century-a-voice-for-the-u-s-salt-industry-goes-quiet">Salt Institute</a> dissolved in 2019. Other organizations such as the <a href="https://affi.org/affi-statement-on-fda-release-of-voluntary-sodium-reduction-goals/">American Frozen Food Institute</a> and major ingredient <a href="https://www.cargill.com/salt-in-perspective/new-report-outlines-how-us-food-companies-can-improve-offerings">suppliers such as Cargill</a> are on board with lowering dietary salt.</p>
<h2>From add-vice to advice</h2>
<p>How can you <a href="https://theconversation.com/hangry-bacteria-in-your-gut-microbiome-are-linked-to-chronic-disease-feeding-them-what-they-need-could-lead-to-happier-cells-and-a-healthier-body-199486">feed your gut microbiome</a> well while being mindful of your salt intake?</p>
<p>Start with limiting your consumption of highly processed foods: salty meats (such as fast food and cured meat), salty treats (such as crackers and chips) and salty sneaks (such as soft drinks, condiments and breads). Up to <a href="https://www.fda.gov/food/nutrition-education-resources-materials/sodium-your-diet">70% of dietary salt</a> in the U.S. is currently consumed from packaged and processed foods. </p>
<p>Instead, focus on foods low in added sodium and sugar and high in potassium and fiber, such as unprocessed, plant-based foods: beans, nuts, seeds, whole grains, fruits and vegetables. <a href="https://doi.org/10.1080/10408398.2017.1383355">Fermented foods</a>, though often high in sodium, may also be a <a href="https://doi.org/10.1016/j.cell.2021.06.019">healthier option</a> due to high levels of <a href="https://doi.org/10.1038/s41598-019-53242-x">short-chain fatty acids</a>, <a href="https://theconversation.com/fiber-is-your-bodys-natural-guide-to-weight-management-rather-than-cutting-carbs-out-of-your-diet-eat-them-in-their-original-fiber-packaging-instead-205159">fiber</a>, <a href="https://gutbites.org/2024/01/18/like-fiber-polyphenols-in-food-boost-glp-1-ignite-mitochondria-help-coordinate-metabolic-health/">polyphenols</a> and potassium.</p>
<p>Finally, consider the balance of dietary sodium and potassium. While sodium helps keep fluid in your blood vessels, potassium helps keep fluid <a href="https://gutbites.org/2024/03/02/too-much-or-too-little-salt-balanced-advice-on-sodium-to-potassium-ratios/">in your cells</a>. Dietary sodium and potassium are best consumed <a href="https://gutbites.org/carb-fiber-ratio-calculator/#NCS">in balanced ratios</a>.</p>
<p>While all advice is best taken with a grain of salt, your microbiome gently asks that it just not be large.</p><img src="https://counter.theconversation.com/content/224591/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Damman is on the scientific advisory board at Oobli and One BIO.</span></em></p>Salt is an essential nutrient that has helped civilizations flavor and preserve their foods for millennia. Too much dietary salt, however, is linked to a host of health problems.Christopher Damman, Associate Professor of Gastroenterology, School of Medicine, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2233412024-02-13T02:26:14Z2024-02-13T02:26:14ZWhy ban ham from school canteens? And what are some healthier alternatives for kids’ lunches?<figure><img src="https://images.theconversation.com/files/575144/original/file-20240212-18-jxuhh8.jpg?ixlib=rb-1.1.0&rect=37%2C37%2C4100%2C2773&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/toasted-sandwich-ham-cheese-176817788">Shutterstock/Joe Gough</a></span></figcaption></figure><p>Western Australia has introduced a limit on ham in school canteens. Parents are reportedly <a href="https://www.news.com.au/lifestyle/parenting/school-life/western-australia-introduces-new-limits-on-ham-at-school-canteens-banning-iconic-lunch/news-story/19b927b35e1122a01ab4539bc477a95d">confused and frustrated</a>. So what has changed and what evidence is it based on?</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1756620394126082196"}"></div></p>
<h2>Reclassifying processed meats</h2>
<p>The WA Department of Health has reconfigured its system for classifying food and drink in public schools. It uses a traffic light approach, allocating green, amber or red colours to foods and drinks. </p>
<p>Ham and other processed red meats <a href="https://www.health.wa.gov.au/%7E/media/Corp/Documents/Health-for/Obesity-physical-activity-and-nutrition/WA-school-food-and-drink-criteria-FAQ.pdf">have been moved</a> from an “amber” label to a “red” label. </p>
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Read more:
<a href="https://theconversation.com/yes-we-still-need-to-cut-down-on-red-and-processed-meat-124486">Yes, we still need to cut down on red and processed meat</a>
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<p>Each colour is <a href="https://www.health.wa.gov.au/%7E/media/Corp/Documents/Health-for/Obesity-physical-activity-and-nutrition/WA-school-food-and-drink-criteria-FAQ.pdf">associated with restrictions</a> on how food and drinks can be sold:</p>
<ul>
<li>green items must account for at least 60% of items on a menu</li>
<li>amber items must account for less than 40% of items on a menu</li>
<li>red items cannot be on the menu.</li>
</ul>
<p>There’s one catch. The new guidelines allow ham to be sold as if it is an amber item, only two days per week, if ham was already on a canteen’s menu prior to the reconfiguration. </p>
<figure class="align-center ">
<img alt="Kids sit in a lunchroom" src="https://images.theconversation.com/files/575145/original/file-20240212-22-ey3jk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575145/original/file-20240212-22-ey3jk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575145/original/file-20240212-22-ey3jk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575145/original/file-20240212-22-ey3jk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575145/original/file-20240212-22-ey3jk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575145/original/file-20240212-22-ey3jk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575145/original/file-20240212-22-ey3jk.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">Ham can still be sold two days a week if it’s already on the canteen’s menu.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cute-schoolchildren-having-meal-canteen-452918419">Shutterstock/WBMUL</a></span>
</figcaption>
</figure>
<h2>Why restrict ham?</h2>
<p>Singling out nutrients or foods as “good” or “bad” can lead to <a href="https://www.scopus.com/inward/record.url?eid=2-s2.0-84907554121&partnerID=10&rel=R3.0.0">confusion and polarised views</a> on diet. Rather than focusing on individual foods, long-term health outcomes are more closely linked to overall <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7071223/">dietary patterns</a>.</p>
<p>Ham itself is not inherently considered junk food. It’s a source of protein and many other nutrients. </p>
<p>However, certain types of ham products – especially highly processed or cured hams – are less healthy options for several reasons:</p>
<p><strong>High sodium content</strong></p>
<p>Many commercially available hams, especially highly processed and cured varieties, can be <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6267163/">high in sodium</a>, which is salt.</p>
<p>Excessive sodium intake is <a href="https://pubmed.ncbi.nlm.nih.gov/32992705/">associated</a> with health issues such as high blood pressure and can increase the risk of heart disease and strokes. </p>
<p>On average, Australian children <a href="https://www.sciencedirect.com/science/article/pii/S2212267218302569">consume more sodium</a> than the <a href="https://www.betterhealth.vic.gov.au/health/healthyliving/salt">recommended upper limit</a>: 600 mg a day for children aged four to eight and 800 mg a day for those aged nine to 13. </p>
<p>The World Health Organization says reducing sodium is <a href="https://www.who.int/news-room/fact-sheets/detail/salt-reduction#:%7E:text=Excess%20sodium%20is%20linked%20to,as%20milk%2C%20meat%20and%20shellfish.">one of the most cost-effective ways</a> nations can improve the health of their populations.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-how-much-salt-is-ok-to-eat-58594">Health Check: how much salt is OK to eat?</a>
</strong>
</em>
</p>
<hr>
<p><strong>Additives</strong></p>
<p>Some processed hams may contain <a href="https://www.sciencedirect.com/science/article/pii/S1051227621002120">additives</a>, preservatives and flavour-enhancers we should limit.</p>
<p><strong>Saturated fat</strong></p>
<p>While ham is a good source of protein, certain cuts can be higher in saturated fat. </p>
<p>Any ham sold in canteens under the new rules (where ham is treated as an “amber” food until the canteen menu changes) must have <a href="https://www.health.wa.gov.au/%7E/media/Corp/Documents/Health-for/Obesity-physical-activity-and-nutrition/Selected-RED-items">less than 3g of saturated fat per 100g</a>. </p>
<p>Diets high in saturated fat are <a href="https://www.heartfoundation.org.au/bundles/healthy-living-and-eating/fats-oils-and-heart-health#:%7E:text=Unhealthy%20saturated%20and%20trans%20fats%20can%20heighten%20your%20risk%20of,and%20mortality%20from%20heart%20disease.">linked to an increased risk of heart disease</a>. However, not all research <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824152/#:%7E:text=Conclusions%3A%20A%20meta%2Danalysis%20of,risk%20of%20CHD%20or%20CVD.">supports this claim</a>.</p>
<p><strong>Processing methods</strong></p>
<p>The methods to process and cure ham may involve smoking, which can produce compounds such as polycyclic aromatic hydrocarbons. In large quantities, these <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8537007/">may cause health concerns</a>, including increasing the risk of bowel cancer.</p>
<h2>What are some ham alternatives?</h2>
<p>Lean, minimally processed ham, prepared without excessive sodium or additives, can potentially be a part of a healthy overall diet. And parents in WA can <a href="https://www.health.wa.gov.au/%7E/media/Corp/Documents/Health-for/Obesity-physical-activity-and-nutrition/WA-school-food-and-drink-criteria-FAQ.pdf">continue packing ham</a> in their child’s lunchbox. </p>
<p>When choosing ham, read the labels and select products with a lower sodium content, minimal additives and healthier preparation methods. </p>
<figure class="align-center ">
<img alt="Girl picks up celery while shopping with her brother and dad" src="https://images.theconversation.com/files/575150/original/file-20240212-16-ey3jk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575150/original/file-20240212-16-ey3jk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575150/original/file-20240212-16-ey3jk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575150/original/file-20240212-16-ey3jk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575150/original/file-20240212-16-ey3jk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575150/original/file-20240212-16-ey3jk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575150/original/file-20240212-16-ey3jk.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">Involve kids in preparing their lunchboxes.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/man-shopping-son-daughter-supermarket-149629991">sirtravelalot/Shutterstock</a></span>
</figcaption>
</figure>
<p>When looking for low-salt alternatives to ham, there are several options to consider: </p>
<ul>
<li><p><strong>turkey breast</strong>. Turkey is a lean meat and can be a good substitute for ham. Look for low-sodium or no-salt-added varieties</p></li>
<li><p><strong>chicken breast</strong>. Skinless, boneless chicken breast is a versatile and low-sodium option. Grilling, baking or roasting can add flavour without relying on salt</p></li>
<li><p><strong>smoked salmon</strong>. While salmon naturally contains some sodium, smoked salmon tends to be lower in sodium than cured ham. Choose varieties with little or no added salt</p></li>
<li><p><strong>roast beef</strong>. Choose lean cuts of roast beef and consider seasoning with herbs and spices instead of relying on salt for flavour</p></li>
<li><p><strong>homemade roasts</strong>. Prepare your own roasts using lean meats such as pork loin, beef sirloin or lamb. This way, you have more control over the ingredients and can minimise added salt</p></li>
<li><p><strong>grilled vegetables</strong>. These can be a tasty alternative to meat. Eggplant, zucchini, capsicum and portobello mushrooms have a satisfying texture and flavour</p></li>
<li><p><strong>beans and legumes</strong>. Beans, lentils and chickpeas can be used as alternatives in various dishes. They are naturally low in sodium and high in protein and fibre.</p></li>
</ul>
<h2>What are some other lunchbox tips?</h2>
<p>Packing lunchboxes can be <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10107882/">challenging and frustrating</a> for parents. </p>
<p>Consider planning ahead, involving your kids, reducing pre-packaged foods, balancing cost and convenience, and giving your kids lunchbox accountability. </p>
<p>Many websites provide <a href="https://www.bestrecipes.com.au/budget/galleries/lunch-box-recipes-kids-31-back-school-lunches/vy6bf9xp">ideas for parents</a>, including websites focused on <a href="https://www.frugalandthriving.com.au/frugal-lunchbox-ideas/">low-cost foods</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/sick-of-packing-school-lunches-already-heres-how-to-make-it-easier-179675">Sick of packing school lunches already? Here's how to make it easier</a>
</strong>
</em>
</p>
<hr>
<p>Remember to keep portions appropriate for kids and to consider any allergies or school regulations when packing lunches. </p>
<p>Making the lunch experience interactive and enjoyable can encourage kids to <a href="https://ijbnpa.biomedcentral.com/articles/10.1186/s12966-019-0798-1">embrace healthier eating habits</a>.</p><img src="https://counter.theconversation.com/content/223341/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lauren Ball works for The University of Queensland and receives funding from the National Health and Medical Research Council, Queensland Health and Mater Misericordia. She is a Director of Dietitians Australia, a Director of the Darling Downs and West Moreton Primary Health Network and an Associate Member of the Australian Academy of Health and Medical Sciences.</span></em></p>Western Australia has introduced a limit on ham in school canteens. Here’s what has changed and the evidence it’s based on.Lauren Ball, Professor of Community Health and Wellbeing, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1687432021-10-06T00:39:49Z2021-10-06T00:39:49ZIs salt good for you after all? The evidence says no<figure><img src="https://images.theconversation.com/files/424609/original/file-20211004-29-106b0av.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/old-wooden-table-salt-shaker-close-402073258">Shutterstock</a></span></figcaption></figure><p><a href="https://en.wikipedia.org/wiki/Salt">Salt</a> is the most common form of sodium and is added to food during manufacturing, home cooking or at the table to enhance the taste or to extend the shelf life. </p>
<p>Most people have heard the advice to <a href="https://www.heartfoundation.org.au/Heart-health-education/Salt-and-heart-health">cut down on salt</a>.
That’s because high sodium intakes are <a href="https://pubmed.ncbi.nlm.nih.gov/33314019/">associated with high blood pressure</a>, a major risk factor for cardiovascular disease, heart attacks and strokes. </p>
<p>So the <a href="https://www.theguardian.com/food/2021/sep/26/food-myths-busted-dairy-salt-steak-swedish-study-science-health-advice">recent headline</a> “Food myths busted: dairy, salt and steak may be good for you after all” was bound to grab-attention. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1442103877160079363"}"></div></p>
<p>In the <a href="https://www.mdpi.com/2072-6643/13/9/3232">research article this headline is based on</a>, the authors examined whether advice to substantially lower sodium intakes was supported by robust evidence. </p>
<p>The article’s premise is that current advice to limit sodium consumption to 2.3 grams a day is unachievable for most people in the long term. And it claims there isn’t good quality evidence to show lower salt intakes reduce the risk of heart attacks and strokes.</p>
<p>The authors suggest that current global sodium intakes, which range from 3-5 grams per day, are associated with the lowest risks for a heart attack, stroke or dying prematurely. And that heart attacks and strokes increase only when sodium intakes are higher or lower than this. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/424708/original/file-20211005-18-1v6w3ht.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/424708/original/file-20211005-18-1v6w3ht.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=354&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424708/original/file-20211005-18-1v6w3ht.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=354&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424708/original/file-20211005-18-1v6w3ht.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=354&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424708/original/file-20211005-18-1v6w3ht.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=445&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424708/original/file-20211005-18-1v6w3ht.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=445&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424708/original/file-20211005-18-1v6w3ht.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=445&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The researchers argue there’s a ‘sweet spot’ for salt intake and heart disease risk.</span>
<span class="attribution"><a class="source" href="https://www.mdpi.com/2072-6643/13/9/3232/htm">Andrew Mente, Martin O’Donnell, and Salim Yusuf. Nutrients 2021, 13(9), 3232</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>But there are a number of controversies about these claims, and the existing advice to limit salt consumption remains. Lets take a closer a look at some of the issues associated with these claims, as well as important research the authors missed.</p>
<h2>Most of us could afford to cut down on salt</h2>
<p>One teaspoon of salt weighs around 5 grams and contains 2 grams of sodium. </p>
<p>Australians consume about 3.6 grams of sodium per day, equivalent to 9.2 grams (about 2 teaspoons) of table salt. </p>
<p>This is higher than the <a href="https://www.nrv.gov.au/nutrients/sodium">suggested dietary target</a> of 2 grams of sodium (5 grams of salt) per day and the <a href="https://www.nrv.gov.au/node/50">adequate intake</a> range of 460-920 milligrams (1.3-2.6 grams of salt) a day. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-how-much-salt-is-ok-to-eat-58594">Health Check: how much salt is OK to eat?</a>
</strong>
</em>
</p>
<hr>
<p>Sodium intakes in Australia are similar to the rest of the world. <a href="https://pubmed.ncbi.nlm.nih.gov/25119608/">Data from 66 countries</a>, accounting for three-quarters of the world’s adult population, reported the average sodium consumption is 3.95 grams per day and ranges from 2.2 to 5.5 grams per day. </p>
<h2>Yes, it’s possible to cut down on salt</h2>
<p>Changing individual behaviour long term is challenging. But it’s possible.</p>
<p>A <a href="https://pubmed.ncbi.nlm.nih.gov/28542317/">2017 systematic review of dietary salt-reduction interventions</a> found individual dietary counselling could reduce a person’s salt consumption by about 2 grams a day (equivalent to 780mg of sodium), over time periods up to five years. </p>
<p>Population-wide strategies that include reformulating manufactured food with lower levels of salt, improved labelling and mass media education <a href="https://pubmed.ncbi.nlm.nih.gov/28542317/">were even more effective in some regions</a>, reducing average salt intakes by around 4 grams a day in Finland and Japan. </p>
<figure class="align-center ">
<img alt="Japanese woman eats ramen from chopsticks." src="https://images.theconversation.com/files/424699/original/file-20211005-16-1c2dwct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/424699/original/file-20211005-16-1c2dwct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424699/original/file-20211005-16-1c2dwct.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424699/original/file-20211005-16-1c2dwct.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424699/original/file-20211005-16-1c2dwct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424699/original/file-20211005-16-1c2dwct.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424699/original/file-20211005-16-1c2dwct.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">Reformulating foods, better labelling and mass education can help reduce salt consumption.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-focus-asian-woman-using-chopsticks-1362448463">Shutterstock</a></span>
</figcaption>
</figure>
<p>The <a href="https://www.mdpi.com/2072-6643/13/9/3232">authors of the latest paper highlight a lack of studies</a> in the population showing they’ve achieved dietary sodium intakes of less that 2.3 grams per day.</p>
<p>But this fails to acknowledge the challenges in conducting such a study to test that, or the importance of reducing your sodium intake relative to what you usually consume. </p>
<h2>Cutting salt lowers your risk of heart disease</h2>
<p>A recently published <a href="https://pubmed.ncbi.nlm.nih.gov/34459569/">randomised trial across 600 villages in rural China</a> shows cutting salt intakes can reduce a person’s risk of cardiovascular disease, heart attack and stroke. </p>
<p>The study included more than 20,000 people with high blood pressure who either had a history of stroke or were aged over 60 years. One group was randomly assigned to use a salt substitute to reduce their sodium intake. The second group continued to use regular salt. Both groups were followed up over five years. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/there-is-no-great-salt-debate-we-should-be-consuming-less-120874">There is no great salt debate: we should be consuming less</a>
</strong>
</em>
</p>
<hr>
<p>The intervention led to a reduction in sodium excreted in the urine (indicating complicance) and a reduction in blood pressure. </p>
<p>The rate of any major cardiovascular event, including heart attack, was 13% lower among those in the salt-substitute group compared to the regular salt group. The rate of strokes was 14% lower.</p>
<p>This trial demonstrates the benefit of reducing dietary sodium intakes, irrespective of a specific daily target.</p>
<figure class="align-center ">
<img alt="Young man in a blue shirt puts salt into a salad bowl while cooking in a kitchen." src="https://images.theconversation.com/files/424700/original/file-20211005-27-q9o91o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/424700/original/file-20211005-27-q9o91o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/424700/original/file-20211005-27-q9o91o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/424700/original/file-20211005-27-q9o91o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/424700/original/file-20211005-27-q9o91o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/424700/original/file-20211005-27-q9o91o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/424700/original/file-20211005-27-q9o91o.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">Australians consume two teaspoons of salt a day, when we should be limiting intake to one.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/delicious-casual-happy-young-man-preparing-1216662058">Shutterstock</a></span>
</figcaption>
</figure>
<h2>Is it risky to have too little salt?</h2>
<p>Humans need <a href="https://www.nrv.gov.au/nutrients/sodium">sodium to maintain essential bodily processes</a> such as fluid volume and cell stability. Sodium levels are balanced though a sensitive system of hormones, chemical processes and nerves to ensure that sodium in excess of needs is excreted in the urine.</p>
<p>There is conflicting evidence about heart health when you have very low sodium intakes. Some researchers have suggested there is a <a href="https://jamanetwork.com/journals/jama/fullarticle/2443580">J-shaped</a> relationship, where <a href="https://jamanetwork.com/journals/jama/fullarticle/2443580">both low and very high intakes increase the risk</a> of poor outcomes (the end of a “J” shape), while the lowest risk is across a broad mid-point of salt intake (the curve in the “J”).</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/salt-how-to-cut-back-without-losing-that-delicious-flavour-106405">Salt: how to cut back without losing that delicious flavour</a>
</strong>
</em>
</p>
<hr>
<p>The <a href="https://pubmed.ncbi.nlm.nih.gov/32591335/">J-shaped curve in some studies on salt and blood pressure</a> can be explained by issues such as measurement error, random variation, other differences (in age, sex, smoking status or socioeconomic status), existing dietary patterns or other health problems, interactions between a major sodium reduction, and the body’s physiological pathways that regulate blood pressure.</p>
<p>Or it could be explained by reverse causation, where the people recruited into the study report low sodium intakes because they have already been advised to follow a low salt diet before enrolling in the trial. </p>
<p>While we wait for more research to explaining discrepancies related to a J-shape curve, <a href="https://pubmed.ncbi.nlm.nih.gov/33314019/">the evidence overwhelmingly finds</a> lower sodium intakes, compared to higher intakes, lead to important reductions in blood pressure. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/seven-things-to-eat-or-avoid-to-lower-your-blood-pressure-63940">Seven things to eat or avoid to lower your blood pressure</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/168743/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Clare Collins is affiliated with the Priority Research Centre for Physical Activity and Nutrition, the University of Newcastle, NSW. She has received research grants from NHMRC, ARC, MRFF, Hunter Medical Research Institute, Diabetes Australia, Heart Foundation, Bill and Melinda Gates Foundation, nib foundation, Rijk Zwaan Australia, WA Dept. Health, Meat and Livestock Australia, and Greater Charitable Foundation. She has consulted to SHINE Australia, Novo Nordisk, Quality Bakers, the Sax Institute and the ABC. She was a team member conducting systematic reviews to inform the Australian Dietary Guidelines update and the Heart Foundation evidence reviews on meat and dietary patterns.</span></em></p>A new study questions whether current global salt limits are too low. But don’t reach for the salt just yet – the guidelines are unlikely to change any time soon.Clare Collins, Laureate Professor in Nutrition and Dietetics, University of NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1526522021-01-21T13:13:27Z2021-01-21T13:13:27ZInvasive tawny crazy ants have an intense craving for calcium – with implications for their spread in the US<figure><img src="https://images.theconversation.com/files/378340/original/file-20210112-23-1duz31c.png?ixlib=rb-1.1.0&rect=6%2C6%2C4019%2C3011&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Multiple queens ensure colonies have a steady output of workers.</span> <span class="attribution"><span class="source">Ryan Reihart</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p><em>The <a href="https://theconversation.com/us/topics/research-brief-83231">Research Brief</a> is a short take about interesting academic work.</em></p>
<h2>The big idea</h2>
<p>In a recent study, <a href="https://chelseprather.wordpress.com/">my colleagues</a> and <a href="https://scholar.google.com/citations?hl=en&user=6GBgzO8AAAAJ">I</a> discovered micronutrients in the ground <a href="https://www.doi.org/10.1002/ECY.3263">can control populations of invasive crazy ants</a> (<em>Nylanderia fulva</em>). </p>
<p>Tawny crazy ants – named for their fast, erratic movements – can blanket the ground by the millions. Originating in South America and now established in parts of the southern U.S., they <a href="https://www.nytimes.com/2013/12/08/magazine/crazy-ants.html">harm other insects, asphyxiate chickens and even short-circuit electronics in homes</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close up photo of a golden-colored ant against a blue background." src="https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=418&fit=crop&dpr=1 600w, https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=418&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=418&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=525&fit=crop&dpr=1 754w, https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=525&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/378389/original/file-20210112-23-1urj0n3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=525&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">At only 0.125 inches (3.2 mm) long, crazy ants are tiny but mighty.</span>
<span class="attribution"><span class="source">Ryan Reihart</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Crazy ants are <a href="https://doi.org/10.1146/annurev.ecolsys.33.010802.150444">liquid feeders</a> <a href="https://doi.org/10.1653/024.096.0219">that consume nectar from plants – and honeydew (or secretions) from certain insects</a>. Ants crave these sugary resources, which <a href="https://doi.org/10.1073/pnas.1115263108">boost their colony growth</a>, enabling them to outcompete native species and ultimately spread. </p>
<p>The nutritional content of nectar and honeydew vary widely, however, <a href="https://www.britishecologicalsociety.org/ant-cravings-sugar-salt-vary-across-us/">depending on the nutrients available in a particular ecosystem</a>. There are 25 chemical elements required to build life – too much or too little of one may cause disease. So far, ecologists only really know about the importance of macronutrients, like nitrogen and phosphorus, that are abundant in living tissue. My team wanted to learn more about what micronutrients might be important to crazy ants.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A man kneeling over a small hole dug in the grass." src="https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=801&fit=crop&dpr=1 600w, https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=801&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=801&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1007&fit=crop&dpr=1 754w, https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1007&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/377606/original/file-20210107-20-1t2ehyf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1007&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Installing a pitfall trap in one of the 128 fertilized study plots.</span>
<span class="attribution"><span class="source">Kiersten Angelos</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>We conducted a fertilization experiment at the <a href="http://www.eih.uh.edu/">University of Houston’s Coastal Center</a> and were able to demonstrate that the abundance of tawny crazy ants decreased 24% where there was more potassium and 45% where there was more sodium and potassium. </p>
<p>What greatly surprised our team was the discovery that ants were 13% more abundant in areas where there was more calcium – even in areas that had more sodium and potassium. This finding, <a href="https://www.doi.org/10.1002/ECY.3263">published in the journal Ecology</a>, could have big implications for the continued spread of crazy ants. </p>
<h2>Why it matters</h2>
<p>Ours is the first study showing calcium is important to an invasive ant, which is somewhat surprising given ants don’t have bones. It turns out, though, calcium is important in their <a href="https://doi.org/10.1016/j.ceca.2012.11.008">egg production</a>, <a href="https://doi.org/10.1080/00218839.2015.1035074">larval development</a> and <a href="https://doi.org/10.1093/aesa/51.2.142">physiological regulation</a>. </p>
<p><a href="https://doi.org/10.1002/ece3.1737">If the spread of crazy ants continues north</a>, the calcium-rich limestone bedrock of the lower U.S. Midwest may provide ideal conditions for populations to explode. Farmlands may be at risk because calcium is found in many fertilizers. Additionally, cities often have <a href="https://doi.org/10.1007/s10980-008-9288-6">more calcium than surrounding areas</a>, thanks to heavy cement use, limestone quarrying and destruction of buildings.</p>
<p>Tawny crazy ants not only are a major threat to the biodiversity and conservation of ecosystems but also <a href="https://doi.org/10.1038/ncomms12986">cost the U.S. billions of dollars in damage annually</a>. </p>
<h2>What still isn’t known</h2>
<p>Our results add to a small but <a href="https://doi.org/10.1111/geb.13196">growing list</a> <a href="https://doi.org/10.1111/ele.13517">of other experiments</a> <a href="https://doi.org/10.1111/ele.13127">that show the importance of micronutrients</a> to insects. </p>
<p>How far will tawny crazy ants make it in the United States? Will calcium influence their spread? Could other micronutrients like magnesium or iron be important to crazy ants?</p>
<p>In a world where <a href="https://doi.org/10.1126/science.1259855">humans are changing the “ingredients” of Earth’s surface soils</a> at an alarming rate, people may be unwittingly creating more favorable habitats for some invasive species. Figuring out which elements are most important to invasive species will be key to predicting, preventing and managing their spread.</p><img src="https://counter.theconversation.com/content/152652/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ryan Reihart receives funding from the National Science Foundation (NSF) Division of Environmental Biology (DEB) grants 1457114 and 1724663 and from the University of Dayton Office for Graduate Academic Affairs through the Graduate Student Summer Fellowship Program. </span></em></p>The spread of tawny crazy ants may be driven, in part, by their need for calcium. The calcium-rich limestone bedrock of the lower U.S. Midwest may provide ideal conditions for populations to explode.Ryan Reihart, Teaching Assistant and Ph.D. Candidate of Ecology, University of DaytonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1160572019-05-07T23:22:03Z2019-05-07T23:22:03ZWhy cheese may help control your blood sugar<figure><img src="https://images.theconversation.com/files/272355/original/file-20190502-103049-1coe4vd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A study from the University of Alberta suggests that the beneficial effects of cheese might not be related to fat but to some other component, such as protein or calcium.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Mmmm, cheese – a food as nutritious as it is delicious. Or is it? </p>
<p>On the one hand, cheese is an excellent source of minerals like calcium and magnesium, vitamins A, B2 and B12, not to mention being a complete protein. </p>
<p>On the other hand, cheese is also a significant source of saturated fat and sodium in our diets. To lower saturated fat intake, consuming reduced-fat cheese is sometimes recommended to lower cardiovascular disease risk. </p>
<p>Paradoxically, however, there is now a growing body of evidence that <a href="https://doi.org/10.1017/S0007114515005000">people who eat lots of cheese do not have a higher risk of cardiovascular diseases</a>, including Type 2 diabetes. </p>
<p>Our research team at the University of Alberta examined the impact of <a href="https://doi.org/10.1016/j.jnutbio.2018.10.018">both reduced- and regular-fat cheese on insulin resistance</a> in the bodies of pre-diabetic rats. We found that both types of cheese reduced insulin resistance, which is important to maintain normal blood sugars.</p>
<h2>Why we used rats</h2>
<p>Many of the studies previously conducted into the impact of cheese on cardiovascular disease (CVD) have been observational. In other words, researchers have studied the usual eating behaviour of large numbers of people, usually for years, and then correlated the amount of cheese (and other dairy foods) eaten with the development of CVD risks, such as high cholesterol or coronary artery disease.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/272360/original/file-20190502-103053-109t14b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272360/original/file-20190502-103053-109t14b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272360/original/file-20190502-103053-109t14b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272360/original/file-20190502-103053-109t14b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272360/original/file-20190502-103053-109t14b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272360/original/file-20190502-103053-109t14b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272360/original/file-20190502-103053-109t14b.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">Observational studies of human eating patterns cannot be used to determine causation.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>A 2016 survey of published observational studies found that cheese had either a <a href="https://doi.org/10.3945/an.115.011403">neutral or beneficial effect on several CVD risk factors</a></p>
<p>These studies are very useful to establish trends associated with usual eating patterns but they can’t definitively say that a particular food causes or prevents a particular disease. </p>
<p>To understand causation better, studies that examine the effects of foods in a controlled setting are useful. These studies can be conducted in humans but there are limitations. Thus, studies in laboratory animals can also be useful, particularly in understanding biochemical mechanisms.</p>
<h2>Cheese and insulin resistance</h2>
<p>Insulin resistance is a condition that commonly develops with ageing and obesity, leading to high blood glucose, and risk factor of CVD and Type 2 diabetes. </p>
<p>Our objective was to <a href="https://doi.org/10.1016/j.jnutbio.2018.10.018">compare how consuming reduced- versus regular-fat cheese affected insulin resistance, and to explore biochemical mechanisms that might explain any observed effects</a>.</p>
<p>We used a rat model of insulin resistance that shares many characteristics with humans. We created the model by feeding the rats high amounts of lard. After four weeks, the rats were divided into three groups: 1) lard diet, 2) lard diet and reduced-fat cheddar cheese, 3) lard diet and regular fat cheddar cheese. </p>
<p>All the diets had the same total amount of fat, only the source of it varied (lard versus cheese). The rats ate these diets for eight more weeks.</p>
<p>The most interesting finding in our research was that both reduced- and regular-fat cheddar cheese reduced insulin resistance in the rats. This suggests that the beneficial effects of cheese might not be related to the amount of fat but to some other component, such as the protein or the calcium.</p>
<h2>Butter versus cheese</h2>
<p>A few new studies in humans have appeared in the literature since we began our study. A group from Laval University and the University of Manitoba <a href="https://doi.org/10.3945/ajcn.116.150300">compared the effects of eating fats from different sources in men and women with abdominal obesity</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/272361/original/file-20190502-103060-12xwz2h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/272361/original/file-20190502-103060-12xwz2h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=316&fit=crop&dpr=1 600w, https://images.theconversation.com/files/272361/original/file-20190502-103060-12xwz2h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=316&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/272361/original/file-20190502-103060-12xwz2h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=316&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/272361/original/file-20190502-103060-12xwz2h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=398&fit=crop&dpr=1 754w, https://images.theconversation.com/files/272361/original/file-20190502-103060-12xwz2h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=398&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/272361/original/file-20190502-103060-12xwz2h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=398&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Another study tested butter, cheese, olive oil and corn oil diets and found no impact on insulin levels.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>The diet duration was four weeks and each diet was assessed in all the participants. Butter, cheese, olive oil and corn oil diets (32 per cent calories from fat) were compared with a higher carbohydrate diet (25 per cent calories from fat). </p>
<p>The researchers examined blood glucose and insulin levels (which are indirect indicators of insulin resistance) and found no effect from any of the fats. However, the blood samples were collected after fasting, so the information about blood sugar was incomplete.</p>
<p>Another <a href="https://doi.org/10.1186/s12986-018-0300-0">study that compared reduced- to regular-fat cheese</a> found no overall differences on LDL-cholesterol characteristics in people with cardiovascular disease risk factors, but did not examine blood sugar-related outcomes.</p>
<h2>Changing blood metabolites</h2>
<p>In our study, we also examined how metabolites in the blood changed after cheese feeding and found similar effects in reduced- and regular-fat cheese. </p>
<p>The changes are related to a specific type of molecule called phospholipids, which have many functions in the body. Interestingly, low-circulating phospholipids are linked with diabetes and insulin resistance in humans. </p>
<p>The rats fed on a lard diet had lower phospholipid levels. These were normalized in the rats that ate cheese. </p>
<p>We are pursuing this line of research now — to understand how cheese regulates phospholipid metabolism and how this relates to insulin resistance.</p><img src="https://counter.theconversation.com/content/116057/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This study was funded by the Dairy Farmers of Canada and the Natural Sciences and Engineering Research Council. A representative of Dairy Farmers of Canada reviewed the manuscript prior to submission but had no role with respect to study design, data collection, analysis or interpretation, writing of the manuscript and its final content, or the decision to submit the manuscript for publication.
Catherine Chan receives funding from Dairy Farmers of Canada, Alberta Agriculture Funding Consortium, Danone Institute, Canadian Institutes for Health Research, Lawson Foundation, Natural Sciences and Engineering Research Council, Canadian Foundation for Dietetics Research, Egg Farmers of Canada, Alberta Health Services </span></em></p>A recent research study found that cheese reduced insulin resistance in prediabetic rat models.Catherine Chan, Professor, Agricultural Life and Environmental Sciences, University of AlbertaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1094062019-04-23T10:43:40Z2019-04-23T10:43:40ZUnderstanding the periodic table through the lens of the volatile Group I metals<figure><img src="https://images.theconversation.com/files/259834/original/file-20190219-43284-bvcjvh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sodium metal explodes on contact with water. </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/sodium-metal-explosion-on-water-159405800?src=8sTQGCqhF0cXE4JHXfFIbg-1-0">Albert Russ/Shutterstock.com</a></span></figcaption></figure><p>The news broke that a railroad car, loaded with pure sodium, had just derailed and was spilling its contents. A television reporter called me for an explanation of why firefighters were not allowed to use water on the flames bursting from the mangled car. While on the air I added some sodium to a bit of water in a petri dish and we observed the vicious reaction. For further dramatic effect, I also placed some potassium into water and astonished everyone with the explosive bluish flames. </p>
<p>Because Group I metals, also known as alkali metals, are very reactive, like the sodium from the rail car or the potassium, they are not found in nature in pure form but only as salts. Not only are they very reactive, they are soft and shiny, can easily be cut even with a dull knife and are the most metallic of all known elements.</p>
<p>I am a chemist who spent his career building new molecules, sometimes using Group I elements. By studying the behavior and trends of Group I elements, we can get a glimpse of how the periodic table is arranged and how to interpret it. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/259839/original/file-20190219-43252-1iql95m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/259839/original/file-20190219-43252-1iql95m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=385&fit=crop&dpr=1 600w, https://images.theconversation.com/files/259839/original/file-20190219-43252-1iql95m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=385&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/259839/original/file-20190219-43252-1iql95m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=385&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/259839/original/file-20190219-43252-1iql95m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=484&fit=crop&dpr=1 754w, https://images.theconversation.com/files/259839/original/file-20190219-43252-1iql95m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=484&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/259839/original/file-20190219-43252-1iql95m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=484&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Periodic Table of the Elements. The Group I metals are on the far left colored red.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/periodic-table-elements-colorful-vector-illustration-786893179?src=L6jraCI7K6wCz27iBZ58fw-1-11">Humdan/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>The basics</h2>
<p>The arrangement of the periodic table and the properties of each element in it is based of the atomic number and the arrangement of the electrons orbiting the nucleus. The atomic number describes the number of protons in the nucleus of the element. Hydrogen’s atomic number is 1, helium’s is 2, lithium’s is 3 and so on. </p>
<p>Each of the 18 columns in the table is called a group or a family. Elements in the same group share similar properties. And the properties can be assumed based on the location within the group. Going from the top of Group I to the bottom, for example, the atomic radii – the distance from the nucleus to the outer electrons – increases. But the amount of energy needed to rip off an outer electron decreases going from the top to the bottom because the electrons are farther from the nucleus and not held as tightly.</p>
<p>This is important because how elements interact and react with each other depends on their ability to lose and gain electrons to make new compounds. </p>
<p>The horizontal rows of the table are called periods. Moving from the left side of the period to the right, the atomic radius becomes smaller because each element has one additional proton and one additional electron. More protons means that electrons are pulled in more tightly toward the nucleus. For the same reason electronegativity – the degree to which an element tends to gain electrons – increases from left to right. </p>
<p>The force required to remove the outermost electron, known as the ionization potential, also increases from the left-hand side of the table, which has elements with a metallic character, to the right side, which are nonmetals.</p>
<p>Electronegativity decreases from the top of the column to the bottom. The melting point of the elements within a group also decreases from the top to the bottom of a group.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/268676/original/file-20190410-2909-1pcgz2z.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/268676/original/file-20190410-2909-1pcgz2z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/268676/original/file-20190410-2909-1pcgz2z.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=320&fit=crop&dpr=1 600w, https://images.theconversation.com/files/268676/original/file-20190410-2909-1pcgz2z.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=320&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/268676/original/file-20190410-2909-1pcgz2z.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=320&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/268676/original/file-20190410-2909-1pcgz2z.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=402&fit=crop&dpr=1 754w, https://images.theconversation.com/files/268676/original/file-20190410-2909-1pcgz2z.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=402&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/268676/original/file-20190410-2909-1pcgz2z.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=402&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Trends of the periodic table.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/0/06/Periodic_trends.png">Sandbh/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Applying the basics to Group I elements</h2>
<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/259848/original/file-20190219-43281-11t51f0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/259848/original/file-20190219-43281-11t51f0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=616&fit=crop&dpr=1 600w, https://images.theconversation.com/files/259848/original/file-20190219-43281-11t51f0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=616&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/259848/original/file-20190219-43281-11t51f0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=616&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/259848/original/file-20190219-43281-11t51f0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=774&fit=crop&dpr=1 754w, https://images.theconversation.com/files/259848/original/file-20190219-43281-11t51f0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=774&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/259848/original/file-20190219-43281-11t51f0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=774&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The outermost electron surrounding the Cesium atom is far from the nucleus and thus easy to remove. That makes cesium highly reactive.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/cesium-atom-shell-1259526397?src=AHbaCa3JuKdPCzaySkfZwA-1-0">gstraub/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>As its name implies, Group I elements occupy the first column in the periodic table. Each element starts a new period. Lithium is at the top of the group and is followed by sodium, Na; potassium, K; rubidium, Rb; cesium, Cs and ends with the radioactive francium, Fr. Because it is highly radioactive, virtually no chemistry is performed with this element. </p>
<p>Because each element in this column has a single outer electron in a new shell, the volumes of these elements are large and increase dramatically when moving from the top to the bottom of the group. </p>
<p>Of all the Group I elements, cesium has the largest volumes because the outermost single electron is loosely held.</p>
<p>In spite of these trends, the properties of the elements of Group I are more similar to each other than those of any other group. </p>
<h2>Alkali metals through history</h2>
<p>Using chemical properties as his guide, Russian chemist Dimitri Mendeleev correctly ordered the first Group I elements into his 1869 periodic table. It is called periodic because every eighth element repeats the properties of the one above it in the table. After arranging all of the then known elements, Mendeleev took the bold step of leaving blanks where his extrapolation of chemical properties showed that an element should exist. Subsequent discovery of these new elements proved his prediction correct. </p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/268681/original/file-20190410-2918-rhg0l6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/268681/original/file-20190410-2918-rhg0l6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/268681/original/file-20190410-2918-rhg0l6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/268681/original/file-20190410-2918-rhg0l6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/268681/original/file-20190410-2918-rhg0l6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/268681/original/file-20190410-2918-rhg0l6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/268681/original/file-20190410-2918-rhg0l6.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">Fireworks owe their vivid colors to the Group I metals.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/view-amazing-new-years-eve-fireworks-1289129893?src=Zxwg1c_YEKkEpLt80RVZ0A-1-7">elena_prosvirova/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>Some alkali metals have been known and put to good use long before Mendeleev created the periodic table. For instance, the Old Testament mentions salt – a combination of the alkali metal sodium with chlorine – 31 times. The New Testament refers to it 10 times and calls sodium carbonate “neter” and potassium nitrate “saltpeter.”</p>
<p>People have known since antiquity that wood ashes produce a potassium salt which, when combined with animal fat, will yield soap. Samuel Hopkins obtained the first U.S. patent on July 31, 1790, for soap under the new patent statute just signed into law by President George Washington a few months earlier. </p>
<p>The pyrotechnic industry loves these Group I elements for their vibrant colors and explosive nature. Burning lithium produces a vivid crimson red color; sodium a yellow one; potassium lilac; rubidium red; and cesium violet. These colors are produced as electrons jump from their home environment orbiting the nucleus and returning back again.</p>
<p>The cesium atomic clock, the most accurate timepiece ever developed, functions by measuring the frequency of cesium electrons jumping back and forth between energy states. Clocks based on electrons jumping provide an extremely precise way to count seconds.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/dmcfsEEogxs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Sodium metal reacts with water to produce sodium hydroxide, hydrogen gas and energy.</span></figcaption>
</figure>
<p>Other applications include sodium vapor lamps and lithium batteries.</p>
<p>In my own research I have used Group I metals as tools to perform other chemistry. Once I was in need of absolutely dry alcohol, and the driest I could buy still contained minute traces of water. The only way to get rid of the last remnant of water was by treating the water-containing alcohol with sodium – a rather dramatic way to remove water.</p>
<p>The alkali elements not only occupy the first column in the periodic table, but they also show the most reactivity of all groups in the entire table and have the most dramatic trends in volume and ionization potential, while maintaining great similarity among themselves.</p><img src="https://counter.theconversation.com/content/109406/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Erwin Boschmann 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>If you are intimidated by the periodic table, then this introduction through the first column of elements will give you a feel for how and why the elements are arranged in this order.Erwin Boschmann, Professor Emeritus of Chemistry & Chemical Biology, IUPUILicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1143762019-04-03T12:47:57Z2019-04-03T12:47:57ZRwanda’s gorillas have figured out where to find their sodium fix. But it’s dangerous<figure><img src="https://images.theconversation.com/files/267521/original/file-20190404-131437-psnnwu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There are about 600 Mountain gorillas left in the Virunga Volcanoes</span> <span class="attribution"><span class="source">Onyx9/Shutterstock</span></span></figcaption></figure><p>Mountain Gorilla conservation in Rwanda is a great <a href="https://www.washingtonpost.com/lifestyle/kidspost/rare-conservation-win-as-mountain-gorilla-population-slowly-grows/2018/11/14/e12ea5c4-e21d-11e8-b759-3d88a5ce9e19_story.html">success story</a>. A number of extreme conservation measures – like daily monitoring and protection, veterinary interventions and controlled ecotourism – have enabled the population to bounce back after a precarious low in the 1960s and 1970s that was brought about by habitat destruction and poaching. </p>
<p>But the population remains fragile. Today <a href="https://www.researchgate.net/publication/264335852_Mountain_gorilla_tourism_generating_wealth_and_peace_in_post-conflict_Rwanda">only around</a> 1,000 mountain gorillas live in two isolated populations: one in the Virunga Volcanoes – straddling the borders of Rwanda, Uganda and DRC – which has increased from 250 to 600 individuals in about 30 years; and a group in the Bwindi National Park in Uganda with about 400 individuals. </p>
<p>The survival of this particular species is important for a number of reasons. Firstly, mountain gorillas are some of our closest living relatives. They can therefore help us understand human evolution and behaviour. Secondly, they fulfil an important role in maintaining the health of tropical forest ecosystems – for instance by dispersing seeds. And finally, they are a tourist attraction that generates revenue for Rwanda and supports conservation activities throughout the country. In the last two years, tourism <a href="https://www.awf.org/blog/mountain-gorilla-tourism-drives-economic-growth-and-conservation">has contributed</a> over US$400 million to the national economy. </p>
<p>In Rwanda’s Volcanoes National Park gorillas have been leaving the confines of the protected area to raid crops – like eucalyptus and bamboo – on nearby agricultural plots. Leaving protected areas is a huge risk to their safety.</p>
<p>My colleagues at the Dian Fossey Gorilla Fund’s <a href="https://gorillafund.org/karisoke-research-center/">Karisoke Research Centre</a> and <a href="https://www.mpg.de/en">Max Planck Institute</a> and I wanted to understand why the gorillas were ranging outside protected areas into croplands. <a href="https://research-repository.uwa.edu.au/en/publications/going-to-extremes-for-sodium-acquisition-use-of-community-land-an">We found</a> that when the gorillas left the national park they often headed straight to eucalyptus trees. Our nutritional analyses showed that eucalyptus are more than a hundred times richer in sodium than the gorillas’ staple foods inside the park. </p>
<p>This led us to conclude that sodium was the main incentive for the gorillas’ escapades. All plants inside the park are low in sodium except a couple of species that grow near the top of the volcanoes. </p>
<h2>For the love of sodium</h2>
<p>We measured sodium content in samples from 34 of the gorilla’s main dietary items and quantified sodium intake by 22 gorillas in three social groups over one year.</p>
<p>The gorillas obtain up to two thirds of their sodium when consuming eucalyptus.</p>
<p>Sodium is a micro-nutrient that’s critically important for physiological processes, like muscle and nerve function and maintaining fluid levels in various parts of the body. </p>
<p>Sodium deficiency can affect bones, growth, and reproduction. A sodium deficit <a href="https://www.elsevier.com/books/wildlife-feeding-and-nutrition/robbins/978-0-12-589382-4">can trigger</a> a specific hunger for it which causes animals to go out of their way to obtain it. </p>
<p>This is as true for gorillas as it is for humans. </p>
<p>It’s possible that the gorillas were eating eucalyptus for other reasons. Perhaps for minerals we didn’t investigate – like iodine – or because of the medicinal benefits that it has. But we also found that gorillas often ventured into the region’s colder subalpine or alpine zones where they targeted plants known as giant groundsels and lobelias. These turned out to be rich in sodium as well.</p>
<h2>Human-wildlife conflict</h2>
<p>Crop raiding is the main source of conflict between people who live in close proximity to the park and wildlife. Farmers <a href="https://www.researchgate.net/publication/283489950_HUMAN-WILDLIFE_CONFLICT_MANAGEMENT_EXPERIENCES_AND_LESSONS_LEARNED_FROM_THE_GREATER_VIRUNGA_LANDSCAPE">generally perceive</a> crop damage by mountain gorillas as a big deterrent to their agricultural development. </p>
<p>The risk is that encounters between gorillas and local people will add to tensions, and lead to local communities being hostile towards wildlife, hampering wildlife conservation efforts. </p>
<p>Close contact between gorillas and people also increases the risk of disease transmission – such as respiratory diseases and intestinal parasites – which could have a detrimental impact on this highly vulnerable ape population.</p>
<p>To discourage the gorillas from crossing into farmlands near the forest, there may need to be a change in agricultural practices such as relying less on plants sought by gorillas for their nutrients. </p>
<p>An ideal scenario would be to establish a buffer zone containing nutritionally unattractive and unpalatable plants. If sufficiently wide, it would discourage gorillas from crossing into croplands.</p><img src="https://counter.theconversation.com/content/114376/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cyril Grueter received funding from Swiss National Science Foundation and Max Planck Society. He works for The University of Western Australia. </span></em></p>In Rwanda gorillas have been leaving protected areas to raid sodium rich crops.Cyril Grueter, Senior Lecturer, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1128952019-03-11T14:20:28Z2019-03-11T14:20:28ZSalt is bad for you: but how it affects your body is still frontier science<figure><img src="https://images.theconversation.com/files/262406/original/file-20190306-100805-2fzbbm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Reducing salt intake can save lives.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Research has <a href="https://www.who.int/news-room/fact-sheets/detail/salt-reduction">shown</a> that excess salt intake is harmful to people’s health. It can lead to high blood pressure and increase the risk of heart disease and stroke. </p>
<p>Globally salt reduction programmes are gaining <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4511674/">traction</a>, whether through awareness campaigns or through governmental interventions. </p>
<p>This has been true in South Africa too. Three years ago it became the first country to implement mandatory <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5884349/">salt targets</a> for staple foods such as bread and soups. This is in line with World Health Organisation (WHO) <a href="http://apps.who.int/gb/ebwha/pdf_files/wha66/a66_8-en.pdf">recommendations</a> to reduce salt intake by 30% by 2025. In South Africa a <a href="https://www.gov.za/documents/foodstuffs-cosmetics-and-disinfectants-act-regulations-reduction-sodium-certain-1">further reduction</a> in sodium targets is set to come into effect later this year.</p>
<p>The approach South Africa took was to target the non-discretionary intake of salt – that’s salt already added as an ingredient to food. It’s view was that this would be the most cost effective approach to prevent hypertension – a key driver of heart disease and stroke. </p>
<p>Research <a href="https://academic.oup.com/heapol/article/31/1/75/2363529">estimates</a> that reducing the amount of salt people eat could prevent an estimated 23,000 cardiovascular diseases and 5,600 deaths every year in South Africa. And that the new laws to reduce salt intake could save the country <a href="https://academic.oup.com/heapol/article/31/1/75/2363529">US$ 51.25 million</a> on health care for cardiovascular diseases. </p>
<p>It’s still early days on whether the new laws are having the desired effect on health – that will take a few more years to feed through. But the policy is certainly working in reducing salt in <a href="https://www.sciencedirect.com/science/article/pii/S0889157517302065">staple</a> foods such as bread. </p>
<p>As part of a <a href="https://bmjopen.bmj.com/content/6/11/e013316.long">WHO study on global ageing</a> we reviewed South Africans’s salt intake before the new laws were implemented, and are now repeating this exercise to determine whether salt intake has reduced. </p>
<p>South Africa has also made concerted efforts to promote <a href="https://www.ncbi.nlm.nih.gov/pubmed/29137143">public awareness</a> on excessive salt intake and cardiovascular health. Research <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5707710/">suggests</a> that this has been effective in changing people’s behaviour such as adding salt to food when cooking and at the table during meals. </p>
<p>But, in the medium to longer term, will these interventions produce the health outcomes the government has forecast? The key indicators would be lower blood pressure, fewer cardiovascular events such as hearts attacks and strokes.</p>
<p>The answer lies partly in policies being adjusted to take into account new scientific findings about how salt affects the body. This is a frontier that’s being explored by scientists around the world. It’s also the subject of <a href="https://journals.sagepub.com/doi/abs/10.1177/2047487318822354">our research</a>. </p>
<p>Our research challenge some assumptions that have been held for decades about how salt affects the body. Our findings – together with those of other international researchers – suggest that the mechanisms surrounding salt and cardiovascular health may be more complex than originally thought. This in turns suggests that there’s significant scope to fine tune policies to improve prevention and treatment of common disorder like hypertension. </p>
<p>We highlight, for example, that salt reduction may significantly reduce the harmful effects of hormones associated with high salt intake. Blood pressure, heart structure and blood vessels can all be affected. This provides further evidence of the important of policies that target salt intake.</p>
<h2>What we know now</h2>
<p>Compelling <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa1304127">evidence</a> over many years has strongly linked high <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa1311889">salt intake</a> with raised blood pressure and cardiovascular events like heart attacks. But emerging research has started to raise questions about the physiological mechanisms for the link between salt intake and raised blood pressure. </p>
<p>A common <a href="https://www.ncbi.nlm.nih.gov/pubmed/2246039">understanding</a> – prevalent in medical text books for decades – has been that a high salt intake results in thirst. The higher water intake consequently leads to increased blood volume which raises blood pressure, and ultimately both water and salt are excreted by the kidneys and blood pressure is maintained. </p>
<p>But German researcher, Jens Titze, recently found salt to be stored in the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4932095/">skin</a>. Researchers have further shown that a high salt intake is accompanied by <a href="https://www.jci.org/articles/view/88532">minimal water loss</a>. These surprising findings were met with scepticism by the global health sciences community, but underscores that a much better understanding of blood pressure mechanisms is required.</p>
<p>US investigators, Alexei Bagrov and Olga Fedorova, identified another <a href="https://www.ncbi.nlm.nih.gov/pubmed/8896650">player</a> in how salt affects cardiovascular health. <a href="https://www.ncbi.nlm.nih.gov/pubmed/9886882">Marinobufagenin</a> is a steroid hormone that has similar properties to active substances found in the venom of the <a href="https://www.ncbi.nlm.nih.gov/pubmed/8387009">Bufo marinus toad</a>. The hormone’s function is to <a href="https://www.ncbi.nlm.nih.gov/pubmed/11230319">manage salt balance</a> and is thus produced in response to high salt intake.</p>
<p>But very high levels of the steroid hormone, in response to excessive salt intake, resulted in <a href="https://www.ncbi.nlm.nih.gov/pubmed/11877366">increased blood pressure</a>, affected heart structure and <a href="https://www.ncbi.nlm.nih.gov/pubmed/26136067">increased</a> the stiffness of the blood vessel walls in animals.</p>
<p>We <a href="https://journals.sagepub.com/doi/abs/10.1177/2047487318822354">recently</a> set out to test this for the first time in healthy young humans. We <a href="https://www.ncbi.nlm.nih.gov/pubmed/29335615">confirmed</a> a strong positive <a href="https://www.ncbi.nlm.nih.gov/pubmed/30382957">association</a> between increased salt intake and an increase in the steroid hormone. </p>
<p>We <a href="https://www.ncbi.nlm.nih.gov/pubmed/30032457">found</a> that high salt intake was associated with the stiffness of the aorta, even in very young people. We then <a href="https://www.ncbi.nlm.nih.gov/pubmed/30382957">tested</a> whether this was due to the steroid hormone or salt itself. When we included both in our statistics, we found that the culprit was the steroid hormone, and not necessarily salt. </p>
<p>Not only was the steroid hormone associated with <a href="https://www.ncbi.nlm.nih.gov/pubmed/30382957">aortic stiffness</a>, but also with increased <a href="https://www.ncbi.nlm.nih.gov/pubmed/29335615">blood pressure</a>, and <a href="https://www.ncbi.nlm.nih.gov/pubmed/29993282">left ventricular mass</a> in young healthy adults who consumed a mean of 11.8 grams (more than two teaspoons) of salt a day. The WHO <a href="https://apps.who.int/iris/bitstream/handle/10665/77985/9789241504836_eng.pdf?sequence=1">recommends</a> an intake of less than 5 grams (one teaspoon) of salt per day.</p>
<h2>Conclusion</h2>
<p>Our findings support South Africa’s second phase implementation of reducing salt in staple foods to further lower the daily intake of salt. </p>
<p>The evidence also strongly supports the importance of continued public awareness campaigns to reduce excessive salt intake to protect cardiovascular health.</p><img src="https://counter.theconversation.com/content/112895/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alta Schutte receives funding from the South African Medical Research Council. She is also a SARChI Research Chair funded by the Department of Science and Technology. She is the President of the International Society of Hypertension.</span></em></p><p class="fine-print"><em><span>Michél Strauss receives funding from the NRF in collaboration with the German Academic Exchange Service (DAAD). The NRF/DAAD In-country Doctoral Scholarship (UID 111862) </span></em></p>South Africa needs to continue public awareness campaigns to reduce excessive salt intake to protect cardiovascular health.Alta Schutte, Research professor, North-West UniversityMichél Strauss, PhD candidate, North-West UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/926632018-03-14T22:51:30Z2018-03-14T22:51:30ZDietary salt, the silent killer: How much is too much?<figure><img src="https://images.theconversation.com/files/210386/original/file-20180314-113458-bsasny.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Most Canadians eat at least double the daily adequate intake of sodium. And, shockingly, 93 per cent of children aged four to eight exceed Health Canada's Tolerable Upper Intake Level.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Salt is the universal flavour enhancer and we can’t seem to get enough of it. </p>
<p>While preparing food at home, or while buying prepared food from grocery stores and restaurants, salt tends to find its way onto our plates. </p>
<p>Does our love for salt come at a cost? How much salt is too much, and should we be concerned? These are the questions that not enough people are asking.</p>
<p>As a PhD candidate in human health and nutritional sciences at the University of Guelph, I study <a href="https://news.uoguelph.ca/2018/02/sweet-bitter-fat-new-u-g-study-reveals-impact-genetics-kids-snack/">how the genetics of taste affects taste perception, taste preference, dietary intake and metabolism</a> in the Guelph Family Health Study. </p>
<p>Part of this research examines how genetics can cause some people to be less sensitive to the taste of salt than others, leading them to prefer higher amounts in their food. </p>
<p>Identifying genetic markers can help us understand who may be more at risk of developing the adverse consequences of excessive salt intake, such as high blood pressure, the silent killer. </p>
<h2>Salt, heart disease and hypertension</h2>
<p>In 2012, <a href="https://www.canada.ca/en/public-health/services/diseases/heart-disease-heart-health.html">about 48,000 lives were claimed by heart disease</a>, the second leading cause of death in Canada. </p>
<p>One of the major <a href="https://www.statcan.gc.ca/pub/82-625-x/2015001/article/14184-eng.htm">silent risk factors for heart disease is high blood pressure or hypertension</a>. While it cannot be seen or felt, high blood pressure puts an enormous strain on blood vessels and weakens the body’s organs, including the heart and kidneys. </p>
<p>In 2014, almost one in five Canadian teens and adults reported being diagnosed with high blood pressure. With such a widespread influence on the health of Canadians, researchers and government have been working to identify and address this growing concern. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/210175/original/file-20180313-30994-4b70c0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/210175/original/file-20180313-30994-4b70c0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/210175/original/file-20180313-30994-4b70c0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/210175/original/file-20180313-30994-4b70c0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/210175/original/file-20180313-30994-4b70c0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/210175/original/file-20180313-30994-4b70c0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/210175/original/file-20180313-30994-4b70c0.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">Genetics mean that some people need more salt on their tongues to taste it.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>While the complex solution to lowering blood pressure in Canadians continues to evade us, it is well-known that we don’t need to look further than our dinner tables to find a culprit.</p>
<p>A certain amount of salt is essential to health. But most Canadians are consuming double and sometimes even triple the daily adequate intake (AI). </p>
<p>In fact, more than 85 per cent of men and between 60 to 80 per cent of women had sodium intakes exceeding 2,300 mg per day — <a href="https://www.canada.ca/en/health-canada/services/food-nutrition/healthy-eating/sodium.html">the Tolerable Upper Intake Level (UL) set by Health Canada</a> — according to the <a href="https://www.canada.ca/en/health-canada/services/food-nutrition/food-nutrition-surveillance/health-nutrition-surveys/canadian-community-health-survey-cchs.html">2004 Canadian Community Health Survey</a>. </p>
<h2>Children exceed tolerable salt levels</h2>
<p>In children aged one to three years and four to eight years, the ULs for sodium are 1,500 mg and 1,900 mg, respectively. </p>
<p>With these adjusted guidelines, even young children are not exempt from this striking pattern. Seventy-seven per cent of children aged one to three years and 93 per cent of children aged four to eight years exceed the UL for sodium, according to the 2004 Canadian Community Health Survey. </p>
<p>At these excessive levels, sodium in salt causes the kidneys to retain water in the blood vessels. </p>
<p>An increased amount of blood in the vessels puts pressure on the walls of the arteries, similar to how pumping gas into an inflating balloon puts pressure its walls. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/210176/original/file-20180313-30986-ye0wic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/210176/original/file-20180313-30986-ye0wic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/210176/original/file-20180313-30986-ye0wic.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/210176/original/file-20180313-30986-ye0wic.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/210176/original/file-20180313-30986-ye0wic.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/210176/original/file-20180313-30986-ye0wic.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/210176/original/file-20180313-30986-ye0wic.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">Seventy-seven per cent of sodium intake in Canada comes from commercially-prepared foods.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Over time and in combination with lifestyle factors, including an overall poor diet and lack of exercise, high blood pressure increases the risk of heart disease.</p>
<h2>A food industry fail</h2>
<p>We know Canadians are eating too much salt, but why is there so much in the diet? </p>
<p>While Canadians love the taste of salt in their food, intake of sodium is not mainly a problem in terms of how food is being prepared in the home. </p>
<p>Health Canada identified that commercially prepared foods account for 77 per cent of sodium intake in Canada. With the dependence of many Canadians on readily available prepared foods at grocery stores and restaurants, part of the solution must be for manufacturers to reduce the amount of sodium in their products. </p>
<p>In 2012, Health Canada published its <a href="https://www.canada.ca/en/health-canada/services/food-nutrition/legislation-guidelines/guidance-documents/guidance-food-industry-reducing-sodium-processed-foods-2012.html">Guidance for the Food Industry on Reducing Sodium in Processed Foods</a>. This challenged the food industry to reduce sodium in a variety of food products, to targeted levels, by the end of 2016. </p>
<p>With this plan, Canadians would meet sodium targets without even having to reduce the amount of salt used at home. </p>
<p>These guidelines were mostly unmet by the food industry by the end of the program. Forty-eight per cent of food categories tested did not make any progress and 86 per cent of food categories did not meet their final sodium reduction goals. </p>
<h2>Consumer responsibility</h2>
<p>While it is tempting to fault the food industry entirely for this shortcoming, we must keep in mind that reducing sodium is more difficult in some products as it helps with food preservation and safety. </p>
<p>Consumer awareness and purchasing actions are also important for reducing sodium in food products. </p>
<p>This is a challenge to Canadians — to read nutrition labels on food products and make informed purchasing decisions. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/210178/original/file-20180313-131584-d40pt1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/210178/original/file-20180313-131584-d40pt1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/210178/original/file-20180313-131584-d40pt1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/210178/original/file-20180313-131584-d40pt1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/210178/original/file-20180313-131584-d40pt1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/210178/original/file-20180313-131584-d40pt1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/210178/original/file-20180313-131584-d40pt1.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">Genetics plays a role in the way that sodium is handled by the kidneys.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Are we ready to choose products with less sodium? With increased pressure on the food industry, perhaps we can improve blood pressure in Canadians.</p>
<h2>The genetics of taste</h2>
<p>Even if the goal of sodium reduction should be a collective effort by Canadians, not everyone responds to dietary sodium in the same way. </p>
<p>From the way that we taste salt to the way our kidneys process sodium, there are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5491159/pdf/krcp-36-117.pdf">important differences in sodium sensitivity</a> between individuals, due in part to genetics. </p>
<p>The Heart and Stroke Foundation <a href="http://www.heartandstroke.ca/get-healthy/healthy-eating/reduce-salt">estimates that one in three people are sodium- sensitive</a>. </p>
<p>One important underlying reason for sodium sensitivity is in the way we taste salt. Genetics may lead some individuals to require more salt on their tongues to taste it; this is called low oral sensitivity. As a result, these individuals may need to consume higher amounts of salt in their food to taste it. </p>
<p>Genetics also plays a role in the way sodium is handled by the kidneys. For some unlucky people, genetic differences in kidney function lead to higher sodium retention and therefore higher water retention in the blood vessels. </p>
<h2>Know what you eat</h2>
<p>Whether sodium sensitivity affects the amount of salt we need for tasting or how the kidney handles sodium, these circumstances present special risks for certain individuals to develop high blood pressure. </p>
<p>Understanding the genetics behind these individual risks, and being able to inform individuals of their sodium sensitivity, are important steps in fighting the rise of hypertension in Canada.</p>
<p>Of course, while genetics are an important piece of the puzzle, there are non-genetic factors which also predispose individuals to high blood pressure or hypertension. </p>
<p>Regardless of sodium sensitivity, it’s important for Canadians to know that eating a poor, calorie-dense diet that includes processed and refined foods is an independent risk factor for hypertension. </p>
<p>Dietary sodium reduction remains the most promising preventative approach to avoiding the silent killer — even for individuals without sodium sensitivity. </p>
<p>If asked today whether you consume too much salt, would you know the answer? </p>
<p>Knowledge is power. Knowing what you eat offers the power to take control of your health.</p><img src="https://counter.theconversation.com/content/92663/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elie Chamoun receives funding from the Ontario Ministry of Agriculture, Food and Rural Affairs. </span></em></p>Most men, women and children in Canada exceed the tolerable upper limits of salt for their bodies. Consumers need to understand how much salt is too much – to avoid hypertension and heart disease.Elie Chamoun, PhD Candidate in Human Health and Nutritional Sciences, University of GuelphLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/759682017-05-04T22:17:38Z2017-05-04T22:17:38ZMore and more restaurants list calories on their menus. What about salt?<figure><img src="https://images.theconversation.com/files/167052/original/file-20170427-15112-12nqgtt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Do you know how much salt is in your food?</span> <span class="attribution"><a class="source" href="http://www.royan.com.ar">Jorge Royan</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Which do you think has more salt: a <a href="https://www.panerabread.com/en-us/company-information/allergen-and-nutrition-information.html">Panera Bread wild blueberry scone</a> or a large order of <a href="http://www.bk.com/menu">Burger King french fries</a>?</p>
<p>Starting May 5, restaurants and food stores across the U.S. were going to be required to include calorie counts on their menus. The Trump administration <a href="http://thehill.com/regulation/healthcare/331466-fda-delays-obamacare-calorie-rule">has delayed</a> calorie labeling until next year, and is considering relaxing the requirements for certain food service establishments, a push that’s been led by the supermarket and pizza lobbies. </p>
<p>In the meantime, some businesses will likely start implementing the labels anyway. The push toward transparency in nutrition is popular – <a href="https://www.ncbi.nlm.nih.gov/pubmed/24631499">more than 60 percent</a> of Americans across political parties are in favor of the policy. Even the National Restaurant Association, the country’s largest food service trade organization, supports it.</p>
<p>But calories don’t capture everything about your food – like the fact that the Panera scone has twice as much salt as the large fries. </p>
<p>This led us to wonder whether consumers accurately estimate the salt in their restaurant meals. We analyzed the meals of more than 1,000 diners and discovered big misperceptions. This suggests consumers need more information about what’s in their restaurant meals. Adding information about the sodium content of menu items could help.</p>
<h2>Calorie labeling</h2>
<p>Over the last decade, it has become increasingly common for restaurants to post calories on menus. New York City started the trend in 2008 by making this a requirement for chain restaurants, and several cities and states soon followed. </p>
<p>Some restaurant chains even started posting this information voluntarily nationwide. For example, Starbucks and McDonald’s label all of the food on their menus (revealing that, surprisingly, a <a href="https://www.starbucks.com/menu/catalog/nutrition?food=hot-breakfast#view_control=nutrition">Starbucks Venti Frappuccino</a> has more calories than a <a href="https://www.mcdonalds.com/us/en-us/about-our-food/nutrition-calculator.html">McDonald’s Cheeseburger</a>!). </p>
<p>As part of the Affordable Care Act (ACA), chain restaurants, supermarkets, movie theaters and similar food retailers with 20 or more locations <a href="https://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/LabelingNutrition/ucm515020.htm">will be required to include calories</a> on menus. Places like Chipotle, AMC Theaters and even Whole Foods will need to post calories on nearly all foods that don’t have a nutrition facts label. Menus will also note that most Americans need to consume about 2,000 calories per day, so consumers have a point of reference. (So far, these rules are not affected by the push to reform the ACA.)</p>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/25790388">It’s not yet clear</a> whether the initiative will push consumers to change their purchases. But there is some evidence that it may motivate restaurants to <a href="https://www.ncbi.nlm.nih.gov/pubmed/28389331">cut the calories</a> in popular menu items. In recent years, restaurants have introduced new <a href="https://www.ncbi.nlm.nih.gov/pubmed/25306397">lower-calorie options</a>, possibly in preparation for the labeling law. </p>
<p>Calorie labeling may seem like a win-win, supported by consumers and restaurants alike, but it has a downside. Because there’s now a federal rule about nutrition disclosures on restaurant menus, state and local governments can’t create a rule with different requirements. This means that cities can’t require chain restaurants to post other nutrients – like sodium – on their menus.</p>
<h2>Sodium on the menu</h2>
<p>Prior to the federal law, state and local governments had considered adding sodium to menu boards. They hoped consumers would use this information to choose lower sodium items and that restaurants would reformulate menu items to be lower in salt. </p>
<p>High sodium intake increases blood pressure, a major risk factor for heart disease and stroke. Though scientists disagree about optimal levels of sodium intake, there is <a href="https://www1.nyc.gov/assets/doh/downloads/pdf/cardio/consensus-statement.pdf">widespread agreement</a> that current levels of consumption among Americans are too high. In the U.S., the average adult consumes about <a href="https://www.cdc.gov/dhdsp/data_statistics/fact_sheets/fs_sodium.htm">3,400 milligrams</a> of sodium each day. That’s nearly 50 percent higher than <a href="https://health.gov/dietaryguidelines/">the current recommended upper limit of 2,300 mg per day</a>. Researchers estimate that a 40 percent reduction in sodium over 10 years could avert up to <a href="https://www.ncbi.nlm.nih.gov/pubmed/23399718">half a million deaths</a>.</p>
<p>Very little of the sodium in your diet comes from the salt shakers on your kitchen table. <a href="https://www.ncbi.nlm.nih.gov/pubmed/1910064">More than 70 percent</a> is from packaged and restaurant foods. Salt may be used to make foods more palatable or as a preservative to extend shelf life. </p>
<p>As a result, high-sodium foods often don’t even taste salty. For example, Panera’s blueberry scone contains 900 mg of sodium – nearly 40 percent of the daily upper limit. Other items can vary widely in sodium content. A tuna sandwich at <a href="http://aubonpain.com/nutrition">Au Bon Pain</a> has 560 mg of sodium, while <a href="https://www.getcosi.com/menu">Cosi’s</a> has 1,099 mg.</p>
<p>In a 2015 survey across <a href="https://www.ncbi.nlm.nih.gov/pubmed/26135590">26 states</a>, most Americans reported taking action to reduce sodium in their diets. But if high-sodium foods don’t always taste salty, and similar items can have drastically different amounts of sodium, do consumers really have the information they need to make low-sodium choices?</p>
<h2>Massively underestimating sodium</h2>
<p>We sought to answer this question by surveying adult and adolescent diners at six fast food restaurants in four New England cities. </p>
<p>We set up shop in restaurant parking lots and asked customers to estimate the recommended daily sodium intake, as well as to identify the amount of sodium in their meal purchase. We then calculated the actual sodium content of their meals by collecting each diner’s receipt and matching purchases to sodium information from restaurant websites.</p>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/28235618">In our study</a>, the sodium content of fast food meals was very high. On average, adult and adolescent meals contained about half of the recommended daily sodium intake. More than 10 percent of meals contained more than an entire day’s worth of sodium. </p>
<p>Yet, awareness of sodium in meals was low. One-quarter of consumers could not provide an estimate. If they did, it was way off the mark. Eighty-eight percent of adolescents and 90 percent of adults underestimated sodium in their meals. On average, adults underestimated sodium by 1,013 mg and adolescents by 876 mg.</p>
<iframe src="https://datawrapper.dwcdn.net/DDuLi/2/" frameborder="0" allowtransparency="true" allowfullscreen="allowfullscreen" webkitallowfullscreen="webkitallowfullscreen" mozallowfullscreen="mozallowfullscreen" oallowfullscreen="oallowfullscreen" msallowfullscreen="msallowfullscreen" width="100%" height="500"></iframe>
<p>Underestimation worsened as sodium content of the meal increased, meaning consumers who purchased the highest-sodium meals had the hardest time with estimates. Most diners also underestimated their daily sodium recommendation, indicating a general lack of awareness both about how much sodium to consume in a day and how much restaurant foods contribute.</p>
<h2>The case for sodium labels</h2>
<p>People likely underestimate the sodium in their meals because there is no visible, prominent information at point of purchase. All of the restaurants in our study provided sodium information in some way – on websites, napkins, cups or posters. This doesn’t appear to be an efficient means of communicating. Prior research has shown that <a href="https://www.ncbi.nlm.nih.gov/pubmed/19299679">fewer than 1 percent</a> of consumers read nutrition information when provided in locations other than menus or menu boards.</p>
<p>Although federal laws prohibit cities and states from requiring sodium information on menu boards, there are policy options for addressing the underestimation problem. For example, New York City recently required chain restaurants to post sodium warning labels on menu boards next to items with more than 2,300 mg of sodium. The labels are considered food safety warnings, as compared to nutrition disclosures, which means they are not preempted by the federal law and are within the city’s authority to regulate. This policy provides information about sodium at point of purchase and encourages restaurants to reformulate their highest sodium items. Other cities and states could enact similar policies. </p>
<p>Alternatively, restaurants could choose to voluntarily add sodium to their menu boards, making healthy choices easier for the <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=fang+cogswell+sodium+2016">53 percent of Americans</a> actively trying to reduce sodium intake.</p><img src="https://counter.theconversation.com/content/75968/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Block receives funding from the National Institutes of Health, the Robert Wood Johnson Foundation, the Patient-Centered Outcomes Research Institute, and Harvard University. He is on the Annual Program Committee for The Obesity Society and on the Obesity and Diabetes Working Group of the Sackler Institute for Nutrition Science of the New York Academy of Sciences..</span></em></p><p class="fine-print"><em><span>Alyssa Moran 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>Evidence suggests that most Americans wildly underestimate the amount of sodium in their food.Alyssa Moran, Sc.D. candidate in the Department of Nutrition, Harvard UniversityJason Block, Assistant Professor, Harvard UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/647652016-09-06T09:05:02Z2016-09-06T09:05:02ZTesla’s batteries have reached their limit – here’s how they could go further<figure><img src="https://images.theconversation.com/files/136585/original/image-20160905-15457-1fpj7es.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Tesla</span></span></figcaption></figure><p>“For the first time, the world’s fastest production car is electric,” said Tesla boss Elon Musk when <a href="http://qz.com/764723/tesla-has-maxed-out-what-its-current-batteries-can-do/">he recently launched</a> the company’s latest battery. The new 100kwh device can propel Tesla’s cars to about 97kph in just 2.5 seconds and allow them to drive 20% further before recharging, compared to previous batteries. </p>
<p>But Musk also admitted that the current design and chemistry of the battery means this is quite close to the theoretical limits that it can achieve. From here it will become exponentially harder to increase the amount of energy a battery of the same size can store. So where could Tesla and other electric vehicle manufacturers go next?</p>
<p>Tesla’s current P90D design uses a battery pack that <a href="https://cleantechnica.com/2016/01/06/a-tale-of-3-battery-packs/">sits underneath the floor</a> of its “skateboard” chassis. This allows the car to carry a large volume of battery cells while maximising the interior space of the vehicle, although it also leaves the battery vulnerable to damage in an accident.</p>
<p>The new P100D battery pack looks the same from the outside and appears to use the same two rows of lithium ion cells. Yet, remarkably, it packs 100kwh of energy density into the same battery model that previously stored 90kwh and weighed just 4% less. That’s over 11 times the amount of electricity that a medium British house <a href="https://www.ukpower.co.uk/home_energy/average-energy-bill">uses on an average day</a>.</p>
<h2>Solid-state batteries</h2>
<p>The difference is in the way the pack is put together, the cooling system and the electronics. For example, a significant improvement in the way the batteries are cooled could have created enough room to fit <a href="https://forums.tesla.com/forum/forums/model-s-going-use-new-version-panasonic-18650-series-battery">56 extra cells</a> to provide the additional 10kwh energy. The 4% increase in weight suggests more components have been added and that perhaps the cell arrangement has been reworked to allow for this extra weight in the same volume. </p>
<p>For Tesla to go much further, however, it may need to consider a completely different way of storing energy. One early-stage technology being studied by companies including <a href="https://cleantechnica.com/2014/06/19/toyota-researching-solid-state-batteries-next-step-evs/">Toyota</a>, <a href="https://cleantechnica.com/2014/11/15/volkswagen-eyeing-400-mile-solid-state-batteries/">Volkswagen</a>, <a href="https://cleantechnica.com/2015/09/21/bosch-solid-state-lithium-ion-batteries-could-hit-ev-market-within-5-years/">Bosch</a> and <a href="http://www.gizmodo.co.uk/2016/05/dysons-electric-car-could-take-on-tesla-thanks-to-solid-state-batteries/">Dyson</a> is solid-state batteries. These are potentially safer, store more energy for their size and could lead to low-cost battery module developments.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/136586/original/image-20160905-15466-22w0it.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/136586/original/image-20160905-15466-22w0it.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/136586/original/image-20160905-15466-22w0it.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/136586/original/image-20160905-15466-22w0it.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/136586/original/image-20160905-15466-22w0it.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/136586/original/image-20160905-15466-22w0it.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/136586/original/image-20160905-15466-22w0it.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Battery ‘skateboard’.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Tesla_Model_S#/media/File:Tesla_Motors_Model_S_base.JPG">Oleg Alexandrov/Wikimedia</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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</figure>
<p>Typical lithium ion batteries such as the one Tesla uses contain a flammable liquid electrolyte, while solid-state batteries use a solid electrolyte that is comparatively safer. This also opens up <a href="http://onlinelibrary.wiley.com/wol1/doi/10.1002/aenm.201300654/abstract">the possibility</a> of using <a href="http://onlinelibrary.wiley.com/doi/10.1002/advs.201500213/full">lithium metal</a> instead of a graphite electrode, as this has a higher energy density and longer cycle life. <a href="http://www.nature.com/ncomms/2015/151204/ncomms10101/full/ncomms10101.html">Recent improvements</a> in electrolyte additives and ceramic shields could solve the problem of lithium electrodes sprouting fibres or “dendrites” that eventually <a href="http://newscenter.lbl.gov/2013/12/17/roots-of-the-lithium-battery/">short-circuit the battery</a>.</p>
<p>Autolib, a Paris-based electric car-sharing service has <a href="https://www.autolib.eu/en/our-commitment/bluecar-menu-en/100-electric/">already started</a> using these solid-state batteries in its 3,000 or so cars. Bosch’s battery company, Seeo, claims to have developed prototype batteries with <a href="http://www.seeo.com/news/seeo-closes-funding-round-and-adds-samsung-ventures/">an energy density of 350 Wh/kg</a> (watt-hour per kilogram). In comparison, the <a href="http://www.orbtronic.com/batteries-chargers/panasonic-3100mah-ncr18650a-li-ion-rechargeable-18650-battery-cell-made-in-japan">Panasonic 18650 cells</a> that Tesla uses have an energy density of just 254 Wh/kg. Simply replacing Tesla’s current cells with these solid-state batteries (once they are ready for production) would help the firm go from a 100kwh battery pack to a 118kwh model – almost twice the improvement Tesla’s new P100D has made on its previous design.</p>
<p>Some believe such strategies could help produce safe batteries that can carry enough charge to really compete with petrol engines. Donald Sadoway, a materials chemist at MIT, says that achieving such high energy densities is key to widespread adoption of electric vehicles. “If we had batteries with 350 Wh/kg we’d have EVs [electric vehicles] with 350 miles of range, and that’s the end of petroleum,” <a href="https://www.theguardian.com/environment/2016/may/11/dysons-electric-car-development-could-become-the-next-tesla">he said</a>.</p>
<h2>Sodium alternative</h2>
<p>However, continuing to use solid-state batteries with lithium electrodes may not be possible because the metal’s rarity means it comes with high financial and environmental costs, especially compared to carbon-based electrodes. Two potential alternatives are sodium ion-based and possibly sodium metal-based batteries, which have higher energy densities than lithium ion batteries. One such prototype battery has <a href="http://onlinelibrary.wiley.com/doi/10.1002/adfm.201403241/abstract">demonstrated 650Wh/kg</a> of energy density, which means 650 miles of range for an electric vehicle in a single charge – more than twice what current lithium ion batteries offer.</p>
<p>Sodium is much more abundant than lithium and its salt (sodium carbonate) is ten times cheaper than the equivalent lithium salt. As the costs of the electrodes and electrolyte take up more than 50% of the cost of a typical cell, batteries using sodium-based reactions will have a key advantage in that respect. Sodium ion batteries can also be completely discharged without damaging the active materials and without creating a hazard – unlike lithium ion batteries, which <a href="http://cen.acs.org/articles/93/i29/Challenging-Lithium-Ion-Batteries-New.html">can catch fire</a> if stored without charge in them.</p>
<p>With these developments in solid-state lithium and sodium technology, we can expect to see electric vehicle batteries with higher energy densities and lower costs than the ones recently revealed by Tesla. But that doesn’t mean we’ll necessarily see them in all electric cars. An alternative strategy would be to put more effort into <a href="http://jalopnik.com/bmw-just-kicked-everybodys-ass-with-its-carbon-fiber-7-1698960901">reducing the body weight</a> of the vehicles by <a href="http://www.digitaltrends.com/cars/lamborghini-forged-carbon-fiber-manufacturing-process/%5D">using carbon composites</a> so they can carry more batteries. This could potentially get us to the range of more than 350 miles in a single charge without the need for a new type of battery. But whatever the innovation is, Tesla and other manufacturers still need a final advance to put electric vehicles within reach of ordinary drivers.</p><img src="https://counter.theconversation.com/content/64765/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vivek Nair 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>Alternative technologies are already leaving Tesla’s batteries in the slow lane.Vivek Nair, Senior research associate, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/585942016-06-13T04:02:17Z2016-06-13T04:02:17ZHealth Check: how much salt is OK to eat?<figure><img src="https://images.theconversation.com/files/126111/original/image-20160610-29222-1xjsus7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A bucket of chips contains around 275mg of sodium, which accounts for 16% of an adult's daily limit.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-122505952.html">Darkkong/Shutterstock</a></span></figcaption></figure><p><a href="https://www.nrv.gov.au/nutrients/sodium">Australian guidelines recommend</a> limiting salt intake to six grams a day or less. The <a href="http://www.who.int/nutrition/publications/guidelines/sodium_intake_printversion.pdf">World Health Organisation advises</a> limiting salt even further: to 5g (for adults) and 2g (for children) per day or less. But for this article, we’ll stick to the Australian guidelines. </p>
<p>What we generally refer to as “salt” – the stuff that we sprinkle on our food – is actually <a href="http://www.foodstandards.gov.au/consumer/nutrition/salthowmuch/Pages/default.aspx">sodium chloride</a>. </p>
<p>It’s the sodium from the salt that <a href="http://www.who.int/nutrition/publications/guidelines/sodium_intake_printversion.pdf">can lead to high blood pressure</a> when consumed in high amounts. </p>
<p>Usually our kidneys are good at getting rid of excess sodium in the urine. But when problems with this occur, excess sodium enters the bloodstream. This can boost the amount of blood pumped around our body. The increased pressure on our blood vessels and heart raises the risk of stroke, as well as heart and kidney problems. </p>
<p>Lowering your sodium intake will improve your health and reduce your risk of experiencing these problems, largely through the reduction in blood pressure.</p>
<p>One gram of salt contains approximately <a href="http://www.foodstandards.gov.au/publications/pages/sodiumlevelsinarange4648.aspx">400 milligrams of sodium</a>. The maximum daily limit for adults is a little less than six times this figure: 2,300 milligrams of sodium per day. </p>
<p>Children need much less sodium. Limits range from 1,000 milligrams of sodium per day for children aged one to three years, and between 1,400mg to 2,000mg for those aged between four to 13 years. </p>
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<img alt="" src="https://images.theconversation.com/files/126104/original/image-20160610-29219-1hakc5f.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/126104/original/image-20160610-29219-1hakc5f.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=330&fit=crop&dpr=1 600w, https://images.theconversation.com/files/126104/original/image-20160610-29219-1hakc5f.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=330&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/126104/original/image-20160610-29219-1hakc5f.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=330&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/126104/original/image-20160610-29219-1hakc5f.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=415&fit=crop&dpr=1 754w, https://images.theconversation.com/files/126104/original/image-20160610-29219-1hakc5f.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=415&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/126104/original/image-20160610-29219-1hakc5f.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=415&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p>The sodium chloride (table salt) we add to other foods during cooking or at the table accounts for less than a quarter of sodium intake. A very small amount of sodium is also present in many foods such as milk and meat that contribute only a very small amount to our overall intake. </p>
<p>Most sodium we eat comes from processed and pre-packaged foods. Sodium is commonly added to foods during processing to add flavour, for preservation and as a raising agent (sodium bicarbonate). </p>
<p>Around <a href="http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/by%20Subject/4364.0.55.008%7E2011-12%7EMain%20Features%7ESodium%7E403">60% of Australians over the age of two years</a> exceeded the recommended daily maximum intake. </p>
<p>The foods that account for <a href="http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/4364.0.55.007Main+Features7152011-12">the largest proportion</a> of sodium intake in Australian adults (about 25%) include biscuits, cakes, pastries, pies, dumplings, pizza, hamburgers, hot dogs, and pasta and rice mixed dishes. </p>
<p>A few slices of takeaway pizza or a hamburger easily provides around 65% of daily upper limit of consumption, with around 1,500mg sodium.</p>
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<img alt="" src="https://images.theconversation.com/files/126112/original/image-20160610-29205-1vszaur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/126112/original/image-20160610-29205-1vszaur.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1021&fit=crop&dpr=1 600w, https://images.theconversation.com/files/126112/original/image-20160610-29205-1vszaur.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1021&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/126112/original/image-20160610-29205-1vszaur.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1021&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/126112/original/image-20160610-29205-1vszaur.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1283&fit=crop&dpr=1 754w, https://images.theconversation.com/files/126112/original/image-20160610-29205-1vszaur.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1283&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/126112/original/image-20160610-29205-1vszaur.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1283&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p>Savoury snack foods contain high amounts of sodium. Many sweet snack foods and bakery products often contain high levels of sodium as well. This is usually from added salt and other additives such as sodium bicarbonate, which helps baked goods rise. </p>
<p>An iced vanilla doughnut or low-fat banana muffin can contain up to 650mg of sodium (roughly 30% of the daily upper limit). </p>
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<img alt="" src="https://images.theconversation.com/files/126047/original/image-20160610-10696-10mbxar.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/126047/original/image-20160610-10696-10mbxar.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1047&fit=crop&dpr=1 600w, https://images.theconversation.com/files/126047/original/image-20160610-10696-10mbxar.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1047&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/126047/original/image-20160610-10696-10mbxar.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1047&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/126047/original/image-20160610-10696-10mbxar.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1316&fit=crop&dpr=1 754w, https://images.theconversation.com/files/126047/original/image-20160610-10696-10mbxar.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1316&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/126047/original/image-20160610-10696-10mbxar.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1316&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p>Some other foods we eat everyday, such as breads and breakfast cereals, contribute a lot of salt to our diets. These foods aren’t always really high in sodium but because we eat of a lot of them, it adds up. A continental bread roll such as a panini or ciabatta can provide up to 450mg per roll (20% of the daily upper limit).</p>
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<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/126048/original/image-20160610-10722-5ykis1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/126048/original/image-20160610-10722-5ykis1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=803&fit=crop&dpr=1 600w, https://images.theconversation.com/files/126048/original/image-20160610-10722-5ykis1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=803&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/126048/original/image-20160610-10722-5ykis1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=803&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/126048/original/image-20160610-10722-5ykis1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1010&fit=crop&dpr=1 754w, https://images.theconversation.com/files/126048/original/image-20160610-10722-5ykis1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1010&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/126048/original/image-20160610-10722-5ykis1.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1010&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p>You already know foods such as processed meats and cheeses are very salty, but just how much might surprise you. A few slices of leg ham or a couple of BBQ sausages will provide around half the daily limit of sodium. Combine that with a few slices of bread for a sandwich and some tomato sauce or cheese, and you will have easily exceeded the upper limit of consumption.</p>
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<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/126113/original/image-20160610-29219-p4ihms.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/126113/original/image-20160610-29219-p4ihms.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=750&fit=crop&dpr=1 600w, https://images.theconversation.com/files/126113/original/image-20160610-29219-p4ihms.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=750&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/126113/original/image-20160610-29219-p4ihms.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=750&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/126113/original/image-20160610-29219-p4ihms.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=943&fit=crop&dpr=1 754w, https://images.theconversation.com/files/126113/original/image-20160610-29219-p4ihms.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=943&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/126113/original/image-20160610-29219-p4ihms.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=943&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p>Passing on added salt at the dinner table is a good habit to reduce sodium intake, but take care adding sauces or condiments as these are likely just as salty. Tomato pasta sauce and stir-fry sauces can contribute up to 480mg in a single serve (up to 20% of the daily limit).</p>
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<figure class="align-center ">
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<p>Because sodium is present in so many processed foods – even sweet snacks and baked goods – you shouldn’t always rely on your taste buds to determine how much you’re consuming. So how can you cut down on your sodium intake?</p>
<p>First, eat fewer packaged and processed foods. In addition to sodium, they often contain high amounts of sugar and fat and very little of any other beneficial nutrients. So reducing your intake of these foods can substantially improve the quality of your diet.</p>
<p>Second, swap processed foods for those cooked or prepared at home. Swap sandwich fillings like processed meats with ones you’ve cooked yourself (such as left over roast meat). Opt for fresh fruits and unsalted nuts instead of packaged sweet or savoury snacks. </p>
<p>Instead of takeaway meals like pizza or frozen dinners, prepare home-cooked versions. Here you can use more fresh food ingredients (which are low in sodium) and you can control the added salt. Fresh foods are also higher in potassium, which has beneficial effects on lowering blood pressure.</p>
<p>Finally, read the labels on packaged foods. Food labels in Australia usually give the figure for sodium rather than salt. So if you are reading a nutrition information panel, try to look out for foods that have less than 400mg sodium per 100g of food. Any packaged food labelled less than 120mg sodium per 100g of food is best. </p>
<p>The George Institute and Bupa Australia’s <a href="http://www.georgeinstitute.org.au/projects/foodswitch">FoodSwitch</a>/<a href="https://itunes.apple.com/au/app/foodswitch/id478225318?mt=8">SaltSwitch app</a> is a useful tool to help you navigate and compare sodium content of packaged foods on the go. You can scan the barcode of the product you’re considering buying and see a list of other products with less sodium.</p><img src="https://counter.theconversation.com/content/58594/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kacie Dickinson has previously received funding from CSIRO and The Heart Foundation and is currently a member of the Dietitians Association of Australia and the Nutrition Society of Australia.</span></em></p>Around 60% of Australians over the age of two years exceeded the recommended daily maximum intake of salt.Kacie Dickinson, Accredited Practising Dietitian; Associate Lecturer in Nutrition and Dietetics, Flinders UniversityLicensed as Creative Commons – attribution, no derivatives.