tag:theconversation.com,2011:/id/topics/microbiome-3734/articlesMicrobiome – 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>
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<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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<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>
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<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/2139262024-02-23T12:57:17Z2024-02-23T12:57:17ZGut microbiome: meet Lactobacillus acidophilus – the gut health superhero<figure><img src="https://images.theconversation.com/files/577544/original/file-20240223-24-46adyy.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5176%2C3445&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Eating yoghurt is one way of getting more _Lactobacillus acidophilus_ into your diet.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-woman-home-eating-yogurt-111275633">Josep Suria/ Shutterstock</a></span></figcaption></figure><p>Your gut is like a bustling city of trillions of microscopic inhabitants – including bacteria. While some of these bacterial inhabitants are villains, causing illness, infection and disease, others are good – supporting our health and keeping things running smoothly. </p>
<p>But one species of bacterium in our gut is so good and does so much for our health, that it might well be compared to a gut superhero. This microbe goes by the name of <em><a href="https://www.cabdirect.org/cabdirect/abstract/19352701869">Lactobacillus acidophilus</a></em>. </p>
<p><em>Lactobacillus acidophilus</em> might sound like a mouthful, but don’t let its long name intimidate you. In simple terms, it’s a tiny bacterium that belongs to a group of microorganisms known for their <a href="https://pubmed.ncbi.nlm.nih.gov/24912386/">probiotic properties</a> – meaning it provides health benefits when consumed in adequate quantities.</p>
<p>This microbe hangs out in your gut (mainly your small intestine) and helps keep things running smoothly. In fact, <em>Lactobacillus acidophilus</em> has an incredible number of important functions.</p>
<p>It acts as a digestion buddy, munching on things you can’t digest entirely – such as certain sugars and fibres. For example, it helps digest foods rich in lactose (such as dairy products like milk, yogurt and cheese), as well as fermentable carbohydrates found in vegetables, fruits and grains. By doing so, <a href="https://pubmed.ncbi.nlm.nih.gov/30468509/">it helps break down your food</a>, making it easier for your body to absorb nutrients.</p>
<p>Since your gut is a delicate ecosystem, <em>Lactobacillus acidophilus</em> plays a crucial role in maintaining the right balance of bacteria by <a href="https://pubmed.ncbi.nlm.nih.gov/22254077/">preventing harmful bacteria</a> from taking over and causing trouble.</p>
<p>This microbe also <a href="https://pubmed.ncbi.nlm.nih.gov/23372900/">strengthens your body’s defence system</a>. It does this by helping your immune cells <a href="https://pubmed.ncbi.nlm.nih.gov/20823239/">communicate better</a> and stay alert so they’re ready to fight off invaders. </p>
<p>And when your stomach is upset or you’re stressed, <em>Lactobacillus acidophilus</em> is the microbe that comes to the rescue, soothing irritation and <a href="https://pubmed.ncbi.nlm.nih.gov/16728323/">helping ease digestive discomfort</a>.</p>
<figure class="align-center ">
<img alt="A man holds his stomach in pain." src="https://images.theconversation.com/files/577545/original/file-20240223-20-cu5btb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/577545/original/file-20240223-20-cu5btb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/577545/original/file-20240223-20-cu5btb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/577545/original/file-20240223-20-cu5btb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/577545/original/file-20240223-20-cu5btb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/577545/original/file-20240223-20-cu5btb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/577545/original/file-20240223-20-cu5btb.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">One of the benefits this microbe has is easing digestive problems.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/man-suffering-stomach-ache-sitting-on-488527312">Antonio Guillem/ Shutterstock</a></span>
</figcaption>
</figure>
<p>All of these important functions mean <em>Lactobacillus acidophilus</em> is a true friend to your body, and its affects on your health are pretty impressive, with benefits such as:</p>
<ul>
<li><strong>Happy tummies:</strong> By maintaining a balanced gut environment, your stomach will feel <a href="https://pubmed.ncbi.nlm.nih.gov/18274900/">more comfortable</a>, and you have less chance of experiencing tummy troubles such as <a href="https://pubmed.ncbi.nlm.nih.gov/16728323/">diarrhoea</a>, constipation and bloating.</li>
<li><strong>Immune support:</strong> By keeping your gut in tip-top shape, <em>Lactobacillus acidophilus</em> <a href="https://pubmed.ncbi.nlm.nih.gov/19651563/">helps protect you</a> from infections and illnesses. It’s shown to be particularly good at keeping <a href="https://pubmed.ncbi.nlm.nih.gov/23594927/">influenza</a> at bay. </li>
<li><strong>Controlling allergies and inflammation:</strong> Some studies suggest that having a strong colony of <em>Lactobacillus acidophilus</em> in your gut might <a href="https://pubmed.ncbi.nlm.nih.gov/19840300/">reduce the risk of allergies</a> and <a href="https://pubmed.ncbi.nlm.nih.gov/24954372/">inflammation-related conditions</a> (such as eczema). It acts like a natural shield against <a href="https://pubmed.ncbi.nlm.nih.gov/26044853/">sneezing fits and sore joints</a>.</li>
<li><strong>Preserving mental wellbeing:</strong> Believe it or not, your gut health can influence your mood. <em>Lactobacillus acidophilus</em> might play a role in <a href="https://pubmed.ncbi.nlm.nih.gov/29521671/">promoting good mental wellbeing</a>.</li>
</ul>
<p>Given all the important roles that <em>Lactobacillus acidophilus</em> plays in your health, if you’re keen to fill your gut with this microbe you can find it in tasty fermented foods such as <a href="https://www.tandfonline.com/doi/abs/10.1080/10408398.2011.621169?casa_token=q5rNmHVBFjAAAAAA:79FQSbhMoQYMVxrw_WvyFaeHmSR50olvQO8JaGY9ZzluOnYAy_CLWaJhx6J8utAb1F6xgl60gYRN8w">yogurt and kefir</a>. </p>
<h2>A deeper look</h2>
<p>Even though we know a lot about <em>Lactobacillus acidophilus</em>, there’s still much to explore. Scientists are currently digging deeper to understand whether there are <a href="https://pubmed.ncbi.nlm.nih.gov/16875422/">different strains of this microbe</a> – and if each of these strains have unique abilities. </p>
<p>Scientists are also working on tailoring probiotics to a person’s specific needs. Imagine having a <a href="https://www.nature.com/articles/s41564-020-0721-1">personalised probiotic</a> superhero designed just for you. People with inflammatory bowel disease, weakened immune systems, allergies and mental health concerns may benefit from personalised products containing probiotic strains such as <em>Lactobacillus acidophilus</em>, because of the benefits it may have for these issues. </p>
<p>And finally, researchers are continuing to investigate the link between gut health and the brain – with scientists taking a particular interest in investigating how specifically <em>Lactobacillus acidophilus</em> might influence <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6445894/">mood and mental wellbeing</a>.</p>
<p><em>Lactobacillus acidophilus</em> is a tiny but mighty superhero in your gut, working hard to keep you healthy and happy. So the next time you enjoy <a href="https://www.tandfonline.com/doi/abs/10.1080/10408398.2011.621169?casa_token=q5rNmHVBFjAAAAAA:79FQSbhMoQYMVxrw_WvyFaeHmSR50olvQO8JaGY9ZzluOnYAy_CLWaJhx6J8utAb1F6xgl60gYRN8w">a yogurt or sip on some kefir</a>, think of it as giving your friendly gut superhero a high-five. </p>
<hr>
<p><em>This article is part of <a href="https://theconversation.com/uk/topics/meet-your-gut-microbes-150943?utm_source=InArticleTop&utm_medium=TCUK&utm_campaign=Health2024">Meet Your Gut Microbes</a>, a series about the rich constellation of bacteria, viruses, archaea and fungi that live in people’s digestive tracts. Scientists are increasingly realising their importance in shaping our health – both physical and mental. Each week we will look at a different microbe and bring you the most up-to-date research on them.</em></p>
<hr><img src="https://counter.theconversation.com/content/213926/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Fermented foods, such as yoghurt and kefir, are great sources of this immune-boosting microbe.Samuel J. White, Senior Lecturer in Genetic Immunology, Nottingham Trent UniversityPhilippe B. Wilson, Professor of One Health, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2209352024-02-15T13:34:14Z2024-02-15T13:34:14ZBacteria in your gut can improve your mood − new research in mice tries to zero in on the crucial strains<figure><img src="https://images.theconversation.com/files/569636/original/file-20240116-23-4k79iu.png?ixlib=rb-1.1.0&rect=0%2C0%2C3295%2C2549&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The difference between one mouse's fear and another mouse's calm might be in their gut bacteria.</span> <span class="attribution"><span class="source">Katriel Cho</span>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p><a href="https://ods.od.nih.gov/factsheets/Probiotics-Consumer/">Probiotics</a> have been getting a lot of attention recently. These bacteria, which you can consume from fermented foods, yogurt or even pills, are linked to a number of <a href="https://my.clevelandclinic.org/health/treatments/14598-probiotics">health and wellness benefits</a>, including reducing gastrointestinal distress, urinary tract infections and eczema. But can they improve your mood, too?</p>
<p>Behavior and mental health are complicated. But the short answer, according to my team’s <a href="https://doi.org/10.1016/j.bbi.2023.11.001">recently published research</a>, is likely yes.</p>
<p>The beneficial bacteria in probiotics become part of a community of other microscopic organisms living in your digestive system called the <a href="https://www.niehs.nih.gov/health/topics/science/microbiome">gut microbiome</a>. Your gut microbiome contains trillions of a diverse range of bacteria, fungi and viruses. </p>
<p><a href="https://doi.org/10.3389/fmicb.2020.02029">Hundreds of species of bacteria</a> are native to the intestinal tract. Each species can be broken down into hundreds of strains that can also be dramatically different from each other in their metabolism, byproducts and environmental preferences.</p>
<p>This bacterial diversity is why not all probiotics are built the same. Many research groups have shown that specific strains of <em>Lactobacillus</em> have <a href="https://doi.org/10.3390/nu15143258">mood-enhancing effects</a>. </p>
<p>But these effects seem to happen only with the right mix of bacteria in the right conditions. For example, a probiotic that can reduce symptoms of stress in someone who is worried about their calculus final may not work in someone with symptoms of post-traumatic stress disorder.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/575084/original/file-20240212-16-hxn0sy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Yogurt parfair on a tablecloth" src="https://images.theconversation.com/files/575084/original/file-20240212-16-hxn0sy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/575084/original/file-20240212-16-hxn0sy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=465&fit=crop&dpr=1 600w, https://images.theconversation.com/files/575084/original/file-20240212-16-hxn0sy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=465&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/575084/original/file-20240212-16-hxn0sy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=465&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/575084/original/file-20240212-16-hxn0sy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=584&fit=crop&dpr=1 754w, https://images.theconversation.com/files/575084/original/file-20240212-16-hxn0sy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=584&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/575084/original/file-20240212-16-hxn0sy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=584&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The probiotics in your yogurt may play a role in boosting mood.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/shallow-focus-photo-of-clear-drinking-glass-GbCEo-Nwyj4">Tanaphong Toochinda/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Studying mood in mice</h2>
<p>In my work <a href="https://scholar.google.com/citations?user=X8XcETAAAAAJ&hl=en">as a neuroscientist</a>, I study how the gut influences the brain. My team and I recently <a href="https://doi.org/10.1016/j.bbi.2023.11.001">conducted experiments</a> in mice that support the idea that gut microbiota play a role in regulating stress.</p>
<p>So how do you measure the mood of mice? </p>
<p>First, we needed to understand how stressed mice behave. So we placed them under <a href="https://doi.org/10.1016/j.bbi.2023.11.001">short periods of stress</a>: They are restrained for two hours each day, given enough room to move around but not enough to groom or stand up. We envision this as the same type of stress people experience when they’re confined to a car or cubical for hours at a time. </p>
<p>Stressed mice soon exhibited depression- and anxiety-like behaviors, which we measured by monitoring how much time they spent hiding when placed in a new environment or how quickly they try to right themselves when flipped upside down.</p>
<p>While it isn’t surprising that stressed mice hide longer and are slower to right themselves, the power of their poop to change their behavior was. </p>
<p>To see if stressed behavior could be transferred through the microbiome, we used another group of mice that were entirely clean. These mice were free from any bacteria, fungi or viruses and lived in a rubber bubble. They essentially had no microbiome at all.</p>
<p>We exposed them to poop from either stressed mice or normal mice by sprinkling soiled bedding in their enclosures. Microbes from the donor mice started to populate the gut microbiomes of the clean mice.</p>
<p>Within a few weeks, the clean mice exposed to poop from stressed mice started to develop stress- and anxiety-like behavior, even though nothing else had changed. Meanwhile, clean mice exposed to poop from normal mice had no differences in their behavior. This finding suggests that the microbes in poop changed the mice’s behavior.</p>
<h2>Which bacteria affect mood?</h2>
<p>The results of our experiments led us back to our original question: Which bacteria can change your mood? </p>
<p>We started by comparing the microbes in the poop of stressed and normal mice. In our analysis, we found that a group of bacteria called <em>Lactobacillus</em> was greatly reduced in the stressed mice. Research has linked this group of bacteria to <a href="https://doi.org/10.1016/j.bbih.2020.100169">stress reduction</a> before. However, <em>Lactobacillus</em> contains over 170 different species and even more strains. </p>
<p>Currently, the probiotic supplements available to patients are <a href="https://www.nccih.nih.gov/health/probiotics-what-you-need-to-know">unregulated and often untested</a>. In order to reliably get the most effective strains to patients, they need to be properly tested. So we had to come up with a way to test how different strains affect anxious behavior. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/574702/original/file-20240209-28-2yorsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of rod-shaped Lactobacillus stained blue" src="https://images.theconversation.com/files/574702/original/file-20240209-28-2yorsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/574702/original/file-20240209-28-2yorsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=358&fit=crop&dpr=1 600w, https://images.theconversation.com/files/574702/original/file-20240209-28-2yorsd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=358&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/574702/original/file-20240209-28-2yorsd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=358&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/574702/original/file-20240209-28-2yorsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=450&fit=crop&dpr=1 754w, https://images.theconversation.com/files/574702/original/file-20240209-28-2yorsd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=450&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/574702/original/file-20240209-28-2yorsd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=450&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Lactobacillus</em> are a diverse range of bacteria that can provide potential health benefits in people.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Lactobacillus_paracasei.jpg">Dr. Horst Neve/Max Rubner-Institut via Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Instead of tackling this colossal task alone, we created a method that other microbiome scientists can also use to look at this group of bacteria as systematically as possible. </p>
<p>To recreate the same experimental conditions for each species of microbe, we created a group of mice with only six species of bacteria in their microbiome, the <a href="https://doi.org/10.1093/ilar/ilv012">bare minimum needed</a> for normal and healthy development, which did not include <em>Lactobacillus</em>. This way, we could add individual strains of <em>Lactobacillus</em> back into the mice’s gut microbiome and observe the effects of each strain on their behavior and biology. </p>
<p>We’ve <a href="https://doi.org/10.1016/j.bbi.2023.11.001">tested two strains</a> so far: <em>Lactobacillus intestinalis</em> ASF360 and <em>Lactobacillus murinus</em> ASF361. Mice with these two strains of <em>Lactobacillus</em> are more resilient to stress and have quieted neural pathways associated with fear.</p>
<h2>What’s next?</h2>
<p>Our study on how different strains of <em>Lactobacillus</em> affect mood is just the beginning. We hope that our research will open avenues for other scientists to test different probiotics. </p>
<p>While researchers are <a href="https://doi.org/10.1016/j.neubiorev.2019.03.023">reaching a consensus</a> that the bacteria in your digestive tract can influence your mood, and vice versa, there is still a lot of testing to be done in both animals and in people.</p>
<p>Our team is starting to develop ways to systematically test which bacteria may provide the best health outcomes in people and which probiotics are the most effective. In the meantime, give the <em>Lactobacillus</em> in your gut some love through a healthy, probiotics-rich diet.</p><img src="https://counter.theconversation.com/content/220935/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrea Merchak has received funding from the National Institutes of Health (T32 NS115657, F31 AI174782).</span></em></p>The organisms living in your gut microbiome can influence your mental and physical health. Researchers have developed a way to better test for those biological effects.Andrea Merchak, Postdoctoral Associate in Neuroscience, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2153112024-02-09T16:50:23Z2024-02-09T16:50:23ZYour unique smell can provide clues about how healthy you are<figure><img src="https://images.theconversation.com/files/574043/original/file-20240207-19-o4ehc8.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5291%2C3516&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/happy-calm-teen-girl-enjoying-good-1325627765">fizkes/Shutterstock</a></span></figcaption></figure><p>Hundreds of chemicals stream from our bodies into the air every second. These chemicals release into the air easily as they have high vapour pressures, meaning they boil and turn into gases at room temperature. They give clues about who we are, and how healthy we are. </p>
<p>Since ancient Greek times, we’ve known that we smell differently when we are unwell. While we rely on blood analysis today, ancient Greek physicians used smell to diagnose maladies. If they took a whiff of your breath and described it as <em>fetor hepaticus</em> (meaning bad liver), it meant you could be headed for liver failure.</p>
<p>If a person’s whiff was sweet or fruity, physicians thought this meant that sugars in the digestive system were not being broken down, and that person had probably diabetes. Science has since shown the ancient Greeks were right – liver failure and <a href="https://tisserandinstitute.org/human-volatilome/">diabetes</a> and many <a href="https://link.springer.com/article/10.1007/s00216-023-04986-z">other diseases</a> including infectious diseases give your breath a distinctive smell.</p>
<p>In 1971, <a href="https://www.nobelprize.org/prizes/peace/1962/pauling/facts/">Nobel Laureate chemist Linus Pauling</a> <a href="https://edu.rsc.org/feature/breath-analysis/2020106.article#:%7E:text=The%20'modern%20era'%20of%20breath,in%20an%20average%20breath%20sample.">counted 250 different</a> gaseous chemicals in breath. These gaseous chemicals are called volatile organic compounds or VOCs. </p>
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<p>Since Pauling’s discovery, other scientists have <a href="https://link.springer.com/article/10.1007/s40291-023-00640-7">discovered hundreds more VOCs</a> in our breath. We have learned that many of these VOCs have distinctive odours, but some have no odour that our noses can perceive. </p>
<p>Scientists believe that whether a VOC <a href="https://tisserandinstitute.org/human-volatilome/">has an odour</a> that our noses can detect or not, they can reveal information about how healthy someone is.</p>
<p>A Scottish man’s Parkinson’s disease onset was <a href="https://www.bbc.co.uk/news/uk-scotland-47627179">identified by his wife</a>, retired nurse Joy Milner, after she was convinced the way he smelled had changed, years before he was diagnosed in 2005. This discovery has <a href="https://www.manchester.ac.uk/discover/news/smell-of-skin-could-lead-to-early-diagnosis-for-parkinsons/">led to research programmes</a> involving Joy Milner to identify <a href="https://www.scientificamerican.com/article/a-supersmeller-can-detect-the-scent-of-parkinsons-leading-to-an-experimental-test-for-the-illness/">the precise smell</a> of this disease. </p>
<p>Dogs can <a href="https://www.nature.com/articles/d41586-022-01629-8">sniff out more diseases</a> than humans because of their more <a href="https://www.understandinganimalresearch.org.uk/news/the-science-of-sniffs-disease-smelling-dogs%20-%20I%20think%20the%20previous%20nature%20link%20has%20more%20credibility%20for%20here%20also">sophisticated olfactory talents</a>. But technological techniques, like <a href="https://www.britannica.com/science/mass-spectrometry">analytical tool mass spectrometry</a>, picks up even more subtle changes in VOC profiles that are being linked to <a href="https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(20)30100-6/fulltext">gut</a>, <a href="https://www-sciencedirect-com.dcu.idm.oclc.org/science/article/pii/S0165993618305168">skin</a> and <a href="https://err.ersjournals.com/content/28/152/190011">respiratory</a> diseases as well as neurological diseases like Parkinson’s. Researchers believe that one day some diseases will be diagnosed simply by breathing into a device. </p>
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<h2>Where do VOCs come from?</h2>
<p>Breath is not the only source of VOCs in the body. They are also emitted from skin, urine and faeces. </p>
<p>VOCs from skin are the result of millions of skin glands removing metabolic waste from the body, as well as waste generated by bacteria and other microbes that live on our skin. Sweating produces extra nutrients for these bacteria to metabolise which can result in particularly odorous VOCs. Odour from sweat only makes up a fraction of the scents from VOCs though.</p>
<p><a href="https://www.nature.com/articles/nrmicro.2017.157">Our skin</a> and also our gut microbiomes are made up from a delicate balance of these microbes. Scientists think <a href="https://journals.lww.com/co-gastroenterology/abstract/2015/01000/the_gut_microbiome_in_health_and_in_disease.12.aspx">they influence our health</a>, but we don’t yet understand a lot about how this relationship works. </p>
<p>Unlike the gut, the skin is relatively easy to study – you can collect skin samples from living humans without having to go deep into the body. <a href="https://www-sciencedirect-com.dcu.idm.oclc.org/science/article/pii/S1471492221002087">Scientists think</a> skin VOCs can offer insights into how the microbiome’s bacteria and the human body work together to maintain our health and protect us from disease.</p>
<p>In my team’s laboratory, <a href="https://iopscience.iop.org/article/10.1088/1752-7163/abf20a">we are investigating</a> whether the skin VOC signature can reveal different attributes of the person it belongs to. These signals in skin VOC signatures are probably how dogs distinguish between people by smell. </p>
<p>We are at a relatively early stage in this research area but we have shown that you can tell males from females based on how acidic the VOCs from skin are. We use mass spectrometry to see this as the average human nose is not sophisticated enough to detect these VOCs. </p>
<p>We can also predict a person’s age with reasonable accuracy to within a few years from their skin VOC profile. This is not surprising considering that oxidative stress in our bodies increases as we age.</p>
<p><a href="https://www.metabolismjournal.com/article/S0026-0495(00)80077-3/pdf">Oxidative stress</a> happens when your antioxidant levels are low and causes irreversible damage to our cells and organs. <a href="https://pubs.acs.org/doi/10.1021/jasms.3c00315">Our recent research</a> found by-products of this oxidative damage in skin VOC profiles. </p>
<p>Not only are these VOCs responsible for personal scent – they are used by plants, insects and animals as a communication channel. Plants are in a <a href="https://www.nature.com/articles/s41598-017-10975-x">constant VOC dialogue</a> with other organisms including pollinators, herbivores, other plants and their natural enemies such as harmful bacteria and insects. VOCs used for this back and forth dialogue are known as pheromones. </p>
<h2>What has science shown about love pheromones?</h2>
<p>In the animal kingdom, there is good evidence VOCs can act as aphrodisiacs. Mice for example have microbes which contribute to a particularly <a href="https://www.sciencedirect.com/science/article/pii/S0960982212012687">smelly compound called trimethylamine</a>, which allows mice to verify the species of a potential mate. <a href="https://www.sciencedirect.com/science/article/abs/pii/S0093691X21003083">Pigs</a> and <a href="https://www.nature.com/articles/4381097a">elephants</a> have sex pheromones too. </p>
<p>It is possible that humans also produce VOCs for attracting the perfect mate. Scientists have yet to fully decode skin – or other VOCs that are released from our bodies. But evidence for human love pheromones so far is <a href="https://www.science.org/content/article/do-human-pheromones-actually-exist">controversial at best</a>. <a href="https://www.newscientist.com/article/dn3835-colour-vision-ended-human-pheromone-use/">One theory suggests</a> that they were lost about 23 million years ago when primates developed full colour vision and started relying on their enhanced vision to choose a mate.</p>
<p>However, we believe that whether human pheromones exist or not, skin VOCs can reveal who and how we are, in terms of things like ageing, nutrition and fitness, fertility and even stress levels. This signature probably contains markers we can use to monitor our health and diagnose disease.</p><img src="https://counter.theconversation.com/content/215311/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Aoife Morrin receives funding from Science Foundation Ireland.</span></em></p>The science of smell is an exciting area of research.Aoife Morrin, Associate Professor of Analytical Chemistry, Dublin City UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2222962024-02-05T16:13:03Z2024-02-05T16:13:03ZA new virus-like entity has just been discovered – ‘obelisks’ explained<figure><img src="https://images.theconversation.com/files/573101/original/file-20240202-31-42ohg4.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C8038%2C5354&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/rear-view-male-doctor-taking-bodily-1510584707">Andrey_Popov/Shutterstock</a></span></figcaption></figure><p>Biological entities called obelisks have been hiding – in large numbers – inside the human mouth and gut. These microscopic entities, which were recently discovered by a team at Stanford University, are circular bits of genetic material that contain one or two genes and self-organise into a rod-like shape. </p>
<p>Although the study is still in <a href="https://www.biorxiv.org/content/10.1101/2024.01.20.576352v1">preprint</a> form, meaning that it has not been peer-reviewed, it has already been extensively written about, including in two heavyweight journals: <a href="https://www.nature.com/articles/d41586-024-00266-7">Nature</a> and <a href="https://www.science.org/content/article/it-s-insane-new-viruslike-entities-found-human-gut-microbes">Science</a>.</p>
<p>Let’s delve deeper into the strange world of very tiny “lifeforms”.</p>
<p>In biology, as in physics, things can get weirder and the rules fuzzier as we move through smaller and smaller scales. </p>
<p>Viruses, being unable to replicate without the help of a host, can most generously be considered to be on the edge of what constitutes life. Yet the estimated <a href="https://www.nationalgeographic.com/science/article/factors-allow-viruses-infect-humans-coronavirus">10 nonillion (one followed by 31 zeroes) individual viruses</a> on the planet can be found in every conceivable habitat and, through infecting and manipulating their hosts, have probably affected the evolutionary trajectories of all life. </p>
<p>Peering even further down into the world of minuscule biological entities, are the viroids – tiny scraps of genetic material (DNA-like molecules known as RNA) that cannot make proteins and, unlike viruses, don’t have a protective shell to encase their genome. </p>
<p>Viroids are examples of ribozymes: RNA molecules that may be a distant echo of the very first self-replicating genetic elements from which cellular life emerged. </p>
<p>Viroids can self-cleave (chop up) and re-ligate (stick back together) their genome as part of the replication cycle. And, despite their simplicity, they can cause serious disease in <a href="https://pubmed.ncbi.nlm.nih.gov/33801996/">flowering plants</a>.</p>
<h2>Between a virus and a viroid – perhaps</h2>
<p>The new <a href="https://www.biorxiv.org/content/10.1101/2024.01.20.576352v1.full">preprint</a> describes “viroid-like colonists of human microbiomes”. If “viroid-like” sounds non-committal, that is entirely deliberate. The newly discovered biological entity falls somewhere between viruses and viroids. </p>
<p>In fact, the name obelisks was proposed not only because of their shape, but also to provide wiggle room in case they turn out to be more like RNA plasmids (a different type of genetic element that resides inside bacteria) than either viruses or viroids.</p>
<p>Like viroids, obelisks have a circular single-stranded RNA genome and no protein coat but, like viruses, their genomes contain genes that are predicted to code for proteins. </p>
<p>All obelisks so far described encode a single major protein known as obulin, and many encode a second, smaller obulin. </p>
<p>Obulins bear no evolutionary resemblance, or “homology”, to any other protein found, and there are few clues as to their function. </p>
<p>By analysing existing datasets taken from the gut and mouth of humans as well as other diverse sources, the Stanford team found almost 30,000 distinct obelisk types. </p>
<p>These obelisk genomes have been previously overlooked because they are so dissimilar to anything described previously. The Stanford team found them using a clever bespoke method for searching databases for single-stranded circular RNA molecules to fish out any viroid-like elements. </p>
<p>It is clear from their results that obelisks are not rare. The researchers found them in datasets spanning the globe and in diverse niches. </p>
<p>These elements were detected in around 7% of microbiome datasets from the human gut and 50% of datasets from the mouth. However, whether these datasets provide a true representation of the prevalence and distribution of obelisks is unclear. </p>
<p>Different obelisk types were found in different body sites and in different donors. Long-term data revealed that people can harbour a single obelisk type for around a year. </p>
<p>Obelisks probably rely on microbial host cells to replicate, including those that live inside humans to replicate. Bacteria or fungi are likely hosts, but it is not known which exact species harbour these elements. </p>
<p>However, the researchers provide a critical lead through the analysis by providing strong evidence that a common bacterial component of dental plaque, <em>Streptococcus sanguinis</em>, plays host to a specific obelisk type.</p>
<figure class="align-center ">
<img alt="Illustration of the human gut full of microbes" src="https://images.theconversation.com/files/573105/original/file-20240202-29-62uqwp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/573105/original/file-20240202-29-62uqwp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/573105/original/file-20240202-29-62uqwp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/573105/original/file-20240202-29-62uqwp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/573105/original/file-20240202-29-62uqwp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/573105/original/file-20240202-29-62uqwp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/573105/original/file-20240202-29-62uqwp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">We might have to re-think the gut microbiome.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/3d-rendered-medical-illustration-microbiome-small-2221001821">SciePro/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Friend or foe?</h2>
<p>As <em>S sanguinis</em> is easy to grow and experiment on in the laboratory, this will provide a valuable model for understanding the fundamentals of obelisk biology. </p>
<p>This is critical, as nothing is known about the broader evolutionary and ecological significance of obelisks. They may be parasitic and harm host cells, or they may be beneficial. </p>
<p>Hosts may have evolved elaborate defence mechanisms against obelisks, or else actively recruit them to gain some unsuspected advantage. If obelisks change or upset the human microbiome, this may in turn have implications for human health – they may even have therapeutic potential. </p>
<p>Alternatively, obelisks may cause neither harm nor benefit to their microbial host, or to humans. Instead, they may simply exist as stealthy evolutionary passengers, silently and endlessly replicating, like the original “selfish gene”.</p><img src="https://counter.theconversation.com/content/222296/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ed Feil 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>Your mouth and your gut is full of them. But we don’t know if they’re friend or foe.Ed Feil, Professor of Microbial Evolution at The Milner Centre for Evolution, University of BathLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2163552024-01-16T19:15:14Z2024-01-16T19:15:14ZSpace travel taxes astronauts’ brains. But microbes on the menu could help in unexpected ways<figure><img src="https://images.theconversation.com/files/565638/original/file-20231213-27-4xr8mj.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5991%2C3000&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-vector/smiling-man-astronaut-presents-shawarma-kebab-1128088580">studiostoks/Shutterstock</a></span></figcaption></figure><p>Feeding astronauts on a long mission to Mars goes well beyond ensuring they have enough nutrients and calories to survive their multi-year journey.</p>
<p>Providing astronauts with the right diet is also paramount in supporting their <a href="https://www.frontiersin.org/articles/10.3389/fncir.2023.1170395/full?trk=public_post_comment-text">mental and cognitive health</a>, in a way unlike previous missions.</p>
<p>So we need to radically rethink how we feed astronauts not only on a challenging mission to Mars, which could be on the cards in the late 2030s or early 2040s, but to prepare for possible settlement on the red planet. </p>
<p>That includes acknowledging the role of microbes in mental health and wellbeing, and providing astronauts with the right foods and conditions for a variety of these beneficial microbes to grow. Our research aims to do just that.</p>
<p>Here’s why a healthy balance of microbes is important under such challenging conditions, and how we could put microbes on the menu.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/was-going-to-space-a-good-idea-218235">Was going to space a good idea?</a>
</strong>
</em>
</p>
<hr>
<h2>Why are missions to Mars so challenging?</h2>
<p>Deep space missions will expose humans to immense physical and psychological challenges. These include prolonged isolation from loved ones, extreme space and resource constraints, and the difficulties of microgravity. </p>
<p>Disruption to astronauts’ circadian rhythms, prolonged radiation exposure and dietary changes can also lower their cognitive performance and wellbeing. </p>
<p>The hazardous conditions, combined with the psychological toll of potential spacecraft failures, can all contribute to mental health problems.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-live-in-space-what-weve-learned-from-20-years-of-the-international-space-station-144851">How to live in space: what we've learned from 20 years of the International Space Station</a>
</strong>
</em>
</p>
<hr>
<h2>Why is diet important for mental health?</h2>
<p>We already know the quality of people’s diet not only influences their physical health, but also their mental and brain health. </p>
<p>Diet quality is <a href="https://www.nature.com/articles/s41380-018-0237-8">consistently and independently linked</a> to the risk of depression or anxiety. Clinical trials <a href="https://pubmed.ncbi.nlm.nih.gov/35441666/">show</a> improving diet quality <a href="https://www.ncbi.nlm.nih.gov/pubmed/30720698">can lead to</a> profound improvements in depression and anxiety symptoms. </p>
<p>Diet also affects the size and function of a specific brain region – the hippocampus – that is crucial to learning and memory, as well as for maintaining <a href="https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-015-0461-x?report=reader">mental health</a>. When even young healthy adults eat “junk” foods, aspects of cognition linked to the hippocampus quickly <a href="https://royalsocietypublishing.org/doi/abs/10.1098/rsos.191338">decline</a>.</p>
<p>On the other hand, research shows a diet containing more and varied plant foods and seafood (which are rich in components called long-chain omega-3 fatty acids and flavonoids) leads to <a href="https://www.nature.com/articles/s41598-022-21927-5">better cognitive performance</a>. This study was conducted in a closed chamber for 45 days, designed to mimic conditions in space.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Plate of salmon on bed of green salad, with lemon slices, on blue wood table" src="https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565649/original/file-20231213-23-owo81l.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">A diet rich in plant food and seafood might help your brain, but how do you turn that into space food that will go the distance?</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/grilled-salmon-vegetables-366852431">Jacek Chabraszewski/Shutterstock</a></span>
</figcaption>
</figure>
<p>Diet can have such consequences by <a href="https://www.ncbi.nlm.nih.gov/pubmed/33144709">altering</a>:</p>
<ul>
<li>immune function</li>
<li>the size and functioning of the hippocampus </li>
<li>chemical messenger (neurotransmitter) systems</li>
<li>how our bodies respond to stress.</li>
</ul>
<p>Diet can also influence the many ways microbes in the gut affect the brain, a link known as the <a href="https://journals.physiology.org/doi/full/10.1152/physrev.00018.2018?rfr_dat=cr_pub">microbiota gut-brain axis</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/essays-on-health-microbes-arent-the-enemy-theyre-a-big-part-of-who-we-are-79116">Essays on health: microbes aren't the enemy, they're a big part of who we are</a>
</strong>
</em>
</p>
<hr>
<h2>Not all foods make the grade</h2>
<p>Space foods need to appeal to a diverse crew and stay nutritious for an extremely long time (likely a three- to five-year mission). They also need to be lightweight and compact enough to fit on the spacecraft.</p>
<p>Once on Mars, challenges include growing fresh food and culturing protein sources. Beyond providing nutrients, we also need to consider providing more recently identified factors including phytonutrients (such as polyphenols), fermentation products and microbes. These will likely be crucial to sustain health and, indeed, life on deep space missions.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/humans-are-going-back-to-the-moon-and-beyond-but-how-will-we-feed-them-189794">Humans are going back to the Moon, and beyond – but how will we feed them?</a>
</strong>
</em>
</p>
<hr>
<h2>Why are microbes so important?</h2>
<p>If you’ve seen the film <a href="https://theconversation.com/the-martian-review-science-fiction-that-respects-science-fact-48373">The Martian</a>, you’ll know microbes are a crucial aspect of growing food, and are essential for keeping humans alive and functioning. </p>
<p>We have co-evolved with, and are hosts to, trillions of different microbes that live on our skin and in all our niches and cavities. This includes our mouths, nose, vagina, lungs and – crucially – our gut.</p>
<p>Most of these microbes are bacteria. The largest number are in the gut, where they influence our digestion, metabolism, and immune, endocrine (hormone) and nervous systems.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/YB-8JEo_0bI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">What is the human microbiome?</span></figcaption>
</figure>
<p>The relationship between gut microbes and <a href="https://journals.physiology.org/doi/full/10.1152/physrev.00018.2018?rfr_dat=cr_pub">mental health and behaviour</a> goes both ways. Gut microbes influence our mental health and behaviour, and these, in turn, influence our gut microbes. </p>
<p>Other components of our microbiomes – viruses, fungi and even parasites – and the oral and lung microbiome are also linked to mental and <a href="https://journals.physiology.org/doi/full/10.1152/physrev.00018.2018?rfr_dat=cr_pub">brain health</a>. </p>
<p>Importantly, we <a href="https://www.nature.com/articles/s41586-022-05620-1">share microbes</a> with others, including via the exchange of air, which is highly relevant in closed-environment systems such as inside spacecrafts.</p>
<p>So ensuring all astronauts have the healthiest and most diverse of microbes for the whole of the mission is vital.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-do-some-farts-smell-and-some-dont-and-why-do-some-farts-feel-hot-215064">Curious Kids: why do some farts smell and some don’t? And why do some farts feel hot?</a>
</strong>
</em>
</p>
<hr>
<h2>How could we encourage healthy microbes?</h2>
<p>It’s not just the food itself we have to think about. We also need to think about how we grow the food if we are to support healthy microbiomes. </p>
<p>Indeed, microbes play an essential role in the nutrient and phytochemical content of plants, and the microbes in soil, plants and humans are interconnected. Research published in 2023 confirms bacteria on vegetables and other plant foods find a home in the <a href="https://www.tandfonline.com/doi/abs/10.1080/19490976.2023.2258565">human gut</a>, enhancing microbe diversity. </p>
<p>But current ways of growing foods on spacecraft don’t use natural soil. Standard “vertical farming” methods grow plants in an alternative growth medium – imagine a next-generation hydroponics system. So we may need to add an optimised microbial cocktail to these systems to enhance the health properties of the foods astronauts grow and eat.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Growing tending plants in a vertical farm" src="https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=421&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=421&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=421&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=529&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=529&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565654/original/file-20231213-19-kwbbo1.png?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>
<figcaption>
<span class="caption">This closed chamber mimics how astronauts will grow fresh crops in space.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/technology/tech-transfer-spinoffs/nasa-research-launches-a-new-generation-of-indoor-farming/">NASA</a></span>
</figcaption>
</figure>
<p><a href="https://www.cell.com/cell/fulltext/S0092-8674(22)01515-X?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS009286742201515X%3Fshowall%3Dtrue">Fermented protein</a> from microbes can be quickly produced in a bioreactor on board the spacecraft, even from food waste. Some types have a meat-like flavour and texture, and can provide all the amino acids humans need as well as useful byproducts from the microbes themselves. </p>
<p>Fermentation itself creates thousands of different bioactive molecules, including some vitamins, that have diverse <a href="https://www.tandfonline.com/doi/abs/10.1080/1028415X.2018.1544332">beneficial effects on health</a>, including possible benefits to mental health.</p>
<p>While we don’t yet know what types of fermented foods are possible in space, we could include fermented foods, such as kimchi and sauerkraut, in astronauts’ diets on Earth.</p>
<p>Probiotics and prebiotics as supplements may also be essential. Probiotics are live microbes that have demonstrated health benefits and prebiotics are food for these healthy microbes.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-is-kombucha-and-how-do-the-health-claims-stack-up-87180">What is kombucha and how do the health claims stack up?</a>
</strong>
</em>
</p>
<hr>
<h2>Benefits on Earth too</h2>
<p>We’re only at the start of learning how to optimise microbes to keep space crews healthy, which is crucial for long space flights and for possible settlement on other planets. </p>
<p>However, this research could have many other applications. We can use what we learn to help create self-sustaining and <a href="https://www.nasa.gov/technology/tech-transfer-spinoffs/nasa-research-launches-a-new-generation-of-indoor-farming/">sustainable food systems</a> on Earth to improve the environment and human health.</p><img src="https://counter.theconversation.com/content/216355/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Felice N Jacka is supported by a National Health and Medical Research Council investigator grant (#1194982). She has received: (1) competitive grant/research support from the Brain and Behaviour Research Institute, the National Health and Medical Research Council, Australian Rotary Health, the Geelong Medical Research Foundation, the Ian Potter Foundation, The University of Melbourne; (2) industry support for research from Meat and Livestock Australia, Woolworths Limited, the A2 Milk Company, Be Fit Foods, Bega Cheese; (3) philanthropic support from the Fernwood Foundation, Wilson Foundation, the JTM Foundation, the Serp Hills Foundation, the Roberts Family Foundation, the Waterloo Foundation and; (4) travel support and speakers honoraria from Sanofi-Synthelabo, Janssen Cilag, Servier, Pfizer, Network Nutrition, Angelini Farmaceutica, Eli Lilly, Metagenics, and The Beauty Chef. She is on the Scientific Advisory Board of the Dauten Family Centre for Bipolar Treatment Innovation and Zoe Limited. Felice Jacka has written two books for commercial publication.</span></em></p><p class="fine-print"><em><span>Dorit Donoviel is Executive Director, NASA-Funded Translational (moving products from lab-bench to practice) Research Institute for Space Health at Baylor College of Medicine. Dorit receives funding from NASA through Cooperative Agreement NNX16AO69A and disburses this funding to research groups and companies performing work to safeguard the health of humans in deep space.</span></em></p>Here’s why a healthy balance of microbes is important for astronauts when they travel to Mars and beyond.Felice Jacka, Alfred Deakin Professor, Deakin UniversityDorit Donoviel, Executive Director/Associate Professor, Baylor College of Medicine Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2202722024-01-16T13:40:52Z2024-01-16T13:40:52ZYour body already has a built-in weight loss system that works like Wegovy, Ozempic and Mounjaro – food and your gut microbiome<figure><img src="https://images.theconversation.com/files/568472/original/file-20240109-26-7fx8si.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2039%2C1467&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Weight loss pills aren't a replacement for a healthy diet and lifestyle.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/capsules-and-pills-in-shape-of-hamburger-royalty-free-image/89127926">JW LTD/Stone via Getty Images</a></span></figcaption></figure><p><a href="https://theconversation.com/drugs-that-melt-away-pounds-still-present-more-questions-than-answers-but-ozempic-wegovy-and-mounjaro-could-be-key-tools-in-reducing-the-obesity-epidemic-205549">Wegovy, Ozempic and Mounjaro</a> are weight loss and diabetes drugs that have made quite a splash in <a href="https://www.nytimes.com/2023/08/17/health/weight-loss-drugs-obesity-ozempic-wegovy.html">health news</a>. They target regulatory pathways involved in both <a href="https://doi.org/10.1111/dom.14496">obesity and diabetes</a> and are widely considered breakthroughs for weight loss and blood sugar control. </p>
<p>But do these drugs point toward a root cause of metabolic disease? <a href="https://doi.org/10.1111/obr.12421">What inspired</a> their development in the first place?</p>
<p>It turns out your body produces natural versions of these drugs – also known as <a href="https://doi.org/10.1111/dom.13129">incretin hormones</a> – in your gut. It may not be surprising that <a href="https://doi.org/10.3390%2Fijms22126623">nutrients in food</a> help regulate these hormones. But it may intrigue you to know that the trillions of <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">microbes in your gut</a> are key for orchestrating this process.</p>
<p><a href="https://gastro.uw.edu/people/faculty/damman-c">I am a gastroenterologist</a> at the University of Washington who studies how <a href="https://gutbites.org/">food and your gut microbiome</a> affect health and disease. Here’s an inside-out perspective on the role natural gut hormones and healthy food play in metabolism and weight loss.</p>
<h2>A broken gut</h2>
<p>Specialized bacteria in your lower gut take the components of food you can’t digest like <a href="https://doi.org/10.3390/microorganisms10122507">fiber</a> and <a href="https://doi.org/10.1016/j.cofs.2020.03.001">polyphenols</a> – the elements of plants that are removed in many processed foods – and transforms them into molecules that stimulate hormones to control your <a href="https://doi.org/10.1016/j.advnut.2023.03.016">appetite and metabolism</a>. These include GLP-1, a natural version of Wegovy and Ozempic.</p>
<p><a href="https://doi.org/10.3389/fendo.2021.721135">GLP-1</a> and other hormones like <a href="https://doi.org/10.1113%2Fjphysiol.2008.164269">PYY</a> help regulate blood sugar through the pancreas. They also tell your brain that you’ve had enough to eat and your stomach and intestines to slow the movement of food along the digestive tract to allow for digestion. This system even has a name: the <a href="https://doi.org/10.1136/gut.34.9.1171">colonic brake</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568486/original/file-20240109-23-4av9qx.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram showing the effects of GLP-1 on various organs of the body" src="https://images.theconversation.com/files/568486/original/file-20240109-23-4av9qx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568486/original/file-20240109-23-4av9qx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=475&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568486/original/file-20240109-23-4av9qx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=475&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568486/original/file-20240109-23-4av9qx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=475&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568486/original/file-20240109-23-4av9qx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=597&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568486/original/file-20240109-23-4av9qx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=597&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568486/original/file-20240109-23-4av9qx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=597&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">GLP-1 serves many functions in the body.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:FunctionsOfGLP-1.png">Lthoms11/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Prior to modern processed foods, metabolic regulatory pathways were under the direction of a <a href="https://doi.org/10.1038/ncomms4654">diverse healthy gut microbiome</a> that used these hormones to naturally regulate your metabolism and appetite. However, <a href="https://doi.org/10.1186/s12963-017-0119-3">food processing</a>, aimed at improving shelf stability and enhancing taste, removes the bioactive molecules like <a href="https://doi.org/10.1177/1559827615588079">fiber</a> and <a href="https://doi.org/10.3390/molecules26030703">polyphenols</a> that help regulate this system. </p>
<p>Removal of these key food components and the resulting decrease in gut microbiome diversity may be an important factor contributing to the rise in <a href="https://doi.org/10.1016/j.advnut.2023.03.016">obesity and diabetes</a>.</p>
<h2>A short track to metabolic health</h2>
<p>Wegovy and Ozempic reinvigorate the colonic brake downstream of food and microbes with molecules similar to GLP-1. Researchers have demonstrated their effectiveness at <a href="https://doi.org/10.1001/jama.2023.2438">weight loss and blood sugar control</a>. </p>
<p>Mounjaro has gone a step further and combined GLP-1 with a second hormone analogue derived from the upper gut called GIP, and studies are showing this combination therapy to be even more effective at <a href="https://doi.org/10.1056/NEJMoa2206038">promoting weight loss</a> than GLP-1-only therapies like Wegovy and Ozempic. </p>
<p>These drugs complement other measures like <a href="https://doi.org/10.1001/jama.2020.12567">gastric bypass surgery</a> that are used in the most extreme cases of metabolic disease. These surgeries may in part <a href="https://doi.org/10.1210/en.2017-00564">work much like Wegovy and Ozempic</a> by bypassing digestion in segments of the gastrointestinal tract and bathing your <a href="https://doi.org/10.1007/s11695-017-2595-8">gut microbes</a> in less digested food. This awakens the microbes to stimulate your gut cells to produce <a href="https://doi.org/10.1080/00365521.2017.1293154">GLP-1</a> and <a href="https://doi.org/10.1016/j.ebiom.2018.12.040">PYY</a>, effectively regulating appetite and metabolism. </p>
<p>Many patients have seen significant improvements to not only their weight and blood glucose but also reductions in important cardiovascular outcomes like <a href="https://doi.org/10.1056/NEJMoa2307563">strokes and heart attacks</a>. <a href="https://doi.org/10.1161/CIRCULATIONAHA.122.059595">Medical guidelines</a> support the use of new incretin-based medications like Wegovy, Ozempic and Mounjaro to manage the interrelated metabolic conditions of diabetes, obesity and cardiovascular disease.</p>
<p>Considering the effects incretin-based medications have on the brain and cravings, medical researchers are also evaluating their potential to treat nonmetabolic conditions like <a href="https://doi.org/10.1172/jci.insight.170671">alcohol abuse</a>, <a href="https://doi.org/10.1126/science.adk5498">drug addiction</a> and <a href="https://doi.org/10.1016/j.jpsychires.2023.05.041">depression</a>.</p>
<h2>A near-magic bullet – for the right folks</h2>
<p>Despite the success and prospect of these drugs to help populations that may benefit most from them, current <a href="https://doi.org/10.1155/2023/9946924">prescribing practices</a> have raised some questions. Should people who are only a little overweight use these drugs? What are the risks of prescribing these drugs to <a href="https://time.com/6285055/wegovy-teenagers-weight-loss-risks/">children and adolescents</a> for lifelong weight management?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568488/original/file-20240109-25-jarss4.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Close-up of a person's socked feet stepping on a scale" src="https://images.theconversation.com/files/568488/original/file-20240109-25-jarss4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568488/original/file-20240109-25-jarss4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568488/original/file-20240109-25-jarss4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568488/original/file-20240109-25-jarss4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568488/original/file-20240109-25-jarss4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568488/original/file-20240109-25-jarss4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568488/original/file-20240109-25-jarss4.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Some people regain weight after stopping incretin-based drugs.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/mid-adult-man-step-on-weight-scales-at-home-royalty-free-image/1468770376?adppopup=true">Oleksandra Troian/Moment via Getty Images</a></span>
</figcaption>
</figure>
<p>While incretin-based therapies seem close to magic bullets, they are not without gastrointestinal side effects like <a href="https://doi.org/10.1517/14740338.2015.987122">nausea, vomiting, diarrhea and constipation</a>. These symptoms are related to how the drugs work to slow the gastrointestinal tract. Other more severe, but rare, side effects include <a href="https://doi.org/10.1001/jama.2023.19574">pancreatitis and irreversible gastroparesis</a>, or inflammation of the pancreas and stomach paralysis.</p>
<p>These drugs can also lead to a <a href="https://doi.org/10.3803/EnM.2019.34.3.247">loss of healthy lean muscle mass</a> in addition to fat, particularly in the absence of exercise. Significant <a href="https://doi.org/10.1111/dom.14725">weight gain</a> after stopping the drugs raises further questions about <a href="https://doi.org/10.2337/dc09-1902">long-term effects</a> and whether it’s possible to transition back to using only lifestyle measures to manage weight.</p>
<h2>All roads lead to lifestyle</h2>
<p>Despite our greatest aspirations for quick fixes, it’s very possible that a <a href="https://gutbites.org/2022/05/18/the-pillars-of-health/">healthy lifestyle</a> remains the most important way to manage metabolic disease and overall health. This includes regular exercise, stress management, sleep, getting outdoors and a balanced diet.</p>
<p>For the majority of the population who don’t yet have obesity or diabetes, restarting the gut’s built-in appetite and metabolism control by reintroducing whole foods and awaking the gut microbiome may be the best approach to promote healthy metabolism.</p>
<p>Adding minimally processed foods back to your diet, and specifically those replete in <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> and <a href="https://gutbites.org/2024/01/10/like-fiber-polyphenols-in-food-boost-glp-1-ignite-mitochondria-help-coordinate-metabolic-health/">polyphenols</a> like flavonoids and carotenoids, can play an important and complementary role to help address the epidemic of obesity and metabolic disease at one of its deepest roots.</p><img src="https://counter.theconversation.com/content/220272/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Damman is on the scientific advisory board at One BIO and Supergut.</span></em></p>Weight loss and diabetes drugs target regulatory pathways involved in metabolism that the microbes in your gut and certain molecules from food already play a key role in regulating.Christopher Damman, Associate Professor of Gastroenterology, School of Medicine, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2179252023-12-27T20:26:29Z2023-12-27T20:26:29ZI collect marsupial poo. A crack team of volunteers across Australia helps me out<figure><img src="https://images.theconversation.com/files/559861/original/file-20231116-15-5v6vpr.jpg?ixlib=rb-1.1.0&rect=0%2C328%2C1484%2C1248&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Tracy Dodd</span></span></figcaption></figure><p>I thought convincing my husband of the merits of my returning to study just as he had retired would be a very tricky sell. So his enthusiasm for the idea caught me by surprise.</p>
<p>He helpfully suggested several interesting topics: sea turtles, dugongs and coral reefs. If it involved a boat in a warm climate, he was behind me 100%.</p>
<p>But if you are going to dedicate three and a half years to studying a single topic, it really needs to excite you, and my interest in gut bacteria and health won out. Much to my hubby’s dismay, I chose to immerse myself in the subject of marsupial poo – and in retaliation he started calling me Dr Poo.</p>
<p>Fortunately, I am not alone in my faecal fetish. As any wildlife carer can tell you, monitoring what comes out of an animal is a vital part of keeping an eye on its health. </p>
<p>So when I set out to find volunteers to collect poo from wild and captive marsupials – specifically eastern grey kangaroos, swamp wallabies, red-necked wallabies, bare-nosed wombats, and ringtail and brushtail possums – over an area from Queensland to Tasmania, it was mainly wildlife carers who answered the call. </p>
<h2>The Marsupial Microbiome Poop Troop</h2>
<p>I enlisted a core group of around 20 people who, every season, dutifully went out in all weathers, armed with their forceps and zip-lock bags, to select fresh pellets from their in-care residents or wild animals that passed through. Then they filled in the paperwork, carefully labelled the bags and stored them in freezers until they could be posted in special temperature-controlled packaging to the university for genetic analysis. </p>
<p>We did this to establish a baseline of what the normal wild gut microbiome looks like in different animals in different areas at different times of the year. This lets us recognise if there is an imbalance in captive animals that can be addressed and prevented by changing diet or introducing supplements.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/559862/original/file-20231116-17-i3bmax.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of marsupial droppings in a yellow cloth." src="https://images.theconversation.com/files/559862/original/file-20231116-17-i3bmax.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/559862/original/file-20231116-17-i3bmax.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/559862/original/file-20231116-17-i3bmax.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/559862/original/file-20231116-17-i3bmax.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/559862/original/file-20231116-17-i3bmax.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/559862/original/file-20231116-17-i3bmax.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/559862/original/file-20231116-17-i3bmax.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A collection of precious kangaroo poo.</span>
<span class="attribution"><span class="source">Diane Lane</span></span>
</figcaption>
</figure>
<p>To aid my communication with these wonderful volunteers, I started a Facebook group page which became known as the Marsupial Microbiome Poop Troop. And it has some colourful members.</p>
<p>There is Kate, who obtains the freshest wombat poo by stalking wild wombats in her local reserve until they produce the goods. Don’t try this at home. Kate has serious wombat-whisperer skills. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-can-you-learn-from-studying-an-animals-scat-126307">What can you learn from studying an animal's scat?</a>
</strong>
</em>
</p>
<hr>
<p>There’s Darryl, who was devastated when the roof blew off his house in a storm and he was without power for two weeks. Not for his wrecked house or loss of possessions, but because his collection of possum poo thawed and he had to throw it away and start again.</p>
<p>Julie wins the prize for most prolific collector. Her poo parcels are the largest by far, and cover quite a few species. The supervisor of the university’s stores, who receives the poo parcels, is not always a fan of Julie’s efforts. He must have highly attuned olfactory senses as he routinely sends me emails announcing the arrival of more “animal excrement” or “malodorous packages” for immediate collection.</p>
<h2>Saving orphaned joeys</h2>
<p>While it all sounds like fun and games, the research we do with the collected poo has serious potential to save many marsupial lives. We have a particular focus on young orphaned joeys. </p>
<p>Whether their mothers were hit by cars, attacked by dogs, or died of other causes, the joeys arrive at wildlife shelters stressed, often injured, and generally cold and hungry. Because marsupials are born so undeveloped – and normally spend a long time in their mother’s pouch – they require an extended period in care when orphaned. </p>
<p>The gut microbiome of these “pinky” joeys is equivalent in development to that of premature human babies. It is still being established at this crucial time, via the mother’s milk, environmental conditions in the pouch, cleaning and grooming. </p>
<p>The sudden loss of parental care, coupled with the stress of being in captivity and a complete change of diet, can do a great deal of harm to the gut microbiota. This can leave the joey open to infections, diarrhoea and dehydration, which can be fatal. </p>
<p>If it were possible to fix this imbalance, the success rate of rearing orphaned marsupials would rise. Their improved general health should mean greater numbers of animals successfully reintroduced to the wild.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/from-the-frontline-saving-australias-threatened-mammals-28337">From the frontline: saving Australia's threatened mammals</a>
</strong>
</em>
</p>
<hr>
<p>While the animals involved in this study are considered “common”, the same principles may be applied to endangered species held in captive breeding programmes once it has been shown to work on the more prolific species.</p>
<p>Without the help of the Poop Troop volunteers, it would have been impossible to sample so widely and consistently. The remaining poo will be kept frozen and made available to future researchers, so these wonderful people have, through their dedication and persistence, made a real contribution to marsupial microbiome research that will continue to help wildlife in the future.</p><img src="https://counter.theconversation.com/content/217925/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Angela Russell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The Marsupial Microbiome Poop Troop collects the droppings of wild marsupials to help save the lives of orphaned joeys.Angela Russell, Graduate researcher PhD candidate, La Trobe UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2121982023-12-20T00:14:19Z2023-12-20T00:14:19ZWhat happens to your vagina as you age?<figure><img src="https://images.theconversation.com/files/565380/original/file-20231213-23-r8q3y2.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3000%2C2276&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-vector/realistic-3d-paper-cut-human-uterus-2210475317">Dedraw Studio/Shutterstock</a></span></figcaption></figure><p>The vagina is an internal organ with a complex ecosystem, influenced by circulating hormone levels which change during the menstrual cycle, pregnancy, breastfeeding and menopause.</p>
<p>Around and after menopause, there are normal changes in the growth and function of vaginal cells, as well as the vagina’s microbiome (groups of bacteria living in the vagina). Many women won’t notice these changes. They don’t usually cause symptoms or concern, but if they do, symptoms can usually be managed.</p>
<p>Here’s what happens to your vagina as you age, whether you notice or not.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/friday-essay-grey-haired-and-radiant-reimagining-ageing-for-women-182336">Friday essay: grey-haired and radiant – reimagining ageing for women</a>
</strong>
</em>
</p>
<hr>
<h2>Let’s clear up the terminology</h2>
<p>We’re focusing on the <a href="https://www.ncbi.nlm.nih.gov/books/NBK545147/">vagina</a>, the muscular tube that goes from the external genitalia (the vulva), past the cervix, to the womb (uterus). Sometimes the word “vagina” is used to include the external genitalia. However, these are different organs and play different roles in women’s health.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/565381/original/file-20231213-17-grlu25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram of female reproductive system including the vagina" src="https://images.theconversation.com/files/565381/original/file-20231213-17-grlu25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/565381/original/file-20231213-17-grlu25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=428&fit=crop&dpr=1 600w, https://images.theconversation.com/files/565381/original/file-20231213-17-grlu25.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=428&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/565381/original/file-20231213-17-grlu25.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=428&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/565381/original/file-20231213-17-grlu25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=538&fit=crop&dpr=1 754w, https://images.theconversation.com/files/565381/original/file-20231213-17-grlu25.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=538&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/565381/original/file-20231213-17-grlu25.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=538&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">We’re talking about the internal organ, the vagina.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/female-reproductive-system-image-diagram-243154639">Suwin66/Shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/vulvas-periods-and-leaks-women-need-the-right-words-to-seek-help-for-conditions-down-there-53638">Vulvas, periods and leaks: women need the right words to seek help for conditions 'down there'</a>
</strong>
</em>
</p>
<hr>
<h2>What happens to the vagina as you age?</h2>
<p>Like many other organs in the body, the vagina is sensitive to female sex steroid hormones (hormones) that change around puberty, pregnancy and menopause. </p>
<p>Menopause is associated with a drop in circulating oestrogen concentrations and the hormone progesterone is no longer produced. The changes in hormones affect the vagina and its ecosystem. <a href="https://www.ncbi.nlm.nih.gov/books/NBK564341/">Effects</a> may include:</p>
<ul>
<li>less vaginal secretions, potentially leading to dryness </li>
<li>less growth of vagina surface cells resulting in a thinned lining</li>
<li>alteration to the support structure (connective tissue) around the vagina leading to less elasticity and more narrowing</li>
<li>fewer blood vessels around the vagina, which <a href="https://pubmed.ncbi.nlm.nih.gov/2989746/">may explain</a> less blood flow after menopause</li>
<li>a <a href="https://www.nature.com/articles/s41564-022-01083-2">shift</a> in the type and balance of bacteria, which can change vaginal acidity, from more acidic to more alkaline. </li>
</ul>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/essays-on-health-microbes-arent-the-enemy-theyre-a-big-part-of-who-we-are-79116">Essays on health: microbes aren't the enemy, they're a big part of who we are</a>
</strong>
</em>
</p>
<hr>
<h2>What symptoms can I expect?</h2>
<p>Many women do not notice any bothersome vaginal changes as they age. There’s also little evidence many of these changes cause vaginal symptoms. For example, there is no direct evidence these changes cause vaginal infection or bleeding in menopausal women. </p>
<p>Some women notice vaginal dryness after menopause, which may be linked to less vaginal secretions. This may lead to pain and discomfort during sex. But it’s not clear how much of this dryness is due to menopause, as younger women also commonly report it. In <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136974/pdf/nihms957122.pdf">one study</a>, 47% of sexually active postmenopausal women reported vaginal dryness, as did around 20% of premenopausal women.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/562316/original/file-20231129-21-kae382.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two cut grapefruit, one drier than the other" src="https://images.theconversation.com/files/562316/original/file-20231129-21-kae382.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/562316/original/file-20231129-21-kae382.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/562316/original/file-20231129-21-kae382.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/562316/original/file-20231129-21-kae382.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/562316/original/file-20231129-21-kae382.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/562316/original/file-20231129-21-kae382.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/562316/original/file-20231129-21-kae382.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Vaginal dryness is common but it can also affect younger women.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/fresh-grapefruit-stale-on-pink-background-1115302421">ECOSY/Shutterstock</a></span>
</figcaption>
</figure>
<p>Other organs close to the vagina, such as the bladder and urethra, are also affected by the change in hormone levels after menopause. Some women experience recurrent urinary tract infections, which may cause pain (including pain to the side of the body) and irritation. So their symptoms are in fact not coming from the vagina itself but relate to changes in the urinary tract. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-long-does-menopause-last-5-tips-for-navigating-uncertain-times-195211">How long does menopause last? 5 tips for navigating uncertain times</a>
</strong>
</em>
</p>
<hr>
<h2>Not everyone has the same experience</h2>
<p>Women vary in whether they notice vaginal changes and whether they <a href="https://www.flinders.edu.au/research/vitalmeno">are bothered</a> by these to the same extent. For example, women with vaginal dryness who are not sexually active may not notice the change in vaginal secretions after menopause. However, some women notice severe dryness that affects their daily function and activities.</p>
<p>In fact, <a href="https://www.imsociety.org/2021/06/21/a-core-outcome-set-for-vasomotor-symptoms-associated-with-menopause-the-comma-core-outcomes-in-menopause-global-initiative/">researchers globally</a> are taking more notice of women’s experiences of menopause to inform future research. This includes prioritising symptoms that matter to women the most, such as vaginal dryness, discomfort, irritation and pain during sex.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/vaginas-pheromones-and-tiktok-what-is-the-strange-new-trend-of-vabbing-187431">Vaginas, pheromones and TikTok: what is the strange new trend of 'vabbing'?</a>
</strong>
</em>
</p>
<hr>
<h2>If symptoms bother you</h2>
<p>Symptoms such as dryness, irritation, or pain during sex can usually be effectively managed. Lubricants may reduce pain during sex. Vaginal moisturisers may reduce dryness. Both are available over-the-counter at your local pharmacy. </p>
<p>While there are many small clinical trials of individual products, these studies <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8942543/">lack the power</a> to demonstrate if they are really effective in improving vaginal symptoms. </p>
<p>In contrast, there is robust evidence that vaginal oestrogen is <a href="https://www.cochrane.org/CD001500/MENSTR_use-postmenopausal-women-creams-pessaries-or-vaginal-ring-apply-oestrogen-vaginally-symptoms-vaginal">effective</a> in treating vaginal dryness and reducing pain during sex. It also <a href="https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD005131.pub2/full">reduces</a> your chance of recurrent urinary tract infections. You can talk to your doctor about a prescription. </p>
<p>Vaginal oestrogen is usually inserted using an applicator, two to three times a week. Very little is absorbed into the blood stream, it is <a href="https://pubmed.ncbi.nlm.nih.gov/31913230/">generally safe</a> but longer-term trials are required to confirm safety in long-term use beyond a year. </p>
<p>Women with a <a href="https://www.menopause.org.au/hp/position-statements/the-use-of-vaginal-estrogen-in-women-with-a-history-of-estrogen-dependent-breast-cancer">history of breast cancer</a> should see their oncologist to discuss using oestrogen as it may not be suitable for them.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/your-vagina-cleans-itself-why-vagina-cleaning-fads-are-unnecessary-and-harmful-88150">Your vagina cleans itself: why vagina cleaning fads are unnecessary and harmful</a>
</strong>
</em>
</p>
<hr>
<h2>Are there other treatments?</h2>
<p>New treatments for vaginal dryness are under investigation. One avenue relates to our growing understanding of how the vaginal microbiome adapts and modifies around changes in circulating and local concentrations of hormones.</p>
<p>For example, a <a href="https://pubmed.ncbi.nlm.nih.gov/29381086">small number of reports</a> show that combining vaginal probiotics with low-dose vaginal oestrogen can improve vaginal symptoms. But more evidence is needed before this is recommended.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-should-healthy-people-take-probiotic-supplements-95861">Health Check: should healthy people take probiotic supplements?</a>
</strong>
</em>
</p>
<hr>
<h2>Where to from here?</h2>
<p>The normal ageing process, as well as menopause, both affect the vagina as we age.</p>
<p>Most women do not have troublesome vaginal symptoms during and after menopause, but for some, these may cause discomfort or distress. </p>
<p>While hormonal treatments such as vaginal oestrogen are available, there is a pressing need for more non-hormonal treatments.</p>
<hr>
<p><em>Dr Sianan Healy, from Women’s Health Victoria, contributed to this article.</em></p><img src="https://counter.theconversation.com/content/212198/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Martha Hickey previously received research funding for a study of an ultrasound device for vaginal dryness (Madorra)</span></em></p><p class="fine-print"><em><span>Louie Ye 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>Dryness, irritation, or pain during sex can be managed. But not everyone has these symptoms or is bothered by them.Louie Ye, Clinical Fellow, Department of Obstetrics and Gynecology, The University of MelbourneMartha Hickey, Professor of Obstetrics and Gynaecology, The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2180832023-11-22T14:24:05Z2023-11-22T14:24:05ZDIY faecal transplants? Don’t try this at home<p>Saffron Cassidy suffered from ulcerative colitis, a type of inflammatory bowel disease, for 15 years before she allegedly cured it using her partner’s poop. “It’s been about three and a half years of having no symptoms whatsoever,” <a href="https://www.yahoo.com/lifestyle/fecal-microbiota-transplantation-010705806.html">she told Yahoo Life</a>. “And my colonoscopies show complete histologic remission.”</p>
<p>Now Cassidy has become an evangelist for the procedure known as faecal microbiota transplants (FMT). She has even <a href="https://www.designershitdocumentary.com/">made a documentary</a>, Designer Shit: A Microbiome Love Story.</p>
<p>There are <a href="https://www.sciencedirect.com/science/article/pii/S019567011830402X?via%3Dihub#sec10">restrictions</a> on the conditions doctors can treat using FMT, but a growing body of published work on FMTs holds promise for a range of disorders. </p>
<p>This has triggered <a href="https://www.insider.com/social-media-teaching-how-to-do-fecal-transplants-at-home-2020-2">several social media videos</a> on how people can generate their own FMT products and administer the treatment in their own homes. However, this DIY approach carries significant risks. </p>
<p>FMT is the process of taking the faeces of an apparently healthy person and transplanting it into the intestines of a recipient in the belief that repopulating the natural microbial ecosystem of a patient with that of another may help alleviate certain medical problems. </p>
<p>Although rooted in <a href="https://www.sciencedirect.com/science/article/pii/S0929664618305552?via%3Dihub">ancient Chinese medicine</a>, modern FMT requires further scientific research to understand the mechanism of action and, more importantly, how to ensure the treatment is performed safely without risking introducing additional health issues to the recipient. </p>
<p>Over the last couple of decades, research into the human gut microbiome has given strong indications that the community of bacteria in our intestines are inextricably linked to both good health and poor health. </p>
<p>In the latter category, our microbiome has been linked with <a href="https://journals.lww.com/nutritiontodayonline/abstract/2016/07000/the_gut_microbiome_and_its_role_in_obesity.3.aspx">obesity</a>, <a href="https://www.frontiersin.org/articles/10.3389/fcimb.2022.733992/full">inflammatory bowel diseases</a>, <a href="https://www.mdpi.com/2072-6643/15/4/942">multiple sclerosis</a>, <a href="https://www.frontiersin.org/articles/10.3389/fpsyt.2018.00669/full">depression</a>, <a href="https://www.bmj.com/company/newsroom/anxiety-might-be-alleviated-by-regulating-gut-bacteria/">anxiety</a>, <a href="https://academic.oup.com/cei/article/209/2/161/6598236?login=false">autoimmune disease</a>, <a href="https://www.frontiersin.org/articles/10.3389/fpsyt.2018.00669/full">sleep disorders</a>, brain disorders such as <a href="https://karger.com/anm/article/77/Suppl.%202/28/821404/Parkinson-s-Disease-and-Gut-Microbiota">Parkinson’s disease</a>, and many more. </p>
<p>So before any FMT treatments can take place, the prospective donors undergo strict screening of their faeces and blood for potentially harmful bacteria or viruses that may further harm the patient – both immediately and in the long run. DIY FMT does not have these safeguards. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/-nDPjGAGEak?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How FMT is used to treat a persistent C diff infection.</span></figcaption>
</figure>
<h2>DIY approach lacks safeguards</h2>
<p>In cases of DIY faecal transplants, the sufferers will often take poo samples from partners, family members, or close friends in the belief that they are healthy. But they will be unaware of any hidden factors that could cause further complications. </p>
<p>Unfortunately, these DIY “success stories” may lead to more people believing that they may be cured of afflictions through repeating the process, but there is no guarantee of success and a very real threat of complications in later years.</p>
<p>How many of us would dream of buying raw materials and taking the risk of trying to make our own medicines at home? Perhaps it is the familiarity of faeces that makes people see it differently from traditional medicine. </p>
<p>Yet it is unlikely that anyone would take the risk of picking a tablet at random from an unmarked box in the hope that it may cure them of a health problem. Yet using unscreened faeces for an FMT procedure is in essence just that.</p>
<p>Scientists are working hard alongside doctors to understand what is needed to be able to provide FMT for a wide range of potential treatments and getting closer every year to reaching this goal. </p>
<p>In the meantime, reports of DIY FMT are likely to increase as success stories are reported in the media. But the final message should always be clear that doing so is gambling with their health.</p><img src="https://counter.theconversation.com/content/218083/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lee Kellingray 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>Social media reports of people trying faecal transplants at home and curing their long-term illness are increasing. But the potential harms are considerable and rarely discussed.Lee Kellingray, Researcher, Translational Microbiome, Quadram InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2170252023-11-13T21:44:00Z2023-11-13T21:44:00ZGulf of St. Lawrence: Analyzing fish blood can show us how healthy they are<figure><img src="https://images.theconversation.com/files/557461/original/file-20231003-21-bibw4p.jpeg?ixlib=rb-1.1.0&rect=30%2C12%2C3995%2C3005&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The industrialization of the fishing industry and changes in the environment have raised many issues about the management of our fisheries.</span> <span class="attribution"><span class="source">(Fanny Fronton)</span>, <span class="license">Fourni par l'auteur</span></span></figcaption></figure><p>The Gulf of St. Lawrence is an invaluable resource for Canada. Fish and shellfish fisheries that date to the 16th century have remained an essential source of income for many communities, including those on the North Shore and Gaspésie or the Îles-de-la-Madeleine.</p>
<p>For example, in <a href="https://publications.gc.ca/collections/collection_2019/mpo-dfo/Fs124-10-2018-eng.pdf">Îles-de-la-Madeleine</a>, nearly 1,800 jobs (for a total of 12,500 inhabitants) were linked to fishing in 2015.</p>
<p>But the industrialization of fishing, and changes in the environment, have brought about many new problems in the management of our fisheries. The abundance of different fish species in the Gulf has fluctuated greatly over the last 20 years.</p>
<hr>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469058/original/file-20220615-9549-jj1phn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em>This article is part of our series, <a href="https://theconversation.com/ca-fr/topics/fleuve-saint-laurent-116908">The St. Lawrence River: In depth</a>.
Don’t miss new articles on this mythical river of remarkable beauty. Our experts look at its fauna, flora and history, and the issues it faces. This series is brought to you by <a href="https://theconversation.com/ca-fr">La Conversation</a>.</em></p>
<hr>
<p>A case in point: the number of Greenland halibut has declined drastically. This year, <a href="https://www.hi.no/hi/nettrapporter/imr-pinro-en-2023-6">landings</a> are six times lower for fishermen compared to last year.</p>
<p>But other species are benefiting from the situation. This is the case for the population of Atlantic halibut, which is at record levels today.</p>
<p>What is causing these changes? And can we predict further changes?</p>
<p>As a doctoral student in biology at the Institut national de la recherche scientifique (INRS), I am trying to find possible answers to these questions as part of my research work.</p>
<h2>A new health monitoring technique</h2>
<p>The means available for studying the health of fish at the individual level are limited. On the one hand, we can calculate indicators from the weight and height of individual fish. But these measurements are too vague and don’t tell us much.</p>
<p>The logistics of performing biopsies on the tissue of fish — which requires taking samples from their muscle or organs — are complex. To carry them out, researchers must have to travel to the ocean, physically collect samples and bring them back to a laboratory. And then there are ethical considerations, since obviously fish must be sacrificed to achieve this.</p>
<p>Even so, these methods are not very effective for detecting stress induced by environmental changes, and are not effective for detecting stress at early stages, before the physical effects can become manifest.</p>
<p>Yet in a context where the abundance of certain fish species is in rapid decline, an analysis of their overall health is necessary. Fortunately, a new tool is being developed: the <a href="https://www.nature.com/articles/s41598-023-32690-6">circulating microbiome</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="viruses in the blood" src="https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=343&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=343&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=343&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=431&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=431&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551779/original/file-20231003-15-6ou9xh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=431&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It is often wrongly believed that blood is sterile.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>A little-known practice</h2>
<p>The circulating microbiome is a biomarker, an alarm signal that can be detected in fish even before their health begins to deteriorate. A good biomarker is sensitive, easy to sample, and inexpensive.</p>
<p>The analysis of the circulating microbiome, made up of the DNA of bacteria found in the blood, is directly inspired by <a href="https://theconversation.com/ladn-%20circulating-a-new-simple-and-rapid-weapon-in-the-diagnosis-and-monitoring-of-cancers-206786">similar analyses performed on humans</a>, which provide a great deal of information.</p>
<p>In particular, these analyses make it possible to detect anomalies resulting from the effect of a stress factor on the body, or the development of a disease.</p>
<p>Changes in the environment can also be detected from studying the circulating microbiome. But a major problem emerges here: a fish is not a human. Humans are studied in such detail that knowledge about their health can then be used for an infinite amount of further research. However, sampling fish blood is not a common practice. So there is a great deal that needs to be done before we can properly evaluate the health of fish.</p>
<p>Since the analysis of the circulating microbiome in fish has never been studied before, a lot of work needs to be done to develop the technique.</p>
<h2>Traces of bacteria in the blood?</h2>
<p>As blood circulates throughout the body, it comes into contact specifically with bacteria that make up the other microbiomes (intestinal, oral, dermal). Both in fish and humans, these bacteria are essential for good health.</p>
<p>When we analyze bacterial DNA in the blood, it is therefore possible to find bacteria from the intestine, mouth, or skin. But the hypothesis that these are bacteria specific to the blood cannot be completely ruled out either.</p>
<p>While some continue to believe that blood is sterile, and therefore does not contain any bacteria, we have known since the 1970s that this hypothesis is false — it was confirmed <a href="https://doi.org/10.1128/jcm.39.5.1956-1959.2001">in the 2000s by genomic studies</a>. It’s possible that in 1674, the Dutch microbiologist Antonie Van Leeuwenhoek may even have observed bacteria in salmon blood <a href="https://doi.org/10.3389/fcimb.2019.00148">under a microscope</a>.</p>
<p>Today, we can analyze these bacteria in detail by targeting a very specific bacterial gene, the 16S ribosomal RNA gene. Present in all bacteria around the world, this gene varies slightly from one species to another. That makes it possible to identify and analyze the biodiversity of the microbiome.</p>
<h2>I eat, therefore I am</h2>
<p>Our recent work has made it possible to characterize, for the first time, the <a href="https://www.nature.com/articles/s41598-023-32690-6">circulating microbiomes of turbot and halibut</a>. We have demonstrated that the two fish species have circulating microbiomes dominated by the presence of the species <em>Pseudoalteromonas</em> and <em>Psychrobacter</em>. These bacteria are known to colonize cold environments, for example the bottom of the Gulf of St. Lawrence, which is around 5°C. They are also known to produce bioactive compounds (antibacterials and antifungals). They are more tenacious than other bacteria.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="person with blue gloves holds a fish" src="https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/551768/original/file-20231003-29-qhulgz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Greenland halibut.</span>
<span class="attribution"><span class="source">(Fanny Fronton)</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<p>However, differences can be observed between the two species. Turbot has more bacteria called <em>Vibrio</em>, some of which metabolize chitin, a molecule that makes up the shells of the invertebrates on which it feeds. Atlantic halibut, for its part, presents more <em>Acinetobacter</em> bacteria, typical of piscivorous (fish-eating) diets in the intestinal microbiomes. The circulating microbiome in these two fish species therefore seems to be influenced by intestinal bacteria, as is the case in humans. We could therefore potentially link a blood microbiome to the fish’s diet, which is often difficult to estimate.</p>
<h2>An embryonic, but promising technique</h2>
<p>So this first bacterial mapping of the blood of these two species probably reflects their respective intestinal microbiome. From this characterization, detection of a variation in the composition of bacteria could be linked to stress, a change in the environment or a physiological change in the animal.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="comic strip" src="https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=907&fit=crop&dpr=1 600w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=907&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=907&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1140&fit=crop&dpr=1 754w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1140&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/540859/original/file-20230802-23891-ctgz3u.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1140&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Comic strip illustrating the principle of analyzing the circulating microbiome.</span>
<span class="attribution"><span class="source">(Fanny Fronton)</span>, <span class="license">Fourni par l'auteur</span></span>
</figcaption>
</figure>
<p>For example, we know that in humans, the loss of <em>Actinobacteria</em> in the circulating microbiome is associated with severe acute <a href="https://doi.org/10.3389/fcimb.2018.00005">pancreatitis</a>. And there are dozens of examples like this in humans.</p>
<p>This study, the result of a collaboration between university researchers from INRS, the University of Québec at Rimouski and the Department of Fisheries and Oceans Canada, provides a small overview of the informative potential offered by the blood microbiomes of fish from the Gulf of St. Lawrence.</p>
<p>Further research will make it possible to estimate their health and better predict the evolution of their population. The dramatic collapse of the cod stock in the late 1980s had a major impact on fishermen. Several of them even fear that this situation will happen again with another species. As turbot remains a species at risk, it is essential to ensure better management of St. Lawrence species.</p>
<p>Only by refining our analysis techniques and deepening our scientific knowledge can we prevent this type of collapse from happening again in the future.</p><img src="https://counter.theconversation.com/content/217025/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fanny Fronton received a grant from the Fondation Armand Frappier.</span></em></p>Blood isn’t sterile, and analyzing the bacteria in it could help assess the health of fish and prevent the collapse of their populations.Fanny Fronton, Doctorante en Écologie halieutique et biologie moléculaire, Institut national de la recherche scientifique (INRS)Licensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2140482023-09-28T12:28:11Z2023-09-28T12:28:11ZYour microbes live on after you die − a microbiologist explains how your necrobiome recycles your body to nourish new life<figure><img src="https://images.theconversation.com/files/550423/original/file-20230926-27-qpnpj4.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1794%2C1668&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">After you die, bacteria harvest your body for the nutrients that help push daisies.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/embroidery-skull-and-roses-grapes-humming-royalty-free-illustration/931298520">Matriyoshka/iStock via Getty Images Plus</a></span></figcaption></figure><p>Each human body contains a <a href="https://www.hmpdacc.org/overview/">complex community of trillions of microorganisms</a> that are important for your health while you’re alive. These <a href="https://open.oregonstate.education/generalmicrobiology/chapter/microbial-symbioses/">microbial symbionts</a> help you digest food, produce essential vitamins, protect you from infection and serve many other critical functions. In turn, the microbes, which are mostly concentrated in your gut, get to live in a relatively stable, warm environment with a steady supply of food.</p>
<p>But what happens to these symbiotic allies after you die? </p>
<p>As an <a href="https://scholar.google.com/citations?user=U_xOnjEAAAAJ&hl=en">environmental microbiologist</a> who studies <a href="https://doi.org/10.1093/femsec/fiad006">the necrobiome</a> – the microbes that live in, on and around a decomposing body – I’ve been curious about our postmortem microbial legacy. You might assume that your microbes die with you – once your body breaks down and your microbes are flushed into the environment, they won’t survive out in the real world. </p>
<p>In our September 2023 study, my research team and I share evidence that not only do your microbes continue to live on after you die, they actually play an important role in <a href="https://doi.org/10.1186/s13717-023-00451-y">recycling your body</a> so that new life can flourish.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/c_ZRZkU-FEw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Your microbes accompany you from cradle to grave.</span></figcaption>
</figure>
<h2>Microbial life after death</h2>
<p>When you die, your heart stops circulating the blood that has carried oxygen throughout your body. Cells deprived of oxygen start digesting themselves in a <a href="https://en.wikipedia.org/wiki/Autolysis_(biology)">process called autolysis</a>. Enzymes in those cells – which normally digest carbohydrates, proteins and fats for energy or growth in a controlled way – start to work on the membranes, proteins, DNA and other components that make up the cells. </p>
<p>The products of this cellular breakdown make excellent food for your symbiotic bacteria, and without your immune system to keep them in check and a steady supply of food from your digestive system, they turn to this new source of nutrition. </p>
<p><a href="https://doi.org/10.7717/peerj.3437">Gut bacteria</a>, especially a class of microbes called <a href="https://doi.org/10.3389/fmicb.2017.02096"><em>Clostridia</em></a>, <a href="https://doi.org/10.1016/j.forsciint.2016.03.019">spread through your organs</a> and digest you from the inside out in a process called <a href="https://www.ncbi.nlm.nih.gov/books/NBK539741/">putrefaction</a>. Without oxygen inside the body, your anaerobic bacteria rely on energy-producing processes that don’t require oxygen, such as fermentation. These create the distinctly odorous-gases signature to decomposition.</p>
<p>From an <a href="https://doi.org/10.1016/j.meegid.2017.09.006">evolutionary standpoint</a>, it makes sense that your microbes would have evolved ways to adapt to a dying body. Like rats on a sinking ship, your bacteria will soon have to abandon their host and survive out in the world long enough to find a new host to colonize. Taking advantage of the carbon and nutrients of your body allows them to increase their numbers. A bigger population means a higher probability that at least a few will survive out in the harsher environment and successfully find a new body.</p>
<h2>A microbial invasion</h2>
<p>If you’re buried in the ground, your microbes are flushed into the soil along with a soup of decomposition fluids as your body breaks down. They’re entering an entirely new environment and encountering a whole new microbial community in the soil.</p>
<p>The <a href="https://doi.org/10.1016/j.tree.2015.06.004">mixing or coalescence</a> of two distinct microbial communities happens frequently in nature. Coalescence happens when the roots of two plants grow together, when wastewater is emptied into a river or even when two people kiss.</p>
<p>The outcome of mixing – which community dominates and which microbes are active – depends on several factors, such as how much environmental change the microbes experience and who was there first. Your microbes are adapted to the stable, warm environment inside your body where they receive a steady supply of food. In contrast, soil is a particularly <a href="https://doi.org/10.1016/B978-0-12-820202-9.00002-2">harsh place to live</a> – it’s a highly variable environment with steep chemical and physical gradients and big swings in temperature, moisture and nutrients. Furthermore, soil already hosts an exceptionally diverse microbial community full of decomposers that are well adapted to that environment and would presumably outcompete any newcomers. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of Clostridium septicum" src="https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=501&fit=crop&dpr=1 600w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=501&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=501&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=629&fit=crop&dpr=1 754w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=629&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/550417/original/file-20230926-19-r1tn2a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=629&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Clostridium septicum</em> is one species of bacteria involved in putrefaction.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/2n1hVng">Joseph E. Rubin/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>It’s easy to assume that your microbes will die off once they are outside your body. However, my research team’s previous studies have shown that the DNA signatures of host-associated microbes can be detected in the soil below a decomposing body, <a href="https://doi.org/10.1371/journal.pone.0130201">on the soil surface</a> and <a href="https://doi.org/10.1371/journal.pone.0208845">in graves</a> for months or years after the soft tissues of the body have decomposed. This raised the question of whether these microbes are still alive and active or if they are merely in a dormant state waiting for the next host.</p>
<p>Our newest study suggests that your microbes are not only living in the soil but also <a href="https://doi.org/10.1186/s13717-023-00451-y">cooperating with native soil microbes</a> to help decompose your body. In the lab, we showed that mixing soil and decomposition fluids filled with host-associated microbes increased decomposition rates beyond that of the soil communities alone.</p>
<p>We also found that host-associated microbes <a href="https://doi.org/10.1186/s13717-023-00451-y">enhanced nitrogen cycling</a>. Nitrogen is an essential nutrient for life, but most of the nitrogen on Earth is tied up as atmospheric gas that organisms can’t use. Decomposers play a critical role recycling organic forms of nitrogen such as proteins <a href="https://doi.org/10.1016/j.soilbio.2018.03.005">into inorganic forms</a> such as ammonium and nitrate that microbes and plants can use. </p>
<p>Our new findings suggest that our microbes are likely <a href="https://doi.org/10.1186/s13717-023-00451-y">playing a part</a> in this recycling process by converting large nitrogen-containing molecules like proteins and nucleic acids into ammonium. Nitrifying microbes in the soil can then convert the ammonium into nitrate. </p>
<h2>Next generation of life</h2>
<p>The recycling of nutrients from detritus, or nonliving organic matter, is a <a href="https://doi.org/10.2307/1930126">core process in all ecosystems</a>. In terrestrial ecosystems, decomposition of dead animals, or carrion, <a href="https://doi.org/10.1007/s00442-012-2460-3">fuels biodiversity</a> and is an important <a href="https://doi.org/10.1002/ece3.7542">link in food webs</a>.</p>
<p>Living animals are a bottleneck for the carbon and nutrient cycles of an ecosystem. They slowly accumulate nutrients and carbon from large areas of the landscape throughout their lives then deposit it all at once in a small, localized spot when they die. One dead animal can support a whole pop-up food web of <a href="https://doi.org/10.1093/femsec/fiad006">microbes</a>, <a href="https://doi.org/10.1371/journal.pone.0241777">soil fauna</a> and <a href="https://doi.org/10.1007/978-3-642-88448-1_6">arthropods</a> that make their living off carcasses. </p>
<p><a href="https://theconversation.com/life-after-death-how-insects-rise-from-the-dead-and-transform-corpses-into-skeletons-148847">Insect</a> and <a href="https://doi.org/10.1890/09-0292.1">animal scavengers</a> help further redistribute nutrients in the ecosystem. Decomposer microbes convert the concentrated pools of nutrient-rich organic molecules from our bodies into <a href="https://doi.org/10.1371/journal.pone.0287094">smaller, more bioavailable forms</a> that other organisms can use to support new life. It’s not uncommon to see <a href="https://doi.org/10.1002/ecs2.1537">plant life flourishing near a decomposing animal</a>, visible evidence that nutrients in bodies are being recycled back into the ecosystem.</p>
<p>That our own microbes play an important role in this cycle is one microscopic way we live on after death.</p><img src="https://counter.theconversation.com/content/214048/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jennifer DeBruyn receives funding from the United States Department of Agriculture, National Science Foundation, Department of Justice, and Defense Advanced Research Projects Agency.</span></em></p>With the help of the microbes that once played an essential role in keeping you alive, the building blocks of your body go on to become a part of other living things.Jennifer DeBruyn, Professor of Environmental Microbiology, University of TennesseeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2041642023-09-10T13:04:13Z2023-09-10T13:04:13ZThe nose knows: How microbiomes and the smells they produce help shape behaviour in bugs, birds, beasts and humans<figure><img src="https://images.theconversation.com/files/547261/original/file-20230908-27-yeuep5.jpg?ixlib=rb-1.1.0&rect=612%2C68%2C4958%2C3759&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The microbiome functions as an 'invisible organ' but it often makes its presence known by emitting sounds and smells.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/the-nose-knows-how-microbiomes-and-the-smells-they-produce-help-shape-behaviour-in-bugs-birds-beasts-and-humans" width="100%" height="400"></iframe>
<p>Microbes are an integral part of most, if not all multi-cellular organisms. In fact, these organisms are the way they are because of the tiny partners they house within and on them. These microbes constitute the microbiome: an “invisible organ” weighing approximately <a href="https://doi.org/10.1007/978-981-10-7684-8">2.5 to three kilograms</a> in an adult human and much more in larger animals.</p>
<p>This unique body part was made visible with the advent of modern molecular imaging technologies. In my book <em><a href="https://www.routledge.com/Microbiomes-and-Their-Functions-Why-Organisms-Need-Microbes/Appanna/p/book/9780367749897">Microbiomes and their Functions</a></em>, I explore how it works in partnership with other visible organs and engages in a variety of physiological functions essential for the development and survival of the hosts. </p>
<p>Microbiomes have been part of all these organisms from the beginning, and have evolved in tandem with them, just as their visible organs have.</p>
<p>The digestive tract, with all its components, is a good example of how organs can be shaped by their microbial inhabitants. The digestive tract has markedly disparate features in a carnivore, an omnivore or a herbivore. Herbivores have the longest digestive tracts and <a href="https://opentextbc.ca/biology/chapter/15-1-digestive-systems/">carnivores have the shortest</a>.</p>
<h2>The microbiome</h2>
<p>The bulk of microbiome is found in the <a href="https://doi.org/10.1007/978-981-10-7684-8_2">digestive tract</a>, where it helps extract nutrients from our diet. The diverse microbes constituting the microbiome not only contribute to optimal digestion, but also help prime our immune system, and produce hormones and neurotransmitters (or their precursors) that have profound influence on our behaviours.</p>
<p>The information-laden molecules generated by the microbiome play a crucial role in the body’s <a href="https://doi.org/10.3389/fimmu.2020.00700">non-verbal communication</a>. These <a href="https://doi.org/10.1038/s41467-020-18871-1">microbiome-derived signals</a> can elicit a range of responses including hunger, satiety (feeling full), mood changes and social behaviour.</p>
<figure class="align-right ">
<img alt="Human silhouette showing the gut-brain connection" src="https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=796&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=796&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=796&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1000&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1000&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547017/original/file-20230907-29-lkr7n3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1000&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The information network between the gut microbiome and the brain is aided by the vagus nerve that connects these two organs.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>The information network between the gut microbiome and the brain is aided by the vagus nerve that <a href="https://routledge.pub/Microbiomes-and-Their-Functions">connects these two organs</a>.</p>
<p>Microbes like Lactobacillus and Bifidobacterium residing in the gut secrete neurotransmitters known to influence human behaviour <a href="https://doi.org/10.3390/cimb44040096">such as GABA</a> (gamma-aminobutyric acid), acetylcholine, norepinephrine, oxytocin and indole metabolites. Indole derivatives are obtained when gut microbes metabolize the essential amino-acid, tryptophan.</p>
<p>For instance, the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4449495">neurotransmitter dopamine</a> is considered a “feel good” hormone and is often associated with positive emotions. However, low levels of this molecule may contribute to anxiety. On the other hand, indoles are linked to satiety, resulting in a tendency to eat less, and are associated with weight loss.</p>
<h2>Smelly signals</h2>
<p>Despite its invisible nature, the microbiome often makes its presence known by emitting sounds and smells. The latter can be powerful signals that can influence behaviour.</p>
<p>These smelly signals can, at a distance or at a close range, prompt happiness, enthusiasm, anxiety, attraction, fear or <a href="https://doi.org/10.1007/978-981-10-7684-8">aggression</a>. The microbially-concocted odours are a very important tool in the communication arsenal that most organisms — including humans — rely on to send or receive non-verbal messages.</p>
<p>The human skin is home to a diverse range of microorganisms known to contribute to different odours. Bacteria like Staphylococcus and Corynebacterium lodge in the warm and moist underarm region of the skin where the apocrine glands, a source of chemicals, abound. The resident bacteria use these chemical nutrients to shape <a href="https://asm.org/Articles/2021/December/Microbial-Origins-of-Body-Odor">body odour</a>.</p>
<p>These apocrine glands generally produce odourless compounds. It is microbes that fashion those compounds into smell signatures characteristic of an individual. These odoriferous signals can serve to attract or repel people and modify social behaviours. For instance, the presence of select bacteria is known to process non-smelly steroids into compounds with a characteristic urine odour, not conducive to making friends. </p>
<h2>Chemical signals in animals, birds, plants, fungi</h2>
<p>In other mammals, odoriferous compounds like trimethylamine or pentanoic acid entice mates, while in animals endowed with a scent pouch, they lure prey, defend or mark territories. Some of the <a href="https://doi.org/10.3389/fevo.2017.00143">pungent chemicals</a> are notoriously reputed to keep <a href="https://www.washingtonpost.com/lifestyle/kidspost/whats-that-smell-for-some-animals-their-stink-helps-keep-them-alive/2018/08/13/9058fc62-9678-11e8-810c-5fa705927d54_story.html">predators at bay</a>. </p>
<p>Birds have a special gland that hosts a diverse microbial population, which generates scent-releasing chemicals. These easily transmittable signals are aimed at repelling predators, attracting mates, recognizing kin, promoting parental care and <a href="https://www.nytimes.com/2019/11/10/science/birds-smell-bacteria.html">identifying proprietary nests</a>.</p>
<figure class="align-center ">
<img alt="A man's hand holding a small shovel with a truffle on it, patting his truffle-hunting dog with his other hand" src="https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547027/original/file-20230907-19-ya50zw.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">Truffles — the highly sought-after edible fungus — recruit select microbes to generate aromatic alcohols that lure small mammals to dig them up, which promotes the dispersal of the truffle’s spores.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>These smelly marks are also key to maintaining the social order of numerous insects. <a href="https://doi.org/10.1186/s40168-018-0588-z">These scents</a> can not only help camouflage the hosts, but can also convert loners to crowd-lovers. For instance, it is a scent that cajoles the solitary <a href="https://doi.org/10.3390/insects11100655">locust</a> into a gregarious lifestyle during the feeding season and triggers an insatiable appetite for vegetation.</p>
<p>Some fungi are known to enlist the fragrance of vapour-like chemicals to assemble their microbiome, which in turn helps the host perform a variety of essential physiological functions.</p>
<p>Truffles — the highly sought-after edible fungus — are renowned for their distinctive smell, but they may be dependent on the microbiome to produce this sweet fragrance. In fact, <a href="https://doi.org/10.1128/aem.01098-15">truffles recruit select microbes</a> to generate aromatic alcohols that lure small mammals to dig them up, which promotes the dispersal of the truffle’s spores.</p>
<p>Plants and algae are also dependent on microbe-derived odour prompts to assist them to survive, and even die and be scavenged. Plants depend on these smell signatures to communicate dangers lurking in their environment and even to fend off insects, birds or <a href="https://doi.org/10.3389/fmicb.2021.772420">other predators</a>.</p>
<p>When some algae bloom beyond control due to environmental conditions, they plot their own demise with the <a href="https://doi.org/10.1201/9781003166481">assistance of microbes</a>. Some of these microbes not only help the algae die, but are also responsible for producing distinctive odours that are detected and decoded as food by birds and fish. The result is a clean-up of the dead algae by feasting birds and fish.</p>
<p>The microbiome and its signature smells are crucial for most organisms, whether human, insect or plant. The silent signals sent by the microbiome are essential communications that influence behaviour, and have evolved to help the host survive and thrive.</p><img src="https://counter.theconversation.com/content/204164/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vasu Appanna receives / has received funding from NATO, NSERC, NOHFC and FEDNOR</span></em></p>The microbiome and its signature smells are crucial for most organisms, whether human, insect or plant. The silent signals sent by the microbiome are essential communications that influence behaviour.Vasu Appanna, Professor, Biochemistry, Laurentian UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2118612023-08-23T12:25:48Z2023-08-23T12:25:48ZAcne bacteria trigger cells to produce fats, oils and other lipids essential to skin health – new research<figure><img src="https://images.theconversation.com/files/543536/original/file-20230818-27-a54vaz.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2094%2C1416&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There's more to the bacterium _Cutibacterium acnes_ than meets the eye.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/cropped-shot-of-the-face-of-a-young-woman-with-royalty-free-image/1581451668">Youngoldman/iStock via Getty Images Plus</a></span></figcaption></figure><p>The skin is the <a href="https://theconversation.com/the-skin-is-a-very-important-and-our-largest-organ-what-does-it-do-91515">largest organ of the body</a>, and it plays a crucial role as the first line of defense against pathogens and insults from the external environment. It provides important functions like temperature regulation and moisture retention. And despite the misconception that lipids harm your skin by causing oiliness and acne, they actually <a href="https://doi.org/10.1126/sciadv.adg6262">play a vital role</a> in maintaining the skin barrier.</p>
<p>Lipids – organic compounds that include <a href="https://www.khanacademy.org/science/biology/macromolecules/lipids/a/lipids">fats, oils, waxes and other types of molecules</a> – are essential components of the outermost layer of skin. Changes to the skin’s lipid composition can disrupt its ability to function as a protective barrier, leading to a <a href="https://doi.org/10.1046/j.0022-202x.2001.01455.x">range of skin diseases</a>, including eczema and psoriasis.</p>
<p>Human skin is colonized by <a href="https://doi.org/10.1038/nrmicro.2017.157">thousands of species of bacteria</a>. One of the most common microbes on the skin, <a href="https://doi.org/10.3390/microorganisms9030628"><em>Cutibacterium acnes</em>, or <em>C. acnes</em></a>, is well known for its potential involvement in causing acne, but its broader effects on skin health are less understood.</p>
<p>I am a <a href="https://profiles.ucsd.edu/samia.l.almoughrabie">researcher in dermatology</a> working in the <a href="https://dermatology.ucsd.edu/research/basic-science/gallo-lab/index.html">Gallo Lab</a> at the University of California, San Diego. My colleagues and I study how the skin defends the body against infections and the environment, with a particular focus on the skin microbiome, or the microbes living on the skin. In our recently published research conducted in collaboration with SILAB, a company developing active ingredients for skincare products, we found that <em>C. acnes</em> triggers certain skin cells to <a href="https://doi.org/10.1126/sciadv.adg6262">significantly increase production of lipids</a> that are important to maintaining the skin barrier.</p>
<h2>Skin bacteria and lipid synthesis</h2>
<p>To determine the role that bacteria play in lipid production, we exposed keratinocytes, the cells that <a href="https://www.britannica.com/science/human-skin/The-epidermis#">make up the epidermis</a>, to different bacteria naturally present on the skin and analyzed changes in lipid composition. </p>
<p>Of the common skin bacteria we tested, only <em>C. acnes</em> triggered an <a href="https://doi.org/10.1126/sciadv.adg6262">increase in lipid production</a> within these cells. More specifically, we found a threefold increase in total lipids, including ceramides, cholesterol, free fatty acids and especially triglycerides. Each of these lipid types are essential to maintaining the skin barrier, locking in moisture and protecting against damage. These findings suggest that <em>C. acnes</em> plays a distinctive role in the lipid skin regulation. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/MWE3U3FItlc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The skin microbiome contains bacteria and other microbes that help protect your body.</span></figcaption>
</figure>
<p>We found that <em>C. acnes</em> induced this increase in lipid production by producing a type of short-chain fatty acid called <a href="https://doi.org/10.1126/sciadv.adg6262">propionic acid</a>. Propionic acid creates an acidic skin environment that provides a number of benefits, including limiting pathogen growth, reducing staph infections and contributing to anti-inflammatory effects in the gut. </p>
<p>We also identified the <a href="https://doi.org/10.1126/sciadv.adg6262">specific gene and receptor</a> that regulate lipid synthesis through <em>C. acnes</em>. Blocking these components also blocked <em>C. acnes</em>-induced lipid synthesis.</p>
<p>In all, our findings highlight the substantial role that a common skin bacterium and its chemical byproducts play in shaping the composition of skin lipids.</p>
<h2>Reinforcing the skin barrier</h2>
<p>Our research suggests that propionic acid from <em>C. acnes</em> has <a href="https://doi.org/10.1126/sciadv.adg6262">multiple advantageous effects</a> on the skin barrier. For example, by increasing the lipid content in skin cells, propionic acid reduced water loss through the skin.</p>
<p>We also found that the lipids skin cells produce after exposure to <em>C. acnes</em> or propionic acid have antimicrobial effects against <em>C. acnes</em>. This suggests that the lipids <em>C. acnes</em> helps produce have a dual role: They not only control the presence of <em>C. acnes</em> on the skin but also contribute to the overall balance of the skin microbiome so one species of microbe doesn’t dominate the rest.</p>
<p>In the complex interplay between the skin and its microbial inhabitants, the ubiquitous <em>C. acnes</em> is emerging as an important player. Further research to better understand the skin microbiome may help lead to new treatments for skin conditions.</p><img src="https://counter.theconversation.com/content/211861/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Samia Almoughrabie 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>Bacteria and lipids get a bad rap for causing breakouts and oily skin. But both play an essential role in helping your skin barrier stay strong against pathogens and insults from the environment.Samia Almoughrabie, Postdoctoral Researcher in Dermatology, University of California, San DiegoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2106682023-08-11T12:38:35Z2023-08-11T12:38:35ZGut microbes are the community within you that you can’t live without – how eating well can cultivate your microbial and social self<figure><img src="https://images.theconversation.com/files/542026/original/file-20230809-15-nrb1kh.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2121%2C1412&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Communal meals are a social glue that binds people together.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/family-and-friends-toasting-drinks-at-home-royalty-free-image/1176845606">Klaus Vedfelt/DigitalVision via Getty Images</a></span></figcaption></figure><p>The age-old adage “<a href="https://doi.org/10.1038/s41575-018-0061-2">you are what you eat</a>” holds profound truth. Nearly every molecule in your body is absorbed from what you eat and drink. Your food choices are directly linked to your <a href="https://doi.org/10.1016/S0140-6736(19)30041-8">physical</a>, <a href="https://doi.org/10.1016/j.npbr.2019.05.007">emotional</a> and <a href="https://doi.org/10.1111%2Fmcn.12321">social</a> health. And scientists are learning that your <a href="https://gutbites.org/2022/09/01/spotlight-on-gut-health/">gut health and the microbial communities</a> within you have a significant role to play in orchestrating these processes. </p>
<p>The gut microbiome takes the components of food that you cannot digest, like <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> and <a href="https://doi.org/10.3389/fnut.2019.00188">phytonutrients</a>, and transforms them into signals that regulate <a href="https://doi.org/10.1038/nrendo.2016.150">how hungry</a> you are, how strong your <a href="https://doi.org/10.1038/s41422-020-0332-7">immune system</a> is, and even how you’re <a href="https://doi.org/10.1001/jamanetworkopen.2021.43941">thinking</a> and <a href="https://doi.org/10.1038/s41598-020-77673-z">feeling</a>. It’s as though the <a href="https://doi.org/10.1016/j.advnut.2023.03.016">communities in your gut microbiome</a> are an orchestra for your health, and you conduct their symphony through food.</p>
<p><a href="https://gastro.uw.edu/people/faculty/damman-c">I am a gastroenterologist</a> who has spent over 20 years studying how food affects the gut microbiome and overall health. The research is increasingly clear: A gut-friendly approach to nutrition is important for happy and healthy communities both inside and out of your body.</p>
<h2>Communities within and without</h2>
<p>The fascinating research on the gut microbiome takes us on a journey into the depths of the intestine, where <a href="https://doi.org/10.1136/bmj.k2179">trillions of microorganisms</a> blur the lines between other and self.</p>
<p><a href="https://doi.org/10.1186/s40168-019-0619-4">The term holobiont</a> describes the combined lives of the microbiome and its vessel, working symbiotically to support each other’s well-being. This relationship is represented at its extreme in the intestines of <a href="https://doi.org/10.1111/j.1365-2435.2008.01442.x">termites</a> and <a href="https://doi.org/10.1186/s40168-022-01298-9">cows</a>, where microbes transform uniform, low-nutrient diets of wood or grass into complete nutrition replete with vitamins and other essential nutrients for health.</p>
<p>When people eat certain foods, like those <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">rich in fiber</a>, they too harbor similar relationships with their microbiomes. You provide your microbes with food and a safe place to live, and they in turn fortify your diet with vital molecules such as <a href="https://doi.org/10.1186/s12864-019-5591-7">vitamins</a>, <a href="https://doi.org/10.1016/b978-0-12-800100-4.00003-9">short-chain fatty acids</a> and <a href="https://doi.org/10.3390%2Fnu13062099">neurotransmitters</a> that are key for regulating your metabolism, immunity and mood.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/542014/original/file-20230809-27177-99vked.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Family smiling and eating together around a dinner table" src="https://images.theconversation.com/files/542014/original/file-20230809-27177-99vked.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/542014/original/file-20230809-27177-99vked.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/542014/original/file-20230809-27177-99vked.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/542014/original/file-20230809-27177-99vked.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/542014/original/file-20230809-27177-99vked.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/542014/original/file-20230809-27177-99vked.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/542014/original/file-20230809-27177-99vked.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">Eating together can help build connection.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/asian-chinese-family-and-cousins-having-reunion-royalty-free-image/1297931559">Patrick Chu/E+ via Getty Images</a></span>
</figcaption>
</figure>
<p>Just as food illuminates the importance of the microbial community within you, it also shines a light on your social community. Food is one of the <a href="https://doi.org/10.1080/13556509.2015.1110934">foundations of culture</a>, serving as the basis of many gifts and shared experiences. You have first dates over drinks and meals, connect with your colleagues over lunch, and share dinners with your family and friends. Food is a type of <a href="https://www.themarginalian.org/2013/04/24/michael-pollan-cooked/">social glue</a> that helps bind communities together.</p>
<p>As you feed your microbiome to cultivate a thriving community within your gut, you also figuratively and literally feed your social community when you <a href="https://doi.org/10.1007/s40750-017-0061-4">break bread with friends and family</a>.</p>
<h2>Convenient fixes sacrifice community</h2>
<p>Convenient, fast, affordable <a href="https://doi.org/10.1017/S1368980010003241">ultraprocessed foods</a> have some enormous benefits in helping feed a growing population and enabling an ever-quickening pace of life, but the latest research is showing that there may be <a href="https://doi.org/10.1016/j.eclinm.2021.100747">collateral damage</a>.</p>
<p>Compared with ancestral diets, industrialized diets may be contributing to <a href="https://doi.org/10.1126/science.aan4834">less diverse</a> microbial communities in your gut. Diversity is important for generating key molecules like <a href="https://doi.org/10.1038/s41467-021-22938-y">butyrate</a> that regulate <a href="http://dx.doi.org/10.1136/gutjnl-2017-314050">appetite</a> and <a href="https://doi.org/10.1038/s41564-018-0337-x">mood</a>. As a result, your microbiome becomes less good at regulating hunger and emotions.</p>
<p>Your social community may also be suffering as result of this disrupted microbial community. In fact, studies on various model organisms have found that microbes can mediate behaviors as diverse as <a href="https://doi.org/10.3389/fmicb.2022.916766">mating</a> and <a href="https://doi.org/10.3390%2Fmicroorganisms11041008">aggression</a> by regulating <a href="https://doi.org/10.1038/s41586-021-03669-y">responses to stress</a>. Food and microbes may affect <a href="https://doi.org/10.1016/j.jpsychires.2015.02.021">social behavior in people</a> as well.</p>
<p>Processed foods do serve a purpose. They are convenient and affordable and can be especially useful for people and families with busy lives and limited time to cook. But some are healthier than others. <a href="https://doi.org/10.1016/j.advnut.2023.03.016">Adding back missing nutrients</a> like fiber and polyphenols to processed foods can help make them healthier, and these can complement a diet of less-processed foods.</p>
<h2>Wisdom cultures around the world</h2>
<p>Anthropological research suggests that <a href="https://doi.org/10.1177/1559827616637066">traditional diets</a> are a particularly important contributor to health and longevity. Communities in Costa Rica, the Mediterranean and Japan that follow traditional diets have many individuals who live for over 100 years. The <a href="https://doi.org/10.3390/nu11081802">Mediterranean</a> and <a href="https://doi.org/10.1016/j.mad.2014.01.002">Okinawan diets</a> have consistently been shown to contribute to better health, including lower rates of obesity and other metabolic diseases.</p>
<p>These diets involve traditional <a href="https://www.theguardian.com/global-development/2014/feb/03/indigenous-diets-fight-modern-illnesses">food choices and combinations</a> as well as natural <a href="https://doi.org/10.1093%2Fcdn%2Fnzz099">food processing and preservation</a> techniques. Combining corn with lime, an ancient process <a href="https://doi.org/10.1016/j.jas.2022.105581">called nixtamalixation</a>, for example, increases <a href="https://doi.org/10.1106/108201302024574">vitamin availability</a> and <a href="https://doi.org/10.1093/jn/133.10.3200">decreases grain toxins</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_LKe9hmXdvM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Nixtamalization is used to make traditional tortillas.</span></figcaption>
</figure>
<p><a href="https://doi.org/10.3390/microorganisms10061151">Fermentation</a> transforms food through live microbes that consume simple carbohydrates, generating <a href="https://doi.org/10.1007/978-1-4939-6634-9_3">antimicrobial chemicals</a> that help preserve food. It also <a href="https://doi.org/10.1038/s41538-022-00152-4">decreases toxins</a> and increases the levels of <a href="https://doi.org/10.1080/10408398.2017.1383355">vitamins and minerals</a> available for absorption. <a href="https://doi.org/10.1016/j.cell.2021.06.019">Fermented foods</a> have been shown to grow diverse microbial communities in the gut, decrease inflammation in the body and reduce the risk of <a href="https://doi.org/10.1016/j.tjnut.2023.02.019">chronic disease</a>.</p>
<p>Communal eating is also intricately woven into the social fabric of <a href="https://scholarscompass.vcu.edu/vcoa_editorial/49/">traditional communities</a>. The longest-lived communities around the world tend to eat at least one of their <a href="https://www.washingtonpost.com/wellness/2023/02/14/centenarians-healthy-eating-habits/">meals together</a> as a family, and eating together is linked to <a href="https://doi.org/10.1016%2Fj.appet.2017.11.084">health benefits</a> including weight regulation and lower depressive symptoms. </p>
<h2>Reembracing community</h2>
<p>Here are a few simple tips to help you eat well and grow your communities – holobiont, family, friends and all:</p>
<ol>
<li><p>Eat the <a href="https://gutbites.org/2022/05/14/missing-microbes-and-the-four-fs-of-food/">four phonetic food F’s</a>: fiber, phytonutrients, healthy fats and ferments. I developed this simple way of categorizing foods to streamline the often complicated advice on how to eat well from the perspective of growing a healthy microbiome. It is also independent of cultural background, as these four categories are common elements in the diets of diverse and long-lived populations around the world.</p></li>
<li><p>Learn the wisdom of traditional food preparation from people who still hold that knowledge. Consider taking a cooking class or spending time in the kitchen learning from a relative or a friend. Then re-share what you learn with your loved ones while preparing and enjoying your own meals. </p></li>
<li><p>You don’t have to be perfect. Even a step toward a healthier meal a day and a communal meal a week can be beneficial.</p></li>
</ol>
<p>It may at first seem daunting to carve out time to follow these deceivingly simple tips. But with a bit of patience and perseverance, they could be inspiration to improve your and your community’s health and wellness.</p><img src="https://counter.theconversation.com/content/210668/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Damman is on the scientific advisory board at BCD Biosciences and Supergut.</span></em></p>Nurturing your gut microbiome can go hand in hand with nurturing your social community, with health benefits all around.Christopher Damman, Associate Professor of Gastroenterology, School of Medicine, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2095062023-07-13T15:38:46Z2023-07-13T15:38:46ZThe bacteria and microbes in your gut can affect your body and mental health – engineering them promises new forms of treatment. Podcast<figure><img src="https://images.theconversation.com/files/536725/original/file-20230711-27-vnioxr.jpg?ixlib=rb-1.1.0&rect=0%2C94%2C7000%2C3898&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The human gut is home to communities of microbes, bacteria and fungi.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>The human body is a complex organism, made up of trillions of cells. But not all of them are human — about half of them are fungi, microbes and bacteria. Scientists are starting to understand how and why these communities — referred to as microbiomes — <a href="https://commonfund.nih.gov/hmp/healthyhuman">are crucial to the functioning of various body systems</a>.</p>
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Read more:
<a href="https://theconversation.com/the-human-microbiome-is-a-treasure-trove-waiting-to-be-unlocked-118757">The human microbiome is a treasure trove waiting to be unlocked</a>
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<p>In this episode of <em><a href="https://theconversation.com/uk/topics/the-conversation-weekly-98901">The Conversation Weekly</a></em>, we speak to three experts who study the gut microbiome: a gastroenterologist, a neuroscientist and a biological engineer. </p>
<p>Their research considers how these microbiomes are important, what the relationship is between microbiomes and well being, and how synthetically engineered microorganisms promise new forms of therapies. </p>
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<h2>Partners in health</h2>
<p>Chris Damman is a gastroenterologist and clinical associate professor at the University of Washington, Wash. Damman investigates how microbiomes in the gut — the digestive system from start to finish — communicate with other body systems. He looks at the gut-brain axis, specifically.</p>
<p>Damman points out the importance of the gut microbiome, which “plays an incredibly important role in digesting our food. We have powerful enzymes that our pancreas and our liver and our stomach, our salivary glands make.” he explains. </p>
<p>“But the enzymes that are our bodies can produce only do so much. So the last part of the small intestine, um, and the large intestine, the colon… it’s there that the microbiome is like our partners in health, converting fibre into things like butyrate and other short chain fatty acids.”</p>
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Read more:
<a href="https://theconversation.com/your-gut-microbiome-may-be-linked-to-dementia-parkinsons-disease-and-ms-144367">Your gut microbiome may be linked to dementia, Parkinson's disease and MS</a>
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<p>Studying the composition and balance of the gut microbiome is starting to reveal connections between it and various neurological conditions. Andrea Merchak, an incoming postdoctoral scholar at the University of Florida, studies the gut biome as it affects and is affected by various conditions.</p>
<p>“Somebody with multiple sclerosis is going to have a different microbiome from when they’re perfectly healthy through diagnosis and then through late stages of disease, that microbiome is gonna change.” </p>
<p>Merchak points out that because of the progression of the condition, multiple sclerosis allows scientists to investigate the gut-brain axis.</p>
<p>“It happens over a really long period of time, which means that we have a really long time to intervene, and a really long time to try and stop what’s going on,” Merchak says. “When a person’s first diagnosed, they’re not necessarily at the point of severe disability yet… We can see it early and we can try and stop it.”</p>
<h2>Engineering the biome</h2>
<p>As scientists learn more about the gut biome and its relationship to disease, they’re also starting to figure out ways to impact the gut biome’s composition to produce different, and more healthful, outcomes.</p>
<p>Tae Seok Moon, a biological engineer at Washington University at St. Louis, Mo., looks at how synthetic biology can be employed within the gut. He is developing sensors that can help adjust the composition of the gut biome and various microbe communities within it.</p>
<p>“What I want to do is, there are some enzyme that break down or synthesize serotonin,” he says. “In response to the serotonin level, bacteria would have the ability to control the concentration of serotonin by producing an enzyme that breakdown serotonin if the serotonin level is too high.”</p>
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<p>Scientists are looking at how manipulating the gut biome can help address various conditions, but Merchak points out that it’s not as straightforward as it sounds.</p>
<p>“We know that if you change what you eat, it changes the composition of your gut microbiome. And so ultimately, if we find beneficial bacteria that we think is going to be promising for a wide swath of people, generally, that’s going to come with a dietary change in order to maintain those populations.”</p>
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<p>This episode was produced and written by Mend Mariwany with assistance from Katie Flood. Mend Mariwany is the executive producer of The Conversation Weekly. Eloise Stevens does our sound design, and our theme music is by Neeta Sarl.</p>
<p>You can find us on Twitter <a href="https://twitter.com/TC_Audio">@TC_Audio</a>, on Instagram at <a href="https://www.instagram.com/theconversationdotcom/">theconversationdotcom</a> or <a href="mailto:podcast@theconversation.com">via email</a>. You can also subscribe to The Conversation’s <a href="https://theconversation.com/newsletter">free daily email here</a>. </p>
<p>Listen to The Conversation Weekly via any of the apps listed above, download it directly via our <a href="https://feeds.acast.com/public/shows/60087127b9687759d637bade">RSS feed</a> or find out <a href="https://theconversation.com/how-to-listen-to-the-conversations-podcasts-154131">how else to listen here</a>.</p><img src="https://counter.theconversation.com/content/209506/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher J. Damman consults for BCD Biosciences and Supergut.</span></em></p><p class="fine-print"><em><span>Tae Seok Moon is affiliated with the Engineering Biology Research Consortium. </span></em></p>In the past two decades, technology has allowed scientists to learn so much more about the human body and its microbiomes. These discoveries may pave the way to new therapies.Nehal El-Hadi, Science + Technology Editor & Co-Host of The Conversation Weekly Podcast, The ConversationMend Mariwany, Producer, The Conversation Weekly, The Conversation Weekly PodcastLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2051592023-07-03T11:53:03Z2023-07-03T11:53:03ZFiber is your body’s natural guide to weight management – rather than cutting carbs out of your diet, eat them in their original fiber packaging instead<figure><img src="https://images.theconversation.com/files/529655/original/file-20230601-21-meilfi.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2121%2C1412&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Whole foods like unprocessed fruits, vegetables and grains are typically high in fiber.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/pattern-of-variety-fresh-of-organic-fruits-and-royalty-free-image/1455279498">Tanja Ivanova/Moment via Getty Images</a></span></figcaption></figure><p>Fiber might just be the key to healthy weight management – and nature packages it in perfectly balanced ratios with carbs when you eat them as whole foods. Think unprocessed fruits, vegetables, whole grains, beans, nuts and seeds. Research suggests that carbohydrates are meant to come packaged in <a href="https://doi.org/10.1007/s00394-019-02165-4">nature-balanced ratios</a> of total carbohydrates to fiber. In fact, certain types of fiber affect how completely your body <a href="https://doi.org/10.1038/s41467-023-38778-x">absorbs carbohydrates</a> and <a href="https://doi.org/10.1016/j.bcdf.2017.07.005">tells your cells how to process them</a> once they are absorbed.</p>
<p>Fiber slows the absorption of sugar in your gut. It also orchestrates the fundamental biology that recent blockbuster weight loss drugs like <a href="https://theconversation.com/drugs-that-melt-away-pounds-still-present-more-questions-than-answers-but-ozempic-wegovy-and-mounjaro-could-be-key-tools-in-reducing-the-obesity-epidemic-205549">Wegovy and Ozempic</a> tap into, but in a natural way. Your microbiome <a href="https://doi.org/10.3389/fendo.2020.00025">transforms fiber into signals</a> that stimulate the gut hormones that are the natural forms of these drugs. These in turn regulate how rapidly your stomach empties, how tightly your <a href="https://doi.org/10.2337/ds16-0026">blood sugar levels</a> are controlled and even how hungry you feel. </p>
<p>It’s as if unprocessed carbohydrates naturally come wrapped and packaged with their own instruction manual for your body on how to digest them.</p>
<p>I am a <a href="https://gastro.uw.edu/faculty/christopher-j-damman-md-ma">physician scientist and gastroenterologist</a> who has spent over 20 years studying how <a href="https://gutbites.org/">food affects the gut microbiome</a> and metabolism. The research is clear – fiber is important not just for happy bowel movements, but also for your blood sugar, weight and overall health.</p>
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<figcaption><span class="caption">Different types of carbs have different effects on the body.</span></figcaption>
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<h2>Carbohydrates without their wrappers</h2>
<p>Unfortunately, most Americans get the majority of their carbohydrates stripped of their natural fibers. Modern processed grains like white rice and white flour as well as many ultraprocessed foods like some sugary breakfast cereals, packaged snacks and juices have removed these fibers. They essentially come unwrapped and without instructions for the body on how much it should absorb and how it should process them. In fact, <a href="https://doi.org/10.1177%2F1559827615588079">only 5% of Americans</a> eat the recommended amount of carbohydrates with enough of their natural packaging intact. Guidelines recommend <a href="https://doi.org/10.1136%2Fbmj-2020-054370">at least 25 to 30 grams</a> of fiber a day from food.</p>
<p>It may not be surprising that lack of fiber <a href="https://doi.org/10.1371/journal.pmed.1003053">contributes to diabetes and obesity</a>. What is surprising is that the fiber gap also likely contributes to <a href="https://doi.org/10.1016/s2468-1253(19)30257-2">heart disease</a>, certain <a href="https://doi.org/10.1093/ajcn/nqaa161">types of cancer</a> and maybe even <a href="https://doi.org/10.3233/jad-215493">Alzheimer’s disease</a>.</p>
<p>One popular approach to mitigating some of the ill health effects of low fiber and high refined carbohydrates has been to <a href="https://doi.org/10.1016/j.jacl.2019.08.003">limit carbohydrate intake</a>. Such approaches include the low-carb, keto, paleo and Atkins diets. Each diet is a variation on a similar theme of limiting carbohydrates to varying amounts in different ways.</p>
<p>There is scientific backing to the benefits of some of these diets. Research shows that limiting carbohydrates <a href="https://doi.org/10.3389/fnut.2021.702802">induces ketosis</a>, a biological process that frees energy from fat reserves during starvation and prolonged exercise. Low-carbohydrate diets can also help people lose weight and <a href="https://doi.org/10.1038/s41392-021-00831-w">lead to improvements</a> in blood pressure and inflammation.</p>
<p>That said, some keto diets may have negative effects on <a href="https://doi.org/10.3390/genes10070534">gut health</a>. It is also unknown how they may affect <a href="https://doi.org/10.3390/nu14173499">heart health, some forms of cancer</a> and other conditions in the long term.</p>
<p>Even more confusing, research shows that people with diets high in plant-sourced carbohydrates, like the Mediterranean diet, tend to lead the <a href="https://doi.org/10.3390%2Fnu13082540">longest and healthiest lives</a>. How can this be reconciled with studies that suggest that low-carbohydrate diets can benefit metabolic health?</p>
<h2>Is a carb a carb?</h2>
<p>The answer may have to do with the <a href="https://doi.org/10.1093%2Fjn%2Fnxac039">types of carbohydrates</a> that studies are evaluating. Limiting simple sugars and refined carbohydrates may improve certain aspects of metabolic health, as these are some of the most easily digested and absorbed calories. But a more sustainable and comprehensive way of improving health may be <a href="https://doi.org/10.3390%2Fnu12103045">increasing the percentage</a> of unprocessed, more complex and slowly absorbed carbohydrates that come with their natural packages and instructions intact – those that have fiber. </p>
<p>These natural carbohydrates can be found in whole grains, beans, nuts, seeds, fruits and vegetables. They come in ratios of total carbohydrate to fiber that <a href="https://doi.org/10.1371%2Fjournal.pone.0231572">rarely exceed 10-to-1 and are often 5-to-1 or lower</a>. Eating mostly whole foods is a simple way to ensure you’re consuming quality carbohydrates with the right ratios.</p>
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<span class="caption">Fruits and vegetables typically come in ideal total carbohydrate-to-fiber ratios.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/young-asian-woman-shopping-fruits-and-vegetables-in-royalty-free-image/1477272111">Oscar Wong/Moment via Getty Images</a></span>
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<p>But who doesn’t like to have a big bowl of pasta or cake with ice cream on occasion? Focusing on packaged processed foods that maintain carb-to-fiber ratios of at least as low as 10-to-1 or ideally 5-to-1 can help you make the best choices when picking more processed foods at the store. Take a look at the nutrition facts label and simply divide total carbohydrates by dietary fiber.</p>
<p>On occasions when you’re eating out or celebrating someone’s birthday, consider taking a fiber supplement with your meal. One pilot study found that a <a href="https://doi.org/10.2337/db22-836-P">supplement containing a blend of fibers</a> decreased the blood sugar spike – an increase in glucose levels in the blood that if <a href="https://doi.org/10.1017/S0029665122000088">too high can damage the body over time</a> – after a meal in healthy individuals by roughly 30%.</p>
<h2>Listen to your body</h2>
<p>While almost all fiber is generally good for health in most people, not all fiber affects the <a href="https://gutbites.org/2022/05/01/are-all-fibers-to-be-plated-equal/">body in the same way</a>. Consuming a <a href="https://doi.org/10.1111/apt.15129">range of different types</a> of fiber generally helps ensure a <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">diverse microbiome</a>, which is linked to gut and overall health.</p>
<p>But certain medical conditions might preclude consuming certain types of fiber. For example, some people can be particularly sensitive to one <a href="https://doi.org/10.1136/gutjnl-2021-326284">class of fiber called FODMAPS</a> – fermentable oligosaccharides, disaccharides, monosaccharides and polyols – that are more readily fermented in the upper part of the gut and can contribute to symptoms of irritable bowel syndrome like bloating and diarrhea. <a href="https://www.health.harvard.edu/diseases-and-conditions/a-new-diet-to-manage-irritable-bowel-syndrome">High-FODMAP foods</a> include many processed foods that contain inulin, garlic powder and onion powder, as well as whole foods including those in the onion family, dairy products, some fruits and vegetables.</p>
<p>Listen to how your body responds to different high-fiber foods. Start low and go slow as you reintroduce foods like beans, seeds, nuts, fruits and vegetables to your diet. If you have trouble increasing your fiber intake, talk with your health care provider.</p>
<p>Tools like this <a href="https://gutbites.org/carb-fiber-ratio-calculator/">online calculator</a> I’ve created can also help you find the highest-quality foods with healthy fiber and other nutrient ratios. It can also show you what proportions of fiber to add back to sugary foods to help achieve healthy ratios.</p>
<p>I wouldn’t endorse eating sweets all the time, but as my three daughters like to remind me, it’s important to enjoy yourself every once in a while. And when you do, consider putting the carbs back in their fiber wrappers. It’s hard to improve upon nature’s design.</p><img src="https://counter.theconversation.com/content/205159/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Damman is on the scientific advisory board at BCD Biosciences and Supergut.</span></em></p>Many processed foods strip carbs of their natural fibers. Eating foods with an ideal total carbohydrate-to-fiber ratio can help with weight management and improve overall health.Christopher Damman, Associate Professor of Gastroenterology, School of Medicine, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2000482023-05-08T12:19:31Z2023-05-08T12:19:31ZClothes moths: Why I admire these persistent, destructive, difficult-to-eradicate and dull-looking pests<figure><img src="https://images.theconversation.com/files/524520/original/file-20230504-1338-tnizp0.jpg?ixlib=rb-1.1.0&rect=78%2C103%2C1284%2C860&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">*Tineola bisselliella* can survive on as little as a hairball and some vitamin B.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Tineola.bisselliella.7218.jpg">Olaf Leillinger/Wikimedia Commons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Every day, I come into the lab to check the moth jar. The jar, which previously housed a liter of honey, now contains a multitude of small golden moths and their wriggly caterpillar offspring.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/524198/original/file-20230503-19-qkt3kv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="smiling woman holds a liter-size jar with scrunched up knitting in it" src="https://images.theconversation.com/files/524198/original/file-20230503-19-qkt3kv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/524198/original/file-20230503-19-qkt3kv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=749&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524198/original/file-20230503-19-qkt3kv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=749&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524198/original/file-20230503-19-qkt3kv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=749&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524198/original/file-20230503-19-qkt3kv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=941&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524198/original/file-20230503-19-qkt3kv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=941&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524198/original/file-20230503-19-qkt3kv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=941&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">The author in the lab with her prized moth jar.</span>
<span class="attribution"><span class="source">Isabel Novick</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>The founding population came from within my house – pests that fervently fed on my sweaters, rugs and horsehair plaster. When they emerge from my walls in the evenings, I chase them with zeal and catch them in jam jars. “Moth!” I shout, jumping up from the couch, knocking over whatever is in front of me. In the lab, I feed them clippings of a mohair sweater that shrank in the wash, which I soak in brewer’s yeast.</p>
<p><a href="https://scholar.google.com/citations?hl=en&user=Cog3A6IAAAAJ&view_op=list_works&gmla=AHoSzlX3j284dvhFbLwvsoW_JOhIs5qvImnVBOhC7QrqXwX53uEoVh9osKUVd9oBWd7foWeY7X0W3TJBE-pg97Ik">I’m a doctoral candidate</a> <a href="https://www.bu.edu/biology/people/profiles/isabel-novick/">studying the evolutionary relationships</a> within the moth family Tineidae. I’m interested in how webbing clothes moths, <em>Tineola bisselliella</em>, have dispersed so widely and colonized our homes so readily. I am using a population genetics approach, examining the DNA of isolated populations of moths from all over the world. They eat crazy stuff. They live mostly indoors. How did this happen?</p>
<h2>Resourceful, vigorous, tanklike eating machines</h2>
<p>Webbing clothes moths are part of a distinctive, primordial lineage called the <a href="https://doi.org/10.1007/978-1-4020-6359-6_3921">fungus moth family</a>. These guys emerged long before more well-known species like silk moths. If you’re unlucky, you are already aware of the destruction they can wreak on sweaters, rugs and upholstery. But you many not realize how fascinating Tineidae are.</p>
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<a href="https://images.theconversation.com/files/524201/original/file-20230503-22-bkppfb.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="little worms on the surface of a knitted material" src="https://images.theconversation.com/files/524201/original/file-20230503-22-bkppfb.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524201/original/file-20230503-22-bkppfb.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=437&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524201/original/file-20230503-22-bkppfb.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=437&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524201/original/file-20230503-22-bkppfb.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=437&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524201/original/file-20230503-22-bkppfb.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=549&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524201/original/file-20230503-22-bkppfb.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=549&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524201/original/file-20230503-22-bkppfb.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=549&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"><em>Tineola bisselliella</em> larvae living it up on a scrap of sweater in the lab.</span>
<span class="attribution"><span class="source">Isabel Novick</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>These moths can eat hair, skin and feathers, all of which comprise a protein called keratin. Keratin – the main ingredient in nails, hoofs and horns – is <a href="https://doi.org/10.1371/journal.pone.0202608">notoriously tough to digest</a>. Biologists still aren’t sure how clothes moths can metabolize keratin, and this is something I aim to address in my research. One study posits that they harbor a <a href="https://doi.org/10.3390/microorganisms8091415">microorganism in their gut</a> that uses digestive enzymes to break down keratin for them.</p>
<p>However mysterious the process may be, their nutritional needs can be met with as little as a hairball and <a href="http://publichealth.lacounty.gov/eh/docs/safety/managing-clothes-moth-infestations.pdf">some vitamin B</a>, which they can glean from sweat, pee and food stains. Not only that, but research suggests these moths somehow <a href="https://agris.fao.org/agris-search/search.do?recordID=US201301122326">produce water as a byproduct of digesting keratin</a>, so they can happily survive within the dry recesses of your home.</p>
<p>Incredibly, webbing clothes moths can safely digest poisonous heavy metals like <a href="https://doi.org/10.1071/BI9510049">arsenic, mercury and lead</a>. They can easily <a href="https://doi.org/10.1016/j.jspr.2005.08.004">chew through soft plastics and metabolize synthetic fabrics</a>. They have been known to feast on <a href="https://www.researchgate.net/publication/292321410_Forensic_entomology_applied_to_a_mummified_corpse">mummified human remains</a> and have even been a recognizable pest long enough to be <a href="https://bible.knowing-jesus.com/topics/Moths">mentioned in the Bible</a>. They are so economically destructive that by the 1990s they were causing up to <a href="https://www.wiley.com/en-us/Introduction+to+Insect+Pest+Management%2C+3rd+Edition-p-9780471589570">US$1 billion in damage per year in the U.S. alone</a>.</p>
<p>This pest insect, over time, has hitchhiked all over the world. It can now be found from Australia to Chile, from Nigeria to Canada. The current hypothesis is that these moths originated in Africa and expanded their range by <a href="https://doi.org/10.1016/j.jspr.2005.08.004">hitchhiking on 19th-century ships</a>. </p>
<p>Scientists consider webbing clothes moths synanthropes: organisms that benefit from, and <a href="https://davidrousefaicp.com/synanthropic-species-why-are-they-important-to-our-future/">have adapted to, human spaces</a>, much like pigeons or bedbugs. They have taken this to an extreme and are now <a href="https://doi.org/10.4081/jear.2011.83">mostly found indoors</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524673/original/file-20230505-27-dokyrv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="color drawing of an insect with long antennae and folded wings" src="https://images.theconversation.com/files/524673/original/file-20230505-27-dokyrv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524673/original/file-20230505-27-dokyrv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=456&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524673/original/file-20230505-27-dokyrv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=456&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524673/original/file-20230505-27-dokyrv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=456&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524673/original/file-20230505-27-dokyrv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=572&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524673/original/file-20230505-27-dokyrv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=572&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524673/original/file-20230505-27-dokyrv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=572&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">These moths aren’t particularly pleasing to the human eye.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/carpet-moth-tineidae-artwork-by-steve-roberts-news-photo/492779087">Steve Roberts/De Agostini Picture Library via Getty Images</a></span>
</figcaption>
</figure>
<p>Researchers are still not sure what evolutionary adaptations have allowed these moths to colonize, and ultimately depend upon, human environments. However, it seems likely to me that their global domination is associated with their diet. Webbing clothes moths are known as <a href="https://doi.org/10.4081/jear.2011.83">facultative keratinophages</a>, which means they can choose to eat and digest keratin, but it’s not a required part of their diet. This kind of nutritional flexibility is common to other well-known synanthropic species – is there anything a raccoon won’t eat? – and may be fundamental to the moths’ successful global dispersal.</p>
<h2>Moth genes from around the world</h2>
<p>To study the differences between populations of webbing clothes moths around the world, I am analyzing a type of genomic data made from sequencing “<a href="https://doi.org/10.1093/sysbio/sys004">ultraconserved elements</a>.” This technique targets specific genes that all moth species share, called orthologs, and compares the variable genetic regions on both sides of the conserved sequence. This data tells researchers like me how distantly related the clothes moths in, say, Australia are to clothes moths in Hawaii.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/524647/original/file-20230505-25-gz6i5l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="about a dozen small dead moths stuck to sticky cardboard" src="https://images.theconversation.com/files/524647/original/file-20230505-25-gz6i5l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/524647/original/file-20230505-25-gz6i5l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=619&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524647/original/file-20230505-25-gz6i5l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=619&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524647/original/file-20230505-25-gz6i5l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=619&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524647/original/file-20230505-25-gz6i5l.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=778&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524647/original/file-20230505-25-gz6i5l.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=778&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524647/original/file-20230505-25-gz6i5l.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=778&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This trap came back with plenty of moths that unwittingly donated themselves to science.</span>
<span class="attribution"><span class="source">Isabel Novick</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>To that end, I’ve spent the past two years internationally shipping pheromone-baited moth traps to interested volunteers. They set up the traps in their closets or storage rooms. After two months, I ask whether they’ve caught anything, request a photo of the trap and have them ship it back to me.</p>
<p>People generally want to help because they hope my research will yield better <a href="https://ipm.ucanr.edu/PMG/PESTNOTES/pn7435.html">methods of moth eradication</a>. Ultimately, it may, but I’m primarily interested in appreciating these organisms from an evolutionary perspective.</p>
<p>So far, I have received over 600 moths. But many of my correspondents don’t catch anything, or catch the wrong thing. Sometimes the trap gets thrown out with the trash. Sometimes I send a trap and never hear from the recipient again. It can be a frustrating process. I end up spending hundreds of dollars and sifting through hundreds of moths, most of them other tineids or pantry moths, looking for the flash of dusty golden wings. </p>
<p>I spend a lot of my time in the lab extracting moth DNA and a lot of time on my computer analyzing it. Ideally, this research will yield a more comprehensive picture of how moths in this family are related to one another, and clarify whether clothes moths from around the world are actually the species we think they are. If these moths are experiencing sexual isolation, we might be using the wrong methods to control them depending on their location. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/524202/original/file-20230503-1364-y4rm31.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="pale moth with dark eye" src="https://images.theconversation.com/files/524202/original/file-20230503-1364-y4rm31.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/524202/original/file-20230503-1364-y4rm31.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=277&fit=crop&dpr=1 600w, https://images.theconversation.com/files/524202/original/file-20230503-1364-y4rm31.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=277&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/524202/original/file-20230503-1364-y4rm31.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=277&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/524202/original/file-20230503-1364-y4rm31.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=348&fit=crop&dpr=1 754w, https://images.theconversation.com/files/524202/original/file-20230503-1364-y4rm31.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=348&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/524202/original/file-20230503-1364-y4rm31.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=348&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"><em>Tineola bisselliella</em> moth, ready for its close-up through the microscope.</span>
<span class="attribution"><span class="source">Isabel Novick</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Appreciation for a pest</h2>
<p>Even though clothes moths can destroy your wardrobe or devour priceless objects like taxidermy, oriental carpets and upholstered furniture <a href="https://www.latimes.com/entertainment-arts/story/2021-04-22/getty-museum-covid-closure-moth-remediation">in museum collections</a>, I can’t help but admire them.</p>
<p>They are not intentionally pests; they are innovative, cunning and endlessly capable. Their ability to capitalize on unfilled niches has allowed them to spread far and wide throughout homes everywhere. They’re not chomping through your drapes with malicious intent; they’re operating exactly as they evolved to, in a way that has worked to their advantage for thousands of years. The reasons people dislike them – being persistent, destructive and difficult to eradicate, not to mention dull-colored – are the reasons they’ve been able to survive and thrive so successfully for so long.</p>
<p>I gently urge you to consider their efficiency and determination as a sort of evolutionary elegance. How incredible is it for something to have evolved to eat the inedible, to occupy the uninhabitable and to overcome every evolutionary obstacle in its way? Of course, that doesn’t mean their damage can’t be devastating, or that battling these moths doesn’t stink. But, from an evolutionary standpoint, the webbing clothes moth should inspire wonder instead of disgust, awe instead of frustration, and instead of exasperation, admiration.</p><img src="https://counter.theconversation.com/content/200048/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>I used to work at the Museum of Science, Boston</span></em></p>An appreciation for the moths that chomp holes in your clothes. They eat the inedible, occupy the uninhabitable and overcome every evolutionary obstacle in their way.Isabel Novick, Doctoral Candidate in Ecology, Behavior and Evolution, Boston UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2044192023-05-03T11:24:28Z2023-05-03T11:24:28ZThousands of unknown viruses discovered in baby poo – why this is not necessarily a bad thing<p>An international team of scientists who spent five years studying the poo of <a href="https://www.nature.com/articles/s41564-023-01345-7">647 Danish babies</a> found something astonishing. The nappy samples contained 10,000 species of virus – ten times the number of bacterial species in the same children. Most of the viruses had never been described before. </p>
<p>This may alarm many readers. Viruses haven’t exactly had a <a href="https://ourworldindata.org/covid-deaths">good reputation</a> in recent years. But what many people don’t realise is that the overwhelming majority of viruses do not make people sick and do not infect humans or animals at all. </p>
<p>The viruses I’m referring to are bacteriophages. They exclusively infect bacteria and make up a large part of the human microbiome. It’s these bacteriophages that the researchers found so abundantly in baby poo. Indeed, around 90% of the viruses found in the nappies of the Danish babies were these bacteria killers.</p>
<p>The human gut microbiome is a complex collection of microorganisms, including bacteria, archaea, microbial eukaryotes and viruses. The viral component of the gut microbiome, or virome, is mainly made up of bacteriophages that help maintain a healthy and diverse microbiome.</p>
<h2>Atlas</h2>
<p>The researchers of this new study – a collaborative team from Denmark, Canada and France – looked at how many of these 10,000 viruses were new and how best to describe all this new viral diversity in an accessible form. </p>
<p>Putting all of them in a large table would be a rather boring read. Instead, they created an “atlas of infant gut DNA virus diversity”, where they grouped the viruses into new virus families and orders based on how similar the genomes were to each other. They found 248 families of which only 16 were previously known. </p>
<p>The researchers named the remaining 232 newly identified virus families after children who took part in the study, such as Sylvesterviridae, Rigmorviridae and Tristanviridae.</p>
<p>An <a href="https://copsac.com/earlyvir/f1y/fig1.svg">interactive version</a> of the atlas is available online.</p>
<figure class="align-center ">
<img alt="Illustration of bacteriophages attacking a bacterium" src="https://images.theconversation.com/files/523793/original/file-20230502-1677-ej65zg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523793/original/file-20230502-1677-ej65zg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523793/original/file-20230502-1677-ej65zg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523793/original/file-20230502-1677-ej65zg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523793/original/file-20230502-1677-ej65zg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523793/original/file-20230502-1677-ej65zg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523793/original/file-20230502-1677-ej65zg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Bacteriophages attacking a bacterium.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/3d-illustration-bacteriophage-infecting-bacterium-1126283543">Design Cells/Shutterstock</a></span>
</figcaption>
</figure>
<h2>Unique viromes</h2>
<p>What is interesting about bacteriophages and other viruses in the gut is that every person has their own unique set, with <a href="https://www.sciencedirect.com/science/article/pii/S1931312819304767">almost no overlap between two different people</a>. </p>
<p>While each gut virome is unique, it is also stable over time in adults, meaning you carry with you the same set of viruses as you age. But right after a baby is born, this virome is very different from that of an adult and it only stabilises after a couple of years. </p>
<p>When comparing the approximately 10,000 viruses of this new study with extensive reference virome collections of healthy adults, the researchers found that only about 800 of these viruses had been found before. </p>
<p>That means that when babies are born and have the first bacteriophages colonise their gastrointestinal tract, these “baby bacteriophages” don’t all stay there, but gradually get replaced with “adult bacteriophages”. </p>
<p>This replacement could be partially linked to the bacterial hosts these bacteriophages infect. For example, <em>Bacteroides</em>, <em>Faecalibacterium</em> and <em>Bifidobacterium</em> were the most prominent hosts that were predicted for the baby bacteriophages. </p>
<p>I’d like to highlight <em>Bifidobacterium</em> species here, which are very important for infant health. These bacteria help with the digestion of breastmilk and so are important early in life, but become less abundant as we age. So it makes sense that the viruses that infect <em>Bifidobacterium</em> are found more in babies and less in adults. </p>
<p>Conversely, the most abundant group of adult gut bacteriophages, members of the order <em>Crassvirales</em> were not as prevalent in baby poo, meaning children acquire these bacteriophages as they age. </p>
<p>With the addition of these 10,000 new virus species and the many new families, from just one group of several hundred Danish babies, it becomes clear that there’s more that we don’t know about the virome than what we do know. But the scientific community is working on it, one baby poo sample at a time.</p><img src="https://counter.theconversation.com/content/204419/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Evelien Adriaenssens receives funding from the Biotechnology and Biological Sciences Research Council (BBSRC) and Medical Research Council (MRC). She is affiliated with the International Committee on Taxonomy of Viruses. </span></em></p>Babies guts found to have ten times as many viral species as bacterial species.Evelien Adriaenssens, Group Leader, Gut viruses & Viromics, Quadram InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2038552023-04-21T14:53:28Z2023-04-21T14:53:28ZHay fever could be linked to our gut and nose bacteria – and probiotics may help symptoms<figure><img src="https://images.theconversation.com/files/522085/original/file-20230420-15-nvus1a.jpg?ixlib=rb-1.1.0&rect=17%2C0%2C5734%2C3837&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Many people suffer with hay fever.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/handsome-hipster-blowing-his-nose-on-287952305">wavebreakmedia/Shutterstock</a></span></figcaption></figure><p>For many people, spring has brought with it the dreaded symptoms of <a href="https://www.nhs.uk/conditions/hay-fever/">hay fever</a>, such as itchy eyes, sneezing and a stuffy nose. Hay fever is common, affecting <a href="https://europepmc.org/article/med/17153005">up to 42%</a> of people. It occurs when the immune system overreacts to allergens including pollen.</p>
<p>Research suggests there could be a link between <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5378446/">hay fever and the microbiome</a>, the collection of microorganisms that live in and on our bodies. Specifically, the composition of a person’s <a href="https://www.karger.com/Article/Abstract/510536">gut</a> and <a href="https://link.springer.com/article/10.1007/s00405-020-06311-1">nasal microbiomes</a> may play a role in the development of hay fever symptoms. </p>
<p>By exploring this connection, we can identify potential alternative treatments that may help reduce the effects of hay fever on people’s daily lives.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/got-allergies-you-could-be-at-lower-risk-of-catching-covid-188486">Got allergies? You could be at lower risk of catching COVID</a>
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<h2>Hay fever and the microbiome</h2>
<p>Studies have shown that people with hay fever often have <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/all.13812">a less diverse gut microbiome</a> compared to those without the condition. Reduced diversity of gut bacteria can lead to an imbalance in the microbiome, and result in higher levels of inflammation (the body’s immune response to irritants, such as an allergens).</p>
<p>So the fact that reduced diversity of gut bacteria can lead to an increased risk of hay fever makes sense since the gut microbiome plays a key role in <a href="https://akjournals.com/view/journals/030/68/3/article-p135.xml">regulating the immune system</a>, and we know the immune system influences allergies. </p>
<p>The gut microbiome is thought to affect immune system function in several ways, including through the production of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9040132/">short-chain fatty acids</a>. These are produced by gut bacteria during the fermentation of dietary fibre (a part of normal digestion). </p>
<p>Short-chain fatty acids are known to have anti-inflammatory properties. Research has shown that lower levels of two bacterial strains which produce short-chain fatty acids – <em>Bifidobacterium</em> and <em>Lactobacillus</em> – are associated with <a href="https://pubmed.ncbi.nlm.nih.gov/21340202/">an increased risk of hay fever</a>.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/hay-fever-why-some-people-suffer-from-it-and-others-dont-202553">Hay fever: why some people suffer from it and others don't</a>
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<p>In addition to the gut microbiome, hay fever also seems to be linked to the <a href="https://www.frontiersin.org/articles/10.3389/fcimb.2022.841995/full">nasal microbiome</a>, the community of microorganisms that inhabit the nasal passages. </p>
<p>The nasal microbiome plays an important role in regulating the immune system and protecting against harmful pathogens that enter our bodies through the nose. Imbalance and reduced diversity of the nasal microbiome can lead to an <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8566799/">increased risk of respiratory infections</a> and <a href="https://www.nature.com/articles/s41564-022-01301-x">exacerbation of hay fever symptoms</a>. </p>
<p>Studies have shown that people with hay fever often have a different <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4101129/">composition of their nasal microbiome</a> compared to those without the condition, with more of certain bacteria such as <em><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2984262/">Staphylococcus aureus</a></em>. This imbalance in the nasal microbiome can lead to increased inflammation and a higher risk of certain hay fever symptoms.</p>
<h2>The potential role of probiotics and prebiotics</h2>
<p>Probiotics are <a href="https://academic.oup.com/ajcn/article/71/6/1682S/4729644?login=false">live microorganisms</a> which enhance the composition of “good” bacteria in the body. Prebiotics, meanwhile, are fibres that stimulate beneficial bacteria in the gut. Essentially, good bacteria <a href="https://www.healthline.com/nutrition/probiotics-and-prebiotics">feed on prebiotics</a>. Both are important for maintaining a healthy gut microbiome, which plays a crucial role in our overall health.</p>
<p>Several strains of <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/alr.21492">probiotic bacteria</a> have been studied in connection to hay fever.</p>
<p>One strain of interest is <em>Lactobacillus acidophilus</em>, which has been found to <a href="https://www.karger.com/Article/Abstract/515352">reduce hay fever symptoms</a> such as congestion, itching and sneezing. Another is <em>Lactobacillus rhamnosus GG</em>, which has shown potential in preventing hay fever development in infants.</p>
<p>Other <a href="https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1440-1711.2000.00886.x">strains</a> such as <em><a href="https://www.nature.com/articles/ejcn2012197">Bifidobacterium lactis</a></em>, <em>Bifidobacterium bifidum</em> and <em>Lactobacillus casei</em> have also shown some promise in reducing hay fever symptoms. But further research is needed.</p>
<h2>How does this work?</h2>
<p>Probiotics appear to modulate the immune response and in particular, decrease the production of inflammatory cytokines. These are signalling molecules produced by cells of the immune system that promote inflammation.</p>
<p>For example, <em>Lactobacillus acidophilus</em> can <a href="https://www.sciencedirect.com/science/article/pii/S0022030205727144">decrease the expression of</a> inflammatory cytokines associated with allergic inflammation in the mucous membranes in the nasal cavity. </p>
<p>Similarly, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8256161/"><em>Lactobacillus rhamnosus GG</em></a> has been shown to reduce airway hyperresponsiveness (where the airways narrow excessively in response to stimuli), decrease inflammatory cells in the lungs, and reduce inflammatory cytokines.</p>
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<img alt="Six different types of fermented food in jars." src="https://images.theconversation.com/files/522176/original/file-20230420-24-h28hpw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/522176/original/file-20230420-24-h28hpw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522176/original/file-20230420-24-h28hpw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522176/original/file-20230420-24-h28hpw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522176/original/file-20230420-24-h28hpw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522176/original/file-20230420-24-h28hpw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522176/original/file-20230420-24-h28hpw.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">
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<span class="caption">Fermented foods contain probiotics.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/set-fermented-food-great-gut-health-485504767">marekuliasz/Shutterstock</a></span>
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<p>Prebiotics, such as fructo-oligosaccharides, have also been studied for their <a href="https://pubmed.ncbi.nlm.nih.gov/33376575/">potential in hay fever prevention</a>. They’ve been found to increase beneficial gut bacteria such as <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6115998/"><em>Bifidobacterium</em> and <em>Lactobacillus</em></a>. One study showed that fructo-oligosaccharides supplementation in infants <a href="https://www.cambridge.org/core/journals/proceedings-of-the-nutrition-society/article/specific-mixture-of-shortchain-galactooligosaccharides-and-longchain-fructooligosaccharides-induced-an-antiallergic-ig-profile-in-infants-at-risk-for-allergy/22B21443140E6A7F6956CC8F733492D0">decreased their risk</a> of developing hay fever. </p>
<h2>Incorporating probiotics and prebiotics</h2>
<p>If you suffer from hay fever, you may want to consider incorporating probiotics and prebiotics into your routine.</p>
<p>Probiotic supplements are widely available in various forms, including capsules, tablets, powders and drinks. It’s important to choose a supplement that contains the specific strains of probiotic bacteria that have been studied in relation to hay fever. These include <em>Lactobacillus acidophilus</em>, <em>Lactobacillus rhamnosus GG</em>, <em>Bifidobacterium lactis</em>, <em>Bifidobacterium bifidum</em> and <em>Lactobacillus casei</em>. </p>
<p>You can also incorporate <a href="https://www.webmd.com/digestive-disorders/ss/slideshow-probiotics">probiotic-rich foods</a> into your diet. These include fermented foods such as yogurt, kefir, sauerkraut, kimchi and kombucha.</p>
<p>As for prebiotics, fructo-oligosaccharides are <a href="https://www.webmd.com/diet/foods-high-in-prebiotic">commonly found in certain foods</a> such as bananas, onions, garlic, asparagus, artichokes and whole grains. Supplements are also available in various forms, including powders and capsules.</p>
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Read more:
<a href="https://theconversation.com/probiotics-regulate-our-immune-system-and-could-help-fight-off-covid-new-research-175470">Probiotics regulate our immune system and could help fight off COVID – new research</a>
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<p>Sometimes, taking probiotics and prebiotics may have <a href="https://www.tandfonline.com/doi/abs/10.1517/14740338.2014.872627">side effects</a>, including digestive discomfort such as gas, bloating and diarrhoea. To minimise these risks, it’s recommended you start with a low dose and gradually increase this over time. It’s also worth consulting a healthcare provider before taking these supplements, especially if you have a medical condition or are on medications.</p><img src="https://counter.theconversation.com/content/203855/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Research suggests there could be a link between hay fever and the microbiome. Exploring this connection paves the way for potential treatments.Samuel J. White, Senior Lecturer in Genetic Immunology, Nottingham Trent UniversityPhilippe B. Wilson, Professor of One Health, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1994862023-04-10T12:09:59Z2023-04-10T12:09:59ZHangry bacteria in your gut microbiome are linked to chronic disease – feeding them what they need could lead to happier cells and a healthier body<figure><img src="https://images.theconversation.com/files/519904/original/file-20230406-28-pmixy3.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C788%2C443&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The gut microbiome may play a role in regulating the body's appetite, cognition and immune responses. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/gut-bacteria-royalty-free-image/1471910154">nopparit/iStock via Getty Images Plus</a></span></figcaption></figure><p>Diet-related chronic diseases <a href="https://www.whitehouse.gov/briefing-room/statements-releases/2022/09/27/executive-summary-biden-harris-administration-national-strategy-on-hunger-nutrition-and-health/">have reached</a> a <a href="https://foodperiodictable.org">critical juncture</a> in the U.S. </p>
<p>Nearly half the population has <a href="https://www.cdc.gov/diabetes/data/statistics-report/index.html">prediabetes or diabetes</a>. Over 40% are <a href="https://www.cdc.gov/obesity/data/adult.html">overweight or obese</a>. <a href="https://www.alz.org/media/Documents/alzheimers-facts-and-figures.pdf">One in nine people over the age of 65</a> has Alzheimer’s disease, the development of which researchers are exploring the <a href="https://doi.org/10.1016/S1474-4422(20)30231-3">potential role of diet</a>. Poor diet is also linked to <a href="https://doi.org/10.1093%2Fnutrit%2Fnuaa025">poor mental health</a>, <a href="https://doi.org/10.1161/CIR.0000000000001031">cardiovascular disease</a> and <a href="https://www.cancer.gov/about-cancer/causes-prevention/risk/diet">cancer</a>. It was responsible for <a href="https://www.cspinet.org/eating-healthy/why-good-nutrition-important">nearly 1 in 5 deaths in the U.S.</a> and accounted for <a href="https://doi.org/10.1016/S2468-2667(20)30203-6">over US$140 billion</a> in U.S. health care spending in 2016.</p>
<p>Though American waists are getting bigger, research is showing that the gut microbiome – the bacteria living in our digestive tracts – and the energy-producing compartments of cells, the mitochondria, remain hungry for nutrients missing in the American diet.</p>
<p>I am a <a href="https://gastro.uw.edu/faculty/christopher-j-damman-md-ma">physician scientist and gastroenterologist</a> who has spent over 20 years studying how food can affect the gut microbiome and whole body health. The ultraprocessed food that makes up an <a href="https://doi.org/10.1093/ajcn/nqab305">increasing part the American diet</a> has removed vital nutrients from food. Adding those nutrients back may be important for health in part by feeding the microbiome and mitochondria that turn food into fuel. </p>
<h2>Your health is what you eat</h2>
<p>Research has consistently shown that the <a href="https://doi.org/10.1111/joim.13333">Mediterranean diet</a> and <a href="https://doi.org/10.1016/j.foodres.2022.111501">other whole food diets</a> are associated with better health and longer lives, and <a href="https://theconversation.com/ultraprocessed-foods-like-cookies-chips-frozen-meals-and-fast-food-may-contribute-to-cognitive-decline-196560">ultraprocessed foods and drinks</a> like soda, chips and fast food, among others, are linked with <a href="https://doi.org/10.1080/10408398.2022.2084359">poor health outcomes</a> such as diabetes, cardiovascular disease, cancer and other diseases. </p>
<p>But improving the diet of an individual, let alone a population, is challenging. Whole foods are sometimes <a href="https://www.usda.gov/media/blog/2018/07/24/what-drives-consumers-purchase-convenience-foods">less convenient</a> and <a href="https://doi.org/10.1093/jn/nxab318">less tasty</a> for modern lifestyles and preferences. Furthermore, food processing can be beneficial by <a href="https://www.hsph.harvard.edu/nutritionsource/processed-foods/">preventing spoilage and extending shelf life</a>. <a href="https://doi.org/10.1016/j.gfs.2022.100649">Whole grain processing</a> in particular extends shelf life by removing the germ and bran that otherwise rapidly spoil. Long-term storage of affordable calories has helped address <a href="https://www.ers.usda.gov/data-products/ag-and-food-statistics-charting-the-essentials/food-security-and-nutrition-assistance/">food insecurity</a>, a primary challenge in public health. </p>
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<figcaption><span class="caption">What you eat changes the composition of your gut microbiome.</span></figcaption>
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<p>Much of the public health conversation around diet has focused on what to avoid: added sugars and refined carbs, some fats, salt and additives. But modern food processing, while increasing the concentration of some nutrients, has removed other key nutrients, producing potential <a href="https://doi.org/10.1038/s43016-019-0013-1">long-term health costs</a>. Equally important is <a href="https://doi.org/10.3390/diseases4010014">what to add back</a> into diets: fibers, <a href="https://theconversation.com/phytonutrients-can-boost-your-health-here-are-4-and-where-to-find-them-including-in-your-next-cup-of-coffee-132100">phytonutrients</a>, micronutrients, missing fats and fermented foods.</p>
<p>Only 5% of the U.S. population gets <a href="https://doi.org/10.1177%2F1559827615588079">sufficient fiber</a>, a prebiotic nutrient linked to metabolic, immune and neurologic health. Americans are likely also deficient in <a href="https://doi.org/10.3390%2Fnu11061355">phytonutrients</a>, <a href="https://doi.org/10.1136/bmj.f1378">potassium</a> and certain <a href="https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/">healthy fats</a> linked to lower rates of cardiovascular disease and cancer. </p>
<p><a href="https://doi.org/10.1038/s41575-020-00390-5">Fermentation</a> is nature’s version of processing, creating foods with natural preservatives, flavors and vitamins. Recent research suggests fermented foods can <a href="https://doi.org/10.1016/j.cell.2021.06.019">improve gut microbiome diversity</a> and dampen systemic inflammation.</p>
<p>Figuring out which bioactive nutrients contribute to disease can help both individuals and institutions develop diets and foods that are personalized to different health conditions, economic constraints and taste preferences. It can also help maximize nutrients in a way that is convenient, affordable and familiar to the modern palate. </p>
<h2>Of microbiomes and mitochondria</h2>
<p>Understanding how nutrients affect the gut microbiome and mitochondria could help determine which ingredients to add to the diet and which to temper.</p>
<p>In your lower gut, bacteria transform undigested bioactive nutrients into <a href="https://doi.org/10.1016/j.tem.2020.12.003">biochemical signals</a> that stimulate gut hormones to slow down digestion. These signals also regulate the immune system, controlling how much of the body’s energy goes toward inflammation and fighting infection, and <a href="https://doi.org/10.3389%2Ffmicb.2022.798917">cognition</a>, influencing appetite and <a href="https://doi.org/10.3390%2Fmicroorganisms9040716">even mood</a>.</p>
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<figcaption><span class="caption">A number of factors are involved in aging.</span></figcaption>
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<p>The microbiome’s biochemical signals also <a href="https://doi.org/10.3389%2Ffmicb.2022.1056499">regulate the growth and function</a> of energy-producing mitochondria across many cell types, including those in fat, muscles, heart and the brain. When these cues are <a href="https://doi.org/10.1038/s43016-019-0013-1">missing in ultraprocessed diets</a>, mitochondria <a href="https://doi.org/10.3390/diseases4010014">function less well</a>, and their dysregulation has been linked to <a href="https://doi.org/10.3389/fendo.2018.00283">obesity</a>, <a href="https://doi.org/10.3389/fphys.2019.00532">diabetes</a>, <a href="https://doi.org/10.1186/s13024-020-00376-6">Alzheimer’s disease</a>, <a href="https://doi.org/10.3389/fpsyt.2021.546801">mood disorders</a> and <a href="https://doi.org/10.1016%2Fj.molcel.2016.02.011">cancer</a>. A better understanding of how diet could improve the function of the <a href="https://doi.org/10.1016/j.advnut.2023.03.016">microbiome-mitochondria axis</a> could help provide a way to reduce the burden of chronic disease.</p>
<p><a href="https://www.britannica.com/biography/Hippocrates">The Greek physician Hippocrates</a>, regarded as the father of medicine, supposedly once said “Let food be thy medicine,” and a <a href="https://doi.org/10.1016/j.advnut.2023.03.016">growing body research</a> suggests that, yes, food can be medicine. I believe that shining a light on the <a href="https://gutbites.org/">connection between diet, health and the microbiome and mitochondria</a> could help societies reach a bright future in which unhealthy aging <a href="https://doi.org/10.1111/obr.13366">isn’t an inevitability</a> of growing older.</p><img src="https://counter.theconversation.com/content/199486/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Damman is medical and science officer at Supergut and on the scientific advisory board at BCD Biosciences.</span></em></p>Research has examined how ultraprocessed foods can contribute to diabetes, cardiovascular disease, cancer and mood disorders. A healthier diet is one way to use food as medicine.Christopher Damman, Associate Professor of Gastroenterology, University of WashingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1951622023-04-05T12:23:16Z2023-04-05T12:23:16ZInnies, outies and omphalophobia: 7 navel-gazing questions about belly buttons answered<figure><img src="https://images.theconversation.com/files/517462/original/file-20230324-1164-blenfn.jpg?ixlib=rb-1.1.0&rect=0%2C374%2C3564%2C2404&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Your genes determine the look of your navel.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/young-girl-looking-at-her-belly-button-royalty-free-image/97766642">Mike Kemp/Tetra images via Getty Images</a></span></figcaption></figure><p><em>Everyone has one, but you might not know much about it. Here <a href="https://scholar.google.com/citations?user=iGYBbvEAAAAJ&hl=en&oi=ao">biologist Sarah Leupen</a>, who teaches human and comparative animal physiology, explains the ins and outs of belly buttons.</em></p>
<h2>1. Why do I even have a belly button?</h2>
<p>Your belly button, or navel – <a href="https://link.springer.com/chapter/10.1007/978-3-319-62383-2_1">clinically, your umbilicus</a> – is the permanent scar left from where your umbilical cord connected your circulatory system, when you were a fetus, to the placenta. Fetuses don’t breathe, eat or eliminate waste, so the placenta provides an exchange site for the mother to deliver oxygen and nutrients from her bloodstream to the fetus, as well as collecting its wastes to eliminate from her body.</p>
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<a href="https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="closeup of umbilical cord stump on infant" src="https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517463/original/file-20230324-27-hz5plh.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">Once the umbilical cord is cut, the stump dries up and falls off, revealing the baby’s navel.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/close-up-umbilical-cord-royalty-free-image/525032060">Wacharaphong/iStock via Getty Images Plus</a></span>
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<p>After the baby is born, the physician or other attendant cuts the cord and clamps off the stub, which then dries and falls off after about a week, leaving the point of connection – your belly button – remaining.</p>
<p>If the cord is not cut, as has been the practice in some times and places and as is becoming trendy again in others, it will close off after an hour or so, then naturally detach a few days after birth. Some health care practitioners are <a href="https://www.med.umich.edu/1libr/Pediatrics/LotusBirthHandout.pdf">concerned that this “lotus birth”</a> could be an infection risk, since the umbilical cord remains attached to the placenta, which is dead tissue once out of the mother’s body.</p>
<h2>2. If it’s a scar, why doesn’t it disappear over time?</h2>
<p>If you injure just the outer layers of your skin, as in a cut or burn, the scar will soon completely disappear, especially in young people. And newborns are very young people. But unlike in those situations, the umbilicus involves more tissue layers — not just the skin but the connective tissue underneath – so it makes sense it doesn’t just blend in with the rest of your abdominal wall once it’s healed.</p>
<p>What about some pretty complicated surgeries that don’t leave scars? Doctors perform many operations in ways that deliberately avoid scarring, which is not nature’s way. In fact, one way to minimize scarring for surgeries uses this existing scar – surgeons can take advantage of the navel as an incision site for <a href="https://doi.org/10.1053/j.sempedsurg.2011.05.003">removing your appendix</a> or <a href="https://doi.org/10.3109/13645706.2011.649039">gall bladder</a> or for <a href="https://doi.org/10.1016/j.soard.2010.12.007">weight-loss surgery</a>.</p>
<p>But if you don’t like the way your umbilical scar looks, plastic surgery to change its appearance, <a href="https://www.nytimes.com/2002/12/15/magazine/the-year-in-ideas-umbilicoplasty.html">called umbilicoplasty</a>, is possible. People sometimes take this cosmetic option after pregnancy or the removal of a piercing, or just to make an “outie” into an “innie.”</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="smooth belly with an outie belly button" src="https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=381&fit=crop&dpr=1 600w, https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=381&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=381&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=479&fit=crop&dpr=1 754w, https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=479&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/515931/original/file-20230316-19-jzc793.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=479&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Outies are much less common than innies.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/8kd8nw">Zeev Barkan/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<h2>3. But why do some people have outies, anyway?</h2>
<p>The look of your belly button is not related to the location of the clamp or where your doctor cut the cord.</p>
<p>Outies are simply an example of <a href="https://learn.genetics.utah.edu/content/basics/observable/">normal human variation</a>, like the way some people have curly hair or dimples. When the tip of the umbilical cord’s remnant pokes out past the skin around it, you have an outie; <a href="http://dx.doi.org/10.1007/978-3-319-62383-2_22">about 10% of people have these</a>. Any concave navel is called an “innie” and a convex one an “outie.”</p>
<p>Sometimes outies can be caused by an umbilical hernia in the baby or another medical problem, but most of it is just due to what your genes encoded. You might also temporarily have an outie during late pregnancy, when the abdominal pressure from the growing fetus stretches your navel and may push it out.</p>
<h2>4. How deep does it go?</h2>
<p>You can probably easily probe the depth of your own navel – there are no hidden recesses there. What’s under it is the same as what’s under the skin of the rest of your abdomen: your abdominal muscles, to which the navel is attached by a short umbilical stalk, and the peritoneum, the membrane that lines the abdominal cavity. Under that lie your guts – that is, your intestines and other abdominal organs. If you keep following this imaginary journey back, you’ll get to your spine – the belly button is usually lined up <a href="http://dx.doi.org/10.1007/978-3-319-62383-2_22">between the third and fourth lumbar vertebrae</a> (L3 and L4).</p>
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<figcaption><span class="caption">Learn how to find your pet’s belly button.</span></figcaption>
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<h2>5. Do other animals have belly buttons?</h2>
<p>Because the navel is a scar from where the umbilical cord connected the fetus to the placenta, all placental mammals have them. That includes all mammals except <a href="https://www.britannica.com/animal/marsupial">marsupials</a> (like kangaroos and possums) and <a href="https://www.britannica.com/animal/monotreme">monotremes</a> (like platypuses and echidnas).</p>
<p>Your cat or dog or guinea pig does have a belly button, but because it’s a flatter scar than a person’s rather than a concave one, and is covered in fur, you might have missed it.</p>
<h2>6. Is there anything besides lint in there?</h2>
<p>Like any concave surface, if you have an innie, it probably gathers bits of debris occasionally. Your navel also has microbiota, just like the rest of your skin. Because it’s pretty protected from soap and abrasion, a more <a href="https://en.wikipedia.org/wiki/Skin_flora#Umbilical_microbiome">stable and diverse bacterial community</a> lives in your navel than elsewhere on your skin’s surface.</p>
<p>The innovative <a href="http://robdunnlab.com/projects/belly-button-biodiversity/">Belly Button Biodiversity project</a> at North Carolina State University has revealed a lot about these little friends. The researchers found <a href="https://doi.org/10.1371/journal.pone.0047712">over 2,000 species of bacteria</a> in the first 60 belly buttons they investigated.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1422846688276979715"}"></div></p>
<p>It looks like most people have a set of eight common belly button bacteria, but the project is discovering new ones all the time.</p>
<h2>7. Why do belly buttons gross out some people?</h2>
<p>There hasn’t really been much research into why some people find belly buttons to be repulsive.</p>
<p>It may overlap with <a href="https://healthresearchfunding.org/fear-bellybuttons/">omphalophobia</a>, the fear of belly buttons and touching them. There’s no specific treatment beyond the therapy or anti-anxiety medications a doctor might prescribe for any other phobia.</p>
<p>Whatever your feelings about belly buttons, they’re harmless. What’s more, they’re part of your evolutionary legacy as a mammal, the group of animals so invested in their offspring that they invented a way to deliver nutrients and oxygen, the mother’s bread and breath, straight into their developing young. Your navel can be a reminder of that first life-sustaining care you received from another person before you were even born.</p><img src="https://counter.theconversation.com/content/195162/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah Leupen 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>All mammals who get nutrients from their parent via a placenta before birth are left with a belly button. It’s a visual reminder of this original connection.Sarah Leupen, Principal Lecturer in Biological Sciences, University of Maryland, Baltimore CountyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2001992023-03-01T13:25:49Z2023-03-01T13:25:49ZBile acids and gut microbes could potentially treat multiple sclerosis, according to new research in mice<figure><img src="https://images.theconversation.com/files/512506/original/file-20230227-716-vd1jv0.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2309%2C1299&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Multiple sclerosis involves the immune system attacking the protective myelin sheath of neurons.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/neuron-tem-view-royalty-free-image/1204279188">koto_feja/iStock via Getty Images Plus</a></span></figcaption></figure><p><a href="https://www.mayoclinic.org/diseases-conditions/multiple-sclerosis/symptoms-causes/syc-20350269">Multiple sclerosis</a> is characterized by an immune system gone haywire. A patient’s immune system starts treating the protective coating of the nerves – called <a href="https://my.clevelandclinic.org/health/body/22974-myelin-sheath">myelin</a> – as dangerous. The subsequent nerve damage can cause a variety of symptoms, including muscle weakness, pain and vision loss. MS currently has no cure, and doctors still don’t completely understand what causes it.</p>
<p>While there is a genetic component to MS, <a href="http://doi.org/10.1101/cshperspect.a028944">environmental factors</a> also play a big role in determining whether someone will develop the disease. <a href="https://doi.org/10.1016/j.intimp.2020.107024">Recent evidence</a> suggests that what’s in your digestive tract may also be a meaningful contributor to disease risk. </p>
<p>My colleagues <a href="https://scholar.google.com/citations?user=X8XcETAAAAAJ&hl=en">and I</a> at the University of Virginia are working to understand the two-way communication between the human body and the bacteria that live in its digestive system. In our <a href="https://doi.org/10.1371/journal.pbio.3002000">recently published research</a>, we found that bile acid in the intestines could be harnessed to protect people at high risk of MS from developing the disease, offering a new avenue for drug development.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/512502/original/file-20230227-155-mhfk7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram comparing healthy nerve and nerve affected by multiple sclerosis" src="https://images.theconversation.com/files/512502/original/file-20230227-155-mhfk7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/512502/original/file-20230227-155-mhfk7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=356&fit=crop&dpr=1 600w, https://images.theconversation.com/files/512502/original/file-20230227-155-mhfk7f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=356&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/512502/original/file-20230227-155-mhfk7f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=356&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/512502/original/file-20230227-155-mhfk7f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=447&fit=crop&dpr=1 754w, https://images.theconversation.com/files/512502/original/file-20230227-155-mhfk7f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=447&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/512502/original/file-20230227-155-mhfk7f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=447&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Multiple sclerosis results when the immune system attacks the protective myelin sheath of neurons.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/multiple-sclerosis-royalty-free-illustration/530457339">ttsz/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<h2>The gut microbiome and autoimmunity</h2>
<p><a href="https://www.hsph.harvard.edu/nutritionsource/microbiome/">Trillions of bacteria</a> live in the human gut. They help the body with everything from digesting food to preventing the overgrowth of infectious and dangerous bacteria. They also <a href="https://www.youtube.com/watch?v=gnZEge78_78&t=151s">“educate” the immune system</a> to recognize what is dangerous and what is not. If this process is disturbed, the immune system may become overactive and start to treat natural parts of the body as dangerous. This is called autoimmunity.</p>
<p>Scientists believe that one way bacteria and the immune system communicate with each other is through the <a href="https://doi.org/10.1038/s41423-020-00585-5">aryl hydrocarbon receptor, or AHR</a>, which resides in most cells of the body. This protein acts like an emergency call center – when it encounters certain chemicals, it will identify the appropriate response and send a signal to the cell recommending what it should do.</p>
<p>While researchers have shown that <a href="https://doi.org/10.3390/ijms19123851">signals from AHR</a> influence multiple sclerosis development, how it does so is unclear. To better understand what AHR is doing specifically in the guts of patients with MS, we genetically engineered mice that are missing AHR in some of their immune cells. By silencing AHR’s activity, we could understand what role it may be playing in autoimmunity.</p>
<p>We expected to learn more from this experiment about the molecular communication of immune cells. Instead we found something surprising: The gut environment in these mice <a href="https://doi.org/10.1371/journal.pbio.3002000">had changed</a>. Specifically, the chemical composition of their guts had been altered, indicating that the metabolism of gut bacteria had shifted. This meant that AHR is not only sensing what’s going on in the gut, but the receptor is also actively shaping its environment.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/gnZEge78_78?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The gut contains the largest number of immune cells in the body.</span></figcaption>
</figure>
<p>More importantly, we found that mice without AHR were able to recover from MS. In our mouse model of MS, we induced autoimmunity by immunizing mice against myelin, the protective layer surrounding neurons. This meant that the immune system of the mice was primed to attack myelin, leading to the poor muscle control and paralysis seen in MS. We wanted to test whether the gut microbiome played a role in why mice without AHR were able to recover. When we transplanted the gut bacteria from the digestive tracts of mice without AHR into mice with AHR, we found that the mice with AHR were also able to recover from paralysis. This meant that the gut microbiome was driving recovery from MS.</p>
<p>We also found that the guts of mice without AHR had high levels of <a href="https://www.healthline.com/health/bile-salts">bile acids</a> – chemicals produced in the liver and secreted into the intestines that help with digestion. Bile acids are often broken down by the resident bacteria in the gut. </p>
<p>One bile acid in particular, called taurocholic acid, was especially concentrated in mice without AHR. To test whether taurocholic acid offered protection against MS, we fed this chemical to mice with AHR as they started to develop autoimmunity to myelin. While control mice that were fed saline became paralyzed from the waist down, the mice that were fed taurocholic acid just got a little wobbly before they recovered.</p>
<p>With further investigation, we discovered that these mice were able to recover their motor control because their immune cells were not as strong. Exposing their immune cells to bile acids shortened the life span of the cells, thus preventing them from causing as much damage to myelin and motor neurons.</p>
<p>While we still do not understand why bile acids weaken immune cells, we believe it may be a key step to understanding how to interrupt autoimmunity in MS and other autoimmune disorders.</p>
<h2>Better treatments for multiple sclerosis</h2>
<p>Current available therapies for autoimmune disorders like MS are <a href="https://www.nationalmssociety.org/Treating-MS/Medications">immunosuppressant drugs</a> that quiet the immune response. While these drugs can reduce relapse and delay disease progression, they can also put patients at high risk of infection and difficult side effects. With the <a href="https://www.nationalmssociety.org/coronavirus-covid-19-information">COVID-19 pandemic</a>, the danger of having a weakened immune system has become even more apparent. </p>
<p>Finding other avenues to quiet an overactive immune system, such as through bile acids, could help researchers create safer drugs that could help prevent or treat disease. The body produces eight different bile acids that each have different chemical properties. Our team is working to identify whether taurocholic acid is truly the best option for treating MS or if another bile acid – or a combination of several – would be more effective. </p>
<p>Bile acids are far from ready to be used as treatment in people. But we believe that the key to preventing multiple sclerosis may be inside us already.</p><img src="https://counter.theconversation.com/content/200199/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrea Merchak receives funding from National Institutes of Health grant R33 MH108156, National Institutes of Health grant T32 NS115657, The Owens Family Foundation, UVA Trans University Microbiome Initiative pilot grant.
</span></em></p>The gut microbiome plays a big role in mediating how the immune system responds to perceived threats, which include the body’s own nerves.Andrea Merchak, Ph.D. Candidate in Neuroscience, University of VirginiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2003382023-02-22T01:59:36Z2023-02-22T01:59:36ZThere could be alien life on Mars, but will our rovers be able to find it?<figure><img src="https://images.theconversation.com/files/511377/original/file-20230221-946-yjfk13.jpg?ixlib=rb-1.1.0&rect=0%2C187%2C4032%2C2158&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists think Mars rovers may have some blind spots when it comes to finding signs of life. </span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Robotic rovers are currently exploring the surface of Mars. Part of a rover’s mission is to survey the planet for signs of life. There might be nothing to find – but what if there is, and the rovers just can’t “see” it?</p>
<p>New research published today in <a href="https://doi.org/10.1038/s41467-023-36172-1">Nature Communications</a> suggests the rovers’ current equipment might not actually be up to the task of finding evidence of life. </p>
<p>As an extreme environment microbiologist, the challenges of searching for life where it seems near-impossible are familiar to me. </p>
<p>In astrobiology, we study the diversity of life in sites on Earth with environmental or physical features that resemble regions already described on Mars. We call these terrestrial environments “Mars analogue” sites.</p>
<h2>Limits of detection</h2>
<p>The new research, led by Armando Azua-Bustos at the Center for Astrobiology in Madrid, tested the sophisticated instruments currently in use by NASA’s Curiosity and Perseverance rovers – as well as some newer lab equipment planned for future analysis – in the Mars analogue of the Atacama Desert. </p>
<figure class="align-center ">
<img alt="A red, dusty, barren landscape, with a medium size rock formation. One scientist is climing the rock. Another is crouched at its base." src="https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511268/original/file-20230221-26-ixl70u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Scientists take samples from the Atacama Desert’s arid soil.</span>
<span class="attribution"><span class="source">Armando Azua-Bustos/Centro de Astrobiología</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Azua-Bustos and colleagues found the rovers’ testbed equipment – tools for analysing samples in the field – had limited ability to detect the traces of life we might expect to find on the red planet. They were able to detect the mineral components of the samples, but were not always able to detect organic molecules.</p>
<p>In my team’s case, our Mars analogue sites are the cold and hyper-arid deserts of the Dry Valleys and Windmill Islands in Antarctica.</p>
<p>In both of these sites, life exists despite extreme pressures. Finding evidence of life is challenging, given the harsh conditions and the scarcity of microbial life present. </p>
<p>First, we must define the biological and physical boundaries of life existing (and being detected) in analogue “extreme” environments. Then we need to develop tools to identify the “biosignatures” for life. These include organic molecules like lipids, nucleic acids and proteins. Finally, we determine how sensitive tools need to be to detect those biosignatures, on Earth and also Mars. This tells us the limits of our detection.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Y7eF-mjXkLU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Traces of life are scarce in the Atacama Desert.</span></figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/perseverance-the-mars-rover-searching-for-ancient-life-and-the-aussie-scientists-who-helped-build-it-141590">Perseverance: the Mars rover searching for ancient life, and the Aussie scientists who helped build it</a>
</strong>
</em>
</p>
<hr>
<h2>The search for a dark microbiome</h2>
<p>In my field of extreme microbiology, “microbial dark matter” is when the majority of microscopic organisms in a sample have not been isolated and/or characterised. To identify them, we require next-generation sequencing <strong>need to define</strong>. Azua-Bustos’s team go one step further, proposing a “dark microbiome” which contains potentially relic, extinct Earth species.</p>
<p>Azua-Bustos’s team found sophisticated laboratory techniques could detect a dark microbiome in the Atacama Desert’s Martian-like hyper-arid soil samples. However, the rovers’ current equipment wouldn’t be able to detect it on Mars. </p>
<p>In samples with such scarce biomass, we use highly sensitive laboratory methods to detect microbial life, including gene sequencing and visualising cells using microscopic analysis. Prototypes for genome sequencing in the field are being developed, but they do not have the sensitivity needed for low biomass samples – yet.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511372/original/file-20230221-26-9xc7jp.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">Professor Belinda Ferrari in Antarctica.</span>
<span class="attribution"><span class="source">Dr Eden Zhang</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/there-is-water-on-mars-but-what-does-this-mean-for-life-48310">There is water on Mars, but what does this mean for life?</a>
</strong>
</em>
</p>
<hr>
<h2>Different planet, different rules</h2>
<p>The search for life on other planets also relies on our understanding of what life would need to exist, with the <a href="https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.0020302">simplest list</a> being energy, carbon and liquid water. </p>
<p>On Earth, most organisms use photosynthesis to harness energy from sunlight. This process requires water, which is almost totally unavailable in dry desert environments like Antarctica and the Atacama Desert – and, most likely, Mars. We think a process we dubbed “atmospheric chemosynthesis” could be filling this gap.</p>
<p>My team first discovered atmospheric chemosynthesis in the cold desert soils of Antarctica. In this overlooked metabolic process, bacteria literally “<a href="https://www.nature.com/articles/nature25014">live on thin air</a>” by consuming trace levels of hydrogen and carbon monoxide gas from the atmosphere. </p>
<figure class="align-center ">
<img alt="A photo of the vast, barren Antarctic landscape. There is a cloudless blue sky, ice, ocean in the far distance, and a very tiny hut visible in the mid distance." src="https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=345&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=345&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=345&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=434&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=434&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511374/original/file-20230221-26-1zucql.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=434&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Antarctica is one of the few places on Earth with permafrost similar to areas on Mars.</span>
<span class="attribution"><span class="source">Dr Belinda Ferrari</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We think dry desert microbiomes may rely on this process for energy as well as water, which is a byproduct of the process. Ecosystems like the ones we’ve found in Antarctica now offer one of the most <a href="https://www.liebertpub.com/doi/full/10.1089/ast.2021.0066">promising ecological models</a> in the search for Martian life. </p>
<p>We now believe there is potential for life in the ice-cemented subsurface of Mars. My team – alongside collaborators at NASA and the University of Pretoria – <a href="https://www.liebertpub.com/doi/full/10.1089/ast.2021.0066">plan to investigate</a> this in Antarctica’s University Valley, by defining the environmental limits to energy, metabolic water and carbon production via trace gas consumption. </p>
<figure class="align-center ">
<img alt="A human in a red coat looks tiny, crouching in front of enormous reddish rock formations that have ice in between." src="https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/511563/original/file-20230222-20-sivq4n.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">University Valley has a layer of dry permafrost soil overlaying ice-rich permanently frozen ground. Some Martian environments have similar features.</span>
<span class="attribution"><span class="source">Jackie Goordial/McGill University</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/discovery-of-microbe-rich-groundwater-in-antarctica-guides-search-for-life-in-space-40931">Discovery of microbe-rich groundwater in Antarctica guides search for life in space</a>
</strong>
</em>
</p>
<hr>
<h2>We won’t find what we can’t define</h2>
<p>Our new knowledge of target biosignatures and the level of sensitivity needed to detect them will be critical when designing or optimising future instrumentation to be deployed on missions aimed at finding life. </p>
<p>The goal of future missions to Mars, including the <a href="https://www.researchgate.net/publication/236125178_The_Icebreaker_Life_Mission_to_Mars_A_Search_for_Biomolecular_Evidence_for_Life">Icebreaker Life</a> mission planned for 2026, is to search for evidence of life. The Icebreaker Life will sample ice-cemented ground, similar to Antarctic dry permafrost, and if it detects signs of life, a Mars Sample Return mission would be a high priority.</p>
<p>Returning samples to Earth for laboratory analysis is risky. As we found with our Antarctic soil samples, challenges can include contamination, preservation of cold temperatures during transport, and the need for specialist quarantine laboratories, to analyse samples without destroying them. </p>
<p>But as Asua-Bustos suggests, bringing samples to Earth for detailed lab analyses may be the only sure way to detect – or rule out – the presence (or past presence) of life.</p><img src="https://counter.theconversation.com/content/200338/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Belinda Ferrari receives funding from the Australian Research Council. While not directly related to this article her previous funding has led to new research questions on the habitability of Mars.</span></em></p>Our Mars rovers might not be sensitive enough to detect signs of life. But lessons from Antarctica might make future missions more successful.Belinda Ferrari, Professor of Microbiology, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1958102023-01-31T13:16:07Z2023-01-31T13:16:07ZMicrobes in your food can help or hinder your body’s defenses against cancer – how diet influences the conflict between cell ‘cooperators’ and ‘cheaters’<figure><img src="https://images.theconversation.com/files/506674/original/file-20230126-31491-80kf4u.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1731%2C1731&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">You can change your gut microbiome composition by eating different foods.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/bacteria-and-germs-on-food-royalty-free-image/596371624">wildpixel/iStock via Getty Images</a></span></figcaption></figure><p>The microbes living in your food can affect your risk of cancer. While some help your body fight cancer, others help tumors evolve and grow. </p>
<p>Gut microbes can influence your cancer risk by changing how your cells behave. Many cancer-protective microbes support normal, cooperative behavior of cells. Meanwhile, cancer-inducing microbes undermine cellular cooperation and increase your risk of cancer in the process. </p>
<p>We are <a href="https://scholar.google.com/citations?user=8abR970AAAAJ&hl=en">evolutionary</a> <a href="https://search.asu.edu/profile/2854856">biologists</a> who study how cooperation and conflict occur inside the human body, including the ways cancer can evolve to exploit the body. Our <a href="https://doi.org/10.1007/s13668-022-00420-5">systematic review</a> examines how diet and the microbiome affect the ways the cells in your body interact with each other and either increase or decrease your risk of cancer.</p>
<h2>Cancer is a breakdown of cell cooperation</h2>
<p>Every human body is a symphony of multicellular cooperation. <a href="https://www.scientificamerican.com/article/our-bodies-replace-billions-of-cells-every-day/">Thirty trillion cells</a> cooperate and coordinate with each other to make us viable multicellular organisms. </p>
<p>For multicellular cooperation to work, cells must engage in behaviors that <a href="https://doi.org/10.1111/eva.12303">serve the collective</a>. These include controlled cell division, proper cell death, resource sharing, division of labor and protection of the extracellular environment. Multicellular cooperation is what allows the body to function effectively. If genetic mutations interfere with these proper behaviors, they can lead to the breakdown of cellular cooperation and the emergence of cancer.</p>
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<figcaption><span class="caption">The food in your diet affects the composition of your gut microbiome.</span></figcaption>
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<p>Cancer cells can be thought of as <a href="https://press.princeton.edu/books/hardcover/9780691163840/the-cheating-cell">cellular cheaters</a> because they do not follow the rules of cooperative behavior. They mutate uncontrollably, evade cell death and take up excessive resources at the expense of the other cells. As these cheater cells replicate, cancer in the body begins to grow.</p>
<p>Cancer is fundamentally a problem of having multiple cells living together in one organism. As such, it has been around <a href="http://dx.doi.org/10.1098/rstb.2014.0219">since the origins of multicellular life</a>. This means that cancer suppression mechanisms have been evolving for hundreds of millions of years to help keep would-be cancer cells in check. Cells monitor themselves for mutations and induce cell death, also known as apoptosis, when necessary. Cells also monitor their neighbors for evidence of abnormal behavior, sending signals to aberrant cells to induce apoptosis. In addition, the body’s immune system monitors tissues for cancer cells to destroy them.</p>
<p>Cells that are able to evade detection, avoid apoptosis and replicate quickly have an evolutionary advantage within the body over cells that behave normally. This process within the body, called <a href="https://doi.org/10.1371/journal.pcbi.0020108">somatic evolution</a>, is what leads cancer cells to grow and make people sick.</p>
<h2>Microbes can help or hinder cell cooperation</h2>
<p>Microbes can affect cancer risk through changing the ways that the cells of the body interact with one another. </p>
<p>Some microbes can <a href="https://doi.org/10.1007/s13668-019-0257-2">protect against cancer</a> by helping maintain a healthy environment in the gut, reducing inflammation and DNA damage, and even by directly limiting tumor growth. Cancer-protective microbes like <em>Lactobacillus pentosus</em>, <em>Lactobacillus gasseri</em> and <em>Bifidobacterium bifidum</em> are found in the environment and different foods, and can live in the gut. These microbes <a href="https://doi.org/10.1007/s13668-022-00420-5">promote cooperation among cells</a> and limit the function of cheating cells by strengthening the body’s cancer defenses. <em>Lactobacillus acidophilus</em>, for example, increases the <a href="https://doi.org/10.1017/s0007114510000516">production of a protein called IL-12</a> that stimulates immune cells to act against tumors and suppress their growth.</p>
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<figcaption><span class="caption">Gut bacteria can influence the effectiveness of certain cancer treatments.</span></figcaption>
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<p>Other microbes can promote cancer by inducing mutations in healthy cells that make it more likely for cellular cheaters to emerge and outcompete cooperative cells. <a href="https://doi.org/10.1002/path.5047">Cancer-inducing microbes</a> such as <em>Enterococcus faecalis</em>, <em>Helicobacter pylori</em> and <em>Papillomavirus</em> are associated with increased tumor burden and cancer progression. They can release toxins that damage DNA, change gene expression and <a href="https://doi.org/10.1007/s13668-019-0257-2">increase the proliferation</a> of tumor cells. <a href="https://doi.org/10.1002/ijc.23484"><em>Helicobacter pylori</em></a>, for example, can induce cancer by secreting a protein called Tipα that can penetrate cells, alter their gene expression and drive gastric cancer.</p>
<h2>Healthy diet with cancer-protective microbes</h2>
<p>Because what you eat determines the amount of cancer-inducing and cancer-preventing microbes inside your body, we believe that the microbes we consume and cultivate are an important component of <a href="https://doi.org/10.1007/s13668-022-00420-5">a healthy diet</a>.</p>
<p>Beneficial microbes are typically found in <a href="https://doi.org/10.1002/ijc.31959">fermented</a> and plant-based diets, which include foods like vegetables, fruits, yogurt and whole grains. These foods have high nutritional value and contain microbes that increase the immune system’s ability to fight cancer and lower overall inflammation. <a href="https://doi.org/10.1093%2Fcdn%2Fnzy005">High-fiber foods are prebiotic</a> in the sense that they provide resources that help beneficial microbes thrive and subsequently provide benefits for their hosts. Many cancer-fighting microbes are abundantly present in fermented and high-fiber foods. </p>
<p>In contrast, harmful microbes can be found in highly-processed and meat-based diets. The Western diet, for example, contains an abundance of red and processed meats, fried food and high-sugar foods. It has been long known that meat-based diets are linked to higher cancer prevalence, and that red meat is a <a href="https://doi.org/10.2533/chimia.2018.718">carcinogen</a>. Studies have shown that meat-based diets are associated with cancer-inducing microbes including <a href="https://doi.org/10.1007/s13668-022-00420-5"><em>Fusobacteria</em> and <em>Peptostreptococcus</em></a> in both humans and other species.</p>
<p>Microbes can enhance or interfere with how the body’s cells cooperate to prevent cancer. We believe that purposefully cultivating a microbiome that promotes cooperation among our cells can help reduce cancer risk.</p><img src="https://counter.theconversation.com/content/195810/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gissel Viridiana Marquez Alcaraz receives funding from the National Cancer Institute. </span></em></p><p class="fine-print"><em><span>Athena Aktipis receives funding from the National Cancer Institute and the John Templeton Foundation.</span></em></p>Cancer cells are ‘cheaters’ that do not cooperate with the rest of the body. Certain microbes in your diet can either protect against or promote tumor formation by influencing cell cooperation.Gissel Marquez Alcaraz, Ph.D. Student in Evolutionary Biology, Arizona State UniversityAthena Aktipis, Associate Professor of Psychology, Center for Evolution and Medicine, Arizona State UniversityLicensed as Creative Commons – attribution, no derivatives.