tag:theconversation.com,2011:/africa/topics/gut-microbes-23988/articlesGut microbes – The Conversation2024-02-21T13:04:38Ztag:theconversation.com,2011:article/2232242024-02-21T13:04:38Z2024-02-21T13:04:38ZGut bacteria may explain why grey squirrels outcompete reds – new research<p>Across large parts of the UK, the native red squirrel has been replaced by the grey squirrel, a North American species. As well as endangering reds, grey squirrels pose a threat to our woodlands because of the damage they cause to trees. </p>
<p><a href="https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.001793">New research</a> from my colleagues and I compared the gut bacteria of red and grey squirrels. We found that differences between the two may explain their competition and red squirrel decline, as well as why grey squirrels are so destructive to woodland.</p>
<p>Grey squirrels were introduced to the UK between 1876 and 1929 and have displaced reds in most areas of the UK. Greys carry a virus called “squirrelpox”, which doesn’t affect them but leads to sickness and often death in red squirrels.</p>
<p>Grey squirrels are bigger than red squirrels and compete with them <a href="https://www.frontiersin.org/articles/10.3389/fevo.2023.1083008/full">for food and habitat</a>.
Acorns, a widespread food source, contain tannins, which are hard for red squirrels to digest. But greys can digest acorns easily, giving them an extra edge in competing for resources. </p>
<p>Grey squirrels frequently strip the bark from deciduous trees. In commercial plantations, the damage can lead to fungal infection and result in the tree producing low quality timber. The annual cost is an <a href="https://rfs.org.uk/insights-publications/rfs-reports/report-overview-the-cost-of-grey-squirrel-damage-to-woodland-in-england-and-wales/">estimated £37 million.</a> with sycamore, oak, birch and beech frequently targeted. </p>
<p>The grey squirrels select the strongest growing trees as these have bark containing the largest volume of sap. Intriguingly, grey squirrels do not select trees with the <a href="https://www.researchgate.net/publication/230344319_Bark-stripping_by_Grey_squirrels_Sciurus_carolinensis">highest sugar content</a>. This observation has led scientists to posit that the squirrels consume bark to obtain <a href="https://www.sciencedirect.com/science/article/pii/S0378112716300421?via%3Dihub">certain micro-nutrients</a>. </p>
<h2>Gut bacteria</h2>
<p>All mammals have microorganisms living in their intestines. For example, the typical human colon is host to at least <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5847071/">160 bacterial species</a>, while in birds, research has found thousands of different bacterial species in <a href="https://pubmed.ncbi.nlm.nih.gov/33868800/">chicken intestines.</a></p>
<p>The bacteria break down foods and help synthesise vitamins, complementing the enzymes secreted by the body. The diversity of these microorganisms, known as the “microbiota”, can reflect the level of health and also the diet of an individual. But we don’t know enough about the microbiota living in squirrel intestines. </p>
<p>The types of microbes present vary between species, yet the extent to which they differ between grey and red squirrels is unclear. We explored this and investigated the potential for any differences to affect competition between the two squirrel species. We also examined whether gut bacteria might be playing a role in bark stripping behaviour.</p>
<p>We sampled bacterial DNA from red and grey squirrel intestinal contents and performed gene sequencing to identify the range of bacteria present in the samples. The results were analysed to compare any important differences between the two.</p>
<figure class="align-center ">
<img alt="A cute red squirrels with a large bushy tail stands on the branch of a tree." src="https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=430&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=430&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=430&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=541&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=541&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576545/original/file-20240219-20-ivfdqj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=541&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">Ynys Môn off the north Wales coast is one of the few places in the UK where greys have been eradicated in favour of red squirrels.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/red-squirrel-views-around-north-wales-2232607907">Gail Johnson/Shutterstock</a></span>
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<h2>Calcium</h2>
<p>Calcium is an important nutrient in the body and is required for healthy bones, muscles and nerves. It is especially needed by lactating animals and ones that are young and growing.</p>
<p>We found that grey squirrels may have the capacity to obtain the calcium that exists in tree bark thanks to the presence of a bacteria called “oxalobacter” in their gut. The calcium in tree bark comes in an insoluble form and is hard for an animal to digest. But oxalobacter would be able to change this into a form that could be more digestible. </p>
<p>Calcium levels <a href="https://www.sciencedirect.com/science/article/pii/S0378112716300421?via%3Dihub">increase in trees</a> as active growth resumes after winter dormancy. This happens immediately before the main squirrel bark-stripping season of May to July. Our research may therefore help to explain the destructive behaviour of grey squirrels and why red squirrels appear to strip bark much less frequently.</p>
<p>Our research also identified a significantly higher diversity of bacteria in the intestines of grey squirrels compared to red squirrels. This could hold the key to further understanding why grey squirrels outcompete red squirrels in the UK. </p>
<p>A more diverse range of bacteria being sustained in the gut means that grey squirrels potentially may be able to access a broader range of resources than red squirrels in addition to acorns.</p>
<h2>Adenovirus</h2>
<p>The grey squirrel harbours not just the squirrelpox virus, but also another potential threat – adenovirus. While this virus causes severe intestinal lesions in some red squirrels, curiously, grey squirrels never exhibit the same symptoms.</p>
<p>This discrepancy underscores the fascinating and complex potential role of gut microbiota. Research increasingly reveals their influence on everything from digestion to immune response, and even susceptibility to disease.</p>
<p>In the context of red squirrels, understanding how variations in their gut bacteria might predispose them to adenovirus becomes crucial. This is especially pertinent for captive breeding programs, where adenovirus infections pose a hurdle to successful reintroductions of red squirrels into the wild.</p>
<p>Given we only sampled red and grey squirrels from north Wales, we hope that future studies will map the gut microbiota of other European populations too. Such future research will continue to improve our knowledge of the competition between red and grey squirrels.</p><img src="https://counter.theconversation.com/content/223224/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Craig Shuttleworth 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>New research suggests the gut bacteria of red and grey squirrels differ significantly, potentially explaining the decline of the native red and the success of its grey counterpart.Craig Shuttleworth, Honorary Visiting Research Fellow, Bangor UniversityLicensed 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>
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Read more:
<a href="https://theconversation.com/was-going-to-space-a-good-idea-218235">Was going to space a good idea?</a>
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<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>
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<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>
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<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>
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<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>
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<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>
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<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>
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</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>
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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/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/2060452023-07-05T12:23:01Z2023-07-05T12:23:01Z‘E. coli’ is one of the most widely studied organisms – and that may be a problem for both science and medicine<figure><img src="https://images.theconversation.com/files/534368/original/file-20230627-19-w2lrsx.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2133%2C1404&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">_E. coli_ as a model organism helped researchers better understand how DNA works.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/researcher-with-e-coli-bacteria-royalty-free-image/521677434">Ed Horowitz Photography/The Image Bank via Getty Images</a></span></figcaption></figure><p>In 1857, a young pediatrician named <a href="https://doi.org/10.1038/nrmicro1810">Theodor Escherich</a> discovered what may very well be the most well-studied organism today. The rod-shaped bacterium named <em>Escherichia coli</em>, better known as <em>E. coli</em>, is a very common microbe residing in your gut. It’s also the workhorse of early molecular biology.</p>
<p>Luck likely played a role in its rise in popularity among scientists. Even under 19th-century lab conditions, where sterilization techniques were not perfect and little was known about what food bacteria need to survive, this microbe was easy to cultivate and grow quickly. It can <a href="https://doi.org/10.1098/rspb.2018.0789">replicate in under 20 minutes</a> and can use a variety of <a href="https://doi.org/10.1186/s12918-014-0133-z">carbon sources for energy</a>. </p>
<p>As the first species to have its <a href="https://doi.org/10.1128/jb.29.2.205-213.1935">physiology thoroughly explored</a>, <em>E. coli</em> has contributed fundamental knowledge to the fields of microbiology, molecular genetics and biochemistry, including how DNA replicates, how genes create proteins and how bacteria share genetic material among themselves – a huge <a href="https://theconversation.com/antibiotic-resistance-is-at-a-crisis-point-government-support-for-academia-and-big-pharma-to-find-new-drugs-could-help-defeat-superbugs-169443">cause of antibiotic resistance</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram of E. coli structure" src="https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=365&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=365&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=365&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=458&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=458&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534417/original/file-20230627-17-qy37yx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=458&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>E. coli</em> is a rod-shaped bacterium with flagella that help it move.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/coli-bacteria-micro-biological-vector-royalty-free-illustration/957344970">VectorMine/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>However, the favored use of <em>E. coli</em> in the lab has also <a href="https://doi.org/10.1529/biophysj.107.104398">led to oversimplifications</a> in the world of microbiology, distracting researchers from the thousands of other bacterial species that <a href="https://doi.org/10.1073/pnas.1707009114">remain understudied</a>. </p>
<p>As <a href="https://doerr.wicmb.cornell.edu/current-lab-members/">microbiologists</a> <a href="https://scholar.google.com/citations?user=yYroRg8AAAAJ&hl=en">studying the</a> inner mechanisms of <a href="https://theconversation.com/looming-behind-antibiotic-resistance-is-another-bacterial-threat-antibiotic-tolerance-200226">antibiotic tolerance</a>, we and colleagues in <a href="https://doerr.wicmb.cornell.edu/">our lab</a> examine bacterial species that physiologically differ from <em>E. coli</em> in hopes of expanding the existing pool of knowledge within microbiology. For instance, drugs like penicillin fall into a class of antibiotics that target the outer defenses of the bacteria. We found that while <em>E. coli</em> succumbs to this attack, species like <em>Vibrio</em> or <em>Klebsiella</em> can <a href="https://theconversation.com/looming-behind-antibiotic-resistance-is-another-bacterial-threat-antibiotic-tolerance-200226">tolerate it and survive</a>. </p>
<p>A one-size-fits-all approach may have worked in the past, but embracing the true diversity of microbes could help scientists better fight the rise of antibiotic resistance.</p>
<h2>Scientific good of <em>E. coli</em></h2>
<p>Researchers worked out the very foundations of life using <em>E. coli</em>. The significance of this bacterium for the field of biology is probably best captured by the biochemist <a href="https://www.nobelprize.org/prizes/medicine/1965/monod/facts/">Jacques Monod</a>, who famously said, “What is true for <em>E. coli</em> is true for the elephant.” </p>
<p>Because researchers were able to watch regions of <a href="https://doi.org/10.1038/158558a0"><em>E. coli</em>‘s DNA become mobile</a>, allowing bacteria to transfer DNA among one another in a process called conjugation, scientists learned to manipulate this process to genetically alter organisms and study the effects of different genes. </p>
<p><em>E. coli</em> helped reveal that <a href="https://doi.org/10.1101/SQB.1963.028.01.011">bacterial chromosomes are circular</a> and that <a href="https://doi.org/10.1016/S0022-2836(59)80045-0">manipulating a specific enzyme</a> can allow scientists to easily clone parts of the bacterial genome. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of E. coli, colored orange" src="https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=516&fit=crop&dpr=1 600w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=516&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=516&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=648&fit=crop&dpr=1 754w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=648&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/534393/original/file-20230627-27-wdxgtr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=648&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">While <em>E. coli</em> are common residents in your gut, certain strains can cause serious infections.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/coli-sem-royalty-free-image/1414386430">Steve Gschmeissner/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<p><em>E. coli</em> also opened doors to using a type of <a href="https://theconversation.com/viruses-are-both-the-villains-and-heroes-of-life-as-we-know-it-169131">bacterial viruses called phages</a> as an <a href="https://doi.org/10.1085/jgp.22.3.365">alternative to antibiotics</a>. </p>
<p>Widely available knowledge about and methods to study <em>E. coli</em> led to its prominence in academic and commercial research and drug production. In 2015, <a href="https://doi.org/10.4014/jmb.1412.12079">nearly 30% of proteins used as treatments</a> for a wide range of diseases like hepatitis C and multiple sclerosis were derived from <em>E. coli</em>.</p>
<h2>Model organism drawbacks</h2>
<p><em>E. coli</em>’s track record has solidified its place in the lab as a <a href="https://doi.org/10.1007/978-1-4419-9863-7_76">model organism</a>. Model organisms are nonhuman species researchers use to study biology, with the expectation that the findings can be applied to other species like humans. Species are often chosen for their ease of maintenance, quick life cycles and overall cost-effectiveness. </p>
<p>However, model organisms have their drawbacks. Some researchers have argued that drawing parallels across species can <a href="https://theconversation.com/expanding-alzheimers-research-with-primates-could-overcome-the-problem-with-treatments-that-show-promise-in-mice-but-dont-help-humans-188207">sometimes fall short</a>, leading to assumptions about more complex species that may not be true.</p>
<p>Additionally, study findings using nonmodel organisms are often less visible in the broader scientific community, since many researchers focus on organisms with known and defined traits. This bias results in a shadow space where progress is not immediately incorporated into broader scientific knowledge, which can slow down research that actually covers a range from bacteria to elephants.</p>
<h2>ESKAPE pathogens don’t include <em>E. coli</em></h2>
<p>Model organisms are not perfect, and <em>E. coli</em> may not be an effective species to use to study many human bacterial infections. Focusing research on this microbe limits the exploration of how other bacteria infiltrate and infect human hosts. While some <a href="https://doi.org/10.1038/nrmicro818">strains of <em>E. coli</em> can be deadly</a>, they are not the only worrisome pathogens today. </p>
<p><a href="https://doi.org/10.1128/cmr.00181-19">ESKAPE pathogens</a>, a group of bacteria that are highly resistant to antibiotics, pose a massive global health threat because they can quickly evolve traits that allow them to evade immune systems and available treatments. Species within ESKAPE, such as <em>Klebsiella pneumoniae</em> and <em>E. cloacae</em>, are able to resist multiple drugs and <a href="https://doi.org/10.1128/aac.00756-19">exhibit physical characteristics</a> that <em>E. coli</em> does not, such as the ability to remove their cell wall and evade certain drugs.</p>
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<figcaption><span class="caption">Antibiotic-resistant bacteria are a major global health threat.</span></figcaption>
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<p>Our lab is studying the unique traits that allow ESKAPE pathogens to survive antibiotics – traits we would not have known about if we used only <em>E. coli</em> as a model organism in our research.</p>
<p>With the many basics of fundamental bacterial cell and molecular biology covered thanks to <em>E. coli</em>, it may be time for researchers to turn toward the new pathogens wreaking havoc on society. Model organisms are wondrous tools, but they have limited power to allow findings to be extrapolated to other organisms. Better understanding the underpinnings of bacterial infections and antibiotics for a given disease requires studying the specific organism.</p><img src="https://counter.theconversation.com/content/206045/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Megan Keller receives funding from National Science Foundation. </span></em></p><p class="fine-print"><em><span>Tobias Dörr receives funding from National Institutes of Health. </span></em></p>Researchers uncovered the foundations of biology by using E. coli as a model organism. But over-reliance on this microbe can lead to knowledge blind spots with implications for antibiotic resistance.Megan Keller, Ph.D. Candidate in Microbiology, Cornell UniversityTobias Dörr, Associate Professor of Microbiology, Cornell 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/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>
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<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>
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<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>
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<figcaption><span class="caption">The gut contains the largest number of immune cells in the body.</span></figcaption>
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<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/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>
</figure>
<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.tag:theconversation.com,2011:article/1951322022-12-29T11:29:07Z2022-12-29T11:29:07ZCOVID and your gut: how a healthy microbiome can reduce the severity of infection – and vice versa<figure><img src="https://images.theconversation.com/files/499773/original/file-20221208-26-7plsqe.jpg?ixlib=rb-1.1.0&rect=0%2C17%2C5991%2C3970&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/man-holding-decorative-model-intestine-healthy-1984197083">Helena Nechaeva/Shutterstock</a></span></figcaption></figure><p>A vast combination of microorganisms live in our gut, including bacteria, fungi and viruses. Collectively, we refer to this as the <a href="https://ep.bmj.com/content/102/5/257">the microbiome</a>. </p>
<p>Despite their tiny size, these microbes have significant effects on our health and wellbeing. In fact, the microbiome is often referred to as the “second brain” due to the extensive relationship it has with the body’s organs and systems. </p>
<p>One role in particular the microbes in our gut play is supporting <a href="https://www.nature.com/articles/s41422-020-0332-7">immune function</a>. They help to control local and systemic inflammation, the process by which the immune system protects us from harmful pathogens.</p>
<p>So it’s not entirely surprising that <a href="https://www.spandidos-publications.com/10.3892/etm.2021.10942">research has shown</a> the make-up of bacteria in the gut may influence the severity of a COVID infection. At the same time, evidence is beginning to suggest a COVID infection could <a href="https://www.nature.com/articles/s41467-022-33395-6">affect the balance</a> of bacteria in the gut, which might go some way to explaining why some people have persistent symptoms after a COVID infection.</p>
<p>The microbes in our gut provide essential signals for our immune responses across the body, including in the lungs. A “healthy” gut microbiome comprises a broad range of bacteria, though is not identical in every person. Studies have previously shown that a <a href="https://www.gastrojournal.org/article/S0016-5085(20)35508-6/fulltext">healthy gut microbiome</a> can improve the immune response to respiratory infections by regulating immune cells and messages.</p>
<p>On the flip side, evidence shows a poorer composition of gut bacteria increases susceptibility to <a href="https://www.tandfonline.com/doi/abs/10.4161/gmic.21288">influenza infections in the lungs</a>, and leads to reduced <a href="https://journals.aai.org/jimmunol/article/188/3/1411/86536/Transient-TLR-Activation-Restores-Inflammatory">clearance of germs</a> from the lungs in mice. </p>
<p>With COVID, it similarly appears that the make-up of the gut microbiome can influence the course of disease. Research has shown <a href="https://gut.bmj.com/content/70/4/698?fbclid=IwAR3xoYiPLesEADHzgSynOiDEoq271zUtjFedRyHDBl1xAwfYq6xVn3C08kY">an association</a> between the microbiome profile and levels of inflammatory markers in patients with COVID, where patients with a poorer combination of gut bacteria show signs of too much inflammation. This suggests the microbiome influences the severity of a COVID infection via effects on the immune response.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/gut-bacteria-could-help-protect-against-covid-and-even-lead-to-a-new-drug-new-research-175173">Gut bacteria could help protect against COVID and even lead to a new drug – new research</a>
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<h2>Unbalancing the microbiome</h2>
<p>Just as the composition of our gut bacteria appears to influence how we fare with COVID, the reverse might also be true – a COVID infection could affect the make up of our gut bacteria. Specifically, it seems COVID might throw off the balance between “good” and “bad” microbes in a person’s microbiome.</p>
<p>Studies have shown a significant difference in the gut microbiome between <a href="https://gut.bmj.com/content/70/2/276.abstract">COVID patients</a> and healthy people. We see a reduction in <a href="https://www.nature.com/articles/s41467-022-33395-6">bacterial diversity</a> in the gut in COVID patients – so a smaller range of species, as well as substantial differences in the species of bacteria present.</p>
<p>Notably, scientists have observed a reduction in a group known as <a href="https://gut.bmj.com/content/70/4/698">commensal bacteria</a> in COVID patients, which act on the immune system to help prevent invasion by pathogens. This may increase our risk of other infections after COVID. Simultaneously, there appears to be an increase in a variety of opportunistic pathogenic bacteria that are known to cause infections. </p>
<p>This “imbalance” is called dysbiosis, and these changes have been shown to still be present in patients <a href="https://gut.bmj.com/content/70/4/698">30 days post-infection</a>.</p>
<figure class="align-center ">
<img alt="An illustration of the bacteria Peptococcus, part of the human microbiome." src="https://images.theconversation.com/files/499775/original/file-20221208-7231-60amw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/499775/original/file-20221208-7231-60amw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/499775/original/file-20221208-7231-60amw4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/499775/original/file-20221208-7231-60amw4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/499775/original/file-20221208-7231-60amw4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/499775/original/file-20221208-7231-60amw4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/499775/original/file-20221208-7231-60amw4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&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">Our gut bacteria can affect COVID outcomes – and vice versa.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/bacteria-peptococcus-anaerobic-grampositive-cocci-they-1008020533">Kateryna Kon/Shutterstock</a></span>
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<p>Recent studies have suggested gut dysbiosis is linked to the movement of gut bacteria <a href="https://www.nature.com/articles/s41467-022-33395-6">into the blood</a> during a COVID infection. In mice, COVID caused changes in a variety of parameters associated with gut barrier permeability, meaning things can theoretically move more easily through the gut wall.</p>
<p>In 20% of human COVID patients in this same study, certain bacteria from the gut had migrated into the bloodstream. This group was at higher risk of developing a secondary infection in the blood.</p>
<p>Research is now also showing that dysbiosis following COVID may contribute to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8435248/">long COVID</a>, with gut dysbiosis more prevalent in patients presenting with <a href="https://onlinelibrary.wiley.com/doi/10.1002/jmv.27684">long-term COVID symptoms</a>. This makes sense because dysbiosis seems to put the body in a heightened and constant state <a href="https://gut.bmj.com/content/70/4/698">of inflammation</a> – something that’s associated with chronic COVID symptoms. </p>
<h2>Supporting your immunity</h2>
<p>As we continue to develop a more comprehensive understanding of gut microbes and their role in inflammation, how can you help keep your immune system healthy to protect yourself against COVID and other infections?</p>
<p>Certain nutrients, <a href="https://onlinelibrary.wiley.com/doi/full/10.1002/jmv.25707">including</a> vitamins A, C, D and E as well as iron, zinc and omega-3 fatty acids, all have positive effects on immune responses against viral infection.</p>
<p>A <a href="https://www.mdpi.com/1422-0067/19/12/3720">Mediterranean diet</a>, which is rich in vitamins, minerals and dietary fibre, has an anti-inflammatory effect in the gut. Interestingly, a strain of bacteria known as <em>Faecalibacterium prausnitzii</em> <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7359750/">is key to immune regulation</a>. It’s frequently low in the western diet, but abundant in the Mediterranean diet.</p>
<p>Ideally you should avoid too many refined cereals, sugars and animal fats, which can all <a href="https://www.nature.com/articles/nm.3444">heighten inflammation</a> in the body.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/coronavirus-how-to-keep-your-gut-microbiome-healthy-to-fight-covid-19-134158">Coronavirus: how to keep your gut microbiome healthy to fight COVID-19</a>
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<p>Probiotics, supplementary blends of live bacteria, may also have benefits. A blend of bacterial strains <em>Lactiplantibacillus plantarum</em> and <em>Pediococcus acidilactici</em> <a href="https://www.tandfonline.com/doi/abs/10.1080/19490976.2021.2018899">was shown to reduce</a> the quantity of virus detected in the nasal passage and lungs, as well as the duration of symptoms in COVID patients. </p>
<p>This combination also significantly increased the <a href="https://www.tandfonline.com/doi/abs/10.1080/19490976.2021.2018899">production of COVID-specific antibodies</a>, suggesting probiotics act directly by interacting with the immune system, rather than solely changing the composition of the gut microbiome.</p>
<p>Finally, moderate <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7387807/">exercise</a> can also help support the immune system to fight COVID.</p><img src="https://counter.theconversation.com/content/195132/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Philippe B. Wilson is Chief Scientific Officer of NHS Willows Health.</span></em></p><p class="fine-print"><em><span>Samuel J. White 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 microbes in our gut have many roles, including to support immune function.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/1930122022-11-29T02:03:17Z2022-11-29T02:03:17ZWhat did pregnancy do to my gut? From nausea to constipation and farting<figure><img src="https://images.theconversation.com/files/492934/original/file-20221102-23-ut9jtz.jpg?ixlib=rb-1.1.0&rect=1%2C0%2C997%2C666&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/pregnant-woman-nude-belly-holding-toilet-1867480576">Shutterstock</a></span></figcaption></figure><p>It’s two weeks after the birth of your healthy bub and you notice your gut isn’t feeling quite right. Maybe you feel a bit bloated. Maybe you’re farting more than usual.</p>
<p>What’s going on?</p>
<p>Pregnancy changes the structure and function of virtually every organ system, including some big changes to the gut. These changes can explain some common symptoms.</p>
<p>And no, you’re not imagining it. Some gut symptoms, such as constipation and gassiness, can hang around after you’ve given birth.</p>
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Read more:
<a href="https://theconversation.com/health-check-what-causes-bloating-and-gassiness-107605">Health Check: what causes bloating and gassiness?</a>
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<h2>Nausea is common</h2>
<p>The <a href="https://www.health.gov.au/resources/pregnancy-care-guidelines/part-i-common-conditions-during-pregnancy/nausea-and-vomiting">most common</a> gut symptom in pregnancy is nausea, which affects up to <a href="https://pubmed.ncbi.nlm.nih.gov/30786126/">85% of women</a> in the first trimester. </p>
<p>This is thought to be largely due to the effects of the hormone <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3676933">human chorionic gonadotropin</a>.</p>
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<p>Levels of the hormone are highest at the end of the first trimester and start to level off for the rest of the pregnancy. That explains why nausea tends to become less common <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3676933">as your pregnancy progresses</a>.</p>
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Read more:
<a href="https://theconversation.com/health-check-what-can-you-eat-to-help-ease-morning-sickness-in-pregnancy-55039">Health Check: what can you eat to help ease 'morning' sickness in pregnancy?</a>
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<h2>Reflux can be painful</h2>
<p>Other hormonal changes can lead you to develop another common symptom, <a href="https://pubmed.ncbi.nlm.nih.gov/17662101">reflux</a>.</p>
<p>Levels of the hormone progesterone, for instance, steadily rise over the course of a pregnancy. This can lead to the oesophageal sphincter muscle – which is at the lower end of your food pipe, before it meets the stomach – to become more lax.</p>
<p>The loosening of this muscle makes it easier for stomach acid to move back up into the food pipe. This can cause a painful burning sensation in the upper part of your abdomen or just behind the breastbone.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1587582167294492674"}"></div></p>
<p>Later in the pregnancy, your growing uterus and baby can start to really push up on your stomach. </p>
<p>This can also lead to <a href="https://pubmed.ncbi.nlm.nih.gov/14705378">reflux</a> as direct pressure on the stomach forces stomach acid back into the food pipe.</p>
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<p>
<em>
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Read more:
<a href="https://theconversation.com/explainer-what-is-gastric-reflux-18791">Explainer: what is gastric reflux?</a>
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<h2>Is constipation normal? And haemorrhoids?</h2>
<p>Increased levels of progesterone and the hormone oestrogen lead to a decrease in muscular contractions (peristalsis) throughout the gut. </p>
<p>This means you’re more likely to become constipated during pregnancy. Constipation affects about <a href="https://pubmed.ncbi.nlm.nih.gov/9609265">40% of pregnant women</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/493213/original/file-20221103-23-ldyjhf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Pregnant women sitting on toilet, holding tummy" src="https://images.theconversation.com/files/493213/original/file-20221103-23-ldyjhf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/493213/original/file-20221103-23-ldyjhf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/493213/original/file-20221103-23-ldyjhf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/493213/original/file-20221103-23-ldyjhf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/493213/original/file-20221103-23-ldyjhf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/493213/original/file-20221103-23-ldyjhf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/493213/original/file-20221103-23-ldyjhf.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">Constipation and haemorrhoids are common in pregnancy.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/constipation-pregnant-women-648533710">Shutterstock</a></span>
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Read more:
<a href="https://theconversation.com/health-check-what-causes-constipation-114290">Health Check: what causes constipation?</a>
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<p>Increased levels of oestrogen also lead to your blood vessels and connective tissue (tissue that connect one type to another, such as ligaments) becoming softer. </p>
<p>This, plus pressure from the growing baby, and increased blood volume and flow, can contribute to the development of <a href="https://pubmed.ncbi.nlm.nih.gov/25633397">haemorrhoids</a> – columns of cushioned tissue and blood vessels found close to the opening of the anus.</p>
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Read more:
<a href="https://theconversation.com/explainer-why-do-people-get-haemorrhoids-and-how-do-you-get-rid-of-them-94820">Explainer: why do people get haemorrhoids and how do you get rid of them?</a>
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<p>Your body also needs more water and sodium in pregnancy to help produce amniotic fluid (liquid that surrounds the growing baby in the uterus) and build the blood supply of the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1595116">growing baby</a>. This necessary water and sodium is absorbed from your intestines and can contribute to constipation, and an increased risk of haemorrhoids. </p>
<p>Haemorrhoids are very common during pregnancy. <a href="https://pubmed.ncbi.nlm.nih.gov/6861574">One study</a> found 86% of pregnant women reported them.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-why-do-people-get-haemorrhoids-and-how-do-you-get-rid-of-them-94820">Explainer: why do people get haemorrhoids and how do you get rid of them?</a>
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<h2>No wonder I feel full</h2>
<p>Oestrogen is thought to be <a href="https://journals.physiology.org/doi/full/10.1152/ajpregu.2001.280.5.R1546">responsible</a> for decreasing the movement of the stomach in pregnancy, keeping the food in the stomach longer and making it more likely you’ll feel full. </p>
<p>During the third trimester, your growing uterus and baby also start to really push up on the abdominal organs. No wonder you’re likely to feel pressure on your stomach and discomfort the closer you are to the end of your pregnancy.</p>
<p>You can also feel pressure at the other end of the gut. Pressure from the expanding uterus on the end part of the colon (the sigmoid colon) can also make you feel constipated even if you’re not. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mega-study-confirms-pregnant-women-can-reduce-risk-of-stillbirth-by-sleeping-on-their-side-114601">Mega study confirms pregnant women can reduce risk of stillbirth by sleeping on their side</a>
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<h2>I have incontinence. Is that because of how I gave birth?</h2>
<p>There has been a lot of debate about whether urinary or faecal incontinence is more likely after a vaginal or a caesarean birth.</p>
<p>However, the strongest evidence we have suggests the mode of birth <a href="https://obgyn.onlinelibrary.wiley.com/doi/full/10.1111/aogs.14027">makes no difference</a>. If you’ve had incontinence <a href="https://obgyn.onlinelibrary.wiley.com/doi/full/10.1111/aogs.14027">during pregnancy</a> this is the <a href="https://pubmed.ncbi.nlm.nih.gov/31273486/">strongest predictor</a> of having it afterwards.</p>
<p>Urinary incontinence that doesn’t improve within three months of giving birth is more likely to <a href="https://link.springer.com/article/10.1007/s00192-018-3577-7">persist</a>. So if you’ve experienced this during pregnancy, you might like to see a <a href="https://bjsm.bmj.com/content/48/4/299.short?casa_token=Kp_p41d8NRsAAAAA:nxhZxxJFfU1RpW44GFPYa2kr6tnV4ObnyxeLawhjSHWRYHozfUU_Zp5qiFXkrlWqEu6JynLcYhdt">pelvic floor physio</a>. </p>
<p>Fortunately, faecal incontinence after pregnancy is very uncommon, affecting only <a href="https://pubmed.ncbi.nlm.nih.gov/25803402">around 3%</a> of women. However if this persists, please seek medical attention.</p>
<h2>Why am I still constipated?</h2>
<p>A <a href="https://pubmed.ncbi.nlm.nih.gov/33030260/">study from Finland</a> on more than 400 women found constipation affected 47% of women in the first few days after a vaginal birth and 57% of women in the first few days after a caesarean.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1209260992011685888"}"></div></p>
<p>The researchers suggested this may be caused by too much physical inactivity and insufficient intake of fluids after birth, or the effects of anaesthetic and disturbance to the intestines during surgery. </p>
<p>One month after childbirth, constipation became less common. Some 9% of women were constipated after a vaginal birth and 15% after a caesarean.</p>
<h2>Feeling gassy? No, you’re not imaging it</h2>
<p>The Finnish study also found excess farting is extremely common a few days after birth. It affected 81% of women but this number dropped to 30% one month after birth. </p>
<p>Bloating is another common symptom found a few days after birth affecting 59% of women, and this decreases to 14% of women one month afterwards.</p>
<p>So why is this happening? We can look to your gut microbiome for clues. This is the unique universe of micro-organisms (bugs), and their genes, that live in your gut.</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">Remind me again, what is the microbiome?</span></figcaption>
</figure>
<p>During and after pregnancy, there are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5648614/">profound changes</a> to the gut microbiome. These may cause an increase in gas production or lead to constipation.</p>
<p>So the good news from the Finnish study is that normal bowel function is restored quickly after childbirth for most women, but might be a touch longer for women after a caesarean.</p>
<hr>
<p><em>If you’re concerned about gut symptoms during or after pregnancy, seek advice from a health-care professional, who can discuss treatment and referral options.</em></p><img src="https://counter.theconversation.com/content/193012/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kate Levett receives funding from an NHMRC Early Career Fellowship. </span></em></p><p class="fine-print"><em><span>Vincent Ho 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>Pregnancy changes the structure and function of virtually every organ system of the body. That includes some big changes to the gut.Vincent Ho, Senior Lecturer and clinical academic gastroenterologist, Western Sydney UniversityKate Levett, Research Fellow University of Notre Dame Australia; Adjunct Fellow (National Institute of Complementary Medicine), Western Sydney University, University of Notre Dame AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1903482022-10-25T22:43:45Z2022-10-25T22:43:45ZWhat are postbiotics and how can they improve our gut health?<figure><img src="https://images.theconversation.com/files/490282/original/file-20221018-22859-g3xky2.jpg?ixlib=rb-1.1.0&rect=0%2C26%2C4493%2C2964&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.pexels.com/photo/photograph-of-a-person-s-hand-picking-vegetables-7341749/">Photo by Alesia Kozik/Pixabay</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Many of us are familiar with probiotics, such as certain yogurts and fermented foods, full of “good” bacteria that can keep the gut healthy.</p>
<p>You might even have heard of prebiotics, foods rich in complex carbohydrates (dietary fibre) that help foster good bacteria in the large intestine. Popular prebiotic foods include oats, nuts and legumes.</p>
<p>But what about postbiotics? What are they and how do they affect our gut health?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-should-you-eat-after-youve-been-on-antibiotics-and-can-probiotics-and-prebiotics-get-your-gut-back-to-normal-163363">What should you eat after you've been on antibiotics? And can probiotics and prebiotics get your gut back to normal?</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/489713/original/file-20221014-17-cmyp4e.jpg?ixlib=rb-1.1.0&rect=0%2C8%2C1917%2C1267&q=45&auto=format&w=1000&fit=clip"><img alt="A colourful display of fruits and vegetables." src="https://images.theconversation.com/files/489713/original/file-20221014-17-cmyp4e.jpg?ixlib=rb-1.1.0&rect=0%2C8%2C1917%2C1267&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/489713/original/file-20221014-17-cmyp4e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489713/original/file-20221014-17-cmyp4e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489713/original/file-20221014-17-cmyp4e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489713/original/file-20221014-17-cmyp4e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489713/original/file-20221014-17-cmyp4e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489713/original/file-20221014-17-cmyp4e.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 vegetables and fruits increases the levels of prebiotics in your body.</span>
<span class="attribution"><a class="source" href="https://pixabay.com/photos/fruit-vegetables-market-stall-428057/">Image by Michal Jarmoluk from Pixabay</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>What is a postbiotic?</h2>
<p>Postbiotics are essentially the by-products of our gut microbiota. In other words, your body <a href="https://www.health.harvard.edu/nutrition/what-are-postbiotics#:%7E:text=So%2C%20what%20are%20postbiotics%3F,the%20growth%20of%20harmful%20bacteria">produces postbiotics</a> <em>after</em> digesting prebiotic and probiotic foods.</p>
<p>Examples of postbiotics include the short-chain fatty acids butyric acid (or butyrate), acetic acid (or acetate) and propionic acid (or propionate).</p>
<p>These molecules are produced when good probiotic bacteria break down dietary fibre from foods such as fruits and vegetables, grains and legumes.</p>
<p>These postbiotic molecules are important for your gut microbiota. Healthy probiotic bacteria thrive on these short-chain fatty acids in our gut. </p>
<p>And some postbiotics can help suppress “bad” bacteria. For example, probiotic bacteria (such as <em>Lactococcus lactis</em>) produce special chemicals called bacteriocins which can <a href="https://www.sciencedirect.com/science/article/pii/S1040842821002171">prevent</a> the colonisation of pathogens like <em>E. coli</em> in the gut. This process is known as “colonisation resistance”.</p>
<p>Microbial fermentation is where microbes in the gut break down complex carbohydrates. Microbial fermentation of <a href="https://pubs.acs.org/doi/pdf/10.1021/acs.jafc.8b04102">plant-based diets</a> (which are rich in polyphenols), in particular, leads to the production of the postbiotic phenylacetic acid. This postbiotic can reduce the growth of harmful <a href="https://academic.oup.com/pcp/article/60/2/243/5289543?login=true">pathogens</a> in the body.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/489716/original/file-20221014-20-oy88m9.jpg?ixlib=rb-1.1.0&rect=0%2C26%2C5991%2C3961&q=45&auto=format&w=1000&fit=clip"><img alt="A customers holds a shopping bag while looking at vegetables." src="https://images.theconversation.com/files/489716/original/file-20221014-20-oy88m9.jpg?ixlib=rb-1.1.0&rect=0%2C26%2C5991%2C3961&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/489716/original/file-20221014-20-oy88m9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/489716/original/file-20221014-20-oy88m9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/489716/original/file-20221014-20-oy88m9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/489716/original/file-20221014-20-oy88m9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/489716/original/file-20221014-20-oy88m9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/489716/original/file-20221014-20-oy88m9.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 plant-rich diet is good for postbiotic production.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/unrecognizable-customer-near-greens-in-supermarket-7129141/">Photo by Michael Burrows/Pexels</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Not all postbiotics are good</h2>
<p>Not all postbiotics are heroes, though.</p>
<p>One type of postbiotic is bile acids, which are produced when we eat too many <a href="https://journals.lww.com/co-gastroenterology/Fulltext/2014/05000/Bile_acids_and_the_gut_microbiome.18.aspx">high-fat foods</a>.</p>
<p>Bile acids have been linked to <a href="https://www.nature.com/articles/s41385-019-0162-4">inflammation</a> and <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7225675/">colon cancer</a>.</p>
<p>Staying on a high-protein, low-carbohydrate diet for the long term often means people don’t eat enough fibre, which is linked to a <a href="https://academic.oup.com/ajcn/article/93/5/1062/4597729">higher risk</a> of colon cancer.</p>
<p>This may be due to the production of <a href="https://academic.oup.com/ajcn/article/93/5/1062/4597729">hazardous postbiotics</a> like bile acids.</p>
<h2>What’s the link between postbiotics and cancer?</h2>
<p>Our recent <a href="https://www.tandfonline.com/doi/full/10.1080/19490976.2022.2038865">review</a> (led by my colleague Kayla Jaye at Western Sydney University) found short-chain fatty acids – particularly butyrate – have shown promising results against breast and colorectal cancer cells in previous laboratory studies.</p>
<p>One clinical <a href="https://iopscience.iop.org/article/10.1088/1742-6596/1146/1/012037/pdf">study</a> showed colorectal cancer patients produced significantly lower levels of short-chain fatty acids in their gut than healthy participants.</p>
<p>Another <a href="https://link.springer.com/article/10.1007/s10096-020-04036-x">study</a> found the numbers of bacteria that produce short-chain fatty acids were low in premenopausal breast cancer patients. </p>
<p>Some cellular and animal <a href="https://www.mdpi.com/1422-0067/23/16/9490/htm">studies</a> have also reported that the postbiotic butyrate can help chemotherapy work better against breast cancer and regulate the immune system.</p>
<p>As <a href="https://academic.oup.com/ajcn/article/93/5/1062/4597729">reported</a> in epidemiological studies, a fibre-rich diet, particularly whole grains, can lower the risk of colorectal cancer. This is mainly because fibre-rich diets lead to the production of short-chain fatty acids in the colon.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/490285/original/file-20221018-15124-ybay5v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two bags of legumes sit on a kitchen bench." src="https://images.theconversation.com/files/490285/original/file-20221018-15124-ybay5v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/490285/original/file-20221018-15124-ybay5v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490285/original/file-20221018-15124-ybay5v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490285/original/file-20221018-15124-ybay5v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490285/original/file-20221018-15124-ybay5v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490285/original/file-20221018-15124-ybay5v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490285/original/file-20221018-15124-ybay5v.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">The best way to improve the levels of good postbiotics is to consume more vegetables, fruits, legumes, wholegrain bread, nuts and seeds.</span>
<span class="attribution"><a class="source" href="https://www.pexels.com/photo/high-angle-shot-of-cereal-and-beans-inside-of-white-plastic-5843562/">Photo by Karolina Grabowska/Pexels</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>OK great, so what do I eat to get more postbiotics in my gut?</h2>
<p>Dietary fibre is the key. </p>
<p>Women and men should consume at least <a href="https://www.monash.edu/medicine/ccs/gastroenterology/prebiotic/faq">25 and 30 grams</a> of fibre, respectively, every day. But few Australians meet this recommendation. </p>
<p>The best way to improve the levels of good postbiotics is to consume more vegetables, fruits, legumes, wholegrain bread, nuts and seeds.</p>
<p>Jerusalem artichokes, garlic, onion, leek and asparagus are fantastic prebiotic vegetables.</p>
<p>A diet rich in fruits and vegetables increases the levels of postbiotics like short-chain fatty acids in the gut. It also helps reduce <a href="https://journals.asm.org/doi/10.1128/msystems.01174-21">bile acids</a>.</p>
<p>Gut health is all about diversity, which means eating a variety of fruits, vegetables, legumes and whole grains to support healthy gut microbiota. </p>
<p>You can also include fermented foods like sauerkraut and kimchi in your diet. These fermented foods have both prebiotic fibre and live probiotic bacteria, which can help produce healthy postbiotics in the gut. </p>
<p>Of course, further research is needed. But to ensure good gut health, you should include plenty of fruits, vegetables and legumes in your diet.</p><img src="https://counter.theconversation.com/content/190348/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Deep Jyoti Bhuyan 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 body produces postbiotics after digesting prebiotic and probiotic foods – and many postbiotics are crucial to good gut health.Deep Jyoti Bhuyan, Research Fellow in Healthy Ageing, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1907132022-09-15T18:01:59Z2022-09-15T18:01:59ZHumans evolved with their microbiomes – like genes, your gut microbes pass from one generation to the next<figure><img src="https://images.theconversation.com/files/484929/original/file-20220915-17-nhg34h.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3840%2C2155&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The gut microbiome may also play a role in personalized medicine.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/bacteria-lactobacillus-in-human-intestine-royalty-free-image/1338810328">nopparit/iStock via Getty Images Plus</a></span></figcaption></figure><p>When the first humans moved out of Africa, they carried their gut microbes with them. Turns out, these microbes also evolved along with them.</p>
<p>The <a href="https://doi.org/10.1146/annurev-micro-090110-102830">human gut microbiome</a> is made up of hundreds to thousands of species of bacteria and <a href="https://microbiologysociety.org/why-microbiology-matters/what-is-microbiology/archaea.html">archaea</a>. Within a given species of microbe, different strains carry different genes that can <a href="https://doi.org/10.1016/j.chom.2022.08.009">affect your health and the diseases you’re susceptible to</a>. </p>
<p>There is <a href="https://doi.org/10.1016/j.cell.2019.01.001">pronounced variation</a> in the microbial composition and diversity of the gut microbiome between people living in different countries around the world. Although researchers are starting to understand what factors affect microbiome composition, such as diet, there is still limited understanding on why different groups have different strains of the same species of microbes in their guts. </p>
<p>We are researchers who study <a href="https://scholar.google.com/citations?user=KEmIhncAAAAJ&hl=en">microbial evolution</a> and <a href="https://scholar.google.com/citations?user=up7dycYAAAAJ&hl=en">microbiomes</a>. Our <a href="https://www.science.org/doi/10.1126/science.abm7759">recently published study</a> found that not only did microbes diversify with their early modern human hosts as they traveled across the globe, they followed human evolution by restricting themselves to life in the gut.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/VzPD009qTN4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The gut microbiome plays a key role in many areas of your health.</span></figcaption>
</figure>
<h2>Microbes share evolutionary history with humans</h2>
<p>We hypothesized that as humans fanned out across the globe and diversified genetically, so did the microbial species in their guts. In other words, gut microbes and their human hosts “codiversified” and evolved together – just as human beings diversified so that people in Asia look different from people in Europe, so too did their microbiomes.</p>
<p>To assess this, we needed to pair human genome and microbiome data from people around the world. However, data sets that provided both the microbiome data and genome information for individuals were limited when we started this study. Most publicly available data was from North America and Western Europe, and we needed data that was more representative of populations around the world. </p>
<p>So our research team used existing data from Cameroon, South Korea and the United Kingdom, and additionally recruited mothers and their young children in Gabon, Vietnam and Germany. We collected saliva samples from the adults to ascertain their genotype, or genetic characteristics, and fecal samples to sequence the genomes of their gut microbes.</p>
<p>For our analysis, we used data from 839 adults and 386 children. To assess the evolutionary histories of humans and gut microbes, we created <a href="https://www.khanacademy.org/science/ap-biology/natural-selection/phylogeny/a/phylogenetic-trees">phylogenetic trees</a> for each person and as well as for 59 strains of the most commonly shared microbial species.</p>
<p>When we compared the human trees to the microbial trees, we discovered a gradient of how well they matched. Some bacterial trees didn’t match the human trees at all, while some matched very well, indicating that these species codiversified with humans. Some microbial species, in fact, have been along for the evolutionary ride for over hundreds of thousands of years. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two phylogenetic trees comparing human genetic diversity across geographic regions to the genetic diversity of _Collinsella aerofaciens_" src="https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=273&fit=crop&dpr=1 600w, https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=273&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=273&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=344&fit=crop&dpr=1 754w, https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=344&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/484917/original/file-20220915-26-syoolq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=344&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 two phylogenetic trees of human participants (left) and one bacterial species (right) closely match, indicating that they likely diversified together over the course of evolution.</span>
<span class="attribution"><a class="source" href="http://www.doi.org/10.1126/science.abm7759">Reprinted with permission from Suzuki et al., Science Volume 377, abm7759 (2022)</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>We also found that microbes that evolved in tandem with people have a unique set of genes and traits compared with microbes that had not codiversified with people. Microbes that partnered up with humans have smaller genomes and greater oxygen and temperature sensitivity, mostly unable to tolerate conditions below human body temperature.</p>
<p>In contrast, gut microbes with weaker ties to human evolution have traits and genes characteristic of free-living bacteria in the external environment. This finding suggests that codiversified microbes are very much dependent on the environmental conditions of the human body and must be transmitted quickly from one person to the next, either passed down generationally or between people living in the same communities. </p>
<p>Confirming this mode of transmission, we found that mothers and their children had the same strains of microbes in their guts. Microbes that were not codiversified, in contrast, were more likely to survive well outside of the body and may be transmitted more widely through water and soil.</p>
<h2>Gut microbes and personalized medicine</h2>
<p>Our discovery that gut microbes evolved right along with their human hosts offers another way to view the human gut microbiome. Gut microbes have passed between people over hundreds to thousands of generations, such that <a href="https://doi.org/10.1126/science.aaz6827">as humans changed, so did their gut microbes</a>. As a result, some gut microbes behave as though they are part of the human genome: They are packages of genes that are passed between generations and shared by related individuals.</p>
<p><a href="https://www.genome.gov/genetics-glossary/Personalized-Medicine">Personalized medicine</a> and genetic testing are starting to make treatments more specific and effective for the individual. Knowing which microbes have had long-term partnerships with people may help researchers develop microbiome-based treatments specific to each population. Clinicians are already using <a href="https://doi.org/10.1126/scitranslmed.abk1107">locally sourced probiotics</a> derived from the gut microbes of community members to treat malnutrition.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration of gut bacteria on intestinal villi." src="https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/484949/original/file-20220915-19-qzu5f6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Gut bacteria could be used to help treat various diseases and conditions.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/gut-bacteria-probiotics-royalty-free-image/1325237120">Artur Plawgo/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Our findings also help scientists better understand how microbes transition ecologically and evolutionarily from “free-living” in the environment to dependent on the conditions of the human gut. Codiversified microbes have traits and genes <a href="https://doi.org/10.1146/annurev.genet.41.110306.130119">reminiscent of bacterial symbionts</a> that live inside insect hosts. These shared features suggest that other animal hosts may also have gut microbes that codiversified with them over evolution.</p>
<p>Paying special attention to the microbes that share human evolutionary history can help improve understanding of the role they play in human well-being.</p><img src="https://counter.theconversation.com/content/190713/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 organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>As early modern humans spread across the globe, their gut microbes genetically changed with them. Understanding the origins of gut microbes could improve understanding of their role in human health.Taichi A. Suzuki, Postdoctoral Research Associate in Microbiome Science, Max Planck Institute for BiologyRuth Ley, Director, Department of Microbiome Science, Max Planck Institute for BiologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1879052022-08-19T12:42:26Z2022-08-19T12:42:26ZWhat is listeria? A microbiologist explains the bacterium behind recent deadly food poisoning outbreaks<figure><img src="https://images.theconversation.com/files/479719/original/file-20220817-21-a18luh.jpg?ixlib=rb-1.1.0&rect=132%2C0%2C3875%2C2951&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Investigators in Florida traced a listeria outbreak to ice cream.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/ice-cream-jar-with-4-flavors-strawberry-vanilla-royalty-free-image/1279372828?adppopup=true">Graiki/Moment via Getty Images</a></span></figcaption></figure><p>Bacteria do, and will, end up in food. Everyone eats – intentionally or unintentionally – <a href="https://doi.org/10.7717/peerj.659">millions to billions</a> of live microbes every day. </p>
<p>Most are completely harmless, but some can cause serious illnesses in humans. Because of these potential pathogens, there is a long <a href="https://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/pregnancy-nutrition/art-20043844">list of foods to avoid</a>, including uncooked eggs, raw fish and unwashed fruits and vegetables, particularly for pregnant women. The foods themselves are not bad, but the same cannot be said for certain bacterial passengers, such as <em>Listeria monocytogenes</em>, or listeria for short. </p>
<p>This particular pathogen has found ways to indiscriminately get into our foods. While deli and dairy foods like cold cuts, cheese, milk and eggs are frequently culprits for causing listeriosis – the general name for listeria-caused infections – fresh vegetables and fruits have also been implicated.</p>
<p>The variety of foods responsible for <a href="https://www.cdc.gov/listeria/outbreaks/index.html">U.S. listeria outbreaks in the past decade</a> shows just how easily these bacteria get around. Listeria has turned up in <a href="https://www.cdc.gov/listeria/outbreaks/eggs-12-19/index.html">hard-boiled eggs</a>, <a href="https://www.cdc.gov/listeria/outbreaks/enoki-mushrooms-03-20/index.html">enoki mushrooms</a>, <a href="https://www.cdc.gov/listeria/outbreaks/precooked-chicken-07-21/index.html">cooked chicken</a> and, <a href="https://www.cdc.gov/listeria/outbreaks/packaged-salad-12-21-b/index.html">in 2021, packaged salad</a> – <a href="https://www.cdc.gov/listeria/outbreaks/packaged-salad-mix-12-21/index.html">twice</a>.</p>
<p>Even the frozen aisle is not spared from listeria contamination. Contaminated ice cream in Florida was behind this year’s listeria outbreak, with 25 reported cases spanning 11 states since January 2021, according to <a href="https://www.cdc.gov/listeria/outbreaks/monocytogenes-06-22/details.html">an early August 2022 report</a> from the Centers for Disease Control and Prevention. Those who fell ill ranged in age from less than 1 to 92 years old, and 24 of the cases have involved hospitalizations.</p>
<p>How can such a tiny organism bypass extensive disinfection efforts and wreak such havoc? <a href="https://scholar.google.com/citations?user=G_tH2rUAAAAJ&hl=en">As a microbiologist</a> who has been working with listeria and trying to solve these mysteries, I’d like to share some insider secrets about this unique little pathogen and its strategies of survival inside and outside our bodies.</p>
<h2>Farm to table</h2>
<p>To prevent consumer exposure to listeria, the food industries follow <a href="https://www.fda.gov/files/food/published/Draft-Guidance-for-Industry--Control-of-Listeria-monocytogenes-in-Ready-To-Eat-Foods-%28PDF%29.pdf">stringent disinfection and surveillance guidelines</a> from the Food and Drug Administration and the U.S. Department of Agriculture. Any detection of listeria triggers a recall of potentially contaminated food products. </p>
<p>Since 2017, there have been <a href="https://www.fsis.usda.gov/recalls">over 270 listeria-related food recalls</a>. These are incredibly costly and can sometimes lead to fears in consumers <a href="https://www.npr.org/sections/thetwo-way/2018/01/29/581531318/panera-bread-recalls-cream-cheese-across-u-s-over-listeria-fears">as well as nationwide disruptions in food services</a>. However, the recalls represent one of the few tools that the food industry has to protect consumers from foodborne infections. </p>
<p>Not all listeria strains are created equal. <a href="https://doi.org/10.1016/j.ijmm.2010.05.002">Genetic variations</a> in listeria make a big difference in whether the pathogen ends up being involved in multistate outbreaks or simply hitching a ride harmlessly through our digestive tract. Essentially, based on the <a href="https://doi.org/10.1093/jaoac/85.2.524">different methods used</a>, listeria can be subtyped into different lineages, with some associated with outbreaks more frequently than others.</p>
<p>Researchers are investigating ways to tell these listeria strains apart, distinguishing the less harmful ones from those that are particularly dangerous, or hypervirulent. Being able to accurately identify them can help policymakers assess risks and make economically feasible decisions to improve food safety.</p>
<figure class="align-center ">
<img alt="Illustration of red-orange rod-shaped Listeria bacteria." src="https://images.theconversation.com/files/477025/original/file-20220801-70681-jygdr6.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6000%2C3979&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/477025/original/file-20220801-70681-jygdr6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477025/original/file-20220801-70681-jygdr6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477025/original/file-20220801-70681-jygdr6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477025/original/file-20220801-70681-jygdr6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477025/original/file-20220801-70681-jygdr6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477025/original/file-20220801-70681-jygdr6.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">Listeria is an intracellular pathogen. Inside the body, it can grow inside a cell and spread to neighboring cells.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/listeria-monocytogenes-illustration-royalty-free-illustration/685023881">Kateryna Kon/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<h2>Listeria is tough</h2>
<p>Listeria can live in any place where food is grown, packaged, stored, transported, prepared or served. Our research team has even found listeria in <a href="https://doi.org/10.3390/pathogens7030060">organic lettuce harvested from a backyard garden</a>. </p>
<p>Listeria can survive and grow in temperatures as cold as <a href="https://ask.usda.gov/s/article/Can-Listeria-grow-at-refrigerator-temperatures">24 degrees Fahrenheit</a> (-4.4 Celsius) because it has <a href="https://doi.org/10.1080/10408390701856272">adapted to cold temperatures</a> and developed <a href="https://doi.org/10.4315/0362-028X-69.6.1473">tricks for overcoming cold stress</a>. Considering the average refrigerator maintains a temperature range of 35 F to 38 F (1.7 C to 3.3 C), even when the food is stored properly at refrigeration temperatures, a harmless few listeria can grow to dangerous levels of contamination over time.</p>
<p>Listeria is also extremely versatile in adapting to and surviving all kinds of disinfection processes. When it grows on surfaces, listeria protects itself with <a href="https://doi.org/10.3390%2Fpathogens6030041">a biofilm structure</a>, a kind of coating that forms a physical and chemical barrier and prevents disinfectants from reaching the bacteria within.</p>
<p>Surviving the harsh conditions outside our body is only the first part of the story. Before even beginning to cause infections, listeria needs to get to the intestines without getting caught and destroyed by the body’s defenses.</p>
<p>Traveling and surviving passage through a <a href="https://doi.org/10.3389%2Ffcimb.2014.00009">human digestive tract is not easy</a> for bacteria. Saliva enzymes can degrade bacterial cell walls. So can stomach acids and bile salts. Antibodies in our digestive tract can recognize and target bacteria for degradation. Moreover, <a href="https://doi.org/10.1084%2Fjem.20170495">resident gut microbes</a> are strong competitors for the limited amount of space and nutrients in our intestines.</p>
<p>After digestion, the body’s intestinal movement sends traffic one way – out of the body. In order to stick around and cause infections, bacteria have to attach themselves and hang on against the bowel movement while competing for nutrients. Successful pathogens can establish these survival and attachment tasks while undermining our immune defenses. </p>
<p>Listeria that manage to stick around in our intestines can trigger an immune response. In healthy people, that might manifest as <a href="https://www.cdc.gov/listeria/symptoms.html">minor diarrhea or vomiting that goes away without medical attention</a>. </p>
<p>However, those with compromised immune systems or immune systems temporarily weakened as a result of medication or <a href="https://doi.org/10.3389/fimmu.2020.575197">pregnancy</a> can be more susceptible to severe infections. In the absence of an effective immune system, listeria can invade other tissues and organs by creating an efficient niche for growth.</p>
<h2>Listeria in stealth mode</h2>
<p>Listeria is what we microbiologists call an intracellular pathogen. In an infected individual, listeria can grow inside a cell and <a href="https://doi.org/10.1083%2Fjcb.146.6.1333">spread to neighboring cells</a>. Hiding inside our cells this way, listeria avoids detection by antibodies or other immune defenses that are designed to detect and destroy threats that exist outside of our cells.</p>
<p>Once in stealth mode, listeria can move into and infect different organs. Wherever it goes, inflammation follows as the body’s immune system tries to go after the bacteria. The inflammation eventually results in collateral damage in nearby tissues. </p>
<p>In fact, deaths from listeria infections are often associated with the more invasive forms of the disease in which the microbes have breached the intestinal barriers and moved to other body parts. <a href="https://www.cdc.gov/listeria/symptoms.html">Life-threatening illnesses</a> that can result from listeria include meningitis – inflammation around the brain and spinal cord that can occur when these microbes infect the brain – or <a href="https://doi.org/10.1016/j.ijantimicag.2017.12.032">endocarditis</a>, infection of the heart’s inner lining. And in pregnant individuals, if the pathogen reaches the placenta, it can spread to the fetus and cause stillbirth or miscarriage.</p>
<p>As such, invasive listeria cases often have an alarmingly high <a href="https://www.fda.gov/animal-veterinary/animal-health-literacy/get-facts-about-listeria#">hospitalization rate of more than 90% and a fatality rate that can reach 30%</a>. </p>
<p>The scary statistics argue for a proactive and effective infection control to protect vulnerable populations, such as elderly or pregnant individuals, from listeria exposure. </p>
<h2>Think, cook and eat</h2>
<p>If you have risk factors and want to take extra precautions, maybe turn that unpasteurized cider into a hot, mulled cider to kill the bacteria with boiling and simmering. Eat soft cheeses on foods that get cooked, such as pizzas or grilled sandwiches, instead of eating them cold, straight from the refrigerator. Essentially, use heat to bring out the delicious flavors and eliminate potential listeria contamination in your food. </p>
<p>Ultimately, it’s nearly impossible to live in a completely sterile environment, eating food devoid of all living microorganisms. So enjoy your favorites, but <a href="https://www.fsis.usda.gov/food-safety">stay up to date with ongoing recalls</a> and follow the expiration guidelines, especially for ready-to-eat food.</p><img src="https://counter.theconversation.com/content/187905/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Yvonne Sun 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>Listeria causes serious illness and food recalls nearly every year.Yvonne Sun, Assistant Professor of Microbiology, University of DaytonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1777482022-03-17T01:42:27Z2022-03-17T01:42:27ZA poo dose a day may keep bipolar away. When it comes to mental health, what else could poo do?<figure><img src="https://images.theconversation.com/files/451146/original/file-20220309-793-6zoqhi.jpg?ixlib=rb-1.1.0&rect=1%2C28%2C997%2C669&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/woman-toilet-160277366">Shutterstock</a></span></figcaption></figure><p>In a world first, two Australians with bipolar have had poo transplants, their symptoms improved, and their cases written up in <a href="https://journals.sagepub.com/doi/abs/10.1177/0004867420912834">peer-reviewed</a> <a href="https://pubmed.ncbi.nlm.nih.gov/35165993/">journals</a>.</p>
<p>One of us (Parker) treated the second of these patients with so-called faecal microbiota transplantation, and published his case study in recent weeks. The other (Green) is part of a team recruiting people with depression to a poo transplant clinical trial.</p>
<p>We’d be the first to admit it’s early days for this type of treatment for bipolar or other mental health issues. There are many hurdles before we could see poo transplants for these become commonplace.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1500188402901159937"}"></div></p>
<p>So we do not advocate people abandon their existing medication, try this at home or demand their psychiatrist offer them a “crapsule” (a poo capsule and yes, that’s a word).</p>
<p>Yet the limited results for bipolar so far are promising. Here’s what the evidence tells us about the prospect of poo transplants for mental health.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/poo-transplants-beyond-the-yuck-factor-what-works-what-doesnt-and-what-we-still-dont-know-82265">Poo transplants beyond the yuck factor: what works, what doesn't and what we still don't know</a>
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<h2>Let’s start with bipolar</h2>
<p>There are different types of <a href="https://theconversation.com/what-is-bipolar-disorder-the-condition-kanye-west-lives-with-143198">bipolar disorder</a>. This is when people have distinct periods of <a href="https://www.mind.org.uk/information-support/types-of-mental-health-problems/hypomania-and-mania/about-hypomania-and-mania/">mania (or a form known as hypomania)</a> – with, for example, elevated mood, increased activity and decreased sleep – and periods of depression.</p>
<p>People with bipolar usually take medication to manage their symptoms, generally for life. These medications are mainly mood stabilisers (such as lithium), but many also take antipsychotics. These medications come with risks and side effects, which depend on the medication. Side effects can include weight gain, sedation and <a href="https://library.neura.edu.au/bipolar-disorder/physical-features-bipolar-disorder/functional-changes-physical-features-bipolar-disorder/bodily-functions/motor-dysfunction-3/">movement disorders</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1288402621837893632"}"></div></p>
<h2>What happened to the two patients?</h2>
<p>In 2020, Russell Hinton, a private psychiatrist, <a href="https://journals.sagepub.com/doi/abs/10.1177/0004867420912834">described how he treated</a> the first patient. This was a woman who had tried more than a dozen different medications for her bipolar. She had been hospitalised ten times, had gained considerable weight and judged she had no quality of life.</p>
<p>After a poo transplant from her husband, she became symptom-free over the next five years, lost 33 kilograms, required no medication and her career bloomed.</p>
<p>Gordon Parker and colleagues at the University of New South Wales <a href="https://pubmed.ncbi.nlm.nih.gov/35165993/">reported their results</a> with the second patient last month. This was a young man who developed bipolar as a teenager, had tried numerous medications and became progressively intolerant of their side effects.</p>
<p>After a poo transplant, he was able to progressively cease all medications over the next year, and had virtually no mood swings. He also noted an improvement in his anxiety and ADHD (attention deficit hyperactivity disorder).</p>
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Read more:
<a href="https://theconversation.com/adhd-looks-different-in-adults-here-are-4-signs-to-watch-for-178639">ADHD looks different in adults. Here are 4 signs to watch for</a>
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<h2>How could this possibly work?</h2>
<p>Trillions of bacteria live in our guts. This so-called gut microbiome has a huge impact on our health in general, not just the health of our brain.</p>
<p>Differences in gut bacteria have been linked to <a href="https://www.nature.com/articles/s41367-019-0011-7">obesity</a>, <a href="https://www.thelancet.com/journals/ebiom/article/PIIS235239641930800-X/fulltext">diabetes</a> and <a href="https://www.gastrojournal.org/article/S0016-5085(19)34649-9/fulltext">irritable bowel syndrome</a>.</p>
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<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>
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<p>The idea behind poo transplants is to change the gut microbiome. You take poo, with all its micro-organisms, from a healthy person and give it to the one being treated.</p>
<p>You can do this “top down”, for example, by swallowing poo capsules (crapsules), or by delivering poo through a tube inserted into the nose, to the stomach or intestine. </p>
<p>Alternatively, you can insert the poo “bottom up”. You can do this with an enema, a simple, painless procedure in which a syringe transfers the poo into the rectum. Or you can use a colonoscopy, a procedure performed under a general anaesthetic involving inserting a tube higher up into the colon.</p>
<p>Poo transplants are already <a href="https://theconversation.com/poo-transplants-and-probiotics-does-anything-work-to-improve-the-health-of-our-gut-65480">used to treat</a> the often life-threatening gut infection caused by the bacterium <em>Clostridium difficile</em>.</p>
<p>They have also been trialled, with various degrees of success, in people with <a href="https://pubmed.ncbi.nlm.nih.gov/33345703/#:%7E:text=Preliminary%20data%20suggest%20that%20FMT,UC%20being%20the%20most%20compelling">irritable bowel syndrome, ulcerative colitis</a>, <a href="https://www.nature.com/articles/s41467-021-21472-1">HIV</a> and <a href="https://pubmed.ncbi.nlm.nih.gov/32279172/">hepatitis</a>, among other medical conditions.</p>
<p>Side effects from poo transplants <a href="https://pubmed.ncbi.nlm.nih.gov/33345703/#:%7E:text=Preliminary%20data%20suggest%20that%20FMT,UC%20being%20the%20most%20compelling">are rare</a>, and usually relate to the way in which they are given, for example side effects of the anaesthetic from poo transplants delivered by colonoscopy.</p>
<h2>So how about mental health?</h2>
<p>Abnormal gut microbiomes <a href="https://www.nature.com/articles/s41380-022-01456-3">have been linked</a> to bipolar, depression and schizophrenia.</p>
<p>When poo from depressed humans is given to rats, they appear to develop a <a href="https://pubmed.ncbi.nlm.nih.gov/27491067/">rat version of depression</a>. Likewise, when mice are given poo from someone with schizophrenia, they <a href="https://www.science.org/doi/10.1126/sciadv.aau8317">develop a mouse version of schizophrenia</a>.</p>
<p>These are indirect findings. Yet they suggest poo transplants may have the potential to treat some mental health conditions.</p>
<p>So how exactly do bacteria in the gut impact mental health? There are many <a href="https://pubmed.ncbi.nlm.nih.gov/31460832/">different ways</a>, each complicated and interacting with each other. </p>
<p>For example, these bacteria act directly on the gut wall, sending signals to the brain via the vagus nerve. The bacteria also produce large quantities of chemicals (for example, <a href="https://pubmed.ncbi.nlm.nih.gov/31460832/">short-chain fatty acids</a>), which impact virtually all body systems including the immune system. We know brain function relies heavily on immune cells.</p>
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Read more:
<a href="https://theconversation.com/stomach-and-mood-disorders-how-your-gut-may-be-playing-with-your-mind-50847">Stomach and mood disorders: how your gut may be playing with your mind</a>
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<h2>Don’t try this at home</h2>
<p>At this stage, any evidence suggesting poo transplants may help people with depression or bipolar is, essentially, anecdotal.</p>
<p>Some people have tried their own version at home, involving poo donors who have not been screened for diseases.</p>
<p>One high-profile example is Dave Hosking from the Australian band Boy & Bear. He used a “<a href="https://www.rollingstone.com/music/music-features/boy-bear-dave-hosking-fecal-transplant-919384/">poo roadie</a>” to provide him with transplants on tour to help manage his depression and anxiety.</p>
<p>We wouldn’t recommend this. Poo transplants should only be carried out under the supervision of medical professionals, using an approved and thoroughly screened poo product.</p>
<p>Poo transplants are <a href="https://www.legislation.gov.au/Details/F2021C01065">tightly regulated in Australia</a>. Donations must be screened for harmful bacteria, fungi, parasites or viruses. Donors must also not have any health condition thought to be associated with gut bacteria, such as an autoimmune condition, cancer or obesity.</p>
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<strong>
Read more:
<a href="https://theconversation.com/boosting-your-gut-health-sounds-great-but-this-wellness-trend-is-vague-and-often-misunderstood-155472">Boosting your ‘gut health’ sounds great. But this wellness trend is vague and often misunderstood</a>
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<h2>What happens next?</h2>
<p>We need larger, well-designed studies to show poo transplants have a real effect, and any improved symptoms cannot be explained by other factors. </p>
<p>We also need to look for markers in the microbiome that could predict a successful result. If we knew those markers, we could optimise treatment and better measure the results. </p>
<p>The first author’s centre is recruiting <a href="https://foodandmoodcentre.com.au/projects/movingmoods/">people with depression</a> to trial poo transplants. The study will randomise participants to have an enema or placebo enema. If successful, a larger study is planned. </p>
<p>In Canada, there are three such studies under way evaluating poo transplants. These are for <a href="https://pubmed.ncbi.nlm.nih.gov/34261526/">bipolar</a>, <a href="https://clinicaltrials.gov/ct2/show/NCT04805879">depression</a>, with or without <a href="https://clinicaltrials.gov/ct2/show/NCT05174273?cond=fmt&draw=8">irritable bowel syndrome</a>. </p>
<p>Though promising, we cannot conclude at this time whether poo transplants work for bipolar or depression.</p>
<p>Until the results of these studies are in, it’s too early to say if the early results with bipolar can be replicated on a larger scale.</p>
<hr>
<p><em>If this article has raised issues for you, or if you’re concerned about someone you know, call Lifeline on 13 11 14.</em></p><img src="https://counter.theconversation.com/content/177748/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jessica Green is affiliated with:
1. Food & Mood Centre, IMPACT, Deakin University
2. Department of Psychiatry, Peninsula Health
3. Monash Alfred Psychiatry Research Centre, Monash University</span></em></p><p class="fine-print"><em><span>Gordon Parker is affiliated with the Discipline of Psychiatry and Mental Health
School of Clinical Medicine, University of New South Wales
</span></em></p>Two Australians with bipolar have been successfully treated with poo transplants, allowing them to come off, or reduce, their medications. Here’s where the science is up to.Jessica Green, PhD Candidate and Consultant Psychiatrist, Deakin UniversityGordon Parker, Scientia Professor, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1756102022-01-27T19:01:09Z2022-01-27T19:01:09ZGut microbes help hibernating ground squirrels emerge strong and healthy in spring<figure><img src="https://images.theconversation.com/files/442826/original/file-20220126-27-13smcdk.jpg?ixlib=rb-1.1.0&rect=63%2C369%2C3142%2C1959&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When not hibernating, ground squirrels need to feast to store energy.</span> <span class="attribution"><a class="source" href="https://doi.org/10.1126/science.abh2950">Robert Streiffer</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Ground squirrels spend the end of summer gorging on food, preparing for hibernation. They need to store a lot of energy as fat, which becomes their primary fuel source underground in their hibernation burrows all winter long.</p>
<p>While hibernating, ground squirrels enter <a href="https://doi.org/10.1111/brv.12137">a state called torpor</a>. Their metabolism drops to as low as just 1% of summer levels and their body temperature can <a href="https://doi.org/10.1152/physrev.00008.2003">plummet to close to freezing</a>. Torpor greatly reduces how much energy the animal needs to stay alive until springtime.</p>
<p>That long fast comes with a downside: no new input of protein, which is crucial to maintain the body’s tissues and organs. This is a particular problem for muscles. In people, long periods of inactivity, like prolonged bed rest, <a href="https://doi.org/10.1186/s13728-015-0036-7">lead to muscle wasting</a>. But muscle wasting is minimal in hibernating animals. Despite as much as six to nine months of inactivity and no protein intake, they preserve muscle mass and performance remarkably well – a very handy adaptation that helps ensure a successful breeding season come spring.</p>
<p>How do hibernators pull this off? It’s been <a href="https://doi.org/10.1086/650471">a real head-scratcher</a> <a href="https://doi.org/10.1152/ajpregu.1991.261.5.R1214">for hibernation biologists for decades</a>. <a href="https://scholar.google.com/citations?user=TUVZbtcAAAAJ&hl=en&oi=ao">Our research</a> <a href="https://scholar.google.com/citations?user=zuJyGe8AAAAJ&hl=en&oi=ao">team tackled</a> this question by investigating how hibernating animals might be getting a major assist <a href="https://doi.org/10.1126/science.abh2950">from the microbes that live in their guts</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="small mammal curled into a ball, nestled in wood chips" src="https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/442827/original/file-20220126-23-o570i5.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">The 13-lined ground squirrel shows minimal signs of muscle wasting, even after hibernating for up to six months.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1126/science.abh2950">Robert Streiffer</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>A nitrogen-recycling system</h2>
<p>We knew from previous research that a hibernator’s <a href="https://doi.org/10.1016/j.cbpa.2020.110875">gastrointestinal system undergoes dramatic changes</a> in its structure and function from summer feeding to winter fasting. And it’s not only the animals who are fasting all winter long – their gut microbes are, too. Along with our microbiology collaborators, we figured out that <a href="https://doi.org/10.1146/annurev-nutr-071816-064740">winter fasting changes the gut microbiome</a> quite a bit.</p>
<p>And then we wondered … could gut microbes play a functional role in the process of hibernation itself? Could certain bacteria help keep muscle and other tissues working when the mostly immobile animals aren’t eating?</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="brown cow munching grass" src="https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=671&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=671&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=671&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=843&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=843&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443024/original/file-20220127-6424-ql553k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=843&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Microbes in their guts help ruminants, including cows, hold on to the nitrogen they need to build proteins.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/brown-cow-royalty-free-image/1219160750">Lemanieh/ iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>Biologists had previously identified a clever trick in ruminant animals, such as cattle, that helps them survive times when protein intake in the diet is low or protein needs are especially high, such as during pregnancy. A process <a href="https://doi.org/10.1079/NRR200498">called urea nitrogen salvage</a> allows the animal to recoup nitrogen – a critical ingredient for building protein – that would otherwise be excreted in urine as the waste product urea. Instead, the urea’s nitrogen is retained in the body and used to make amino acids, the building blocks of proteins.</p>
<p>This salvage operation depends on the chemical breakdown of urea molecules to release their nitrogen. But here’s the kicker: Chemical breakdown of urea requires urease, an enzyme that animals do not produce. So how does a cow, for instance, get that nitrogen out of urea?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="ball and stick model of a chemical structure" src="https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/443025/original/file-20220127-16-1kqqp1u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A model of the urea molecule, with two nitrogen atoms (in blue) along with a carbon (gray), an oxygen (red) and four hydrogen (white) atoms.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/urea-molecule-royalty-free-illustration/147217473">LAGUNA DESIGN/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<p>It turns out certain microbes that are normal residents of animals’ guts can do just that. They make the urease enzyme and use it to chemically split urea molecules, freeing up the nitrogen, which becomes part of ammonia molecules. Microbes then absorb ammonia and use it to make new protein for themselves.</p>
<p>Peculiarities of the ruminant digestive system allow those animals to benefit greatly from this process. But for other animals – like hibernators and us – it was less clear whether and how the urea nitrogen could make its way into the animals’ bodies to support protein synthesis.</p>
<p>This was our challenge as scientists: Could we demonstrate urea nitrogen recycling in hibernators and show that it is particularly helpful to them the longer they fast?</p>
<h2>Our experimental game plan</h2>
<p>Using the 13-lined ground squirrel, <a href="https://doi.org/10.1126/science.abh2950">we designed experiments to investigate</a> key steps in urea nitrogen salvage.</p>
<p>First, we injected into the squirrel’s bloodstream urea molecules in which the two nitrogen atoms were replaced by a heavier form of nitrogen that naturally occurs only in tiny amounts in the body.</p>
<p>We were able to follow these heavier nitrogen atoms as the injected urea moved from the blood into the gut, then as microbial urease broke down the urea into its component parts, and finally into the squirrels’ tissue metabolites and proteins. Wherever we saw higher levels of the heavier form of nitrogen, we knew that urea was the source of the nitrogen, and therefore gut microbes had to be responsible for getting the urea nitrogen back into the animals’ bodies.</p>
<p>To confirm that the microbes were doing the nitrogen recycling, we compared squirrels that had normal gut microbiomes to squirrels that didn’t. We treated some animals with antibiotics to reduce gut microbes at three times of the year: summer; early winter, when they were one month into fasting and hibernation; and late winter, whwithen they were four months into fasting and hibernation.</p>
<p>In squirrels with normal microbiomes, we saw evidence of urea nitrogen salvage at each step of the process that we tested. But squirrels with depleted microbiomes displayed minimal urea nitrogen salvage. Our observations confirmed that this process was indeed dependent on the gut microbes’ ability to break down urea and liberate its nitrogen in the hibernators’ guts. Hibernators’ liver and muscle tissue incorporated the most urea nitrogen during late winter – that is, the longer they’d been hibernating and without food.</p>
<p>We also found that the ground squirrels contribute to this remarkable symbiosis. During hibernation, their gut cells increase production of proteins called urea transporters. These molecules are lodged in intestinal cell membranes and shepherd urea from the blood into the gut where the microbes that contain urease are found. This assist means that what little urea the animal makes during hibernation has an easier route to the gut.</p>
<p>Finally, we found that it wasn’t just squirrels who benefited from this process. The microbes too were using the urea nitrogen to build their own proteins, showing that urea nitrogen salvage provides both parties with this important molecular building block during the long winter fast.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Fal-vhNgxvs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Every few weeks, hibernating squirrels arouse temporarily, as seen in this time-lapse video. They don’t eat or drink or leave the burrow, but the short increase in body temperature lets enzymes like urease do their jobs.</span></figcaption>
</figure>
<h2>Could this kind of symbiosis help humans?</h2>
<p>This example of hibernator-microbe symbiosis has potential clinical applications. For example, undernourishment, which affects millions of people globally, leads to a progressive decline in muscle mass and compromises health. Sarcopenia, which is muscle wasting that is a natural part of aging, impairs mobility and makes people more susceptible to injury. A detailed understanding of how the hibernator nitrogen salvage system is most effective when the risk of tissue loss and muscle wasting is greatest could lead to new therapeutics to help people in similar situations.</p>
<p>[<em>Over 140,000 readers rely on The Conversation’s newsletters to understand the world.</em> <a href="https://memberservices.theconversation.com/newsletters/?source=inline-140ksignup">Sign up today</a>.]</p>
<p>Another potential application is in human spaceflight, during which crew members experience <a href="https://doi.org/10.33549/physiolres.934550">high rates of muscle atrophy</a> because of a microgravity-induced suppression of muscle protein synthesis. Even the extensive exercise regime that astronauts undertake to offset this is insufficient. A microbiome-based countermeasure that facilitates muscle protein synthesis similar to the process we have observed in hibernators may be worth investigating.</p>
<p>These applications, though theoretically possible, are a long way from delivery. But studies in the 1990s demonstrated that humans are capable of <a href="https://doi.org/10.1097/01.mco.0000196142.72985.d3">recycling small amounts of urea nitrogen with the help of their gut microbes</a>. So the necessary machinery is in place – it just needs to be optimized.</p><img src="https://counter.theconversation.com/content/175610/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hannah V. Carey received funding from the U.S. National Science Foundation for this work.</span></em></p><p class="fine-print"><em><span>Matthew Regan receives funding from the Natural Sciences and Engineering Research Council of Canada and the Canadian Space Agency.</span></em></p>Months not eating or moving don’t result in muscle wasting and loss of function for animals that hibernate. New research found gut microbes help their hosts hold onto and use nitrogen to build proteins.Hannah V. Carey, Professor Emeritus of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-MadisonMatthew Regan, Assistant Professor of Biological Sciences, Université de MontréalLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1632582021-06-24T20:11:52Z2021-06-24T20:11:52ZWe found more than 54,000 viruses in people’s poo — and 92% were previously unknown to science<figure><img src="https://images.theconversation.com/files/408090/original/file-20210624-19-j2pxgb.jpeg?ixlib=rb-1.1.0&rect=7%2C0%2C4985%2C3742&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Research published today in <a href="https://www.nature.com/articles/s41564-021-00928-6">Nature Microbiology</a> has identified 54,118 species of virus living in the human gut — 92% of which were previously unknown. </p>
<p>But as we and our colleagues from the Joint Genome Institute and Stanford University in California found, the great majority of these were bacteriophages, or “phages” for short. These viruses “eat” bacteria and can’t attack human cells.</p>
<p>When most of us think of viruses, we think of organisms that infect our cells with diseases such as mumps, measles or, more recently, COVID-19. However, there are a vast number of these microscopic parasites in our bodies — mostly in our gut — that target the microbes that live there. </p>
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Read more:
<a href="https://theconversation.com/know-your-bugs-a-closer-look-at-viruses-bacteria-and-parasites-49695">Know your bugs – a closer look at viruses, bacteria and parasites</a>
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<h2>Everybody poos (but not all poo is the same)</h2>
<p>There has recently been much interest in the <a href="https://www.sciencedirect.com/science/article/pii/S0092867418302216">human gut microbiome</a>: the collection of microorganisms that live in our gut. </p>
<p>Besides helping us digest our food, these microbes have many other important roles. They protect us against pathogenic bacteria, modulate our mental well-being, prime our immune system when we are children, and have an ongoing role in immune regulation into adulthood. </p>
<p>It’s fair to say the human gut is now the most well-studied microbial ecosystem on the planet. Yet <a href="https://www.nature.com/articles/s41587-020-0603-3">more than 70%</a> of the microbial species that live there have yet to be grown in the laboratory. </p>
<p>We know this because we can access the genetic blueprints of the gut microbiome via an approach known as <a href="https://www.nature.com/articles/455481a">metagenomics</a>. This is a powerful technique whereby DNA is directly extracted from an environment and randomly sequenced, giving us a snapshot of what is present within and what it might be doing. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/408102/original/file-20210624-23-1im1ar9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/408102/original/file-20210624-23-1im1ar9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/408102/original/file-20210624-23-1im1ar9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/408102/original/file-20210624-23-1im1ar9.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/408102/original/file-20210624-23-1im1ar9.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/408102/original/file-20210624-23-1im1ar9.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/408102/original/file-20210624-23-1im1ar9.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/408102/original/file-20210624-23-1im1ar9.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Biologists estimate there are a few hundred trillion viruses living within and outside our bodies.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>Metagenomic studies have revealed how far we still have to go to catalogue and isolate all the microbial species in the human gut — and even further to go when it comes to viruses. </p>
<h2>11,810 samples of poo</h2>
<p>In our new research, we and our colleagues computationally mined viral sequences from 11,810 publicly available faecal metagenomes, taken from people in 24 different countries. We wanted to get an idea of the extent to which viruses have taken up residence in the human gut.</p>
<p>This effort resulted in the Metagenomic Gut Virus catalogue, the largest such resource to date. This catalogue comprises 189,680 viral genomes which represent more than 50,000 distinct viral species. </p>
<p>Remarkably (but perhaps predictably), more than 90% of these viral species are new to science. They collectively encode more than 450,000 distinct proteins — a huge reservoir of functional potential that may either be beneficial or detrimental to their microbial, and in turn human, hosts.</p>
<p>We also drilled down into subspecies of different viruses and found some showed striking geographical patterns across the 24 countries surveyed. </p>
<p>For example, a subspecies of the recently described and enigmatic <a href="https://www.nature.com/articles/ncomms5498">crAssphage</a> was prevalent in Asia, but was rare or absent in samples from Europe and North America. This may be due to localised expansion of this virus in specific human populations.</p>
<p>One of the most common functions we discovered in our molecular field trip were diversity-generating retroelements (DGRs). These are a class of genetic elements that mutate specific target genes in order to generate variation that can be beneficial to the host. In the case of DGRs in viruses, this may help in the ongoing evolutionary arms race with their bacterial hosts.</p>
<p>Intriguingly, we found one-third of the most common virally-encoded proteins have unknown functions, including more than 11,000 genes distantly related to “beta-lactamases”, which enable resistance to antibiotics such as penicillin.</p>
<h2>Linking gut viruses to their microbial hosts</h2>
<p>Having identified the phages, our next task was to link them to their microbial hosts. <a href="https://www.nature.com/articles/nrmicro1793">CRISPRs</a>, best known for their many applications in gene editing, are bacterial immune systems that “remember” past viral infections and prevent them from happening again. </p>
<p>They do this by copying and storing fragments of the invading virus into their own genomes, which can then be used to specifically target and destroy the virus in future encounters.</p>
<p>We used this record of past attacks to link many of the viral sequences to their hosts in the gut ecosystem. Unsurprisingly, highly abundant viral species were linked to highly abundant bacterial species in the gut, mostly belonging to the bacterial phyla Firmicutes and Bacteroidota.</p>
<p>So what can we do with all of this new information? One promising application of an inventory of gut viruses and their hosts is phage therapy. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5547374/">Phage therapy</a> is an old concept predating antibiotics, in which viruses are used to selectively target bacterial pathogens in order to treat infections. </p>
<p>There has been <a href="https://www.frontiersin.org/articles/10.3389/fpubh.2020.00144/full">discussion</a> of potentially customising people’s gut microbiomes using dietary interventions, probiotics, prebiotics or even “transpoosions” (faecal microbiota transplants), to improve an individual’s health.</p>
<p>Phage therapy may be a useful addition to this objective, by adding species or even subspecies-level precision to microbiome manipulation. For example, the bacterial pathogen <a href="https://www.sciencedirect.com/science/article/pii/S1075996413000826"><em>Clostridioides difficile</em></a> (or Cdiff for short) is a leading cause of hospital-acquired diarrhoea that could be specifically targeted by phages.</p>
<p>More subtle manipulation of non-pathogenic bacterial populations in the gut may be achievable through phage therapy. A complete compendium of gut viruses is a useful first step for such applied goals. </p>
<p>It’s worth noting, however, that projections from our data suggest we’ve only investigated a fraction of the total gut viral diversity. So we’ve still got a long way to go.</p>
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Read more:
<a href="https://theconversation.com/how-do-viruses-mutate-and-jump-species-and-why-are-spillovers-becoming-more-common-134656">How do viruses mutate and jump species? And why are 'spillovers' becoming more common?</a>
</strong>
</em>
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<img src="https://counter.theconversation.com/content/163258/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Phil Hugenholtz P.H. is a co-founder of Microba Life Sciences, which is a microbial genomics company
developing microbiome-based diagnostics and therapeutics and offers metagenomic gut
microbiome reports.</span></em></p><p class="fine-print"><em><span>Soo Jen Low 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>You could say there are a ‘crapload’ of viruses in the human gut. Luckily, most of these do not attack our cells, but instead feed on bacteria.Philip Hugenholtz, Professor of Microbiology, School of Chemistry and Molecular Biosciences, The University of QueenslandSoo Jen Low, Postdoctoral Research Fellow, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1571922021-03-17T18:03:03Z2021-03-17T18:03:03ZFeeding cows a few ounces of seaweed daily could sharply reduce their contribution to climate change<figure><img src="https://images.theconversation.com/files/389896/original/file-20210316-17-14btskg.jpg?ixlib=rb-1.1.0&rect=0%2C5%2C3994%2C2988&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A little seaweed with that?</span> <span class="attribution"><a class="source" href="https://flic.kr/p/iokr9s">Cowirrie/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Methane is a short-lived but powerful greenhouse gas and the <a href="https://www.epa.gov/climate-indicators/climate-change-indicators-climate-forcing">second-largest contributor to climate change after carbon dioxide</a>. And the majority of human-induced methane emissions <a href="https://www.nationalacademies.org/our-work/anthropogenic-methane-emissions-in-the-united-states-improving-measurement-monitoring-reporting-and-development-of-inventories">comes from livestock</a>. </p>
<p>About 70% of agricultural methane comes from <a href="https://www.epa.gov/sites/production/files/2021-02/documents/us-ghg-inventory-2021-chapter-5-agriculture.pdf">enteric fermentation</a> – chemical reactions in the stomachs of cows and other grazing animals as they break down plants. The animals burp out most of this methane and pass the rest as flatulence. </p>
<p>There are <a href="https://www.beefmarketcentral.com/story-world-cattle-inventory-country-usda-146-106898">roughly 1 billion cattle</a> around the world, so reducing enteric methane is an effective way to reduce overall methane emissions. But most options for doing so, such as <a href="https://doi.org/10.2527/jas.2013-6583">changing cows’ diets</a> to more digestible feed or adding more fat, are <a href="https://doi.org/10.3168/jds.2014-9138">not cost-effective</a>. A 2015 study suggested that using seaweed as an additive to cattle’s normal feed <a href="https://doi.org/10.1007/s10811-015-0639-9">could reduce methane production</a>, but this research was done in a laboratory, not in live animals.</p>
<p>We study <a href="https://scholar.google.com/citations?user=SwXk1rcAAAAJ&hl=en">sustainable</a> <a href="https://www.researchgate.net/profile/Breanna-Roque">agriculture</a>, focusing on livestock. In a <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0247820">2021 study</a>, we showed that using red seaweed (<em>Asparagopsis</em>) as a feed supplement can reduce both methane emissions and feed costs without affecting meat quality. If these findings can be scaled up and commercialized, they could transform cattle production into a more economically and environmentally sustainable industry. </p>
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<figcaption><span class="caption">Cows’ special digestive system is a major methane brewer.</span></figcaption>
</figure>
<h2>Plant-digesting machines</h2>
<p>Ruminant animals, such as cows, sheep and goats, can digest plant material that is indigestible for humans and animals with simple stomachs, such as pigs and chickens. This unique ability stems from ruminants’ four-compartment stomachs – particularly the rumen compartment, which contains a host of different microbes that ferment feed and break it down into nutrients. </p>
<p>This process also generates byproducts that the cow’s body does not take up, such as carbon dioxide and hydrogen. Methane-producing microbes, called methanogens, use these compounds to form methane, which the cow’s body expels.</p>
<p>We first analyzed this problem in a 2019 study, the first such research that was conducted in cattle rather than in a laboratory. In that work, we showed that supplementing dairy cows’ feed with about 10 ounces of seaweed a day <a href="https://doi.org/10.1016/j.jclepro.2019.06.193">reduced methane emissions by up to 67%</a>. However, the cattle that ate this relatively large quantity of seaweed consumed less feed. This reduced their milk production – a clear drawback for dairy farmers.</p>
<p>Our newer study sought to answer several questions that would be important to farmers considering whether to use seaweed supplements in their cattle. We wanted to know whether the seaweed was stable when stored for up to three years; whether microbes that produce methane in cows’ stomachs could adapt to the seaweed, making it ineffective; and whether the type of diet that the cows ate changed the seaweed’s effectiveness in reducing methane emissions. And we used less seaweed than in our 2019 study. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/389879/original/file-20210316-21-1u8brz2.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/389879/original/file-20210316-21-1u8brz2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/389879/original/file-20210316-21-1u8brz2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=430&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389879/original/file-20210316-21-1u8brz2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=430&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389879/original/file-20210316-21-1u8brz2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=430&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389879/original/file-20210316-21-1u8brz2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=541&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389879/original/file-20210316-21-1u8brz2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=541&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389879/original/file-20210316-21-1u8brz2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=541&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 steer eats alfalfa pellets as equipment measures his gas emissions, including methane.</span>
<span class="attribution"><span class="source">Breanna Roque</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
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<h2>Better growth with less feed</h2>
<p>For the study, we added 1.5 to 3 ounces of seaweed per animal daily to 21 beef cows’ food for 21 weeks. As with most new ingredients in cattle diets, it took some time for the animals to get used to the taste of seaweed, but they became accustomed to it within a few weeks. </p>
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<a href="https://images.theconversation.com/files/389881/original/file-20210316-15-qmfjvs.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Steer in barn, University of California, Davis." src="https://images.theconversation.com/files/389881/original/file-20210316-15-qmfjvs.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/389881/original/file-20210316-15-qmfjvs.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=668&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389881/original/file-20210316-15-qmfjvs.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=668&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389881/original/file-20210316-15-qmfjvs.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=668&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389881/original/file-20210316-15-qmfjvs.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=839&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389881/original/file-20210316-15-qmfjvs.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=839&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389881/original/file-20210316-15-qmfjvs.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=839&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cattle in the study adjusted quickly to seaweed supplements in their food.</span>
<span class="attribution"><span class="source">Breanna Roque</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
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<p>As we expected, the steers released a lot more hydrogen – up to 750% more, mostly from their mouths – as their systems produced less methane. Hydrogen has minimal impact on the environment. Seaweed supplements did not affect the animals’ carbon dioxide emissions.</p>
<p>We also found that seaweed that had been stored in a freezer for three years maintained its effectiveness, and that microbes in the cows’ digestive systems did not adapt to the seaweed in ways that neutralized its effects. </p>
<p>We fed each of the animals three different diets during the experiment. These rations contained varying amounts of dried grasses, such as alfalfa and wheat hay, which are referred to as forage. Cattle may also consume fresh grass, grains, molasses and byproducts such as almond hull and cotton seed.</p>
<p>Methane production in the rumen increases with rising levels of forage in cows’ diet, so we wanted to see whether forage levels also affected how well seaweed reduced overall methane formation. Methane emissions from cattle on high-forage diets decreased by 33% to 52%, depending on how much seaweed they consumed. Emissions from cattle fed low-forage diets fell by 70% to 80%. This difference may reflect lower levels of an enzyme that is involved in producing methane in the guts of <a href="https://doi.org/10.2527/jas.2015-0268">cattle-fed low-fiber diets</a>. </p>
<p>One important finding was that the steers in our study converted feed to body weight up to 20% more efficiently than cattle on a conventional diet. This benefit could reduce production costs for farmers, since they would need to buy less feed. For example, we calculate that a producer finishing 1,000 head of beef cattle – that is, feeding them a high-energy diet to grow and add muscle – could reduce feed costs by US$40,320 to $87,320 depending on how much seaweed the cattle consumed. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/389909/original/file-20210316-15-bjc9sc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of methane sources by continent." src="https://images.theconversation.com/files/389909/original/file-20210316-15-bjc9sc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/389909/original/file-20210316-15-bjc9sc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/389909/original/file-20210316-15-bjc9sc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/389909/original/file-20210316-15-bjc9sc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/389909/original/file-20210316-15-bjc9sc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=489&fit=crop&dpr=1 754w, https://images.theconversation.com/files/389909/original/file-20210316-15-bjc9sc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=489&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/389909/original/file-20210316-15-bjc9sc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=489&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Global methane sources include fossil fuel and biomass combustion, agriculture (mainly livestock), the breakdown of waste in landfills and natural decomposition in wetlands.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1088/1748-9326/ab9ed2">Jackson et al., 2020</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
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<p>We don’t know for certain why feeding cattle seaweed supplements helped them convert more of their diet to weight gain. However, previous research has suggested that some rumen microorganisms can use hydrogen that is no longer going into methane production to generate <a href="https://doi.org/10.1371/journal.pone.0161362">energy-dense nutrients</a> that the cow can then use for added growth.</p>
<p>When a panel of consumers sampled meat from cattle raised in our study, they did not detect any difference in tenderness, juiciness or flavor between meat from cattle that consumed seaweed and others that did not. </p>
<p>Commercializing seaweed as a cattle feed additive would involve many steps. First, scientists would need to develop aquaculture techniques for producing seaweed on a large scale, either in the ocean or in tanks on land. And the U.S. Food and Drug Administration would have to approve using seaweed as a feed supplement for commercial cattle. </p>
<p>Farmers and ranchers could also earn money for reducing their cattle’s emissions. Climate scientists would have to provide guidance on quantifying, monitoring and verifying methane emission reductions from cattle. Such rules could allow cattle farmers to earn credits from carbon offset programs around the world.</p><img src="https://counter.theconversation.com/content/157192/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ermias Kebreab receives funding from the Foundation for Agricultural Research, Elm Innovations, the David and Lucile Packard Foundation and the Grantham Foundation. He advises feed additive companies such as Blue Ocean Barns and Mootral. </span></em></p><p class="fine-print"><em><span>Breanna Roque 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>Cow burps and farts are no joke – they’re a big factor in climate change. A new study shows that daily seaweed supplements could tame this major methane source while saving ranchers money.Ermias Kebreab, Associate Dean and Professor of Animal Science. Director, World Food Center, University of California, DavisBreanna Roque, Ph.D. Student in Animal Biology, University of California, DavisLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1332952020-04-01T14:03:44Z2020-04-01T14:03:44ZPeanut allergy may start in the gut – opening up new ways to tackle it<figure><img src="https://images.theconversation.com/files/322622/original/file-20200324-155640-11bs8ma.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/peanut-butter-sandwich-63361243">Shutterstock/JiriHera</a></span></figcaption></figure><p>Severe food allergies can be terrifying, both for the person affected and their loved ones. Allergies are <a href="https://www.ncbi.nlm.nih.gov/pubmed/20920770?dopt=Abstract">increasing</a> and affect between 3% and 6% of the <a href="https://www.ncbi.nlm.nih.gov/pubmed/21236480?dopt=Abstract">population</a>. But science has yet to fully grasp the reasons why. One theory – which appears to be backed up by the evidence of a <a href="https://www.ncbi.nlm.nih.gov/pubmed/32139586">new study</a> – is that the answer lies in the human gut. </p>
<p>More specifically, the antibodies produced in the human gut. Antibodies are an important part of our immune system that help us recognise and eliminate “foreign” antigens (proteins on the surface of a substance that triggers an immune response). Foreign antigens are found on viruses, bacteria and other things that may cause us harm, as well as the food we eat. </p>
<p>Antibodies are made by B-cells (a type of white blood cell called a <a href="https://www.bbc.co.uk/bitesize/guides/ztp9q6f/revision/4">lymphocyte</a>) which mature in the bone marrow before migrating to other parts of the body. Then the B-cells make antibodies in response to foreign antigens they meet. This new study suggests that B-cells can influence whether an immune response is too “strong” against peanut antigens, by producing too much of a type of antibody that encourages severe allergic reactions, and not producing enough of the antibodies that keep our bodies from overreacting in this way.</p>
<h2>Antibodies and allergies</h2>
<p>Humans produce five different types of antibodies or immunoglobulins (Ig) – IgA, IgM, IgG, IgD and IgE. IgE, which is known as the “allergy antibody”, mainly protects us against parasite infections, but it also helps to cause anaphylaxis – a serious, rapid allergic reaction that can cause an itchy rash, throat or tongue swelling, shortness of breath, vomiting and ultimately death. Anaphylaxis can occur in people who are allergic to peanuts as well as <a href="https://www.food.gov.uk/business-guidance/allergen-guidance-for-food-businesses">other foods</a>.</p>
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<p>IgE is usually the least abundant type of antibody, at only 0.05% of antibodies in the blood, but it can cause the most powerful of immune reactions. IgG is the most common antibody in the blood, at around 75%. IgG helps other immune cells to clear away dangerous material.</p>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/32139586">Researchers</a> sequenced all the Ig antibody genes from B-cells in tissues from different organs of 19 people with a peanut allergy and compared them with those of non-allergic people. The results showed that more IgE-producing B-cells reside within the gut of those with allergies, compared with those who don’t. There were roughly equal numbers of B-cells in the blood and bone marrow of both groups, so it is the gut-residing B-cells that are different.</p>
<p>The report found that non-allergic people make more of the common IgG-type antibodies in response to peanut proteins than allergic people. These antibodies can neutralise the negative effect of the “allergic antibody” and therefore it may be that people with peanut allergies may not only produce too much IgE, but may not produce enough IgG.</p>
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Read more:
<a href="https://theconversation.com/curious-kids-if-you-have-lots-of-the-thing-youre-allergic-to-does-your-body-get-used-to-it-104881">Curious Kids: if you have lots of the thing you're allergic to, does your body get used to it?</a>
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<p>The research shows that gut tissue is a likely place for the development of the IgE allergy antibody in people who are allergic to peanuts. This makes sense because the gut is the site of vast quantities of foreign proteins, in the form of microflora (the microbes that live within us) and in the food we eat. But usually, people’s immune systems do not react to their gut contents because they have formed <a href="https://www.ncbi.nlm.nih.gov/pubmed/29338074">“tolerant” immune responses</a> early in life.</p>
<p>The timing of first exposure to proteins (of microbe or food origin) may be influencing how much <a href="https://www.ncbi.nlm.nih.gov/pubmed/28601684">IgE and IgG antibodies</a> are made. So if more allergic antibodies are made, then it renders that person “sensitive” (and more likely to be allergic), rather than tolerant. This is why immune <a href="https://www.ncbi.nlm.nih.gov/pubmed/24702950">tolerance training</a> through exposure to antigens while in the womb and early life, through proteins in the mother’s diet and her intestinal microflora, is particularly important.</p>
<p>An increasing <a href="https://www.ncbi.nlm.nih.gov/pubmed/30340391">body of evidence</a> supports the hypothesis that early antigen exposure increases tolerance and lowers risk of childhood food allergies and other diseases. Historically, pregnant women were advised to limit their intake of peanuts, as it was initially thought that consumption during pregnancy could increase the risk of an allergic child. </p>
<h2>Eating nuts during pregnancy</h2>
<p>Evidence now suggests that avoiding nuts during pregnancy may prevent the foetus being exposed to nut antigens in the womb, where tolerance starts to be developed, and therefore <a href="https://www.ncbi.nlm.nih.gov/pubmed/24366539">increase the risk</a> of an allergic child.</p>
<p>This hypothesis is also supported by recent evidence showing that intestinal microflora (of both mother and child) plays a major role <a href="https://www.ncbi.nlm.nih.gov/pubmed/27126036">in immune tolerance development</a>, both while in the womb and in early life. So eating nuts during pregnancy, or when breastfeeding, may reduce the risk of a child developing an allergy.</p>
<p>The new study also discovered that many people share similar peanut-reactive IgE DNA sequences, which was surprising as one person’s antibodies are usually different from another’s. </p>
<p>This suggests that IgE antibodies in different people recognise peanut proteins in a similar way, which could help scientists in developing drugs to neutralise the “allergic antibodies” that cause anaphylaxis. Such drugs could be taken before or after exposure to lessen the allergic reaction and prevent anaphylaxis. But it may be several years before this type of treatment is available.</p><img src="https://counter.theconversation.com/content/133295/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rachael Rigby 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>Evidence from a new study could help scientists develop drugs to neutralise the ‘allergic antibodies’ that cause anaphylaxis.Rachael Rigby, Senior Lecturer in Gastro-Intestinal Health, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1215872020-01-23T17:33:13Z2020-01-23T17:33:13ZProbiotics: What they are and how you might benefit from them<figure><img src="https://images.theconversation.com/files/304349/original/file-20191128-178121-1xivflu.jpg?ixlib=rb-1.1.0&rect=269%2C22%2C4580%2C2971&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Increased scientific understanding of the role microbes play in humans and other animals has led to the development of probiotics to improve heath. </span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>Probiotics are <a href="http://www.fao.org/3/a-a0512e.pdf">live microorganisms, usually bacteria, that can be consumed to offer health benefits</a>. </p>
<p>The ability of certain microbes to confer health benefits on their host was recognized more than 100 years ago. In 1904, Elie Metchnikoff, a scientist at the Pasteur Institute, claimed that <a href="https://www.smithsonianmag.com/science-nature/science-lecture-accidentally-sparked-global-craze-yogurt-180958700/">Bulgarian peasants lived longer by eating yogurt made from bacteria that served to ferment the milk</a>. Parisians rushed out to buy yogurt in response.</p>
<p>However, the huge variety of bacteria living on the planet was not appreciated back then. More recently, the development of technology that identifies organisms from their DNA has allowed scientists to show that <a href="https://doi.org/10.1093/femsle/fnz117">plants, animals, insects and humans can be hosts for many different types of microorganisms</a>.</p>
<p>This has fostered <a href="https://www.newscientist.com/round-up/microbiome/">the term “microbiome”</a> as studies have uncovered the <a href="https://doi.org/10.1038/nature06244">range of organisms present throughout the human body and their association with many diseases</a> — from cardiovascular and digestive diseases to anxiety, allergies and infection.</p>
<p>Recognition of the roles that microbes play has led to the purposeful development of <a href="https://www.healthlinkbc.ca/health-topics/tw2302spec">microbes (probiotics)</a> that aim to restore and maintain health in humans and other life forms. </p>
<h2>From babies to honey bees</h2>
<p>One research group discovered that some strains of probiotic lactobacilli can be used instead of antibiotics to <a href="https://doi.org/10.1086/652763">treat women with infectious mastitis</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/304351/original/file-20191128-178066-jgyuhm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/304351/original/file-20191128-178066-jgyuhm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/304351/original/file-20191128-178066-jgyuhm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/304351/original/file-20191128-178066-jgyuhm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/304351/original/file-20191128-178066-jgyuhm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/304351/original/file-20191128-178066-jgyuhm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/304351/original/file-20191128-178066-jgyuhm.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 research study shows probiotics to be an efficient alternative to antibiotics for the treatment of infectious mastitis during lactation.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>The use of probiotics can also be used in other life forms. They can counter the <a href="http://www.dx.doi.org/10.1128/AEM.02820-17">damage pesticides cause to the immune system of insects such as the honey bee</a>. </p>
<p>Research has also shown that gut microbes can affect the drugs we take, <a href="https://doi.org/10.1038/nrmicro.2016.17">processing them to become more active, less active and even toxic</a>. </p>
<h2>Probiotics for urogenital health</h2>
<p>In 1982, Dr. Andrew Bruce, then the chair of urology at Toronto General Hospital, and I decided to try to use lactobacilli to reduce the incidence of urinary and vaginal infections among women. </p>
<p>The idea was based on the finding that <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1941341">lactobacilli are dominant in the vagina and urethra of healthy women, but <em>E. coli</em> and other pathogens displace them in disease</a>. We theorized that by boosting the lactobacilli in the vagina and perineum (the space between the anus and the vulva), we could reduce the ascent of infective bacteria into the bladder.</p>
<p>The laboratory and clinical research took over 20 years to identify the lactobacilli that could best inhibit and disrupt the harmful bacteria. The end result was a product containing <em>Lactobacillus rhamnosus</em> GR-1 and <em>Lactobacillus reuteri</em> RC-14 that is now sold in more than 30 countries as <a href="https://doi.org/10.1139/cjm-2016-0733">a probiotic to alleviate the suffering associated with these conditions</a>.</p>
<p>With no alternative to antibiotics in almost 50 years, the contribution of probiotics to managing urogenital health is tangible and worthy of further exploration.</p>
<p>Other substances called prebiotics (essentially food for beneficial microbes) can also provide health benefits. For example, inulin from the chicory root, or human oligosaccharides in breast milk, <a href="https://doi.org/10.1038/nrgastro.2017.75">stimulate bacteria in the gut</a>. Compounds like lactulose may <a href="https://doi.org/10.1128/AEM.02200-17">help prevent urogenital infection</a>. </p>
<h2>The success of poop transplants</h2>
<p>If someone has a really disrupted intestinal microbiome, such as when antibiotic use leads to infection by <em>Clostridium difficile</em>, then the solution may be a fecal transplant — transferring a healthy person’s poop into their gastrointestinal tract. </p>
<p>As yucky as it sounds, it has a cure rate of <a href="https://dx.doi.org/10.1155%2F2018%2F1394379">80 to 90 per cent for this infection</a>. It is is done by <a href="https://doi.org/10.1038/ismej.2014.13">inserting a healthy stool (which is mostly microorganisms) into the intestine via the rectum</a> or via a tube from mouth to stomach. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/304354/original/file-20191128-178094-oongbr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/304354/original/file-20191128-178094-oongbr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/304354/original/file-20191128-178094-oongbr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/304354/original/file-20191128-178094-oongbr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/304354/original/file-20191128-178094-oongbr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/304354/original/file-20191128-178094-oongbr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/304354/original/file-20191128-178094-oongbr.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">3D illustration of intestinal bacteria.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>The success, and the now recognized link between the gut microbiome and health at other body sites, has led to fecal microbiota transplant being considered to treat other diseases. Examples include multiple sclerosis, digestive and <a href="http://www.dx.doi.org/10.1053/j.gastro.2019.01.033">liver diseases</a>. The rationale is that the transplanted bacteria can produce molecules that affect metabolism and other organ functions. </p>
<h2>Regulation of probiotics</h2>
<p>Probiotics tend to be sold as dietary supplements and foods, which keeps manufacturers from claiming they treat disease, even though some studies have shown efficacy. This dates back to regulators stating that only drugs can cure, treat, prevent and mitigate disease. </p>
<p>While this is an outdated view, it has formed the system within which all health and disease-related products are adjudicated. One result has been to curtail research and development and clinical studies by researchers and companies in the United States and Europe. </p>
<p>Many commercial products have been labelled as probiotic, but only those with clinical evidence to support their benefits should be considered. Experts have summarized the <a href="http://www.probioticchart.ca">tested products available in Canada</a> and the <a href="http://www.usprobioticguide.com">United States</a>, as well as the level of evidence, to help inform consumers and health-care providers.</p>
<p>These lists do not document every product, as many have not undergone the necessary testing in humans. More research is needed, so that probiotic use can be widened to have impacts across society and the ecosystem. </p>
<h2>A multi-billion dollar market</h2>
<p>The global market for probiotics is <a href="https://www.statista.com/statistics/821259/global-probioticsl-market-value/">forecast to reach to about US$69.3 billion by 2023</a>. This illustrates the interest of consumers and health-care providers in this area. In future, more products will be developed for specific health applications. </p>
<p>Because probiotic organisms produce molecules that pass from the intestine into the bloodstream, we may see treatments that could help <a href="https://www.ncbi.nlm.nih.gov/pubmed/27801892">the brain</a>, <a href="https://www.doi.org/10.1097/MPG.0000000000000187">lungs</a>, liver, <a href="http://www.dx.doi.org/10.1016/j.jmii.2015.10.003">skin</a> and <a href="http://www.dx.doi.org/10.1371/journal.pone.0187964">other organs</a>. Hopefully, researchers will compare probiotic strains to drugs to provide a perspective on where probiotics might fit in the spectrum of patient management. </p>
<p>Probiotics are not magic bullets or cures for all ills. For example, products tested so far have not proven valuable in the treatment of Crohn’s disease. Nevertheless, the use of beneficial microbes does represent an important field of science, with specific probiotic strains having the capacity to contribute to the well-being of humans and other life forms. </p>
<p>It is through scientific endeavour that such progress will be made to the betterment of humanity and the planet.</p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/ca/newsletters?utm_source=TCCA&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/121587/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gregor Reid helped to develop and commercialize probiotic strains GR-1 and RC-14 but has had no financial interest in them for over 10 years.
He is Chief Scientific Officer for Seed, a company producing probiotic products.
He has provided advice on probiotics in the past three years to Seed, KGK Science, Acerus Pharma, Danone, Chr Hansen, Altmann, Kimberly Clark Corp., and Metagenics.
He is funded by NSERC, OMAFRA and Kimberly Clark. </span></em></p>From dietary supplements to poop transplants, probiotics are now a multi-billion dollar market.Gregor Reid, Professor at Schulich Medicine & Dentistry, Western UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1276592019-12-04T13:30:39Z2019-12-04T13:30:39ZInequity takes a toll on your gut microbes, too<figure><img src="https://images.theconversation.com/files/304799/original/file-20191202-66998-29wvlu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Affluent neighborhoods have very different microbes from those in poor ones.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/luxury-house-slum-gap-between-poverty-1106629235">Zentangle/Shutterstock.com</a></span></figcaption></figure><p>People worry about having access to clean water, power, health care and healthy foods because they are essential for survival. But do they ever think about their access to microbes? </p>
<p>Every day, humans encounter microbes - in air, water, soil, food and buildings - and pick them up and leave them behind everywhere they go. Although you might be reaching for the hand sanitizer as you read this, many of these microbial exposures are beneficial to human health. But not everyone has equal access to good microbes.</p>
<p>Social equity is the practice of applying justice and fairness to our social policies. Society often measures it in terms of access. Do people have equal access to healthy food and clean water? Medical care? Safe housing? Parks and forests? My idea of “microbes and social equity” is rooted in the fact that we rely on the microbes that live in our bodies or in the environment around us. We need public policies that promote access to microbes. </p>
<p><a href="https://sueishaqlab.org/team/sue-ishaq/">I’m a gut microbiologist</a>, and I want to understand the microbes that pass through our digestive tract and how they impact us. For example, human beings can’t digest plant fiber; <a href="https://doi.org/10.1016/j.cmet.2014.07.003">we actually rely on several species of microbes</a> in our gut to do this, which provides us with the nutrients we need. <a href="https://doi.org/10.1371/journal.ppat.1004506">Microbes also help “train” our immune cells</a> not to attack those trillions of microorganisms living in or on the body, thereby maintaining a delicate truce.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/303199/original/file-20191122-74588-o05qjn.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/303199/original/file-20191122-74588-o05qjn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/303199/original/file-20191122-74588-o05qjn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/303199/original/file-20191122-74588-o05qjn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/303199/original/file-20191122-74588-o05qjn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/303199/original/file-20191122-74588-o05qjn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/303199/original/file-20191122-74588-o05qjn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/303199/original/file-20191122-74588-o05qjn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Not all microbiomes are created equally.</span>
<span class="attribution"><span class="source">Sue Ishaq</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Connecting with good microbes</h2>
<p>I wanted to create a space to learn about and discuss the idea of “Microbes and Social Equity,” so I developed and taught a course at the University of Oregon during the summer of 2019. I focused on how access to basic necessities like nutritious foods (and especially fiber), pre- and postnatal health care, and green space and city parks could influence microbial exposures and individual experiences throughout a lifetime. These findings and discussions have now been published as a <a href="https://doi.org/10.1371/journal.pbio.3000536">peer-reviewed essay in the journal PLoS Biology</a>. </p>
<p>Fibrous foods recruit microbes in the gut, especially ones that break down and ferment complex plant carbohydrates in order to create energy for themselves. In doing so, they produce several molecules (like butyrate) that we use for energy, and they yield a number of health benefits. </p>
<p>The paper in PloS Biology provides examples of research on microbes and health, such as the benefit of a fiber-rich diet in recruiting beneficial <a href="https://doi.org/10.1126/science.aao5774">gut microbes and reducing the symptoms of diabetes</a>. There are specific examples of social policies that might promote access to microbes, such as launching more school nutrition programs that require fruits and vegetables. There are also examples of policies with negative microbial impacts, such as inadequate food-service infrastructure in prisons, which can allow for the spread of foodborne illness.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/303209/original/file-20191122-74584-1qk9sen.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/303209/original/file-20191122-74584-1qk9sen.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=333&fit=crop&dpr=1 600w, https://images.theconversation.com/files/303209/original/file-20191122-74584-1qk9sen.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=333&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/303209/original/file-20191122-74584-1qk9sen.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=333&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/303209/original/file-20191122-74584-1qk9sen.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=419&fit=crop&dpr=1 754w, https://images.theconversation.com/files/303209/original/file-20191122-74584-1qk9sen.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=419&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/303209/original/file-20191122-74584-1qk9sen.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=419&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Providing a safe, supportive environment where women can nurse at work avoids situations like this.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/busy-mother-give-breastfeeding-while-talking-1421859695">Phoderstock/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>My students were especially interested in policies that support maternal health care and enable breastfeeding. Breast milk contains important components to boost the infant immune system, as well as a diverse community of bacteria, some of which <a href="https://doi.org/10.1016/j.chembiol.2017.03.012">support digestion of milk in the infant gut</a> and confer health benefits. </p>
<p>Infants who only receive formula recruit different gut microbes and are missing the ones derived from <a href="https://doi.org/10.1067/mai.2001.111237">breast milk that protect against allergies</a> and other health problems. Policies that provide pre- and postnatal care are known to <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4193436/">improve health outcomes for mothers and infants</a>. These policies also happen to support mother-infant microbial exposure, which can have huge health benefits. The lack of good policies may have the opposite effect: Many women identify a lack of social and infrastructural support as <a href="https://www.ncbi.nlm.nih.gov/books/NBK52688/">preventing them from breastfeeding their infants</a>, which also deprives the babies of the microbes they need.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/304800/original/file-20191202-66998-gb2c5v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/304800/original/file-20191202-66998-gb2c5v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/304800/original/file-20191202-66998-gb2c5v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/304800/original/file-20191202-66998-gb2c5v.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/304800/original/file-20191202-66998-gb2c5v.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/304800/original/file-20191202-66998-gb2c5v.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/304800/original/file-20191202-66998-gb2c5v.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">Urban gardens are one way to encourage exposure to healthy microbes.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-african-american-woman-inspecting-beets-1054297805">Joshua Resnick</a></span>
</figcaption>
</figure>
<h2>Poor-quality city infrastructure leads to poor-quality health</h2>
<p>The quality of the environment greatly impacts health. Plants are known to produce chemical compounds that benefit human health, and exposure to the diverse microbes found in the natural environment can keep our immune systems fit. Living near industrial areas exposes <a href="https://doi.org/10.1089/env.2011.0037">residents to lower air quality, contamination of water sources</a> with hazardous materials, noise pollution, and more. Worse, studies suggest that <a href="https://doi.org/10.1089/env.2008.0506">pollution-heavy industry is often intentionally placed in disadvantaged</a>, low-income, or predominantly minority-resident neighborhoods because they lack the social capital to negotiate better zoning. And, heavily urbanized or <a href="https://doi.org/10.1016/j.scitotenv.2016.07.037">industrial zones disperse different microbes</a> than a forest or park would, changing outdoor microbial exposure for residents of poorly planned neighborhoods. </p>
<p>Inequalities in access - such as only putting parks in wealthier neighborhoods - creates social inequity in resource distribution. But it also creates inequity in microbial exposure and may affect your health. However, zoning could be used to aid in the equitable distribution of resources. </p>
<p>Access is the basis for creating social equity. Globally, many governments have a legal obligation to provide access to a safe and healthy natural environment. If we consider that microbes are integral to maintaining public health, it follows that there is also a legal obligation to provide policy and infrastructure to enable equitable access to microbes. </p>
<p>This can be done by providing affordable maternal health care and parental leave to facilitate breastfeeding and train the immune system with good microbes. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/304806/original/file-20191202-67007-40uzy5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/304806/original/file-20191202-67007-40uzy5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/304806/original/file-20191202-67007-40uzy5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/304806/original/file-20191202-67007-40uzy5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/304806/original/file-20191202-67007-40uzy5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/304806/original/file-20191202-67007-40uzy5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/304806/original/file-20191202-67007-40uzy5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Industrial zones are particularly lacking in good microbes.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/railroad-tracks-detroit-michigan-94905997">Judy Marie Stepanian</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>It can be done with access to an affordable, high-quality diet with lots of fiber, especially by making healthy food available in public schools, prisons and “food deserts” with inadequate shopping options. </p>
<p>It can also be done by equitably distributing natural environments and green space in urban settings. Encouraging urban farms, local farmers’ markets, bike lanes and walking paths, and giving stores incentives to stock and sell healthy food items, can make urban and rural areas healthier by promoting physical activity, good food, clean air and water and diverse microbial exposures.</p>
<p>[ <em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/127659/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sue Ishaq has received funding from the United States Department of Agriculture, The Alfred P. Sloan Foundation, and the University of Oregon for her research in microbiology. She received salary for teaching this class at the University of Oregon but no additional funding for the work.</span></em></p>You probably know about the collection of microorganisms that live in, on and around us. But did you know that not everyone in society has equal access to them? That needs to change.Sue Ishaq, Assistant Professor of Animal and Veterinary Sciences, University of MaineLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1220722019-08-28T11:45:48Z2019-08-28T11:45:48ZWhy a glass of red wine is good for your gut<figure><img src="https://images.theconversation.com/files/288696/original/file-20190820-170956-1ubedl0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">'To gut microbes.'</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/happy-friends-having-fun-outdoor-young-486675022?src=8N-mDdqI3XzeMhmXh-bzTQ-1-2">View Apart/Shutterstock</a></span></figcaption></figure><p>Alcohol consumption guidelines <a href="https://www.theguardian.com/news/datablog/2016/jan/08/how-do-the-uks-new-alcohol-guidelines-compare-with-the-rest-of-the-worlds">vary widely between countries</a>. In the UK and Netherlands, <a href="https://www.theguardian.com/news/datablog/2016/jan/08/how-do-the-uks-new-alcohol-guidelines-compare-with-the-rest-of-the-worlds">no more than one glass</a> of wine or a pint of beer a day is recommended. In the US it is <a href="https://health.gov/dietaryguidelines/2015/guidelines/appendix-9/">double these levels</a>, and <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/add.13341">in Mediterranean countries and Chile</a> it’s even more relaxed when it comes to drinking wine. </p>
<p>Though there is generally a consensus that everyone should drink less and levels of alcohol use are reducing in most countries, <a href="https://theconversation.com/baby-boomers-are-keeping-booze-britain-afloat-but-the-young-are-drinking-less-121659">especially in young adults</a>, more than 3m (or one in 20) deaths globally are attributed to alcohol consumption – making it <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4311234/">100 times more harmful than cannabis, cocaine and heroin</a>. </p>
<p>Drinking any amount of alcohol is said to increase the <a href="https://theconversation.com/drinking-a-pint-of-beer-may-lower-your-life-expectancy-by-the-same-amount-as-smoking-a-cigarette-new-research-90346">risk of many diseases</a>, including cancers, and liver disease. Yet a number of <a href="https://www.ncbi.nlm.nih.gov/pubmed/86728">studies</a> also seem to suggest there might be <a href="https://www.ncbi.nlm.nih.gov/pubmed/9949793">health benefits to a low intake of red wine</a>. </p>
<h2>Red wine and the gut</h2>
<p><a href="https://www.gastrojournal.org/article/S0016-5085(19)41244-4/fulltext">Our new research</a> also adds support to the idea that a small glass of red wine a day might actually be beneficial to your health – specifically to your <a href="https://theconversation.com/gut-microbes-are-tiny-sensors-of-your-general-health-99098">gut bacteria</a>. </p>
<p>This community of trillions of microbe inhabiting our lower intestines is known as the gut microbiota. Research shows that our gut microbiota <a href="https://www.bmj.com/content/361/bmj.k2179">can affect multiple aspects of our general health</a> and play a role in many illnesses but also dictate how <a href="https://theconversation.com/belly-fat-gut-bacteria-checks-could-lead-to-personalised-diets-120035">the food we eat</a> or the drugs we take affect us. This is partly due to the fact that gut microbes are responsible for producing thousands of chemical metabolites, that have <a href="https://theconversation.com/how-gut-bacteria-ensure-a-healthy-brain-and-could-play-a-role-in-treating-depression-33041">effects on our brain</a>, metabolism and immune systems.</p>
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<em>
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Read more:
<a href="https://theconversation.com/moving-to-another-country-could-mess-with-your-gut-bacteria-106095">Moving to another country could mess with your gut bacteria</a>
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<p>Previous research in small studies <a href="https://academic.oup.com/ajcn/article/95/6/1323/4568378">in humans</a> and in <a href="https://www.sciencedirect.com/science/article/pii/S0963996913000616">artificial gut models</a> has suggested that red wine could impact our gut bacteria. And in our recent study we investigated this relationship on a large population scale in different countries to understand how drinking red wine may impact gut health compared to other alcoholic drinks.</p>
<p>We looked at food and drink questionnaire responses and gut bacteria diversity (that is recognised as <a href="https://theconversation.com/i-spent-three-days-as-a-hunter-gatherer-to-see-if-it-would-improve-my-gut-health-78773">a marker of gut health</a>) in almost a thousand female twins in the UK, and then checked our results against two other studies of similar size in the US (<a href="http://humanfoodproject.com/americangut/">the American Gut project</a>) and the Belgium (<a href="http://www.vib.be/en/research/Pages/The%20Flemisch%20Gut%20Flora%20project.aspx">Flemish Gut Project</a>). </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/289627/original/file-20190827-184234-1nu7r3c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289627/original/file-20190827-184234-1nu7r3c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289627/original/file-20190827-184234-1nu7r3c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289627/original/file-20190827-184234-1nu7r3c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289627/original/file-20190827-184234-1nu7r3c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289627/original/file-20190827-184234-1nu7r3c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289627/original/file-20190827-184234-1nu7r3c.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">Looks moderate to me.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/portrait-senior-vintner-young-winemaker-tasting-327865286?src=-1-7">Kinga</a></span>
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</figure>
<p>We found that drinking red wine (even if combined with other alcohols) is linked with an increase in gut bacteria diversity in all three countries. And as a check on other possible genetic or family biases, we also found that twins who drank more red wine than their co-twin also had more diverse gut bacteria. White wine drinkers who should be socially and culturally similar, had no significant differences in diversity, as did drinkers of other types of alcohol, like beer and spirits.</p>
<p>There were other associated benefits of drinking red wine too. Twins who drank red wine had lower levels of obesity and “bad” cholesterol, which we also think is partly because of the associated changes in the gut bacteria.</p>
<h2>Precious polyphenols</h2>
<p>Our study adds to the growing body of evidence that <a href="https://theconversation.com/the-compound-behind-all-those-stories-about-red-wine-being-good-for-you-35291">red wine</a> can, when drunk in moderation, have positive effects on health. The benefits of red wine likely boil down to one key agent: <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2835915/">polyphenols</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/289626/original/file-20190827-184222-1nllcvq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/289626/original/file-20190827-184222-1nllcvq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/289626/original/file-20190827-184222-1nllcvq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/289626/original/file-20190827-184222-1nllcvq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/289626/original/file-20190827-184222-1nllcvq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/289626/original/file-20190827-184222-1nllcvq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/289626/original/file-20190827-184222-1nllcvq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/289626/original/file-20190827-184222-1nllcvq.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">Guts love the polyphenols.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/bunch-grapes-on-vine-sunshine-winegrowers-346371485?src=-1-17">Marako85</a></span>
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<p>These molecules are natural defence chemicals found in nuts and seeds as well as many brightly coloured vegetables and fruits, including grapes. In grape, polyphenols are mostly found in the skins that are in much longer contact in the making of red wine than white. They include the tannins that have a drying effect on your tongue or <a href="https://theconversation.com/the-compound-behind-all-those-stories-about-red-wine-being-good-for-you-35291">resveratrol</a> that promotes good health in people, and they also act as a fuel for our gut bacteria. This probably explains why red wine has a much stronger effect on gut bacteria than white wine. Although non-alcoholic grape juice also contains polyphenols, the fermented version contains more. </p>
<p>While our results are very consistent, as an observational study – where we see if factors are associated more than by chance – we cannot prove causality. To show this we’d ideally need some form of intervention study to test whether red wine directly causes an increase in gut microbiota diversity that leads to improved health. This may be popular, but difficult in practice, however. So for now, all the evidence suggests that if you have to choose an alcoholic drink today, it should definitely be a small glass of red wine.</p><img src="https://counter.theconversation.com/content/122072/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Caroline Le Roy receives funding from the CDRF. </span></em></p><p class="fine-print"><em><span>Tim Spector receives grants from multiple organisations including MRC, Wellcome Trust, NIHR, NIH, CDRF, Danone. He is a scientific founder of ZOE (global) ltd and receives royalties from a book on diet and microbiome "The Diet Myth: the real science behind what we eat" Orion 2016. He also drinks red wine.</span></em></p>We found that drinking red wine is linked with an increase in gut bacteria diversity.Caroline Le Roy, Research Associate in Human Gut Microbiome, King's College LondonTim Spector, Professor of Genetic Epidemiology, King's College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1083202018-12-13T11:46:05Z2018-12-13T11:46:05ZThe key to our humanity isn’t genetic, it’s microbial<figure><img src="https://images.theconversation.com/files/250115/original/file-20181211-76977-1euccsw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The microbes that live in our gut are essential to good health.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/1139164184?size=huge_jpg">Alpha Tauri 3D Graphics/SHutterstock.com</a></span></figcaption></figure><p>What if the key to perfecting the human species were actually … yogurt? </p>
<p>The fantasy of trying to perfect humanity through genetics was recently reignited by the announcement of the <a href="https://theconversation.com/how-a-scientist-says-he-made-a-gene-edited-baby-and-what-health-worries-may-ensue-107764">Chinese scientist claiming</a> to have made the first “CRISPR babies,” which were named for the technique used to edit the DNA of the embryos. While major <a href="https://theconversation.com/the-road-to-enhancement-via-human-gene-editing-is-paved-with-good-intentions-107677">ethical and regulatory concerns</a> are present, fears that CRISPR will lead us into the dystopian world depicted in the movie <a href="https://www.imdb.com/title/tt0119177/">“Gattaca”</a> are unfounded. In fact, if the movie were remade today it would likely be a story about the government mandating probiotics and healthy eating. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/250117/original/file-20181211-76956-cpnsri.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/250117/original/file-20181211-76956-cpnsri.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/250117/original/file-20181211-76956-cpnsri.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=200&fit=crop&dpr=1 600w, https://images.theconversation.com/files/250117/original/file-20181211-76956-cpnsri.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=200&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/250117/original/file-20181211-76956-cpnsri.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=200&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/250117/original/file-20181211-76956-cpnsri.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=251&fit=crop&dpr=1 754w, https://images.theconversation.com/files/250117/original/file-20181211-76956-cpnsri.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=251&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/250117/original/file-20181211-76956-cpnsri.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=251&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Probiotic or yogurt drink filled with billions of beneficial bacteria.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/probiotic-yogurt-drink-pouring-into-glass-1121493248?src=dpWotwn10K3dSiJNImWmOg-1-74">HstrongART/Shutterstock.com</a></span>
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<p><a href="https://theconversation.com/boyer-lectures-the-new-eugenics-is-the-same-as-the-old-just-in-fancier-clothes-103165">Eugenics</a> is the belief that humanity can be perfected through genetic manipulation. Past eugenic policies placed restrictions on marriage and immigration, justified slavery and forced sterilizations, and ultimately culminated in the Holocaust. I am a physician-scientist specializing in allergies who became interested in eugenics not in relation to skin color, but skin rashes. Most prominent researchers who study a a skin rash called eczema were convinced that the vast majority of the disease is determined by <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4791162/">fixed genetic sequences</a>. Many still are. However, just like the studies of intelligence and criminal behavior that came before it, research into the <a href="https://www.ncbi.nlm.nih.gov/pubmed/?term=22197932">genetics of eczema</a> has fallen well short of what the 15th-century techniques had predicted. </p>
<p>To be fair, the public’s fascination with this subject is understandable. Commercial breaks are filled with pseudoscientific claims that your DNA can reveal, for example, that you are 12.4 percent Italian, 3.1 percent Neanderthal, and 1/512th Native American. Spoiler alert: <a href="https://theconversation.com/two-native-american-geneticists-interpret-elizabeth-warrens-dna-test-105274">It can’t</a>. Prominent <a href="http://nymag.com/intelligencer/2018/03/denying-genetics-isnt-shutting-down-racism-its-fueling-it.html?gtm=bottom&gtm=top">magazines</a>, <a href="https://samharris.org/ezra-klein-editor-chief/">podcasts</a> and <a href="https://www.nytimes.com/2018/05/08/opinion/intellectual-dark-web.html">newspapers</a> have pushed the debunked claim that intelligence is genetically encoded. In reality, genetic studies that were supposed to explain at least 80 percent of being a genius have explained <a href="https://doi.org/10.1038/s41588-018-0152-6">only 5 percent</a>. This means your genes, at best, have less impact on your IQ score than a <a href="https://doi.org/10.1016/j.sleep.2009.09.007">good night’s sleep</a>. However, modern misunderstanding of how complex traits are passed down isn’t just burdening society with hucksters and racists. Ignorance is causing us to overlook opportunities for improving health and treating disease.</p>
<h2>Where did ideas like a ‘gene for IQ’ come from?</h2>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/250274/original/file-20181212-110240-17m6fdr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/250274/original/file-20181212-110240-17m6fdr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/250274/original/file-20181212-110240-17m6fdr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/250274/original/file-20181212-110240-17m6fdr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/250274/original/file-20181212-110240-17m6fdr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/250274/original/file-20181212-110240-17m6fdr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/250274/original/file-20181212-110240-17m6fdr.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">Researchers conducting twin studies assumed that common behavior and trait was a result of common genes, not a common environment.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/phop-phratakthailand-august-9an-unidentified-child-695003356?src=wSmW-PLJvOou3F102BarfQ-1-43">natthawut ngoensanthia/Shutterstock.com</a></span>
</figcaption>
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<p>Most of the ideas of “genes for” complex traits come from twin studies that assumed that identical twins and fraternal twins would differ only by the amount of shared DNA. What twin researchers either didn’t realize, or willfully ignored, is that the influence of the environment is also stronger for identical twins. Because identical twins are more likely to be dressed alike and confused for one another, they form more of a <a href="https://www.madinamerica.com/2013/03/the-trouble-with-twin-studies/">shared identity</a>. </p>
<p>Thus, identical twins are more likely to share the same hobbies, eat the same foods, and run in the same social circles than fraternal twins. Modern research shows these differences are more psychology than biology. Furthermore, since identical twins share the same embryonic sac in the womb, their environmental exposures are also <a href="https://doi.org/10.1016/S0378-3782(01)00171-2">more biologically similar</a> than fraternal twins. As such, researchers claiming that twin study data is indicative of genetics are, at best, ill-informed. </p>
<h2>What is the modern understanding of heritable traits?</h2>
<p>It may seem counterintuitive, but just because one change can worsen a gene’s function, that doesn’t mean that a different change can enhance it. When scientists say a gene “contributes to intelligence” they are referring to situations in which mutations in the gene cause a loss of intelligence or delay in cognitive development. They are not implying that a special version of the gene can guarantee a college degree. </p>
<p>Enhancing the functions of genes is most often accomplished via <a href="https://doi.org/10.1056/NEJMra1402513">epigenetic modifications</a> – chemical tags that are attached to the DNA but do not alter the genetic code. If genes are words, sentences and paragraphs, then <a href="https://www.whatisepigenetics.com/fundamentals/">epigenetics</a> is the cadence, emphasis and diction. This is akin to having Hamlet performed by Gilbert Gottfried versus Benedict Cumberbatch. While epigenetic changes can be passed on from parents to children, they can also be altered by <a href="https://theconversation.com/extreme-stress-in-childhood-is-toxic-to-your-dna-99009">stress</a>, <a href="https://theconversation.com/how-your-grandparents-life-could-have-changed-your-genes-19136">diet, environment</a> and <a href="https://well.blogs.nytimes.com/2014/12/17/how-exercise-changes-our-dna/">behavior</a>. Therefore, I believe that environmental modification, not CRISPR, would be needed to enhance the vast majority of genetic functions.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/250283/original/file-20181212-110240-1b4glsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/250283/original/file-20181212-110240-1b4glsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=308&fit=crop&dpr=1 600w, https://images.theconversation.com/files/250283/original/file-20181212-110240-1b4glsy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=308&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/250283/original/file-20181212-110240-1b4glsy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=308&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/250283/original/file-20181212-110240-1b4glsy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=387&fit=crop&dpr=1 754w, https://images.theconversation.com/files/250283/original/file-20181212-110240-1b4glsy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=387&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/250283/original/file-20181212-110240-1b4glsy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=387&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">There are a lot more factors than genes that influence good health.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/health-components-556504684">arka38/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Another way to inherit traits</h2>
<p>A more recently appreciated influencer of heritable traits is the microbiome, the term for all of the microorganisms (bacteria, fungi and viruses) that peacefully co-exist with humans. </p>
<p>From a genetic standpoint, your human genes are <a href="https://doi.org/10.1038/nature08821">probably outnumbered</a> over 100 to 1 by microbial genes. Modern research suggests that the microbiome may be directly involved in diseases ranging from <a href="https://learn.genetics.utah.edu/content/microbiome/disease/">autism to obesity</a>. The microbial influence <a href="https://doi.org/10.1159/000268127">can be passed</a> from mother to child during and <a href="https://doi.org/10.1038/d41586-018-00664-8">possibly before</a> birth, but remains partially sensitive to <a href="https://doi.org/10.1186/1475-2891-13-61">diet</a> and <a href="http://doi.org/10.1016/j.cell.2018.10.029">environment</a> into adulthood. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/250286/original/file-20181212-110228-1v2li1p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/250286/original/file-20181212-110228-1v2li1p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/250286/original/file-20181212-110228-1v2li1p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=881&fit=crop&dpr=1 600w, https://images.theconversation.com/files/250286/original/file-20181212-110228-1v2li1p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=881&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/250286/original/file-20181212-110228-1v2li1p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=881&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/250286/original/file-20181212-110228-1v2li1p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1108&fit=crop&dpr=1 754w, https://images.theconversation.com/files/250286/original/file-20181212-110228-1v2li1p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1108&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/250286/original/file-20181212-110228-1v2li1p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1108&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Gut microbes are known to play a role in mental health.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/gutbrain-connection-gut-brain-axis-concept-643664689?src=37dpIXc2E7W92dSOsymsrQ-1-15">Anatomy Insider/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>The microbiome can even influence your epigenetics. Researchers are just beginning to tap into the potential of microbial treatments for diseases. Similar to our lab’s <a href="https://theconversation.com/applying-live-bacteria-to-skin-improves-eczema-95920">experimental treatment for eczema</a>, live bacterial therapies for <a href="https://doi.org/10.3389/fimmu.2018.01584">food allergies</a>, <a href="http://doi.org/10.1056/NEJMra1600266">depression and anxiety, heart disease and select cancers</a> are in development. As scientists clarify which strains of microbes are most helpful, these treatments are expected to become even more powerful. </p>
<p>Think of it this way: The current and former U.S. presidents <a href="https://www.genome.gov/19016904/faq-about-genetic-and-genomic-science/">share 99.9 percent</a> of their genetic sequence, despite being slightly more than 0.1 percent different. As such, modern scientists do not hide from eugenics-based ideas because they are controversial; they dismiss them because both <a href="https://www.imdb.com/title/tt0119177/">“Gattaca”</a> and <a href="https://www.vox.com/2018/4/10/17182692/bell-curve-charles-murray-policy-wrong">The Bell Curve</a> are to genetics what Flat Earthers are to astrophysics. </p>
<p>While properly conducted <a href="https://ghr.nlm.nih.gov/primer/therapy/genetherapy">gene therapy</a> does offer real hope for curing rare genetic diseases, its limitations stop well short of sci-fi. As just one example, feeding mice <a href="http://dx.doi.org/10.5056/jnm16018">one specific type of bacteria</a> significantly enhanced their memory, whereas genomics has failed to find any genes that could do the same. Ancestry charlatans and neo-eugenicists may deny the fact that people are more a product of their experiences than their genetic heritage, but perhaps their mothers just didn’t <a href="https://www.thelancet.com/action/showPdf?pii=S2214-109X%2818%2930371-1">breastfeed them</a> long enough.</p><img src="https://counter.theconversation.com/content/108320/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Myles receives government funding from The National Institute of Allergy and Infectious Diseases.</span></em></p>The effort to edit the genes of Chinese twins implies that all our traits are determined by our genes. But changing our diet, environment, lifestyle and microbes may have a greater effect.Ian Myles, Head, Epithelial Therapeutics Unit, National Institute of Allergy and Infectious DiseasesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1060952018-11-01T16:02:07Z2018-11-01T16:02:07ZMoving to another country could mess with your gut bacteria<figure><img src="https://images.theconversation.com/files/243479/original/file-20181101-83644-1juu5wq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/gut-bacteria-microbiome-inside-large-intestine-639806734?src=EOpvIjrmRApNR067Ofu3eA-1-5">Anatomy Insider/Shutterstock</a></span></figcaption></figure><p>Moving to a new country can be challenging, not just for us but also for our bacteria. A compelling new study <a href="https://doi.org/10.1016/j.cell.2018.10.029">published in Cell</a> suggests migration between certain countries can profoundly affect the bacteria that live in our digestive systems, with important implications for our health.</p>
<p>We know immigrants to the US are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579065/">more susceptible</a> to developing obesity and metabolic diseases such as diabetes than either people from the same countries who don’t migrate or <a href="http://www.rimed.org/rimedicaljournal/2015/01/2015-01-43-cont-heney.pdf">native-born US citizens</a>, but we don’t really understand why. To try to understand this phenomenon from a health perspective, researchers from the University of Minnesota conducted a large, in-depth study of Chinese and Thai immigrants moving to the US. The authors looked at the diet, gut microbes and <a href="https://www.nhs.uk/common-health-questions/lifestyle/how-can-i-work-out-my-body-mass-index-bmi">body mass index</a> of the immigrants before and after they moved. The evidence showed that the longer immigrants spent in the US, the less diverse their bacteria became, and that this was linked to rising obesity.</p>
<p>The human gut is home to hundreds of different species of bacteria known collectively as the “gut microbiome”. As well as breaking down food, this community of microorganisms helps our bodies <a href="https://gut.bmj.com/content/early/2018/06/22/gutjnl-2018-316723">fight and prevent disease</a>. There is even tantalising evidence that the gut microbiome can <a href="https://gutpathogens.biomedcentral.com/track/pdf/10.1186/1757-4749-5-3">influence our mental health</a>.</p>
<p>A more diverse gut microbiome is associated with <a href="https://www.bmj.com/content/361/bmj.k2179">a healthier digestive system</a>. And things that reduce this diversity, such as antibiotics, stress or changes in diet, can <a href="https://www.ncbi.nlm.nih.gov/pubmed/25126780">help make us more susceptible to conditions</a> like obesity or irritable bowel disease.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/243301/original/file-20181031-122150-1rd2y4x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/243301/original/file-20181031-122150-1rd2y4x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/243301/original/file-20181031-122150-1rd2y4x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/243301/original/file-20181031-122150-1rd2y4x.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/243301/original/file-20181031-122150-1rd2y4x.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/243301/original/file-20181031-122150-1rd2y4x.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/243301/original/file-20181031-122150-1rd2y4x.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/243301/original/file-20181031-122150-1rd2y4x.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Migration from Southeast Asia to the US comes with a loss in gut bacteria diversity.</span>
<span class="attribution"><span class="source">Vangay et al</span></span>
</figcaption>
</figure>
<p>The study compared a total of 514 healthy women, split into those born and living in Thailand, those born in Southeast Asia who later moved to the US, and those born in the US to immigrant parents originally from Southeast Asia. It found that changes to the gut microbiome began as soon as the immigrants arrived in the US and continued to change over decades. The longer they spent living there, the more their microbiomes began to resemble those of native-born Americans of European ethnic origin. The majority of participants, living in the US, also gained weight during the course of the study. </p>
<p>The combination of species that make up our gut microbiomes is strongly influenced by our diets, and so people from different parts of the world tend to have different bacteria. Western guts commonly contain lots of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5679392/"><em>Bacteroides</em> species</a>, which are good at digesting animal fats and proteins. The guts of people with <a href="https://www.nature.com/articles/nature11053">non-Western diets</a> rich in plants tend to be dominated by <em>Prevotella</em> species, which are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3463488/">good at digesting plant fibre</a>. The new study revealed that strains of bacteria from the immigrants’ native countries, particularly <em>Prevotella</em> species, were completely lost, as were relevant enzymes for digesting important plant fibres.</p>
<h2>Cause or effect?</h2>
<p>Studies that suggest that the microbiome can influence human health or disease are often challenged because it is hard to distinguish between cause and effect. In this case, it’s unclear whether changes in the microbiome are directly contributing to the high incidence of obesity in US immigrants. It may be some time before we fully understand whether a less diverse microbiome leads to obesity, or if obesity leads to a less diverse microbiome.</p>
<p>Most of our knowledge in this area comes from studying laboratory mice. Ground-breaking studies from the lab of US biologist <a href="https://www.nature.com/articles/nature05414">Jeff Gordon</a> first found a link between obesity and the gut microbiome in 2006, when they showed mice gained weight when they were given gut bacteria from obese humans. But, we also know high-fat diets <a href="https://www.nature.com/articles/srep32484">drive obesity regardless</a> of what’s in the gut microbime. So it would be premature to suggest that the microbiome alone is responsible for obesity.</p>
<p>With <a href="http://www.oecd.org/berlin/Is-migration-really-increasing.pdf">immigration increasing</a> and eating habits evolving, it is important we better understand how changes in populations, cultures and diets can impact human microbiomes so that we can spot potential health problems. For example, we know that refugees, <a href="https://link.springer.com/article/10.1007/s10903-016-0461-8">particularly children</a>, are more prone to developing obesity so we need to develop novel strategies to combat this. </p>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4372278/">Education is one aspect</a> and another is tackling poverty, which tends to be <a href="https://www.irp.wisc.edu/publications/focus/pdfs/foc262e.pdf">higher among immigrants</a> than native-born citizens. But if the gut microbiome really is central to health and disease then finding ways to treat it directly by prescribing things like <a href="https://theconversation.com/probiotics-a-first-look-at-whats-going-on-in-the-gut-102621">probiotics</a> or even <a href="https://theconversation.com/why-poo-transplants-are-nothing-to-be-sniffed-at-49319">faecal transplants</a> could help. One day we might even have <a href="https://www.nytimes.com/2015/11/10/health/fecal-transplants-made-somewhat-more-palatable.html">microbial “pills”</a> that could help migrants combat the changes to their gut microbiomes and settle more healthily in their new homes.</p><img src="https://counter.theconversation.com/content/106095/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chloe James is affiliated with The Microbiology Society. </span></em></p><p class="fine-print"><em><span>Ian Goodhead receives funding from the Wellcome Trust and Royal Society </span></em></p>Study finds changes to gut microbiome begin as soon as migrants move to the US and continue to change over decades.Chloe James, Senior Lecturer in Medical Microbiology, University of SalfordIan Goodhead, Lecturer in Infectious Diseases, University of SalfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1055962018-10-25T10:38:06Z2018-10-25T10:38:06ZOrganic food and cancer risk – gut microbe expert on latest research<figure><img src="https://images.theconversation.com/files/242112/original/file-20181024-71014-1edh3lv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cutting out pesticides by eating only organic food could slash your cancer risk.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Organic food is an over-hyped and overpriced fad, <a href="https://metro.co.uk/2016/10/17/actually-organic-food-is-pretty-much-a-waste-of-money-according-to-science-6196186/">according to many people</a>. But a <a href="https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2707948">recently published study</a> which followed nearly 69,000 French people over four and a half years seems to indicate there is a link between eating organic foods and a lower cancer risk.</p>
<p>The study found the regular eaters of 16 types of organic products were protected against several cancers by about a quarter. The foods included fruit, vegetables, bread, flour, eggs, meat and cereals. </p>
<p>More than <a href="https://ec.europa.eu/agriculture/organic/eu-policy/data-statistics_en">20% of EU land</a> is now allocated for organic farming and the organic sector is booming. But until now there has been no clear consensus on whether eating organic food is worth the extra cost. So is it time to throw out all your fruit and veg and only shop organic in the future?</p>
<h2>Going organic</h2>
<p>The study suggests people who regularly eat organic plant foods have a reduction in risk of common cancers. The data also shows a reduction for breast cancer after the menopause – but not before.</p>
<p>But while these results suggest a relationship, it is a long way from proof. This is because the study itself was too short and has the usual biases of observational designs – in that people who are healthier are more likely to eat healthier foods. And while the authors adjusted for body weight, social class and educational level, as well as other differences, and still found a consistent effect, the possibility of bias still remains on any single observational study.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/242115/original/file-20181024-71035-1mb547s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/242115/original/file-20181024-71035-1mb547s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/242115/original/file-20181024-71035-1mb547s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/242115/original/file-20181024-71035-1mb547s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/242115/original/file-20181024-71035-1mb547s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/242115/original/file-20181024-71035-1mb547s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/242115/original/file-20181024-71035-1mb547s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=506&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">People who eat more organic foods may be less likely to develop certain cancers, the French study suggests.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>The results, however are most convincing for a reduction in cancer of the immune system called Non-Hodgkin’s lymphoma. This is because two previous studies (also longitudinal and observational) – the largest being a study of 680,000 women over nine years – <a href="https://www.nature.com/articles/bjc2014148">also showed the same preventive effects</a>. The fact that all three studies show a reduction of risk for this type of cancer (by chance or bias alone) is more indicative that there could be a link between organic eating and a lower cancer risk. </p>
<h2>Herbicides and health</h2>
<p>There is no hard evidence that the taste or nutrient differences (fibre, vitamins and minerals) of organic vegetables are very different to regular varieties – although <a href="https://www.ncbi.nlm.nih.gov/pubmed/24968103">analysis suggests</a> they contain more polyphenols. These are compounds that often give plants their colour and provide antioxidant defences and are generally <a href="https://www.medicalnewstoday.com/articles/319728.php">beneficial for human health</a>.</p>
<p>In the US and Europe, fruits and vegetables are regularly sprayed with a range of <a href="https://theconversation.com/new-research-suggests-common-herbicides-are-linked-to-antibiotic-resistance-87678">pesticides and herbicides</a>. Organic plants do still have detectable levels of herbicides and pesticides, but <a href="http://onlinelibrary.wiley.com/doi/10.2903/j.efsa.2016.4611/pdf">they are five times lower</a>
than non-organic products. Many common fruits and cereals such as oats often have high levels – which aren’t reduced much by washing or peeling.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-controversial-weedkiller-has-won-a-new-five-year-lease-in-europe-but-citizens-are-fighting-back-88363">A controversial weedkiller has won a new five-year lease in Europe, but citizens are fighting back</a>
</strong>
</em>
</p>
<hr>
<p>So it could well be that ingesting chemically treated plants over years may actually increase some cancers. <a href="https://theconversation.com/stop-worrying-and-trust-the-evidence-its-very-unlikely-roundup-causes-cancer-104554">A US jury</a>, for example, recently awarded millions of dollars in damages to a groundsman with Non-Hodgkin’s lymphoma who regularly used <a href="https://theconversation.com/a-controversial-weedkiller-has-won-a-new-five-year-lease-in-europe-but-citizens-are-fighting-back-88363">the weed killer Glyphosate</a> (Roundup). This weedkiller is widely used around the world and in more than five million acres of farmland in the UK alone.</p>
<p>The government and the EU maintains that these chemicals are safe for humans at doses found in food. But the safety thresholds are based on old-fashioned lab animal data – where rodents are given doses a thousand times higher and see if they develop extra cancers. The safety tests for foods and chemicals have not changed for decades and do not include the long-term effects, for example, on our gut microbiomes. </p>
<h2>A gut issue</h2>
<p>We have 100 trillion microbes in our lower intestines <a href="https://theconversation.com/i-spent-three-days-as-a-hunter-gatherer-to-see-if-it-would-improve-my-gut-health-78773">that make up a community</a>
that are crucial for the immune system and for the body’s response to cancer and cancer therapies – such as <a href="https://www.ncbi.nlm.nih.gov/pubmed/29302014">immunotherapy for melanoma</a>. These microbes and their genes are much more sensitive to chemicals than we are, and this can lead to disruption in their <a href="https://theconversation.com/postbiotics-and-smart-toilets-new-era-of-harnessing-our-microbial-chemicals-to-keep-us-slim-and-healthy-96861">metabolism and the chemicals they produce</a>.</p>
<p>This new knowledge of the importance of a healthy gut microbiome casts doubt on official advice that all pesticides and herbicides are safe for us over long periods of time. And greater scrutiny of the safety of these widely used chemicals in our foods needs to be carried out in well-funded clinical trials – over years, not weeks. </p>
<p>There may of course be no direct effects on humans. But, as yet, no one has provided evidence to show that such chemicals are not harmful long-term for our immune system. So, while the risks for individuals are likely to be low, until we know for sure, for those who like eating lots of plants, spending a bit more for organic fruit and veg (and porridge oats) may be a price worth paying to keep your gut microbes healthy.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-sauerkraut-is-leading-a-food-revolution-60133">How sauerkraut is leading a food revolution</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/105596/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tim Spector receives grant funding from the MRC, NIHR, Wellcome Trust, EU. CDRF. He is a consultant to Zoe Global Ltd and author of "The Diet Myth: the science behind what we eat". Orion 2016 </span></em></p>New research suggests people who eat organic plant foods have a reduction in risk of common cancers.Tim Spector, Professor of Genetic Epidemiology, King's College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/957242018-05-23T13:10:42Z2018-05-23T13:10:42ZWhat your poo says about your health<figure><img src="https://images.theconversation.com/files/219938/original/file-20180522-51091-h4qo6j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/download/success?u=http%3A%2F%2Fdownload.shutterstock.com%2Fgatekeeper%2FW3siZSI6MTUyNzAxMTY0MiwiYyI6Il9waG90b19zZXNzaW9uX2lkIiwiZGMiOiJpZGxfNDgzMDkzNTU2IiwiayI6InBob3RvLzQ4MzA5MzU1Ni9odWdlLmpwZyIsIm0iOjEsImQiOiJzaHV0dGVyc3RvY2stbWVkaWEifSwid09pVGlzNXFlVG1HWkU3SDBBMm5IRzZUa3NjIl0%2Fshutterstock_483093556.jpg&pi=33421636&m=483093556&src=I0E_GIQDNF6GwSWFZnexYg-1-28">Shutterstock</a></span></figcaption></figure><p>Opening your bowels is a basic function of life. But despite the fact we all do it, pooing is not often thought to be a topic suitable for polite conversation. However, recent <a href="http://www.bbc.co.uk/news/health-43674270">popular interest in gut health</a> and the composition of poo – as well as the <a href="https://www.theguardian.com/news/2018/mar/26/the-human-microbiome-why-our-microbes-could-be-key-to-our-health">bacterial populations that live within it</a> – have helped to put bodily functions more on the map. And these days, more and more people are wondering how often you should go, what happens if you don’t go enough and how you can influence the composition of what is passed.</p>
<p>In the late 1980s, Professor Ken Heaton and colleagues conducted a <a href="http://gut.bmj.com/content/gutjnl/33/6/818.full.pdf">survey of the population</a> in East Bristol, in the UK. They reported the common wisdom that “99% of people defecate between three times per week and three times per day” which was revealed in an earlier study of <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1846921/">factory workers and GP patients</a>. In Bristol, they noted that although the most common bowel habit was once daily, it only occurred in 40% of men and a third of women.</p>
<p>How often we go for a number two can differ from person to person. We all have what’s known as a “<a href="https://www.gastrojournal.org/article/0016-5085(78)90864-8/abstract">gastro-colic reflex</a>” – which means that each time we eat food, our large bowel responds and we should go to the toilet. Through a range of hormones we will experience a “<a href="https://www.ncbi.nlm.nih.gov/pubmed/12870774">call to stool</a>”. Most of us, however – from the time we can walk – suppress this call, so once a day or less has become the new norm.</p>
<p>Urgency, diarrhoea, and constipation can all be features of not going to the toilet enough. And associated with this “relative” constipation are symptoms of bloating, pain and variability of bowel habit. A simple test of how your bowels are working is the “sweetcorn test”. By swallowing a handful of raw sweetcorn – which is not absorbed by the body – the brightly coloured kernels can be easily seen in your motions. This is an easy way to assess your own mouth-to-anus transit time. It should probably be about eight hours.</p>
<h2>The composition of poo</h2>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/26246784">Poo is made up of 75% water</a>. The rest, which is the solid stuff, is up to 50% microbes plus cells that are shed from the bowel lining and food residue. The collective name for the microbes that live inside us is the microbiome and at one time, it was thought that the bugs outnumbered our cells by ten to one. </p>
<p><a href="http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002533">Recent data</a> suggests this may be closer to a ratio of 1.3 to 1 but this will obviously depend on how often you go. Bacteria, viruses, fungi and single cell microbes make up the microbiome and all <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4181834/">may be critical</a> to our health and well-being.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/219983/original/file-20180522-51105-c037fl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219983/original/file-20180522-51105-c037fl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219983/original/file-20180522-51105-c037fl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219983/original/file-20180522-51105-c037fl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219983/original/file-20180522-51105-c037fl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219983/original/file-20180522-51105-c037fl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219983/original/file-20180522-51105-c037fl.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">Up to 75% of people use their phone on the toilet.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/success?u=http%3A%2F%2Fdownload.shutterstock.com%2Fgatekeeper%2FW3siZSI6MTUyNzAyNzAyNSwiYyI6Il9waG90b19zZXNzaW9uX2lkIiwiZGMiOiJpZGxfMjQ2NzEzNjQxIiwiayI6InBob3RvLzI0NjcxMzY0MS9odWdlLmpwZyIsIm0iOjEsImQiOiJzaHV0dGVyc3RvY2stbWVkaWEifSwieG9aSXpBNyt5YWlTVlRxRm9hbk8zbVRhMUlnIl0%2Fshutterstock_246713641.jpg&pi=33421636&m=246713641&src=FFiW_UE5-dA665Qzal7nUw-1-32">Shutterstock</a></span>
</figcaption>
</figure>
<p>From a positive perspective, the bugs in our guts not only breakdown undigestible foodstuffs, but they also produce critical nutrients, prevent certain infections and contribute to the development of our <a href="https://www.sciencedirect.com/science/article/pii/S2095809917301492">immune defence systems</a>. However, <a href="https://www.nature.com/articles/nature05414">obesity</a>, <a href="https://www.ncbi.nlm.nih.gov/pubmed/23023125">type two diabetes</a>, <a href="https://www.ncbi.nlm.nih.gov/pubmed/25870193">high blood pressure</a>, <a href="https://www.ncbi.nlm.nih.gov/pubmed/17699621">inflammatory bowel disease</a>, <a href="https://www.ncbi.nlm.nih.gov/pubmed/23370376">autoimmune disorders</a> and <a href="https://www.ncbi.nlm.nih.gov/pubmed/22968153">mental health problems</a> have all been linked to dysbiosis – or change of the microbiome.</p>
<h2>Gut feelings</h2>
<p>Establishment of our <a href="https://www.ncbi.nlm.nih.gov/pubmed/24503132">microbiome starts at birth</a> and is influenced by the way we are born – either vaginally or by Cesarean – and initially fed. By the time we start eating solid food, we are well on the way to establishing our adult microbiome. What we subsequently <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4303825/">eat can have an impact on the composition</a>, although this effect may be modest. </p>
<p>Our diets also may influence the metabolic products of our microbiome – these are the chemicals that the individual organisms produce – which can also have an impact on us as the host. Fibre, fat, sugars, artificial sweeteners have all been shown to modulate the composition of the <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4303825/">gastrointestinal microbiota</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/219985/original/file-20180522-51130-x2521o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219985/original/file-20180522-51130-x2521o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219985/original/file-20180522-51130-x2521o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219985/original/file-20180522-51130-x2521o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219985/original/file-20180522-51130-x2521o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219985/original/file-20180522-51130-x2521o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219985/original/file-20180522-51130-x2521o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">You inherited all your human DNA from your parents — but your microbiome is more complicated.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/success?u=http%3A%2F%2Fdownload.shutterstock.com%2Fgatekeeper%2FW3siZSI6MTUyNzAyNzMxNSwiYyI6Il9waG90b19zZXNzaW9uX2lkIiwiZGMiOiJpZGxfNDE0NzMzMjkxIiwiayI6InBob3RvLzQxNDczMzI5MS9odWdlLmpwZyIsIm0iOjEsImQiOiJzaHV0dGVyc3RvY2stbWVkaWEifSwiOXZBeTBXMk5uZm1JMnVtUm5hcDhCbkVSb1dFIl0%2Fshutterstock_414733291.jpg&pi=33421636&m=414733291&src=eeeOfIiGUtECdRtfEVUyfQ-1-59">Shutterstock</a></span>
</figcaption>
</figure>
<p><a href="https://www.ncbi.nlm.nih.gov/pubmed/21767445">Experimental data</a> suggests that prebiotic fibres change gut microbiota and increase hormones that tell us that we are full. <a href="https://www.newcastle.edu.au/profile/emma-beckett">Current ongoing research</a> has also shown that antibiotic induced microbial imbalance is associated with changes in bitter taste expression – which influences the foods we prefer to eat. All these relationships are complex, and scientists are just beginning to understand their full impact.</p>
<p>The ultimate way to alter our microbiome is a <a href="http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1002503">faecal transplant</a>, where you take on board the poo from someone else. Unpleasant as this may sound, encouraging data is emerging on the use of poo in the treatment of gastrointestinal infections such as clostridium difficile, early diabetes, multiple sclerosis and inflammatory bowel disease. But it may still be a while before you can buy prized poo over the counter in your local supermarket.</p><img src="https://counter.theconversation.com/content/95724/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Martin Veysey is affiliated to Hull York Medical School and receives funding from Australian Research Council, National Health and Medical Research Council, Central Coast Local Health District. </span></em></p>An expert explains how often you should poo and what it should look like.Martin Veysey, Programme Director MBBS at Hull York Medical School, University of HullLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/830682017-08-31T15:35:55Z2017-08-31T15:35:55ZParasites inside your body could be protecting you from disease<figure><img src="https://images.theconversation.com/files/183484/original/file-20170825-19945-1y6rgd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some E. Coli protect humans from more harmful strains.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>It’s fair to say parasites are generally bad for their hosts. Many cause disease and death so, like most species, we humans usually try to avoid infection at all costs. But it turns out that some parasites, although potentially harmful in isolation, can in fact help hosts to cope with more deadly infections.</p>
<p>Understanding when parasitism is beneficial has important implications for how we manage infectious diseases, but we currently know very little about this phenomenon. <a href="http://dx.doi.org/10.1002/evl3.19">Our new study</a>, published in <a href="http://bit.ly/2wuPJnY">Evolution Letters</a>, tells us that parasites can readily evolve different mechanisms to defend their hosts from other infections, which suggests that host protection should be common in nature.</p>
<p>The idea that “the enemy of my enemy is my friend” <a href="http://nationalinterest.org/feature/chanakya-indias-truly-radical-machiavelli-12146">has been around in human society for a long time</a> but it is far from unique to human conflict. The natural world is full of examples where parasites are harmful under some conditions and helpful under others.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/183482/original/file-20170825-19955-1r6503t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/183482/original/file-20170825-19955-1r6503t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=477&fit=crop&dpr=1 600w, https://images.theconversation.com/files/183482/original/file-20170825-19955-1r6503t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=477&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/183482/original/file-20170825-19955-1r6503t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=477&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/183482/original/file-20170825-19955-1r6503t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=600&fit=crop&dpr=1 754w, https://images.theconversation.com/files/183482/original/file-20170825-19955-1r6503t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=600&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/183482/original/file-20170825-19955-1r6503t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=600&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Friends, for now.</span>
<span class="attribution"><span class="source">U.S. Signal Corps</span></span>
</figcaption>
</figure>
<p>Bacteria that <a href="http://dx.doi.org/10.1038/nature23292">live in our gut</a> can occasionally cause problems, but they also <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4402713/">prevent colonisation by more harmful microbes</a> such as <em>Salmonella enterica</em>, which causes food poisoning. Similarly, bacteria that commonly infect insects are usually costly but can <a href="http://dx.doi.org/10.1371/journal.ppat.1002043">provide protection against more deadly infections</a>. And the larvae of monarch butterflies <a href="http://dx.doi.org/10.1016/j.meegid.2010.11.017">are more likely to survive infection</a> by a parasitic fly when they are also infected by a protozoan (single-celled organism).</p>
<p>Parasites can also help their hosts in other ways, for example by causing more serious disease in other species. This is one of the main reasons <a href="https://theconversation.com/in-defence-of-the-grey-squirrel-britains-most-unpopular-invader-73983">why grey squirrels have rapidly displaced red squirrels</a> from most of the UK. Grey squirrels are carriers of <a href="http://www.northernredsquirrels.org.uk/squirrels/squirrel-pox-virus/">squirrel pox virus</a>, which is usually fatal to red squirrels but is rarely harmful to greys. Likewise, some species of bacteria engage in a form of <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0059043">primitive biological warfare</a> by carrying viruses to which competing bacteria are not immune.</p>
<p>These examples reveal that being infected is not necessarily a bad thing and in fact can sometimes be beneficial. But what they don’t tell us is how and when parasites evolve to be useful to their hosts.</p>
<p><a href="http://dx.doi.org/10.1038/ismej.2015.259">Recent lab experiments</a> have shown that mildly harmful bacteria living inside microscopic worms can evolve in just a few days to protect their hosts from a lethal infection. This striking result indicates that bacteria can rapidly evolve host protection against other infectious diseases.</p>
<p>Still, very little is known about how and when such evolution occurs in nature. And if a parasite evolves to protect its host from a more deadly infection, has the enemy now become a friend?</p>
<h2>From foe to friend</h2>
<p><a href="http://dx.doi.org/10.1002/evl3.19">Using mathematical modelling</a>, we explored the evolution of two forms of host protection: resistance and tolerance. Parasites that protect by conferring resistance to their hosts reduce the likelihood that a second species will be able to infect them, such as when <a href="http://dx.doi.org/10.1038/nature23292">bacteria in the gut prevent colonisation by other microbes</a>. In contrast, parasites that confer tolerance to their hosts reduce the harm caused by another species after it infects them, as appears to be the case with the <a href="http://dx.doi.org/10.1016/j.meegid.2010.11.017">protozoa that protect monarch butterfly larvae from parasitic flies</a>.</p>
<p>We discovered that both forms of host protection evolve under a wide range of conditions even though the protective parasite may have to divert resources from its own growth or reproduction to defend the host. Protection still evolves because this cost is more than offset by the increased survival of the host (and hence the protective parasite).</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/183485/original/file-20170825-19930-1b6vkeq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/183485/original/file-20170825-19930-1b6vkeq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/183485/original/file-20170825-19930-1b6vkeq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/183485/original/file-20170825-19930-1b6vkeq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/183485/original/file-20170825-19930-1b6vkeq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/183485/original/file-20170825-19930-1b6vkeq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/183485/original/file-20170825-19930-1b6vkeq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Monarch butterfly larvae are protected from one parasite by another.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>But there are some notable differences between the two forms of protection. For instance, resistance usually increases the population size of the host, but tolerance can have a negative effect because it increases the overall prevalence of disease. These differences indicate that the mechanism of protection is crucial for determining whether a protective parasite is truly beneficial.</p>
<p>We can now combine <a href="http://dx.doi.org/10.1002/evl3.19">mathematical modelling</a> with <a href="http://dx.doi.org/10.1038/ismej.2015.259">lab experiments</a> of evolving microbes to answer intriguing questions about how other species evolve in response to host protection. Does the host evolve to harbour the protective parasite, and is this how we developed a symbiotic relationship with some of our gut bacteria? Can more harmful parasites evolve to overcome host protection? Answering questions like these can help us <a href="http://www.hopkinsmedicine.org/gastroenterology_hepatology/clinical_services/advanced_endoscopy/fecal_transplantation.html">find new ways to treat infectious diseases</a>.</p>
<p>The results of our research shed light on a fascinating biological phenomenon about which <a href="http://dx.plos.org/10.1371/journal.ppat.1005465">we still know very little</a>. Yet taken together with the growing number of examples of host protection, it is clear – at least if you’re hosting a parasite – that the enemy of your enemy can indeed be your friend.</p><img src="https://counter.theconversation.com/content/83068/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ben Ashby receives funding from the Natural Environment Research Council (NERC). He is affiliated with Sense About Science. </span></em></p>Sometimes the enemy of your enemy is your friend.Ben Ashby, Research fellow, University of BathLicensed as Creative Commons – attribution, no derivatives.