tag:theconversation.com,2011:/ca/topics/blood-type-8610/articlesBlood type – The Conversation2022-03-07T12:19:45Ztag:theconversation.com,2011:article/1783472022-03-07T12:19:45Z2022-03-07T12:19:45ZCOVID: risk of severe disease could be in your blood, new research finds<figure><img src="https://images.theconversation.com/files/450353/original/file-20220307-109389-1mcvc4g.jpg?ixlib=rb-1.1.0&rect=551%2C49%2C7296%2C4611&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/flowing-red-blood-cells-erythrocyte-on-1392918200">MarySan/Shutterstock</a></span></figcaption></figure><p>Multiple factors play a role in complex diseases like COVID, and knowing what they are is important for predicting how different people will be affected. Early on in the pandemic, being <a href="https://gh.bmj.com/content/6/12/e006434">older</a>, <a href="https://evidence.nihr.ac.uk/alert/excess-weight-increases-risks-of-severe-covid-19/">overweight</a> or <a href="https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-021-11579-x">smoking</a> were identified as increasing your risk of developing severe COVID. This then informed public health decisions – the elderly were prioritised in the vaccine rollout, for example.</p>
<p>But there are other biological factors involved in COVID that are less well understood. Consider, for example, the thousands of proteins with different functions that circulate in your blood. Some play a role in the body’s defence against viruses, others transport molecules around the body or act as messengers to distribute information.</p>
<p>Through these functions, <a href="https://pubmed.ncbi.nlm.nih.gov/33153974/">these proteins</a> can <a href="https://www.nature.com/articles/s41598-021-04683-w">impact</a> the development and <a href="https://www.nature.com/articles/s41598-021-98253-9">severity of COVID</a> – and crucially, we don’t all have the same amounts of them inside us. This is why people develop different forms of COVID: some get a runny nose or fever, while others need to go to hospital. An unlucky few may need intensive care, and in the severest cases, some may die.</p>
<p>As the number of proteins in the human body is so large, it’s difficult to pinpoint the exact proteins and biological systems that cause these different outcomes. Nevertheless, this is what <a href="https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1010042">our team</a> aimed to do.</p>
<p>We explored more than 3,000 blood proteins using a technique called <a href="https://www.bmj.com/content/362/bmj.k601">Mendelian randomisation</a>. This is where, instead of directly measuring something that you think has an effect on a disease (in this case, a blood protein) and then seeing if levels of it correlate with disease severity, you instead look at variation in the genes that influence that substance’s levels, and examine how this affects disease outcomes.</p>
<figure class="align-center ">
<img alt="A printout of a person's DNA being looked at by a scientist" src="https://images.theconversation.com/files/450355/original/file-20220307-121610-cgwcln.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/450355/original/file-20220307-121610-cgwcln.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/450355/original/file-20220307-121610-cgwcln.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/450355/original/file-20220307-121610-cgwcln.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/450355/original/file-20220307-121610-cgwcln.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/450355/original/file-20220307-121610-cgwcln.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/450355/original/file-20220307-121610-cgwcln.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">For Mendelian randomisation, you need to know which genes influence the variable characteristics that you’re investigating.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/scientist-analyzes-dna-gel-used-genetics-1046584543">gopixa/Shutterstock</a></span>
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<p>This is because if you look at blood protein levels directly, you can’t be sure that other outside factors – like lifestyle choices, or even having COVID – aren’t affecting them at the point in time when you’re measuring them. Genes, on the other hand, don’t change during someone’s lifetime. They therefore allow you to more reliably identify people with high and low levels of the substances you’re interested in, and so make more robust estimates of how something like a blood protein affects a disease like COVID.</p>
<p>First, we had to identify which <a href="https://pubmed.ncbi.nlm.nih.gov/29875488/">genes</a> are <a href="https://www.nature.com/articles/ncomms14357">associated</a> with different blood proteins. We did this by looking at the results of <a href="https://www.genome.gov/about-genomics/fact-sheets/Genome-Wide-Association-Studies-Fact-Sheet">genome-wide association studies</a>. These are large pieces of research that look at genetic and biological differences across many people, to trace the links between genetic variants and certain characteristics. <a href="https://www.covid19hg.org/">Large-scale genome-wide results</a> have also been able to trace links between genes and the risk of severe COVID too.</p>
<p>Analysing this data, we identified several proteins that potentially increase or decrease the risk of severe COVID. For example, we found that increased levels of a protein called FAAH2 may increase the risk of someone needing hospital treatment for COVID. FAAH2 causes cells to <a href="https://www.nature.com/articles/s41598-020-59120-1">absorb and inactivate</a> substances called endocannabinoids. These have anti-inflammatory effects, and studies have even suggested they <a href="http://www.ncbi.nlm.nih.gov/pubmed/33683968">could be used as treatments</a> for COVID. This would explain why having more proteins that remove them is problematic – this potentially lessens the body’s ability to control inflammation caused by COVID.</p>
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<img alt="Bags of type A blood" src="https://images.theconversation.com/files/450356/original/file-20220307-85965-4lutqe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/450356/original/file-20220307-85965-4lutqe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/450356/original/file-20220307-85965-4lutqe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/450356/original/file-20220307-85965-4lutqe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/450356/original/file-20220307-85965-4lutqe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/450356/original/file-20220307-85965-4lutqe.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/450356/original/file-20220307-85965-4lutqe.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">High levels of the ABO enzyme coinciding with severe COVID strengthens the idea that blood type influences COVID.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/blood-donation-126671510">Sura Nualpradid/Shutterstock</a></span>
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<p>Another influential protein we identified was the ABO enzyme. This determines your blood group and is a <a href="http://www.ncbi.nlm.nih.gov/pubmed/32739464">hot topic</a> in COVID research. Our study showed that having higher levels of the ABO enzyme appears to increase the risk of being hospitalised with COVID and subsequently needing intensive care. <a href="http://www.ncbi.nlm.nih.gov/pubmed/33196417">Previous small studies</a> have shown that blood group A is more common in those with severe COVID. Our findings strengthen the case that the ABO enzyme and blood type influence COVID severity.</p>
<p>COVID can also cause <a href="https://academic.oup.com/eurheartj/article/41/32/3038/5901158">disease in the blood vessels</a>, particularly when severe. But we found that proteins that attract white blood cells to the wall of blood vessels appear to be protective against severe COVID. Attracting more white blood cells like this has long been known to <a href="https://www.nature.com/articles/pr199633">improve the immune response</a> in blood vessel walls, and in COVID specifically this seems to <a href="http://www.ncbi.nlm.nih.gov/pubmed/32882706">help fight off</a> infection.</p>
<p>Identifying these risk factors may help scientists develop new treatments, as these proteins could be targeted by new medicines (or existing ones that have been repurposed). It has also allowed us to draw up a list of proteins that can be prioritised by other researchers, so that in future we can understand even more about what the biological risk factors for COVID are.</p><img src="https://counter.theconversation.com/content/178347/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alish Palmos receives funding from the National Institute for Health Research (NIHR) Biomedical Research Centre (BRC) at the South London and Maudsley NHS Foundation Trust and King’s College London.</span></em></p><p class="fine-print"><em><span>Christopher Hübel and Vincent Millischer do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Genetic research has linked a number of blood proteins to severe COVID – including the enzyme that determines your blood type.Alish Palmos, Postdoctoral Research Associate, King's College LondonChristopher Hübel, Research Associate in Medicine, Psychology and Behavioural Genetics, King's College LondonVincent Millischer, Resident in Psychiatry, Medical University of ViennaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1493032021-02-26T17:19:10Z2021-02-26T17:19:10ZDo genetic differences make some people more susceptible to COVID-19?<figure><img src="https://images.theconversation.com/files/386108/original/file-20210224-19-l9w0vl.jpg?ixlib=rb-1.1.0&rect=1399%2C187%2C1773%2C1077&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/vector-illustration-peoples-wearing-medical-mask-1665447082">males_design/Shutterstock</a></span></figcaption></figure><p>Coronavirus affects people differently – some infected develop life-threatening disease, while others remain asymptomatic. And a year aftere COVID-19 emerged, it’s still unclear why. </p>
<p>To try and answer this question, researchers have started looking at the genetics of people who get COVID-19, and identifying links between developing the disease and variations in specific parts of our DNA. This raises the possibility that some of what makes people susceptible to COVID-19 lies in their genes.</p>
<p>This wouldn’t be surprising. Genetic variation plays a role in susceptibility to <a href="https://www.nature.com/articles/nrg3114">a number of diseases</a>, from HIV to malaria to TB. Researchers know this because they hunt for variations of interest by comparing people’s entire DNA sequences – their genomes – to see whether certain variations coincide with certain disease outcomes. Such analyses are called <a href="https://www.genome.gov/about-genomics/fact-sheets/Genome-Wide-Association-Studies-Fact-Sheet">genome-wide association studies</a>.</p>
<p>For COVID-19, these studies have uncovered two stretches of DNA with variations of interest: one on chromosome 9 and one on chromosome 3. </p>
<h2>Blood types are a mystery</h2>
<p>The region on chromosome 9 is the ABO gene locus, which determines our blood type. Following the first wave of COVID-19 in spring 2020, <a href="https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciaa1150/5880600">studies</a> began to investigate whether blood type was linked to disease susceptibility, particularly in patients with O or AB blood groups. However, the early evidence was contradictory. While some studies suggested a possible link, <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7379446/">others</a> stated that once infected, a person’s blood type doesn’t affect their disease outcomes at all. </p>
<p>Since then, a more consistent pattern has started to emerge: people with blood type A now seem to be more at risk than those with blood type O. More recent research suggests a lower risk of severe disease for <a href="https://link.springer.com/article/10.1007/s00277-020-04169-1">blood type O</a>, even going as far as to suggest that this blood group has a <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa2020283">protective effect</a>. Additional studies have <a href="https://www.medrxiv.org/content/10.1101/2020.04.15.20063107v1.full.pdf">postulated</a> that <a href="https://www.frontiersin.org/articles/10.3389/fcimb.2020.00404/full">blood type A</a> increases risk of infection (though some of these are pre-prints, meaning they have yet to be scrutinised by other scientists).</p>
<p>This conflict between older and newer evidence is most likely due to the relatively small number of cases analysed. As the number increases, we’ll have more confidence in any findings.</p>
<figure class="align-center ">
<img alt="A bag of blood" src="https://images.theconversation.com/files/385926/original/file-20210223-14-1gpep2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/385926/original/file-20210223-14-1gpep2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/385926/original/file-20210223-14-1gpep2u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/385926/original/file-20210223-14-1gpep2u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/385926/original/file-20210223-14-1gpep2u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/385926/original/file-20210223-14-1gpep2u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/385926/original/file-20210223-14-1gpep2u.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">Blood type O, which could offer some protection against COVID-19, is the most common – just under half of Brits have it.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/close-bag-blood-on-blur-background-1068308666">Schira/Shutterstock</a></span>
</figcaption>
</figure>
<p>Blood type has also been associated with COVID-related respiratory failure. A study of 1,600 Spanish and Italian COVID-19 patients <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa2020283">found</a> that people with blood type O had a lower chance of respiratory failure compared with those who had other blood types. When compared with everyone else, people with blood type A had 1.5 times the chance of respiratory failure. </p>
<p>This finding is supported by a <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0239508">paper</a> that analysed the results of seven separate studies, which together looked at data from nearly three million people – including more than 7,500 COVID-19 patients. It found that COVID-positive people are more likely to have blood group A, whereas with blood group O the risk of COVID-19 infection is reduced. This conclusion was backed up by a <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7391292/">further study</a>.</p>
<p>Lastly, there’s also a large <a href="https://www.acpjournals.org/doi/10.7326/M20-4511">Canadian study</a> that found that people with blood type O are at lower risk of infection. The difference was only slightly lower, with the risk of COVID-19 infection being 12% lower for blood type O when compared against all other types. The study also showed that people with blood type O had a 13% lower risk of severe disease or death compared to everyone else. </p>
<p>So why might blood type be having an effect on COVID-19? This research recalls <a href="https://pubmed.ncbi.nlm.nih.gov/15784866/">studies</a> from the 2002–2004 Sars outbreak – also caused by a coronavirus – which hinted at a <a href="https://pubmed.ncbi.nlm.nih.gov/18818423/">possible reduced risk</a> for type O. This earlier research theorised that <a href="https://www.nhs.uk/conditions/blood-groups/">antibodies</a> – proteins in our blood that help fight infections – present in type O blood may inhibit the Sars virus from getting inside cells. But this hasn’t been proven.</p>
<p>Similarly, whether blood type definitely provides some protection against COVID-19 – and if so, whether antibodies in certain blood types are behind this – remains unclear. It does look like there is an association between blood type and disease susceptibility, but more research is needed to know exactly how the two are related.</p>
<h2>An ancient inheritance</h2>
<p>The picture is a bit clearer for chromosome 3. The <a href="https://www.nejm.org/doi/full/10.1056/NEJMoa2020283">genome-wide association study</a> mentioned earlier, involving Spanish and Italian patients, also found an association between severe disease and variation in a small region on this chromosome called 3p21.31. </p>
<p>One of the genes in this region, <a href="https://pubmed.ncbi.nlm.nih.gov/25534429/">SLC6A20</a>, contains the instructions for building a protein that interacts with <a href="https://theconversation.com/ace2-the-molecule-that-helps-coronavirus-invade-your-cells-138369">ACE2</a>, the molecule the virus uses to get inside cells. </p>
<p>Other genes here are for chemokine receptors, which are <a href="https://pubmed.ncbi.nlm.nih.gov/17291188/">involved</a> in inflammation. Given that ACE2 and <a href="https://theconversation.com/inflammation-the-key-factor-that-explains-vulnerability-to-severe-covid-144768">inflammation</a> are both at the heart of severe COVID-19, this could offer clues as to why variation in this particular section of DNA appears to be associated with worse disease.</p>
<p>The variation in this region that increases COVID-19 susceptibility may have been <a href="https://pubmed.ncbi.nlm.nih.gov/32998156/">inherited from Neanderthals</a>. To date, 3p21.31 is the only genetic region significantly associated with severe COVID-19. Having certain genetic variations in this region can therefore be considered a risk factor. </p>
<p>As the pandemic continues, research will continue to move at a rapid pace to develop our understanding of COVID-19 and how we can combat the pandemic. This will include further understanding of how our genes and coronavirus interact – and it may be that other genetic risk factors are discovered.</p><img src="https://counter.theconversation.com/content/149303/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Genes that control blood type and are involved in inflammation have been associated with more severe disease.Vikki Rand, Professor of Biosciences and Head of Research (National Horizons Centre), Teesside UniversityMaria O’Hanlon, PhD Candidate in Biology, Teesside UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1291252020-01-10T13:44:25Z2020-01-10T13:44:25ZYour blood type may influence your vulnerability to norovirus, the winter vomiting virus<figure><img src="https://images.theconversation.com/files/308691/original/file-20200106-123411-1f6nutm.jpg?ixlib=rb-1.1.0&rect=43%2C96%2C5769%2C3796&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Projectile vomiting is common with norovirus.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/man-suffering-sick-stomach-vomiting-674213719">Elnur/Shutterstock.com</a></span></figcaption></figure><p>In the last few months, schools all over the country have closed because of outbreaks of norovirus. Also known as <a href="https://www.cdc.gov/norovirus/about/index.html">stomach flu</a>, norovirus infections cause watery diarrhea, low-grade fever and, most alarming of all, projectile vomiting, which is an extremely effective way of <a href="https://doi.org/10.1371/journal.pone.0143759">spreading the virus</a>.</p>
<p>Norovirus is very infectious and spreads rapidly through a confined population, such as at a school or on a cruise ship. Although most sufferers recover in 24 to 48 hours, norovirus is a leading cause of childhood illness and, in developing countries, results in about <a href="https://www.cdc.gov/norovirus/trends-outbreaks/worldwide.html">50,000 child deaths each year</a>. </p>
<p>Interestingly, not everyone is equally vulnerable to the virus, and whether you get sick or not <a href="https://doi.org/10.3390/v11030226">may depend on your blood type</a>. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308462/original/file-20200103-11909-1c1i1uc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">3D print of Norwalk virus, a type of norovirus. Noroviruses are the most common cause of acute gastroenteritis (infection of the stomach and intestines) in the United States.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/niaid/14550066332/in/photolist-oaJTNC-9kN9fS-zT8zR-zRqum-7JT92b-2fHvpyV-nPdK6g-4nS4tN-bkSbTa-9iHCcg-zRqqG-4dHSzJ-dT7574-ehXMFj-mvhVYa-4BWSQk-fjrZgr-zRqrj-5suMaZ-GdQtN9-FPgYQG-dUtuUb-dMVx4Y-R2HhVV-kc9sdG-e4ZuwX-BhXmt-bBSVNr-2g7RMr6-R2agqV-Qg6WSu-2g7S1zi-7n7421-ehRTcF-dPNyUq-dPGX22-yF16XT-dKeb3j-pBZyB5-dPGXwn-fox1yW-dPGA68-4QTPtv-8i7Pxd-6N6awr-d6BGam-jCdHzU-byxjM8-dQS3gV-dQqL4r">NIH</a></span>
</figcaption>
</figure>
<h2>Norovirus is hard to get rid of</h2>
<p><a href="https://biology.indiana.edu/about/faculty/foster-patricia.html">I am a microbiologist</a>, and I got interested in norovirus because, while norovirus symptoms are distressing under any circumstances, my encounter with the virus was particularly inconvenient. During a seven-day rafting trip down the Grand Canyon, the illness passed through the rafters and crew, one by one. Obviously, the wilderness sanitary facilities were not the best to cope with this outbreak. Luckily, everyone, including me, recovered quickly. It turns out that <a href="https://azdailysun.com/news/local/norovirus-back-in-canyon/article_cd739e60-ea66-5d94-9b1c-7648df60b9fa.html">norovirus outbreaks on Colorado River rafting trips</a> are common. </p>
<p>As debilitating as the illness it causes can be, the norovirus particle is visually beautiful. It is a type of virus known as “non-enveloped” or “naked,” which means that it never acquires the membrane coating typical of other viruses, such as the flu virus. The norovirus surface is a protein coat, called the “capsid.” The capsid protects the norovirus’ genetic material. </p>
<p>The naked capsid coat is one factor that makes norovirus so difficult to control. Viruses with membrane coatings are susceptible to alcohol and detergents, but not so norovirus. <a href="https://www.cdc.gov/vitalsigns/norovirus/index.html">Norovirus can survive</a> temperatures from freezing to 145 degrees Fahrenheit (about the maximum water temperature in a home dishwasher), soap and mild solutions of bleach. Norovirus can persist on human hands for hours and on <a href="https://doi.org/10.4315/0362-028X.JFP-15-570">solid surfaces and food for days</a> and is also resistant to alcohol-based hand sanitizers. </p>
<p>To make things worse, only a tiny dose of the virus – <a href="https://doi.org/10.1002/jmv.21237">as few as 10 viral particles</a> – is needed to cause disease. Given that an infected person can excrete many billions of viral particles, it’s very difficult to prevent the virus from spreading.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308693/original/file-20200106-123364-11tc4wa.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"></a>
<figcaption>
<span class="caption">Norovirus, also called winter vomiting bug, infects cells in the human intestine causing diarrhea, vomiting and stomach pain.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/norovirus-human-intestine-called-winter-vomiting-1098015311">Kateryna Kon/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Susceptibility to norovirus depends on blood type</h2>
<p>When norovirus is ingested, it initially infects the cells that line the small intestine. Researchers don’t know exactly how this infection then causes the symptoms of the disease. But a fascinating aspect of norovirus is that, after exposure, <a href="https://doi.org/10.3390/v11030226">blood type determines, in a large part, whether a person gets sick</a>. </p>
<p>Your blood type – A, B, AB or O – is dictated by genes that determine which kinds of molecules, called oligosaccharides, are found on the surface of your red blood cells. Oligosaccharides are made from different types of sugars linked together in complex ways.</p>
<p>The same oligosaccharides on red blood cells also appear on the surface of cells that line the small intestine. Norovirus and a few other viruses use these oligosaccharides to grab onto and infect the intestinal cells. It’s the specific structure of these oligosaccharides that determines whether a given strain of virus can attach and invade.</p>
<p>The presence of one oligosaccharide, called the H1-antigen, is required for attachment by many norovirus strains. </p>
<p>People who do not make H1-antigen in their intestinal cells make up 20% of the European-derived population and are <a href="https://doi.org/10.1007/s00439-019-02090-w">resistant to many strains of norovirus</a>. </p>
<p>More sugars can be attached to the H1-antigen to give the A, B or AB blood types. People who can’t make the A and B modifications have the O blood type. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=144&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=144&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=144&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=181&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=181&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308689/original/file-20200106-123381-ly8t7m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=181&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Each blood type is distinguished by a different sugar marker on the red blood cell. Cells lining the intestine also have these sugar markers.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/blood-cells-1777906">Fernando Jose V. Soares/Shutterstock.com</a></span>
</figcaption>
</figure>
<h2>Different strains of norovirus infect different people</h2>
<p>Norovirus evolves rapidly. There are <a href="https://doi.org/10.1097/qco.0000000000000476">29 different strains</a> currently known to infect humans, and each strain has different variants. Each one has different abilities to bind to the variously shaped sugar molecules on the intestinal cell surface. These sugars are determined by blood type. </p>
<p>If a group of people is exposed to a strain of norovirus, who gets sick will depend on each person’s blood type. But, if the same group of people is exposed to a different strain of norovirus, different people may be resistant or susceptible. In general, those who do not make the H1-antigen and people with B blood type will tend to be resistant, whereas people with A, AB, or O blood types will <a href="https://doi.org/10.1002/wsbm.1355">tend to get sick</a>, but the pattern will depend on the specific strain of norovirus.</p>
<p>This difference in susceptibility has an interesting consequence. When an outbreak occurs, for example, on a cruise ship, roughly a third of the people may escape infection. Because they do not know the underlying reason for their resistance, I think spared people engage in <a href="https://www.britannica.com/science/magical-thinking">magical thinking</a> – for example, “I didn’t get sick because I drank a lot of grape juice.” Of course, these mythical evasive techniques will not work if the next outbreak is a strain to which the individual is susceptible. </p>
<h2>Immunity to norovirus is short-lived</h2>
<p>A norovirus infection provokes a robust immune response that eliminates the virus in a few days. However, the response appears to be short-lived. Most studies have found that immunity guarding against reinfection with the same norovirus strain lasts <a href="https://doi.org/10.1002/eji.201545512">less than six months</a>. Also, infection with one strain of norovirus offers little protection against infection from another. Thus, you can have repeated bouts with norovirus.</p>
<p>The diversity of norovirus strains and the impermanence of the immune response complicates development of an effective vaccine. Currently, clinical trials are testing the effects of <a href="https://investors.vaxart.com/news-releases/news-release-details/vaxarts-tableted-oral-bivalent-norovirus-vaccine-meets-primary">vaccines made from the capsid proteins</a> of the two most prevalent norovirus strains. </p>
<p>In general, these experimental vaccines produce <a href="https://doi.org/10.1093/infdis/jiw259">good immune responses</a>; the <a href="https://clinicaltrials.gov/ct2/show/NCT03897309">longevity</a> of the immune response is now <a href="https://clinicaltrials.gov/ct2/show/NCT03039790">under study</a>. The next phase of clinical trials will test if the vaccines actually prevent or <a href="https://clinicaltrials.gov/ct2/show/NCT03039790">reduce the symptoms of norovirus infection</a>.</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/129125/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Patricia L. Foster receives funding from the US Army Research Office. She is a member of the Union of Concerned Scientists and Concerned Scientists at Indiana University.</span></em></p>Norovirus, the winter vomiting bug, is highly infectious among people in confined places – like cruise ships. But not everyone is equally vulnerable. Your blood type may determine if you get sick.Patricia L. Foster, Professor Emerita of Biology, Indiana UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1134542019-05-08T20:01:51Z2019-05-08T20:01:51ZAustralia’s ethnic face is changing, and so are our blood types<figure><img src="https://images.theconversation.com/files/273249/original/file-20190508-183103-1jusqev.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">About one in three people living in Australia were born overseas.</span> <span class="attribution"><span class="source">From shutterstock.com</span></span></figcaption></figure><p><em>This article is the second part in a series, <a href="https://theconversation.com/au/topics/where-culture-meets-health-70226">Where culture meets health</a>.</em></p>
<hr>
<p>It’s often said that no matter who we are, “we all bleed red”. But although our blood may be the same colour, we’re as individual on the inside as we are on the surface. Just like our background determines the way we look, where we come from is <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3595629/">one of the major factors</a> that influences the make up of our blood.</p>
<p>About <a href="http://www.abs.gov.au/ausstats/abs@.nsf/lookup/Media%20Release3">half of people</a> living in Australia today were either born overseas, or have a parent born overseas. This increase in the diversity of our population leads to a corresponding diversity in the people who need medical treatment – and their blood types.</p>
<p>We need a broad mix of ethnicities in our donor pool to meet the needs of patients with rare blood types. Providing the right blood and blood products for an ethnically diverse population presents an evolving challenge for blood collection agencies around the world, including here in Australia.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/blood-groups-beyond-a-b-and-o-what-are-they-and-do-they-matter-75063">Blood groups beyond A, B and O: what are they and do they matter?</a>
</strong>
</em>
</p>
<hr>
<p>People from diverse backgrounds <a href="http://diversityhealthcare.imedpub.com/missing-minorities--a-survey-based-descriptionof-the-current-state-of-minority-blood-donorrecruitment-across-23-countries.php?aid=8326">tend to be underrepresented</a> in donor populations. While Australians born overseas account for <a href="http://www.abs.gov.au/ausstats/abs@.nsf/lookup/Media%20Release3">roughly one-third</a> of the population, they account for only one in five blood donors.</p>
<p>This limited diversity in our pool of donors creates challenges in identifying blood matches for transfusion to patients with rare blood types. </p>
<h2>The link between your blood group and where you come from</h2>
<p>Blood types consist not only of the commonly recognised groups such as A, B and O, but <a href="https://www.donateblood.com.au/blog/research/blood-types-and-donuts">also include</a> more than 300 other variants. Each of these variants is a marker on the surface of our red blood cells, and is known as an “antigen”.</p>
<p>Our blood type is inherited from our parents. Like other inherited characteristics such as skin and hair colour, the frequency of blood types in a population <a href="http://www.bloodjournal.org/content/115/23/4635?sso-checked=true">shift in response</a> to stresses in the environment (known as “selection pressure”).</p>
<p>For example, in parts of the world where malaria thrives, the proportion of the population with various blood types <a href="https://theconversation.com/how-our-red-blood-cells-keep-evolving-to-fight-malaria-96117">has altered over time</a> to make people less prone to infection.</p>
<p>So this effect has more to do with where you and your ancestors lived than your ethnic group. One blood type, known as <a href="https://www.ncbi.nlm.nih.gov/books/NBK2271/">Duffy null</a>, is much more frequent in Africans in Africa than in African-Americans, possibly because African Americans are no longer exposed to the malaria parasite.</p>
<p>In short, one reason we have different blood groups is to improve our chances of fighting disease.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-our-red-blood-cells-keep-evolving-to-fight-malaria-96117">How our red blood cells keep evolving to fight malaria</a>
</strong>
</em>
</p>
<hr>
<h2>Who needs specially matched blood?</h2>
<p>Most transfusions of red cells <a href="https://www.science.org.au/curious/people-medicine/why-are-some-blood-types-incompatible-others">are matched</a> for the commonly recognised ABO and Rh blood groups (the Rh group is the one that gives you the “positive” or “negative” in your blood type). </p>
<p>If someone receives a transfusion of blood that doesn’t match their own type, their body may recognise the transfused blood as foreign, and develop antibodies to try and destroy the “invader”. Their body will keep making these antibodies, which can then interfere with future transfusions.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/273254/original/file-20190508-183109-1r2rt4f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/273254/original/file-20190508-183109-1r2rt4f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=382&fit=crop&dpr=1 600w, https://images.theconversation.com/files/273254/original/file-20190508-183109-1r2rt4f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=382&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/273254/original/file-20190508-183109-1r2rt4f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=382&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/273254/original/file-20190508-183109-1r2rt4f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=480&fit=crop&dpr=1 754w, https://images.theconversation.com/files/273254/original/file-20190508-183109-1r2rt4f.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=480&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/273254/original/file-20190508-183109-1r2rt4f.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=480&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Most healthy people are eligible to donate blood.</span>
<span class="attribution"><span class="source">From shutterstock.com</span></span>
</figcaption>
</figure>
<p>Some patients need specially matched red cells for transfusion. This means on top of being matched by ABO and Rh type, the donor’s blood is matched to make sure it doesn’t contain blood group variants that aren’t present in the recipient’s blood. This is more difficult to achieve.</p>
<p>There are three groups of patients who need specially matched blood:</p>
<ol>
<li>patients who have already developed antibodies because they have had a transfusion of blood that is not fully matched in the past</li>
<li>patients who may have developed antibodies to blood group antigens, but other conditions or drug treatments make it hard for their doctors to test for antibodies </li>
<li>patients who need to have many transfusions throughout their life, so doctors want to avoid the development of blood group antibodies. </li>
</ol>
<p>Patients who may need to have multiple transfusions throughout their life include those with disorders affecting the blood such as sickle cell anaemia, thalassemia major and myelodysplasia. </p>
<p>Thalassemia is <a href="https://thalassemia.com/demographics.aspx#gsc.tab=0">most common</a> in people of African, Middle Eastern, Asian, Indian and Mediterranean descent. Sickle cell anaemia <a href="https://www.cdc.gov/ncbddd/sicklecell/data.html">affects these ethnic groups</a> and also people of Hispanic descent.</p>
<h2>Which groups are most in need in Australia at the moment?</h2>
<p>There are so many different blood group antigens, combinations of even the most common blood group types are found in only a small proportion of donors, making it difficult to provide blood fully matched for a particular patient. </p>
<p>In addition, as our patient population becomes more diverse, there is a greater need for blood types that are rare in a Caucasian population.</p>
<p>Ultimately, the distribution of blood groups that we collect from our donors should reflect the distribution of blood groups required by patients who need transfusion.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-whats-actually-in-our-blood-75066">Explainer: what's actually in our blood?</a>
</strong>
</em>
</p>
<hr>
<p>Blood centres in many countries have introduced a <a href="https://pdfs.semanticscholar.org/5ad0/1f8262f443562507c865323ebddd61d4b21c.pdf">variety of campaigns</a> to attract a broader donor group. </p>
<p>At the Australian Red Cross Blood Service, we are interviewing donors from diverse backgrounds to learn more about their experiences in donating blood. Our goal is to build a donor panel that represents the diversity of the broader Australian community. </p>
<p>The benefits are not only for the patients and the health system – research suggests participating in blood donation <a href="https://www.ncbi.nlm.nih.gov/pubmed/17319819">facilitates social inclusion among migrant communities</a>.</p>
<p><em>Dr Alison Gould, Scientific Communications Specialist for the Australian Red Cross Blood Service, co-authored this article.</em></p><img src="https://counter.theconversation.com/content/113454/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tanya Davison is employed by the Australian Red Cross Blood Service as well as Swinburne University of Technology, and receives funding from NHMRC and ARC research grants. Australian governments fund the Australian Red Cross Blood Service for the provision of blood, blood products and services to the Australian community</span></em></p><p class="fine-print"><em><span>James Daly is employed by the Australian Red Cross Blood Service and holds an Adjunct appointment with QUT Schooll of Biomedical Science. Australian Governments fund the Australian Red Cross Blood Service for the provision of blood, blood products and services to the Australian Community</span></em></p><p class="fine-print"><em><span>Robert Flower is employed by the Australian Red Cross Blood Service as well an appointment at the University of Sydney. Australian governments fund the Australian Red Cross Blood Service for the provision of blood, blood products and services to the Australian community</span></em></p>Australia is a cultural melting pot, but our blood donors are less diverse. We need a broad mix of ethnicities in our donor pool to meet the needs of patients with rare blood types.Tanya Davison, Associate professor, Swinburne University of TechnologyJames Daly, Adjunct Associate Professor, Faculty of Health, School of Biomedical Sciences, Queensland University of TechnologyRobert Flower, Associate Professor, University of SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1048672018-10-22T19:56:57Z2018-10-22T19:56:57ZBlood type, Pioppi, gluten-free and Mediterranean – which popular diets are fads?<figure><img src="https://images.theconversation.com/files/241564/original/file-20181022-105761-1j2fo9i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">You might lose weight in the short term but fad diets are impossible to sustain.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/woman-looking-little-salad-tired-about-209306980?src=EcV_PSTALm2ag4aPd3zxKw-2-101">saltodemata/shutterstock</a></span></figcaption></figure><p>Each year, new weight loss diets appear that promise to reveal the ultimate secret of success – if only you buy the book, pills or potions.</p>
<p>Fad diets might achieve short-term results but they are <a href="https://daa.asn.au/smart-eating-for-you/smart-eating-fast-facts/weight-management/how-to-spot-a-dodgy-weight-loss-diet/">difficult to sustain</a> in the long term. </p>
<p><a href="https://daa.asn.au/smart-eating-for-you/smart-eating-fast-facts/weight-management/how-to-spot-a-dodgy-weight-loss-diet/">They often eliminate entire food groups</a>, which means they’re unlikely to provide adequate amounts of key nutrients that are essential for our health and well-being. </p>
<p>Fad diets and rapid weight loss can also increase the risk of serious health problems such as gall bladder disease and <a href="https://theconversation.com/got-gallstones-heres-what-to-eat-and-avoid-53229">gallstones</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-six-tips-for-losing-weight-without-fad-diets-52496">Health Check: six tips for losing weight without fad diets</a>
</strong>
</em>
</p>
<hr>
<p>When <a href="http://healthyweightweek.com.au/fad-free-diet/">assessing whether a diet is a fad, ask yourself</a>, does the diet: </p>
<ol>
<li>contradict advice from qualified health professionals?</li>
<li>promote or ban specific foods or whole food groups?</li>
<li>promote a one-size-fits-all strategy?</li>
<li>promise quick, dramatic or miraculous results with minimal effort?</li>
<li>focus only on short-term results?</li>
<li>promote “miracle” pills, <a href="https://theconversation.com/five-supplements-that-claim-to-speed-up-weight-loss-and-what-the-science-says-89856">supplements</a> or products touted to “burn fat”? </li>
<li>make claims based on personal testimonials or one random study?</li>
</ol>
<p>If the answer to two or more of these questions is “yes”, it’s probably a fad. </p>
<p>So, how do today’s popular diets measure up? Here we road-test the blood type, Pioppi, gluten-free, and Mediterranean diets.</p>
<h2>Blood type diet</h2>
<p>The blood type diet has been around for some time. It’s based on the idea that your blood type is a key factor in predicting your body weight, nutritional requirements, risk of chronic disease, and overall well-being. </p>
<p>According to this diet, those with blood type A should follow what resembles a vegetarian diet. Type Os are supposed to limit carbohydrates and increase their protein intake. Type Bs should avoid chicken, corn, wheat, lentils, tomatoes, peanuts, and sesame seeds; while type ABs should avoid caffeine, alcohol, and cured meats. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/241581/original/file-20181022-105751-dnwlp7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/241581/original/file-20181022-105751-dnwlp7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/241581/original/file-20181022-105751-dnwlp7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/241581/original/file-20181022-105751-dnwlp7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/241581/original/file-20181022-105751-dnwlp7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/241581/original/file-20181022-105751-dnwlp7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/241581/original/file-20181022-105751-dnwlp7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">People with type B blood can still eat chicken and corn.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/download/confirm/489408907?src=cn5IILxUcaQlAG_t-Fjbcg-1-9&size=huge_jpg">Shutterstock</a></span>
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<p>But a comprehensive <a href="http://ajcn.nutrition.org/content/early/2013/05/22/ajcn.113.058693">review of 16 studies</a> found there is no scientific literature to back up this list of dos and don'ts. </p>
<p><strong>Verdict:</strong> Fad diet. It’s highly restrictive and may increase the risk of nutrient deficiencies. </p>
<h2>Pioppi diet</h2>
<p>The Pioppi diet is promoted as resembling the food patterns of people living in the small village of Pioppi, southern Italy, who live long, healthy lives. </p>
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Read more:
<a href="https://theconversation.com/low-carb-paleo-or-fasting-which-diet-is-best-89685">Low carb, Paleo or fasting – which diet is best?</a>
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<p>The traditional eating habits of the people of Pioppi are in line with the Mediterranean diet, and include lots of vegetables, legumes, grains, fruit, fish, olive oil and nuts, as well as modest amounts of cheese, yoghurt, coffee and red wine, small amounts of meat, and very little sugar or highly processed foods. </p>
<p>But the 21-day Pioppi plan is very different to this. It forbids bread and other grains typically consumed in the Mediterranean. It <a href="https://health.spectator.co.uk/the-pioppi-diet-is-a-superficial-lifestyle-guide-based-on-distorted-evidence/">promotes foods</a> not usually consumed by the people of Pioppi, such as coconut fat.</p>
<p>People who follow the Pioppi diet might lose weight because they’re consuming less energy, having eliminated entire food groups. But <a href="https://www.ncbi.nlm.nih.gov/pubmed/26185980">consuming saturated fats</a> (polyunsaturated fat) and <a href="https://www.ncbi.nlm.nih.gov/pubmed/26429077">cutting out grains</a> goes against the current evidence for good heart health.</p>
<p><strong>Verdict:</strong> Fad diet.</p>
<h2>Gluten-free diet</h2>
<p>Gluten is a protein naturally found in wheat, rye and barley, plus some food additives. </p>
<p>People with diagnosed coeliac disease must eliminate gluten from their diet to avoid serious damage to their gut, but many people choose to avoid gluten as a weight-loss strategy. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/if-you-dont-have-coeliac-disease-avoiding-gluten-isnt-healthy-88300">If you don't have coeliac disease, avoiding gluten isn't healthy</a>
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<p>Eliminating gluten does not automatically reduce your kilojoule intake or induce weight loss. But some gluten-containing foods such as pizza, bread, pasta and cakes are energy-dense, so removing them completely will reduce your total energy intake, which may lead to weight loss. </p>
<p>Gluten-free alternatives can be just as high in kilojoules as the gluten containing version, and sometimes can be higher in kilojoules. </p>
<p>Removing gluten-containing without considering what foods will replace them can also reduce your intake of important nutrients such as fibre, folic acid and other B vitamins.</p>
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<img alt="" src="https://images.theconversation.com/files/241582/original/file-20181022-105761-3ecdu7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/241582/original/file-20181022-105761-3ecdu7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/241582/original/file-20181022-105761-3ecdu7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/241582/original/file-20181022-105761-3ecdu7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/241582/original/file-20181022-105761-3ecdu7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/241582/original/file-20181022-105761-3ecdu7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/241582/original/file-20181022-105761-3ecdu7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">There’s no need to forgo whole grains unless you have coeliac disease.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/woman-cut-whole-grain-bread-on-586453910?src=NcG_v_HfCAh7lznyEGD1Yw-1-9">Shutterstock/wideonet</a></span>
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<p>Recent studies <a href="https://www.ncbi.nlm.nih.gov/pubmed/28465308">discourage unnecessary gluten-free diets</a> due to the reduced intake of beneficial whole grains, which are key to a <a href="https://www.eatforhealth.gov.au/guidelines/australian-dietary-guidelines-1-5">healthy diet</a> and are <a href="https://www.ncbi.nlm.nih.gov/pubmed/29091078">associated with lower heart disease and cancer risk</a>. </p>
<p><strong>Verdict:</strong> Fad diet when used for weight loss in people who don’t have coeliac disease.</p>
<h2>Mediterranean diet</h2>
<p>The Mediterranean diet has a strong focus on intake of core foods in addition to olive oil, coffee and wine, and low intake of meat, sugar and highly processed foods. </p>
<p>While the main focus of the Mediterranean diet is not weight loss, when combined with a kilojoule restriction, <a href="https://www.ncbi.nlm.nih.gov/pubmed/20973675">it can be effective for weight loss</a>. </p>
<p>Among studies that did not prescribe an energy restriction, following the Mediterranean diet was not associated with gaining weight. The Mediterranean diet has also been shown to improve <a href="https://www.ncbi.nlm.nih.gov/pubmed/21392646">components of metabolic syndrome</a>, <a href="https://www.ncbi.nlm.nih.gov/pubmed/23505168">even without weight loss</a>. </p>
<p><strong>Verdict:</strong> The Mediterranean diet isn’t a fad but it doesn’t guarantee weight loss unless you also restrict your total kilojoule intake.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-whats-the-best-diet-for-weight-loss-21557">Health Check: what's the best diet for weight loss?</a>
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<p>The best approach to weight loss is to follow a <a href="https://theconversation.com/what-is-a-balanced-diet-anyway-72432">healthy, balanced eating plan</a> and to be physically active. Try to make small changes to your usual eating habits that you can live with. </p>
<p>If you need help or to check whether you are meeting your nutrient needs, consult your GP or a <a href="https://daa.asn.au/find-an-apd/">dietitian</a>. </p>
<p><em>If you would like to learn more about weight loss, you can enrol in our free online course <a href="https://www.edx.org/course/the-science-of-weight-loss-dispelling-diet-myths-0">The Science of Weight Loss – Dispelling Diet Myths</a>.</em></p><img src="https://counter.theconversation.com/content/104867/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Clare Collins is affiliated with the Priority Research Centre for Physical Activity and Nutrition, the University of Newcastle, NSW. She is an NHMRC Senior Research and Gladys M Brawn Research Fellow. She has received research grants from NHMRC, ARC, Hunter Medical Research Institute, Meat and Livestock Australia, Diabetes Australia, Heart Foundation, Bill and Melinda Gates Foundation, nib foundation and Greater Charitable Foundation. She has consulted to SHINE Australia, Novo Nordisk, Quality Bakers, the Sax Institute and the ABC. She was a team member conducting systematic reviews to inform the Australian Dietary Guidelines update and 2017 evidence review on dietary patterns for the Heart Foundation. </span></em></p><p class="fine-print"><em><span>Lee Ashton is affiliated with the Priority Research Centre for Physical Activity and Nutrition at the University of Newcastle.</span></em></p><p class="fine-print"><em><span>Rebecca Williams is affiliated with the Priority Research Centre for Physical Activity and Nutrition at the University of Newcastle. </span></em></p>Diets that promise drastic results with minimal effort, or that ban whole food groups, should ring alarm bells.Clare Collins, Laureate Professor in Nutrition and Dietetics, University of NewcastleLee Ashton, Postdoctoral research fellow, University of NewcastleRebecca Williams, Postdoctoral Researcher, University of NewcastleLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/621792017-03-06T19:24:49Z2017-03-06T19:24:49ZExplainer: what are blood groups and why do they matter?<p>If you’ve ever needed a blood transfusion, or donated blood, you probably would have been asked your blood type. While it was once thought all blood was the same, we now know there are different types of blood, called blood groups. Transfusions between blood groups can be catastrophic, even deadly, so knowing the blood type of donors and recipients is of the utmost importance. </p>
<p>Our bodies contain trillions of red blood cells. Each is covered in an array of proteins and sugars, inherited from our parents, which determine our blood group. We can all be classified into group A, B, AB or O, based on which sugars coat our red blood cells. </p>
<p>We’re also classified as positive or negative, based on whether our blood cells carry a protein called the Rhesus D (RhD) antigen. These two blood group systems (ABO and Rh) give us the eight main blood types: O-, O+, B-, B+, A-, A+, AB-, AB+. </p>
<p><iframe id="tc-infographic-176" class="tc-infographic" height="720" src="https://cdn.theconversation.com/infographics/176/e0bc573a28765ef0177e50122a7960b9e2ce4d22/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>But there are also <a href="http://resources.transfusion.com.au/cdm/ref/collection/p16691coll1/id/863">more than 300 different antigens</a> – proteins and sugars that activate the immune system – expressed on red cells and 36 recognised blood group systems. And they’re just the ones we know about. </p>
<p>While most people know they are, for example, A+ or O-, few people will know (and never need to know) what their expression of other red cell antigens are.</p>
<h2>How were blood groups discovered?</h2>
<p>Transfusion has been practised intermittently <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2588804/pdf/yjbm00009-0056.pdf">since the 1660s</a>. But blood groups weren’t discovered until 1900, before which it was assumed that all blood was of the same type. </p>
<p>This led to some catastrophic transfusions of animal blood into humans in attempts to transfer certain qualities (for example, so the recipient would become meek like a lamb). There were also some fatal transfusions between humans. </p>
<p>For this reason, the practice was banned in the UK and France for more than 100 years.</p>
<p>In 1900, physician <a href="https://www.nobelprize.org/nobel_prizes/medicine/laureates/1930/landsteiner-facts.html">Karl Landsteiner</a>’s experiments showed that some people’s red cells “reacted” with plasma samples from other people, while others did not. This led to him describing the ABO system, the most important blood group system and the basis of safe modern transfusion. </p>
<p>After receiving the 1930 Nobel Prize for Medicine for this work, Landsteiner was experimenting with the blood of Rhesus monkeys when he discovered what is now known as the RhD antigen. </p>
<h2>Compatibility</h2>
<p>If we need to transfuse blood from one person to another, we want to give donor blood that is compatible with the recipient’s blood to minimise the chance of a transfusion reaction. </p>
<p>So if a person is group A, this means she can receive a red cell transfusion from either a group A or a group O donor. She should not receive group B or AB red cells, as she has naturally occurring antibodies (proteins formed as part of the immune response) that will likely cause a transfusion reaction, which may be serious – even <a href="http://www.transfusion.com.au/adverse_transfusion_reactions/classification_and_incidence">fatal</a>.</p>
<p>Around 31% of Australians are A+. It’s the second most common blood group after O+, which make up 40% of the <a href="http://www.donateblood.com.au/learn/about-blood">Australian population</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/135753/original/image-20160829-17872-xwxx3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/135753/original/image-20160829-17872-xwxx3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/135753/original/image-20160829-17872-xwxx3b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/135753/original/image-20160829-17872-xwxx3b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/135753/original/image-20160829-17872-xwxx3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/135753/original/image-20160829-17872-xwxx3b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/135753/original/image-20160829-17872-xwxx3b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">O negative people are universal donors.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-294586571/stock-photo-giving-blood-during-operation.html?src=lvi-MTLSLjTg1w8zL0DsQQ-1-2">www.shutterstock.com</a></span>
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<p>Group O negative people are called “universal donors”. Their red cells express neither group A nor B sugars, nor the RhD antigen, and so are unlikely to cause a reaction in recipients. </p>
<p>Emergency departments and some ambulances carry a stock of O negative blood, because in an emergency this is the safest blood to give a critically ill, bleeding patient of unknown blood type. Only 9% of the Australian population are O negative. </p>
<p>The Australian Red Cross Blood Service needs a diverse group of blood donors to meet the needs of our increasingly diverse patient population. </p>
<h2>What are blood groups for?</h2>
<p>It is likely all of the molecules that cover the surface of cells serve some purpose – often completely unrelated to transfusion. </p>
<p>One of the 36 blood group systems mentioned above is the Colton blood group. This is interesting because the molecules recognised by the immune system as Colton blood group antigens are actually located on an <a href="https://www.nobelprize.org/nobel_prizes/chemistry/laureates/2003/agre-diploma.html">aquaporin (AQP1) molecule</a> - one of a family of molecules responsible for water passage into and out of cells, and abundant in the red cell membrane. Professor Peter Agre and colleagues described this in 1992 and he received a <a href="https://www.nobelprize.org/nobel_prizes/chemistry/laureates/2003/agre-lecture.pdf">Nobel Prize</a> for this work.</p>
<p>Another interesting example is the <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1378024/pdf/10762551.pdf">Duffy protein</a>, named after a haemophiliac patient <a href="http://www.ncbi.nlm.nih.gov/books/NBK2271/">Mr Duffy</a>. In 1950, he developed an antibody to what we know today as the Duffy “a” antigen, to which he had been exposed by receiving a blood transfusion.</p>
<p>One of the known functions of the Duffy antigens is binding one type of malaria parasite, <em>Plasmodium vivax</em>, which grants it entry into the red cell, where it can multiply and then cause the cell to burst. </p>
<p>The red cells of people who lack Duffy antigens are more resistant to infection by this parasite. More than two-thirds of people of African origin lack the Duffy antigens, whereas it is rare for people originating from Europe or Asia to do so. </p>
<p>Many thousands of years ago, in Africa where the <em>Plasmodium vivax</em>-bearing mosquitoes flourished, people who lacked Duffy antigens were resistant to this potentially fatal form of malaria and survived to parent future generations, passing on this particular resilience to their offspring.</p>
<p>Fascinatingly, the normal function of ABO and Rh, the two most important blood group systems, is still essentially unknown. <a href="http://www.ncbi.nlm.nih.gov/books/NBK2267/">The frequency of ABO antigens</a> varies greatly between different populations, and so it is thought that perhaps particular ABO blood types confers survival advantage in different settings. </p>
<p>Different ABO blood types occur more frequently in some medical conditions. Stomach ulcers, for example, are <a href="http://aje.oxfordjournals.org/content/172/11/1280.full.pdf+html">more common</a> in those with group O blood but stomach cancer is more common in those with group A blood. We don’t really know exactly why this occurs, or its consequences.</p><img src="https://counter.theconversation.com/content/62179/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Our bodies contain trillions of red blood cells. Each is covered in an array of proteins and sugars, inherited from our parents, which determine our blood group.Erica Wood, Associate Professor; Head, Transfusion Research Unit, Monash UniversityLucy Fox, Clinical Research Fellow in Haematology, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/637392016-08-11T14:19:46Z2016-08-11T14:19:46ZIs every human voice and fingerprint really unique?<figure><img src="https://images.theconversation.com/files/133561/original/image-20160809-18037-130av7l.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="http://www.shutterstock.com/pic-95091529/stock-photo-sound-wave-background-suitable-as-a-backdrop-for-music-technology-and-sound-projects.html?src=iSDrrG-nAmIvy0qmTXwSNw-1-32">agsandrew</a></span></figcaption></figure><p>Barclays, the UK bank, <a href="http://www.wired.co.uk/article/barclays-voice-security-telephone-banking">is to replace</a> the password system on its phone banking service with personal voice recognition. “Unlike a password, each person’s voice is as unique as a fingerprint,” <a href="http://www.computerweekly.com/news/450301604/Barclays-to-use-voice-recognition-for-phone-banking">said Steven Cooper</a>, Barclays’ head of personal banking. Yet the reality is we have no idea whether either fingerprints or voices are unique at all. </p>
<p>I don’t mean to say that it is impossible that each of us has a physical feature that is unique. The problem <a href="http://www.the-philosopher.co.uk/fingerprints.htm">is that</a> we have no way of <em>knowing</em> whether any of us has such a feature – far less that we all do. </p>
<p>Short of testing all of the 7.4 billion human beings alive today, which is a practical impossibility, we must rely on sampling of some sort. Testing samples of human populations has allowed us any number of vital medical advances. It is great for giving us information about the frequency of particular phenomena within a specified population – blood types, for example. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/133565/original/image-20160809-18053-16y9l92.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/133565/original/image-20160809-18053-16y9l92.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/133565/original/image-20160809-18053-16y9l92.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=920&fit=crop&dpr=1 600w, https://images.theconversation.com/files/133565/original/image-20160809-18053-16y9l92.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=920&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/133565/original/image-20160809-18053-16y9l92.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=920&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/133565/original/image-20160809-18053-16y9l92.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1156&fit=crop&dpr=1 754w, https://images.theconversation.com/files/133565/original/image-20160809-18053-16y9l92.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1156&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/133565/original/image-20160809-18053-16y9l92.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1156&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">One of a kind?</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-103215914/stock-photo-security-concept-fingerprint-on-digital-screen.html?src=MYGcxAIRga60DtOzaF6-Gg-2-34">Maksim Kabakou</a></span>
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<p>Yet sampling cannot establish uniqueness. Sampling could no more inform us that one individual has a particular set of fingerprints than it could inform us how that person will vote. And even if you managed to compare a person’s fingerprints with every other living human being, it wouldn’t establish their uniqueness. What of everyone who is dead? What of all those who are yet to be born?</p>
<p>Neither can you get around this problem with abstract reasoning. If an X will cause a Y then logically whenever there is an X, there will be a Y – or in this case, my fingerprints are caused by a set of factors peculiar to me; therefore everyone has a set of fingerprints caused by their own set of factors. That’s logical, yet it does not follow that whenever there is a Y there will be an X – or that a set of fingerprints can only be produced by the one set of unique factors. This is because the same effect might have had different causes on different occasions. </p>
<h2>The evidence barrier</h2>
<p>The widespread and strongly held belief in the uniqueness of human voices and other physical features characterises and exacerbates a chronic general problem: people misunderstand the nature and significance of quantitative scientific evidence. This is particularly relevant to criminal trials. There is a <a href="http://lpr.oxfordjournals.org/content/8/3/233.full.pdf">danger</a> that accused people are not given fair trials <a href="https://conference.fdiai.org/wp-content/uploads/2014/11/Uniqueness-Fact_or_Fiction1.pdf">because</a> jurors, judges and other court officials put <a href="http://link.springer.com/article/10.1007/s11019-012-9461-1">too much weight</a> on certain forensic evidence. </p>
<p>The <a href="https://www.theguardian.com/society/2007/mar/17/childrensservices.uknews">notorious – later quashed – conviction</a> of Sally Clark, an English solicitor, for the alleged murder of her two babies illustrates well the problem. The case against her turned on the evidence of an expert witness, Sir Roy Meadow, who argued that it was highly improbable that two of her babies could have been the victim of natural cot deaths. </p>
<p>Clark <a href="https://www.theguardian.com/society/2007/mar/17/childrensservices.uknews">was later</a> exonerated by an appeals court after serving three years in prison, but died four years later. Her family said in a statement that she had never recovered from the miscarriage of justice. Meadow <a href="http://www.telegraph.co.uk/news/uknews/1510798/Sir-Roy-Meadow-the-flawed-witness-wins-GMC-appeal.html">was criticised</a> and temporarily struck off for getting the numbers wrong in his assessment of the statistical improbability, but this misses a more fundamental objection to this sort of argument: using statistical unlikelihood in a general forward-looking way is one thing; using it retrospectively with regard to particular instances is quite another. </p>
<p>If you buy a ticket for the lottery, the chances of winning the big prize <a href="http://playlotto.org.uk/lottery/uklottery_odds.html">are about</a> 45 million to one. You might therefore be justified in regarding that as evidence that you are unlikely to win, and not buy a ticket as a result. Yet after the draw is made and Ms X of Glasgow is announced in the newspapers as the winner, the known unlikelihood of winning is obviously not evidence that she did not win. She did win. Unlikely things do happen. </p>
<h2>The way forward</h2>
<p>What do these insights mean in practical terms? People might well argue that even with our limited sampling of human voices, we have good reason to suspect we are very unlikely to come across two different people who have identical voices, even if we could never discount the possibility. Fine. Let us say that. </p>
<p>Human voice patterns or iris recognition need not be assumed to be unique to be useful tools for protecting private access to our bank accounts. In the same way, fingerprints need not be assumed to be unique to be useful in courts. </p>
<p>Dangers and misunderstandings occur when too much is claimed for such techniques. They are of <a href="http://www.clpex.com/TheDetail.htm?issue=496">limited usefulness</a>. They should not be relied upon totally – as overriding evidence or for security systems on their own. They must be relied upon only as part of a wider case or system of checks. </p>
<p><em>Correction: the piece previously said that the chances of winning the lottery are 14m to one. That is no longer the case.</em></p><img src="https://counter.theconversation.com/content/63739/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Hugh McLachlan 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>Saying they are is to dangerously misunderstand the limits of scientific enquiry.Hugh McLachlan, Professor of Applied Philosophy, Glasgow Caledonian UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/316942014-09-16T12:19:48Z2014-09-16T12:19:48ZPeople with blood type AB more at risk of cognitive decline and dementia<figure><img src="https://images.theconversation.com/files/59021/original/kd7ftw8w-1410771611.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Don't bank on it.</span> <span class="attribution"><a class="source" href="http://pixabay.com/en/blood-bags-red-red-blood-cells-91171/">Sabinurce</a></span></figcaption></figure><p>As the number of elderly people <a href="https://www.census.gov/population/international/files/97agewc.pdf">increases</a>, so do concerns about cognitive impairment and dementia. Minor difficulties with memory and thinking can be a normal part of the ageing process, but our recent work found that people with the blood type AB may be at higher risk for significant cognitive problems than the rest of the population.</p>
<p>There are four main <a href="http://www.britannica.com/EBchecked/topic/1429/ABO-blood-group-system">ABO blood system</a> types: A, B, AB and O, which are determined by the presence of certain molecules (<a href="http://www.redcrossblood.org/learn-about-blood/blood-types">A and B antigens</a>) on the surface of red blood cells. Of these, type AB is by far the least common, found in only about 4% of people in the US. </p>
<p>Our research group at the University of Vermont, led by Mary Cushman, found that the odds of developing cognitive impairment were 82% higher in those with blood type AB, compared to those with blood type O, which had the lowest risk. These results, which were <a href="http://www.neurology.org/content/early/2014/09/10/WNL.0000000000000844.short">published in Neurology</a>, build on previous research showing that people with blood type O <a href="http://www.medpagetoday.com/Cardiology/MyocardialInfarction/34205">are at lower risk</a> for cardiovascular diseases, including stroke.</p>
<p>We used information gathered from a larger study on stroke risk factors <a href="http://www.regardsstudy.org/">known as</a> the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study, which followed more than 30,000 people from around the US who were aged 45 and above, for an average of 3.4 years. In this time, 495 people developed cognitive impairment, characterised by thinking and memory problems. We compared this group with 587 individuals who did not develop cognitive problems. In the group with cognitive impairment, 6% had blood type AB, compared with 4% in the control group and in the general population.</p>
<p>We also looked at blood levels of a protein called factor VIII, which is involved in blood coagulation. Elevated factor VIII is a risk factor for stroke and coronary artery disease and may also be related to dementia risk. We found that people with blood type AB also had the highest levels of factor VIII, nearly 40% higher than people with blood type O. High factor VIII alone increased the risk of cognitive problems by nearly a quarter.</p>
<p>The gene that determines ABO blood type can cause differences in factor VIII levels by affecting the clearance of a carrier protein that circulates the blood attached to factor VIII. This carrier protein is <a href="http://ghr.nlm.nih.gov/gene/VWF">called von Willebrand factor</a> (named after Erik von Willebrand, a Finnish doctor who first described a hereditary <a href="http://www.mayoclinic.org/diseases-conditions/von-willebrand-disease/basics/definition/con-20030195">blood coagulation disease</a>) and is also important for blood clotting and linked to cardiovascular disease. The effect of blood type on coagulation proteins may be part of the connection between ABO type, cardiovascular disease, and cognition problems. However, the differences in factor VIII levels accounted for only about a fifth of extra risk of cognitive impairment we saw with blood type AB.</p>
<h2>Blood links to other health problems</h2>
<p>Non-O blood types <a href="http://www.ncbi.nlm.nih.gov/pubmed/24381150">have been linked</a> to several forms of vascular disease, including heart attack and <a href="http://www.ncbi.nlm.nih.gov/pubmed/25187297">venous thromboembolism</a> (a disease that includes deep vein thrombosis). Blood type AB, in particular, has been <a href="http://www.ncbi.nlm.nih.gov/pubmed/22895671">associated</a> <a href="http://newsroom.heart.org/news/blood-type-may-influence-heart-23737">with heart disease</a>, and our group <a href="http://www.ncbi.nlm.nih.gov/pubmed/24444093">recently published a study</a> showing a higher risk of stroke with this blood type.</p>
<p>Our findings on blood type and cognitive impairment add to a growing body of evidence that cardiovascular health and brain health are closely related. Many common risk factors for heart disease and stroke <a href="http://www.alzheimers.org.uk/site/scripts/documents_info.php?documentID=161">are also tied</a> to memory problems and dementia, such as diabetes, high blood pressure, and high cholesterol. </p>
<p>Because blood type is already known to affect the risk of cardiovascular disease, it represents another link between vascular health and brain function. </p>
<p>With that in mind, there is no reason to panic if you have blood type AB. There are a number of lifestyle factors that can reduce your risk of cognitive problems and dementia, and many of them have more of an impact than your blood type. Getting regular exercise, eating well and not smoking, for example, are important for both cardiovascular and brain health – and keeping blood pressure, cholesterol, and blood sugar under control will also lower your risk for these problems. Scientists recommend keeping your brain active as well, through activities like games and puzzles, and learning new skills.</p><img src="https://counter.theconversation.com/content/31694/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kristine Alexander 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>As the number of elderly people increases, so do concerns about cognitive impairment and dementia. Minor difficulties with memory and thinking can be a normal part of the ageing process, but our recent…Kristine Alexander, Postdoctoral Fellow of Medicine, University of VermontLicensed as Creative Commons – attribution, no derivatives.