tag:theconversation.com,2011:/global/topics/hydration-29636/articlesHydration – The Conversation2024-01-02T20:16:45Ztag:theconversation.com,2011:article/2154522024-01-02T20:16:45Z2024-01-02T20:16:45ZIs cold water bad for you? What about drinking from the hose or tap? The facts behind 5 water myths<figure><img src="https://images.theconversation.com/files/557689/original/file-20231106-25-np8o5o.jpg?ixlib=rb-1.1.0&rect=11%2C25%2C2449%2C1600&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/little-girl-drink-water-public-drinking-1543468013">Shutterstock</a></span></figcaption></figure><p>We know the <a href="https://www.health.qld.gov.au/news-events/doh-media-releases/releases/stay-hydrated-and-sun-safe-during-the-summer-months">importance of staying hydrated</a>, especially in hot weather. But even for something as simple as a drink of water, conflicting advice and urban myths abound. </p>
<p>Is cold water really bad for your health? What about hot water from the tap? And what is “raw water”? Let’s dive in and find out.</p>
<h2>Myth 1: Cold water is bad for you</h2>
<p>Some recent <a href="https://www.tiktok.com/discover/drinking-cold-water-is-bad-for-you">TikToks</a> have suggested cold water causes health problems by somehow “contracting blood vessels” and “restricting digestion”. There is <a href="https://www.medicalnewstoday.com/articles/325038#risks">little evidence</a> for this. </p>
<p>While a <a href="https://journals.sagepub.com/doi/10.1046/j.1468-2982.2001.00211.x">2001 study</a> found 51 out of 669 women tested (7.6%) got a headache after drinking cold water, most of them already suffered from migraines and the work hasn’t been repeated since. </p>
<p>Cold drinks were shown to <a href="https://www.jnmjournal.org/journal/view.html?doi=10.5056/jnm.2012.18.4.391">cause discomfort</a> in people with achalasia (<a href="https://www.hopkinsmedicine.org/health/conditions-and-diseases/achalasia">a rare swallowing disorder</a>) in 2012 but the study only had 12 participants. </p>
<p>For most people, the temperature you drink your water is down to personal preference and circumstances. Cold water after exercise in summer or hot water to relax in winter won’t make any difference to your overall health. </p>
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Read more:
<a href="https://theconversation.com/dont-like-drinking-plain-water-10-healthy-ideas-for-staying-hydrated-this-summer-191859">Don’t like drinking plain water? 10 healthy ideas for staying hydrated this summer</a>
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<h2>Myth 2: You shouldn’t drink hot tap water</h2>
<p>This belief has a grain of scientific truth behind it. Hot water is generally a <a href="https://www.ncbi.nlm.nih.gov/books/NBK431100/">better solvent than cold water</a>, so may dissolve metals and minerals from pipes better. Hot water is also often stored in tanks and may be heated and cooled many times. Bacteria and other disease-causing microorganisms tend to <a href="https://www.sciencedirect.com/science/article/abs/pii/S0301421514000172">grow better in warm water</a> and can build up over time. </p>
<p>It’s better to fill your cup from the cold tap and get hot water for drinks from the kettle. </p>
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<a href="https://images.theconversation.com/files/557687/original/file-20231106-29-605ipk.jpg?ixlib=rb-1.1.0&rect=5%2C10%2C3616%2C2579&q=45&auto=format&w=1000&fit=clip"><img alt="woman drinks from bottle" src="https://images.theconversation.com/files/557687/original/file-20231106-29-605ipk.jpg?ixlib=rb-1.1.0&rect=5%2C10%2C3616%2C2579&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557687/original/file-20231106-29-605ipk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=430&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557687/original/file-20231106-29-605ipk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=430&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557687/original/file-20231106-29-605ipk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=430&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557687/original/file-20231106-29-605ipk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=540&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557687/original/file-20231106-29-605ipk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=540&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557687/original/file-20231106-29-605ipk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=540&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">Hot or cold, so long as the water is treated it probably won’t affect your health.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/woman-drinking-water-241325890">Shutterstock</a></span>
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<h2>Myth 3: Bottled water is better</h2>
<p>While bottled water might be safer in <a href="https://press.un.org/en/2003/sgsm8707.doc.htm">certain parts of the world</a> due to pollution of source water, there is no real advantage to drinking bottled water in Australia and similar countries. </p>
<p>According to <a href="https://sustainability.uq.edu.au/projects/recycling-and-waste-minimisation/real-cost-bottled-water">University of Queensland</a> researchers, bottled water is not safer than tap water. It <a href="https://www.campaignlive.co.uk/article/cokes-bottled-water-dasani-revealed-tap/203811">may even be tap water</a>. Most people <a href="https://pubmed.ncbi.nlm.nih.gov/30189556/">can’t tell the difference</a> either. Bottled water usually costs (substantially) more than turning on the tap and is <a href="https://www.sciencedirect.com/science/article/pii/S0048969721039565#bb0120">worse for the environment</a>.</p>
<p>What about lead in tap water? This problem hit the headlines after a <a href="https://www.cdc.gov/nceh/casper/pdf-html/flint_water_crisis_pdf.html">public health emergency</a> in Flint, Michigan, in the United States. But Flint used lead pipes with a corrosion inhibitor (in this case orthophosphate) to keep lead from dissolving. Then the city switched water sources to one <a href="https://pubs.acs.org/doi/full/10.1021/acs.est.6b04034">without a corrosion inhibitor</a>. Lead levels rose and a public emergency was declared.</p>
<p>Fortunately, lead pipes haven’t been used in Australia since the 1930s. While lead might be present in some old plumbing products, it is <a href="https://www.health.gov.au/sites/default/files/documents/2020/02/enhealth-guidance-lead-in-drinking-water-from-some-plumbing-products-enhealth-guidance-lead-in-drinking-water-from-some-plumbing-products.pdf">unlikely to cause problems</a>.</p>
<h2>Myth 4: Raw water is naturally healthier</h2>
<p>Some people bypass bottled and tap water, going straight to the source. </p>
<p>The “<a href="https://www.sbs.com.au/food/article/raw-water-is-it-a-healthy-trend-or-a-dangerous-fad/5mqtpmxmy">raw water</a>” trend emerged a few years ago, encouraging people to drink from rivers, streams and lakes. There is even a <a href="https://findaspring.org">website</a> to help you find a local source. </p>
<p>Supporters say our ancestors drank spring water, so we should, too. However, our ancestors also often died from dysentery and cholera and their <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5719695/#:%7E:text=The%20first%20encounters%20began%20about,approximately%2033%20years%20of%20age">life expectancy was low</a>. </p>
<p>While it is true even highly treated drinking water can contain low levels of things like <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6449537/">microplastics</a>, unless you live somewhere very remote, the risks of drinking untreated water are <a href="https://press.un.org/en/2003/sgsm8707.doc.htm">far higher</a> as it is more likely to contain pollutants from the <a href="https://www.epa.vic.gov.au/for-community/current-projects-issues/water-quality-alerts">surrounding area</a>.</p>
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Read more:
<a href="https://theconversation.com/travelling-around-australia-this-summer-heres-how-to-know-if-the-water-is-safe-to-drink-196294">Travelling around Australia this summer? Here's how to know if the water is safe to drink</a>
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<h2>Myth 5: It’s OK to drink directly from hoses</h2>
<p>Tempting as it may be, it’s probably best not to drink from the hose when watering the plants. Water might have sat in there, in the warm sun for weeks or more potentially leading to <a href="https://pubs.acs.org/doi/pdf/10.1021/es502652n">bacterial buildup</a>.</p>
<p>Similarly, while drinking water fountains are generally perfectly <a href="https://www.abc.net.au/news/2023-06-01/are-public-drinking-taps-a-health-risk/102415840">safe to use</a>, they can contain a <a href="https://www.mdpi.com/2073-4441/14/6/908">variety of bacteria</a>. It’s useful (though not essential) to run them for a few seconds before you start to drink so as to get fresh water through the system rather than what might have been sat there for a while.</p>
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<a href="https://images.theconversation.com/files/557688/original/file-20231106-21-ssiwkb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="drop of water suspended below tap" src="https://images.theconversation.com/files/557688/original/file-20231106-21-ssiwkb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/557688/original/file-20231106-21-ssiwkb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=379&fit=crop&dpr=1 600w, https://images.theconversation.com/files/557688/original/file-20231106-21-ssiwkb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=379&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/557688/original/file-20231106-21-ssiwkb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=379&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/557688/original/file-20231106-21-ssiwkb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=477&fit=crop&dpr=1 754w, https://images.theconversation.com/files/557688/original/file-20231106-21-ssiwkb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=477&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/557688/original/file-20231106-21-ssiwkb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=477&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">There is a tiny risk that hot water might come with some contaminants from pipes or tanks.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/drop-pure-water-dripping-tap-selective-1312274558">Shutterstock</a></span>
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Read more:
<a href="https://theconversation.com/drinking-fountains-in-every-town-wont-fix-all-our-water-issues-but-its-a-healthy-start-204912">Drinking fountains in every town won't fix all our water issues – but it's a healthy start</a>
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<p>We are fortunate to be able to take safe drinking water for granted. Billions of people around the world are <a href="https://www.who.int/multi-media/details/5-years-into-the-race-to-the-2030-targets-safe-drinking-water">not so lucky</a>. </p>
<p>So whether you like it hot or cold, or somewhere in between, feel free to enjoy a glass of water this summer. </p>
<p>Just don’t drink it from the hose.</p><img src="https://counter.theconversation.com/content/215452/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Oliver A.H. Jones is Deputy Director of the Water: Emerging Technology and Tools (WETT) Research Centre at RMIT University. He has received funding from Melbourne Water and EPA Victoria for research into water pollution.</span></em></p>There are a lot of myths and strongly held beliefs around one of life’s simplest activities – drinking water.Oliver A.H. Jones, Professor of chemistry, RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2092072023-07-17T12:22:43Z2023-07-17T12:22:43ZAs a summer heat wave pummels the US, an expert warns about the dangers of humidity – particularly for toddlers, young athletes and older adults<figure><img src="https://images.theconversation.com/files/536162/original/file-20230706-15-iudxu0.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6720%2C4466&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Symptoms of heatstroke include a throbbing headache, dizziness, confusion and nausea.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/senior-couple-royalty-free-image/1282773408?phrase=older+people+suffering+from+heat+outside+heatstroke&adppopup=true">milan2099/E+ via Getty Images</a></span></figcaption></figure><p><em>Because of climate change, summers are getting <a href="https://www.theguardian.com/us-news/2022/jun/10/us-summer-temperatures-rising-climate-science">hotter and more humid</a> – much more humid. SciLine interviewed <a href="https://hhd.psu.edu/contact/w-kenney-phd">Dr. W. Larry Kenney</a>, professor of physiology and kinesiology at Penn State University, who discussed <a href="https://theconversation.com/how-hot-is-too-hot-for-the-human-body-our-lab-found-heat-humidity-gets-dangerous-faster-than-many-people-realize-185593">why humid heat can be dangerous to human health</a> and, in some cases, life-threatening; how heat stresses the body, particularly the cardiovascular system; and why infants, athletes and older adults are especially susceptible.</em></p>
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<figcaption><span class="caption">W. Larry Kenney discusses the dangers of high heat and humidity.</span></figcaption>
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<p><em>Below are some highlights from the discussion. Answers have been edited for brevity and clarity.</em></p>
<p><strong>How is climate change affecting the frequency and severity of heat waves in the U.S.?</strong></p>
<p><strong>Kenney:</strong> When climatologists talk about the changing climate and global warming, the focus is on the average temperature on Earth – the average surface temperature, the average ocean temperature and so on. Humans are tropical animals; we evolved in tropical climates. And so a change of a couple of degrees Fahrenheit in the average Earth’s temperature doesn’t have much of an effect on human health directly. </p>
<p>However, if you think of the range of climates <a href="https://changingclimates.colostate.edu/docs/BellCurveAveragesExtremes.pdf">as a bell-shaped curve</a>, and then think of that whole curve shifting toward hotter temperatures, it’s the extremes that are dangerous. So we’ll have more hot days and more extremely hot days, which result in an increased frequency, duration and intensity <a href="https://www.cnn.com/2023/07/05/world/hottest-day-world-climate-el-nino-intl/index.html">of environmental heat waves</a>.</p>
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<p><strong><em><a href="https://theconversation.com/how-hot-is-too-hot-for-the-human-body-our-lab-found-heat-humidity-gets-dangerous-faster-than-many-people-realize-185593">Read Kenney’s in-depth story on his research for The Conversation.</a></em></strong></p>
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<p><strong>Why is humid heat particularly dangerous?</strong></p>
<p><strong>Kenney:</strong> The primary means by which humans get rid of body heat that’s built up is by evaporation of sweat. The more humid it is, the <a href="https://engineering.mit.edu/engage/ask-an-engineer/why-do-we-sweat-more-in-high-humidity/#:%7E">less of the sweat that we produce evaporates</a>, and the less of that powerful cooling mechanism we have at our disposal. </p>
<p><strong>Other than sweating, how does the body respond to heat stress?</strong></p>
<p><strong>Kenney:</strong> The other way we cope with increased body temperature is unique to humans. We pump a lot of blood to the skin to dissipate heat to the environment. So under extremely hot resting conditions, we may pump as much blood to the skin as we pump to the entire rest of the body. </p>
<p>And as we pump more and more blood to the skin, the heart has to work harder and heart rate increases. And in some cases, in some vulnerable populations, that can put a <a href="https://www.health.harvard.edu/blog/heat-is-hard-on-the-heart-simple-precautions-can-ease-the-strain-201107223180">great strain on an already-compromised heart</a>.</p>
<p><strong>Why are infants and older adults particularly vulnerable to heat and humidity?</strong></p>
<p><strong>Kenney:</strong> Infants are particularly <a href="https://www.childrens.com/health-wellness/keeping-your-baby-safe-and-cool-in-summer">vulnerable to high heat and humidity</a>, primarily because they’re at the mercy of adults to make good decisions to make sure that they’re protected from hot conditions, adequately hydrated, properly fed and so on. </p>
<p>Coupled with that, infants don’t have a very well-developed thermoregulatory system. Their ability to dissipate heat, once body temperature is elevated … is lower than that of adults. </p>
<p>And so, unfortunately every summer, there are a number of deaths of children <a href="https://injuryfacts.nsc.org/motor-vehicle/motor-vehicle-safety-issues/hotcars/#:%7E">left in hot cars by accident</a>, which is a real tragedy. </p>
<p>On the other part of the age spectrum, the elderly are also particularly <a href="https://www.cdc.gov/disasters/extremeheat/older-adults-heat.html#:%7E">vulnerable to high heat and humidity</a> for a number of reasons, including socioeconomic factors – lack of access to air conditioning, becoming more sedentary and less fit, and going outdoors less often. </p>
<p>And then physiological changes occur with aging, including a lesser ability to pump blood to the skin, accompanied by more strain on the heart and a lower ability to produce sweat and evaporate that sweat for cooling. </p>
<p>So individuals on both ends of the age spectrum tend to be particularly vulnerable to what we term classic heatstroke.</p>
<p><strong>Are there any government regulations in place to protect workers from heat?</strong></p>
<p><strong>Kenney:</strong> The National Institute for Occupational Safety and Health provides <a href="https://www.cdc.gov/niosh/mining/UserFiles/works/pdfs/2017-127.pdf">guidance on work/rest cycles</a>, depending on how hard people are working and how hot and humid the environment is. </p>
<p>There is also good information available on <a href="https://www.cdc.gov/niosh/topics/heatstress/acclima.html#:%7E">heat acclamation procedures</a> for those workers, getting them ready to better tolerate conditions of high heat and humidity. Unfortunately, this is not an enforceable standard. </p>
<p><strong>What should coaches and athletes know about staying safe when exercising in hot conditions?</strong></p>
<p><strong>Kenney:</strong> Most of the athletes who succumb to heat-related disorders do so during the first few days of training for their sport – in particular <a href="https://www.pbs.org/newshour/science/how-extreme-heat-affects-young-athletes">football players during late July and early August</a>, when the players have not really become truly acclimated to exercise in those hot environments. </p>
<p>Coaches need to be knowledgeable about gradually acclimating their athletes to the heat. They also need to be knowledgeable about <a href="https://www.sportsmd.com/2018/07/10/coaches-how-to-keep-your-athletes-hydrated-in-summer-heat/">proper hydration practices</a>. And another thing that coaches need to realize is that many heat-related deaths in athletes across many sports are associated with coaches <a href="https://komonews.com/news/local/federal-way-school-district-5-million-525-pay-family-allen-harris-high-school-football-workout-practice-conditioning-sudden-cardiac-arrest-wrongful-death-lawsuit-settle">having the players run wind sprints</a> or do intense exercise at the end of, or very late in, the practice. </p>
<p>The athletes already have a high heat buildup. That’s then exacerbated by pushing themselves really hard at the end of practice and core temperature soars. In terms of the athletes, they first and foremost need to listen to their bodies and not push themselves beyond their physiological limits. </p>
<p>There’s no way that really trying to tough it out when you have signs and symptoms of heat-related strain or illness makes sense, because your attitude can’t overcome physiology.</p>
<p><strong>Is the heat index a good measurement of how hot it feels and how people’s bodies are affected by heat?</strong></p>
<p><strong>Kenney:</strong> The heat index was developed in 1979 and <a href="https://www.weather.gov/ama/heatindex#:%7E">popularized by the National Weather Service</a> as a measure of how hot it feels when temperature is combined with relative humidity. And there’s a long, complex equation that’s used for calculating the heat index. </p>
<p>The problem with using the heat index for human health and safety is that it’s a perceptual index – it’s truly an estimate of how hot we feel in that environment, not the effects of that heat and humidity on the human body. </p>
<p>A better measurement that many people have used is something called <a href="https://www.weather.gov/tsa/wbgt">wet-bulb temperature</a>. That involves taking a typical mercury thermometer, putting a wick over the bulb and then saturating that wick with water. And as water evaporates from that wick, it cools down the temperature measured by the thermometer. In many ways, it mimics a human sweating and evaporating that sweat. </p>
<p>So wet-bulb temperature is becoming known as a <a href="https://www.iflscience.com/southern-us-reaches-dangerous-wet-bulb-temperature-heres-what-that-means-69665">better index of heat strain</a>. It’s not perfect. It doesn’t account for radiation from the Sun, for example‚ but it’s much better than the heat index because it’s much more physiological.</p>
<p><em>Watch the <a href="https://www.sciline.org/health-medicine/heat-humidity-health/">full interview</a> to hear more about how heat and humidity affect your health.</em></p>
<p><em><a href="https://www.sciline.org/">SciLine</a> is a free service based at the nonprofit American Association for the Advancement of Science that helps journalists include scientific evidence and experts in their news stories.</em></p><img src="https://counter.theconversation.com/content/209207/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>W. Larry Kenney receives funding from the National Institutes of Health in the form of a research grant. He also serves on scientific advisory boards or panels for the American Council on Exercise, Nike, and GoodSport.</span></em></p>As temperatures rise in the US, so does the incidence of heat-related deaths, including heatstroke.W. Larry Kenney, Professor of Physiology, Kinesiology and Human Performance, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2028292023-04-04T20:20:45Z2023-04-04T20:20:45ZPrime drinks aren’t suitable for children and pregnant women. Here’s why<figure><img src="https://images.theconversation.com/files/519151/original/file-20230403-14-8ognt5.jpg?ixlib=rb-1.1.0&rect=48%2C796%2C8003%2C4357&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/los-angeles-california-united-states-02012023-2275143831">Shutterstock</a></span></figcaption></figure><p>Prime drinks have been heavily promoted in Australia, leading to <a href="https://au.news.yahoo.com/woolworths-shoppers-in-frenzy-to-get-hands-on-cult-drink-prime-062849789.html">frenzied sales</a> in supermarkets, as well <a href="https://www.abc.net.au/news/2023-03-29/prime-logan-paul-ksi-drink-australian-schools-ban/102154550">bans in schools</a>. </p>
<p>Prime offers two products: one is marketed as a “hydration” drink, the other as an “energy” drink. The latter comes with a <a href="https://drinkprime.com/pages/faq">warning</a> it’s not suitable for people under 18 years of age, or pregnant or lactating women and isn’t legally sold in stores in Australia.</p>
<p>But both drinks may pose problems to under-18s and women who are pregnant or lactating. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1637195918595313665"}"></div></p>
<h2>What’s in Prime Energy?</h2>
<p>Prime Energy contains <a href="https://drinkprime.com/pages/faq">200 milligrams</a> of caffeine per can, which is equivalent to about two to three instant coffees. This caffeine content is roughly double what is <a href="https://www.foodstandards.gov.au/consumer/generalissues/pages/caffeine.aspx">legally allowed</a> for products sold in Australia. </p>
<p>Despite its name, Prime Energy drink contains only about 40 kilojoules from carbohydrates, which is one of our body’s key sources of energy. The “energy” in Prime Energy refers to the caffeine, which makes you feel more alert and lessens the perceived effort involved in any work you do. </p>
<p>Caffeine <a href="https://www.ais.gov.au/__data/assets/pdf_file/0003/1001379/Caffeine-Infographic-final.pdf">does provide performance benefits</a> for athletes aged over 18. However, given the high quantities in the drinks, there may be better ways to get caffeine in more appropriate doses. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/can-coffee-improve-your-workout-the-science-of-caffeine-and-exercise-92366">Can coffee improve your workout? The science of caffeine and exercise</a>
</strong>
</em>
</p>
<hr>
<h2>Caffeine is a concern during pregnancy</h2>
<p>Health guidelines recommend <a href="https://www.foodstandards.gov.au/consumer/generalissues/Pages/Caffeine.aspx">limiting</a> caffeine intake during pregnancy and while breastfeeding to below 200mg a day. </p>
<p>Theoretically, this drink alone, with 200mg of caffeine per can, should be fine. But practically, diets include many other sources of caffeine including coffee, tea, chocolate and cola drinks. Consumption of these alongside the energy drinks would increase the intake for pregnant women above this safety threshold. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/518988/original/file-20230403-14-14bsg4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/518988/original/file-20230403-14-14bsg4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/518988/original/file-20230403-14-14bsg4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=840&fit=crop&dpr=1 600w, https://images.theconversation.com/files/518988/original/file-20230403-14-14bsg4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=840&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/518988/original/file-20230403-14-14bsg4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=840&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/518988/original/file-20230403-14-14bsg4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1056&fit=crop&dpr=1 754w, https://images.theconversation.com/files/518988/original/file-20230403-14-14bsg4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1056&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/518988/original/file-20230403-14-14bsg4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1056&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://www.foodstandards.gov.au/consumer/generalissues/Pages/Caffeine.aspx">FSANZ</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Why is caffeine a problem for fetuses and babies?</h2>
<p>Caffeine can cross the placenta into the growing fetus’s bloodstream. Fetuses can’t break down the caffeine, so it remains in their circulation. </p>
<p>As the pregnancy proceeds, the mother becomes <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5872737/">slower at clearing caffeine</a> from her metabolism. This potentially exposes the fetus to caffeine for longer. </p>
<p>Studies have shown a high intake of caffeine is associated with <a href="https://link.springer.com/article/10.1007/s10654-014-9944-x">growth restriction</a>, <a href="https://pubmed.ncbi.nlm.nih.gov/26026343/">reduced birth weight, preterm birth and stillbirth</a>. Some experts argue there is <a href="https://ebm.bmj.com/content/26/3/114">no safe limit of caffeine intake</a> during pregnancy. </p>
<p>With breastfeeding, <a href="https://adc.bmj.com/content/54/10/787.short">caffeine passes into the breast milk</a>. It remains in the baby’s circulation, as they’re unable to metabolise it. <a href="https://pubmed.ncbi.nlm.nih.gov/9849117/">Evidence shows</a> that caffeine may make babies more colicky, irritable and less likely to sleep.</p>
<h2>What about in kids?</h2>
<p>Children also have a limited ability to break down caffeine. Combined with their lighter body mass, a caffeine-based drink will have a more pronounced effect. </p>
<p>As such, safe caffeine levels are determined on a weight basis: <a href="https://www.foodstandards.gov.au/code/proposals/Documents/P1056%20SD1%201st%20CFS%20Safety%20Assessment.pdf">3mg per kg of body weight per day</a>. For example, children aged 9 to 13 years, who weigh no more than 40kg, should have no more than 120mg of caffeine per day. Those aged between 14 to 17 years who weigh less than 60kg should have no more than 180mg per day.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1640853762519728129"}"></div></p>
<p><a href="https://www.internationaljournalofcardiology.com/article/S0167-5273(15)30918-9/fulltext">Studies have shown</a> higher intakes increase the risk of heart problems, such as heart palpitations, chest pain, shortness of breath and fainting. This may reflect underlying heart rhythm problems, which have in some case ended up with <a href="https://www.internationaljournalofcardiology.com/article/S0167-5273(15)30918-9/fulltext">children and teenagers</a> presenting to hospital emergency departments.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/should-teens-taking-adhd-anxiety-and-depression-drugs-consume-energy-drinks-and-coffee-166864">Should teens taking ADHD, anxiety and depression drugs consume energy drinks and coffee?</a>
</strong>
</em>
</p>
<hr>
<h2>What about Prime Hydrate, which doesn’t contain caffeine?</h2>
<p>This drink contains branch chain amino acids, or BCAA, which the supplements industry promotes as helping gain muscle bulk. There are three BCAA: valine, leucine and isoleucine.</p>
<p>However, there is no evidence they provide any benefit. As such, the <a href="https://www.ais.gov.au/nutrition/supplements/group_c">Australian Institute of Sport</a> has concluded they are not an effective supplement for athletes. </p>
<p>Supplements in general are not recommended in <a href="https://www.nccih.nih.gov/health/dietary-and-herbal-supplements">children or pregnant women</a> as they have not been tested in these groups. </p>
<p>There is also concern about the impact of BCAA and how they may impact the growth of the fetus. A <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7178017/">scientific animal study</a> has shown altered patterns of growth with fetal mice. </p>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7551332/">No human studies</a> have examined BCAA and fetal growth, so that research needs to be done before recommendations can be given to pregnant women. They should avoid these ingredients in the absence of evidence.</p>
<p>Similarly, there has been no testing of these supplements in children under 18 years, so there is no guarantee of their safety. </p>
<p>Performance-enhancing sport supplements are <a href="https://journals.humankinetics.com/view/journals/ijsnem/24/5/article-p570.xml">not recommended</a> for children and adolescents, as they are still developing physically as well as refining and improving their sporting skills. </p>
<figure class="align-center ">
<img alt="Children running" src="https://images.theconversation.com/files/519150/original/file-20230403-28-nwlh6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/519150/original/file-20230403-28-nwlh6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/519150/original/file-20230403-28-nwlh6e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/519150/original/file-20230403-28-nwlh6e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/519150/original/file-20230403-28-nwlh6e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/519150/original/file-20230403-28-nwlh6e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/519150/original/file-20230403-28-nwlh6e.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">Children shouldn’t use performance-enhacing supplements.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>What does the science say about BCAA?</h2>
<p>Scientists have been investigating how BCAA affect adults. Circulating BCAA can affect carbohydrate metabolism in the muscle and therefore can <a href="https://www.mdpi.com/2072-6643/14/7/1454">change insulin sensitivity</a>. BCAA are elevated in adults with diet-induced obesity and are associated with <a href="https://www.mdpi.com/2072-6643/14/7/1454">increased future risk of type 2 diabetes</a>, even when scientists account for other baseline risk factors.</p>
<p>Adults with obesity and insulin resistance have been found to have higher levels of BCAA. <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.2047-6310.2012.00087.x">Emerging evidence suggests</a> children and adolescents with obesity also have higher levels of BCAA, which may predict future insulin resistance, a risk factor for diabetes. </p>
<p>However we don’t yet know if these elevated levels of BCAA in the blood are because people are overweight or obese, or if it plays a role in them becoming overweight or obese.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/do-athletes-really-need-protein-supplements-92773">Do athletes really need protein supplements?</a>
</strong>
</em>
</p>
<hr>
<p>The bottom line is we have clear evidence that caffeine is problematic for children and women who are pregnant and lactating. And there is emerging evidence BCAA may be also problematic.</p><img src="https://counter.theconversation.com/content/202829/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Evangeline Mantzioris is affiliated with Alliance for Research in Nutrition, Exercise and Activity (ARENA) at the University of South Australia. Evangeline Mantzioris has received funding from the National Health and Medical Research Council, and has been appointed to the National Health and Medical Research Council Dietary Guideline Expert Committee.</span></em></p>Prime has two offerings: one is marketed as a ‘hydration’ drink, the other as an ‘energy’ drink. But what’s actually in them?Evangeline Mantzioris, Program Director of Nutrition and Food Sciences, Accredited Practising Dietitian, University of South AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1918592022-12-29T20:55:51Z2022-12-29T20:55:51ZDon’t like drinking plain water? 10 healthy ideas for staying hydrated this summer<figure><img src="https://images.theconversation.com/files/492252/original/file-20221028-24414-abphfh.jpg?ixlib=rb-1.1.0&rect=41%2C311%2C3952%2C4628&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://images.pexels.com/photos/1844155/pexels-photo-1844155.jpeg?auto=compress&cs=tinysrgb&w=800">Pexels/Marcos Flores</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Have you heard the saying “water is life?” Well, it’s true. </p>
<p>Water is an <a href="https://www.hsph.harvard.edu/nutritionsource/water/">essential nutrient</a>. Our body cannot produce sufficient water to live, so we need to consume water through food and fluids to survive. </p>
<p>Maintaining hydration is one of the most fundamental components of good health. But lots of people don’t like drinking plain water much. The good news is there are many other healthy ways to help you stay hydrated.</p>
<h2>Why hydration is important</h2>
<p>Water is vital for many aspects of body functioning. About half our blood is “blood plasma”, which is over 90% water. Blood plasma is essential for carrying energy, nutrients and oxygen to the cells in the body that need it most. Water helps to remove waste products via the kidneys. It also helps keep joints lubricated, the digestive system functioning, the body’s temperature controlled and skin plump and strong. </p>
<p>If you don’t consume enough water, you may experience symptoms of dehydration such as headaches, dizziness, tiredness, low concentration, constipation and a dry mouth. Being severely dehydrated increases the risk of <a href="https://www.kidney.org/atoz/content/kidneystones">kidney stones</a> and <a href="https://www.healthdirect.gov.au/urinary-tract-infection-uti">urinary tract infections</a>.</p>
<p>If you feel thirsty, it means your body is already <a href="https://my.clevelandclinic.org/health/treatments/9013-dehydration#:%7E:text=If%20you're%20thirsty%2C%20you,life%2Dthreatening%20illnesses%20like%20heatstroke.">mildly dehydrated</a>, so make sure you pay attention to what your body is telling you.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/492254/original/file-20221028-23823-ercwbt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="person drinks from fancy glass water bottle" src="https://images.theconversation.com/files/492254/original/file-20221028-23823-ercwbt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/492254/original/file-20221028-23823-ercwbt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/492254/original/file-20221028-23823-ercwbt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/492254/original/file-20221028-23823-ercwbt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/492254/original/file-20221028-23823-ercwbt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/492254/original/file-20221028-23823-ercwbt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/492254/original/file-20221028-23823-ercwbt.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">Maybe a fancy water bottle will help?</span>
<span class="attribution"><a class="source" href="https://images.pexels.com/photos/6766667/pexels-photo-6766667.jpeg?auto=compress&cs=tinysrgb&w=1260&h=750&dpr=2">Pexels/Ekaterina Bolovtsova</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-urine-sterile-do-urine-therapies-work-experts-debunk-common-pee-myths-191862">Is urine sterile? Do urine 'therapies' work? Experts debunk common pee myths</a>
</strong>
</em>
</p>
<hr>
<h2>How much fluid do you need?</h2>
<p>The amount of fluid we need changes as we age. Relative to our body weight, our needs decrease. So, a newborn baby has higher fluid needs (per kilogram body weight) than their parent, and older adults have lower fluid needs than younger adults. </p>
<p>Fluid requirements are related to metabolic needs and vary from person-to-person. The normal turnover of water in adults is approximately 4% of total body weight per day. So, for example, if you weigh 70 kilograms, you’ll lose about 2.5 to 3 litres of water a day (not including sweating). This means you will need to consume that amount of water from food and drinks to maintain your hydration. </p>
<p>Eight cups (or two litres) a day is often <a href="https://www.npr.org/2022/09/21/1124371309/busting-common-hydration-water-myths?utm_source=npr_newsletter&utm_medium=email&utm_content=20221016&utm_term=7386723&utm_campaign=health&utm_id=31926817&orgid=&utm_att1=">mentioned</a> as the amount of water we should aim for and a nice way to track your intake. But it doesn’t account for individual variation based on age, gender, body size and activity levels. </p>
<p>Alcohol is a diuretic, which means it dehydrates the body by promoting water loss through urine. This fluid loss is a key factor that contributes to the severity of a hangover. Always have a glass of water in between alcoholic drinks to help stay hydrated.</p>
<p>Caffeinated drinks (like tea and coffee) only have a mild diuretic effect. For most healthy adults, it’s okay to consume up to 400 mg of caffeine a day – that’s about four cups of coffee or eight cups of tea. If you drink more than this, it may impact your hydration levels.</p>
<p>To check your specific requirements, check out the Australian <a href="https://www.nrv.gov.au/nutrients/water">guidelines</a> for fluid intake. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-do-i-wake-up-thirsty-183731">Why do I wake up thirsty?</a>
</strong>
</em>
</p>
<hr>
<h2>People who should take extra care</h2>
<p>Some people are at greater risk of the harmful health effects from dehydration and need to pay special attention to their fluid intake. </p>
<p>The highest priority groups are babies, young kids, pregnant women, and older adults. These groups are at greater risk for many reasons, including relatively higher water needs per kilo of body weight, reduced ability to detect and respond to symptoms of dehydration, and barriers to consuming fluids regularly.</p>
<p>Family and friends can play an important role in <a href="https://www.agedcareguide.com.au/information/hydration-for-elderly-people-and-the-dangers-of-dehydration">supporting loved ones</a> to maintain hydration, especially during warm weather.</p>
<h2><strong>Ten ideas for keeping fluids up this summer</strong></h2>
<ol>
<li><p><strong>Download a water reminder app on your phone</strong>
This will help keep you on track during the day and give you digital “high fives” when you hit your water goals.</p></li>
<li><p><strong>Add sugar-free flavouring</strong>
Try a sugar-free fruit infusion in your water to make it more appealing. Prepare a jug in the refrigerator and infuse it overnight so it’s chilled for you the next day. Fill it up and take it everywhere with you!</p></li>
<li><p><strong>Add some fresh fruit</strong>
Add some slices of lime, lemon, berries, pineapple or orange to your water bottle for some natural flavouring. If the bottle is kept in a fridge, the fruit will stay fresh for about three days. </p></li>
<li><p><strong>Make a jug of iced tea (not the bottled stuff)</strong>
There are many great sugar-free recipes online. Tea contributes to fluid intake too. For green and black teas, brew in boiling water then cool overnight on the bench before refrigerating. Fruit teas can be made using cold water immediately.</p></li>
<li><p><strong>Add a dash of cordial to your water</strong>
A small amount of cordial in your water is a healthier alternative to drinking a sugar-sweetened soft drink or fruit juice. Diet cordials have less added sugar again.</p></li>
<li><p><strong>Make a fruit ‘slushie’</strong>
Combine fresh fruit, ice and water at home in the morning and sip to increase your fluid intake for the day.</p></li>
<li><p><strong>Buy a soda maker for your home</strong>
Some people find plain water tastes better with bubbles. Sparkling mineral water is great too, as long as there is no added sugar or sweeteners. </p></li>
<li><p><strong>Before you eat anything, have a glass of water</strong>
Make it a rule with yourself to have a glass of water before every snack or meal.</p></li>
<li><p><strong>Eat water-rich fruits and vegetables</strong>
Many fruits and vegetables have a high water content. Some of the best include berries, oranges, grapes, carrots, lettuce, cabbage, spinach and melons. Keep a container full of cut-up fruit to snack on in your fridge.</p></li>
<li><p><strong>Use a water bottle</strong>
Take it with you during the day and keep it by your bed overnight.</p></li>
</ol>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/492253/original/file-20221028-53244-adtnmp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="strawberry splashes into glass of water" src="https://images.theconversation.com/files/492253/original/file-20221028-53244-adtnmp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/492253/original/file-20221028-53244-adtnmp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/492253/original/file-20221028-53244-adtnmp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/492253/original/file-20221028-53244-adtnmp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/492253/original/file-20221028-53244-adtnmp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/492253/original/file-20221028-53244-adtnmp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/492253/original/file-20221028-53244-adtnmp.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">Infusing water with fruit might make it more appealing.</span>
<span class="attribution"><a class="source" href="https://images.pexels.com/photos/2311854/pexels-photo-2311854.jpeg?auto=compress&cs=tinysrgb&w=800">Pexels/Lisa Fotios</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>A tip on water bottles</h2>
<p>Water bottles are everywhere and sometimes seem to offer <a href="https://www.refinery29.com/en-au/emotional-support-water-bottle-girlies-tiktok-trend">emotional support</a> as well as hydration. </p>
<p>Having a water bottle you enjoy using can go a long way in helping you keep up your fluids during the day. </p>
<p>Pay attention to the material of the water bottle and use one that helps you form good habits. Some people prefer metal water bottles as they can keep water cooler for longer (others feel like they are camping). Some prefer glass bottles because the water isn’t affected by any flavours from the container (others fear breaking the glass). </p>
<p>Consider the practical aspects, too: Will it fit in your bag? Will it be light enough to carry with you? Can you “chug” on it when you’re exceptionally thirsty? Does the lid require screwing? How durable is it in preventing leaks? Do some <a href="https://www.marthastewart.com/7842071/best-water-bottles-hydration">homework</a> on your water bottle, an essential accessory!</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1563908243755253762"}"></div></p><img src="https://counter.theconversation.com/content/191859/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lauren Ball receives funding from the National Health and Medical Research Council. She is a Director of Dietitians Australia and an Associate Member of the Australian Academy of Health and Medical Sciences.</span></em></p><p class="fine-print"><em><span>Emily Burch 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>If you don’t consume enough water, you may experience symptoms of dehydration such as headaches, dizziness, tiredness, low concentration, constipation and a dry mouth.Lauren Ball, Professor of Community Health and Wellbeing, The University of QueenslandEmily Burch, Dietitian and Researcher, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1841282022-08-22T12:26:15Z2022-08-22T12:26:15ZTwo surprising reasons behind the obesity epidemic: Too much salt, not enough water<figure><img src="https://images.theconversation.com/files/471724/original/file-20220629-12-h11vd4.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3600%2C2398&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Salty french fries may taste good, but they just contribute to dehydration and obesity.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/cropped-image-of-tempted-boy-holding-french-fries-royalty-free-image/660559557?adppopup=true">William Voon/EyeEm via Getty Images</a></span></figcaption></figure><p>Scientific studies and <a href="https://www.washingtonpost.com/health/what-percent-young-adults-obese/2021/12/03/b6010f98-5387-11ec-9267-17ae3bde2f26_story.html">media coverage</a> are rife <a href="https://doi.org/10.1002/oby.22073">with warnings</a> on how <a href="https://doi.org/10.31883/pjfns/110735">sugar</a>, <a href="https://doi.org/10.1111/jhn.12559">carbohydrates</a>, <a href="https://doi.org/10.3945/jn.111.153460">saturated fat</a> and <a href="https://www.hsph.harvard.edu/obesity-prevention-source/obesity-causes/physical-activity-and-obesity/">lack of exercise</a> contribute to obesity. And <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7721435/">tens of millions of Americans are still overweight or obese</a> in large part because of the classic Western diet and lifestyle. </p>
<p>As an <a href="https://drrichardjohnson.com/about/#">educator, researcher and professor of medicine</a>, I have <a href="https://drrichardjohnson.com/books/">spent more than 20 years</a> <a href="https://scholar.google.com/citations?user=dTgECeMAAAAJ&hl=en">investigating the causes of obesity</a>, as well as related conditions such as diabetes, high blood pressure and chronic kidney disease. </p>
<p>Throughout my many years of studying obesity and related health conditions, I’ve observed that relatively little is said about two significant pieces of this very complex puzzle: lack of hydration and excessive salt intake. Both are known to contribute to obesity. </p>
<h2>Lessons learned from a desert sand rat</h2>
<p>Nature provides a clue to the role these factors play with the desert sand rat <em>Psammomys obesus</em>, a half-pound rodent with a high-pitched squeak that lives in the salty marshes and deserts of Northern Africa. It survives, barely, by eating the stems of <em>Salicornia</em> – the glasswort – a plant that looks a bit like asparagus. </p>
<p>Although low in nutrients, the glasswort’s fleshy, succulent sap is filled with water that’s rich in salt, at concentrations as high as what’s found in seawater.</p>
<p>Recent studies <a href="https://doi.org/10.1073/pnas.1713837115">have provided new insights</a> into why the desert sand rat might crave the salty sap of glasswort. Although this has not yet been proven specifically in the sand rat, it is likely that a high-salt diet helps the sand rat convert the relatively low amount of carbohydrates it’s ingesting into fructose, a type of sugar that occurs naturally in fruits, honey and some vegetables.</p>
<p>This <a href="https://doi.org/10.1111/joim.12993">helps the animal survive</a> when food and fresh water are sparse. This is because fructose activates a “survival switch” that stimulates foraging, food intake and the storage of fat and carbohydrates that protect the animal from starvation.</p>
<p>However, when the rat is brought into captivity and given the common rodent diet of about 50% carbohydrates, it <a href="https://doi.org/10.1152/ajplegacy.1965.208.2.297">rapidly develops obesity and diabetes</a>. But if given fresh vegetables low in starchy carbohydrates, the rodent remains lean. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A desert sand rat, with prominent whiskers and a brown and white coat, takes a look outside its burrow." src="https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=433&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=433&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=433&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=544&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=544&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471738/original/file-20220629-21-kvfn1y.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=544&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The desert sand rat, also known as the fat sand rat, is actually a gerbil. It’s found in Asia as well as Africa.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/fat-sand-rat-emerging-from-burrow-in-coastal-royalty-free-image/617548398?adppopup=true">Kristian Bell/Moment via Getty Images</a></span>
</figcaption>
</figure>
<p><a href="https://drrichardjohnson.com/books/">My research</a>, and the research of many other scientists over the decades, shows that many Americans unwittingly behave much like a captive desert sand rat, although few are in settings where food and water are limited. They are constantly activating the survival switch. </p>
<h2>Fructose and our diets</h2>
<p>As mentioned, fructose, a simple sugar, appears to have a key role in activating this survival switch that leads to fat production.</p>
<p>Small amounts of fructose, like that found in an individual fruit, are not the problem – rather it is excessive amounts of fructose that are problematic for human health. Most of us get our fructose from table sugar and high-fructose corn syrup. Intake of these two sugars <a href="https://www.usatoday.com/story/news/world/2014/03/05/five-percent-of-calories-should-be-from-sugar/6097623/">totals approximately 15% of calories</a> in the average American diet. </p>
<p>These sugars encourage people to eat more, which can lead to <a href="https://doi.org/10.1038/s41574-021-00627-6">weight gain, fat accumulation and prediabetes</a>. </p>
<p>Our bodies also make fructose on their own – and experimental studies suggest it may be enough to <a href="https://doi.org/10.1074/jbc.RA118.006158">trigger the development of obesity</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A spoonful of sugar, surrounded by sugar cubes, on a wooden table." src="https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=461&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=461&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=461&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=579&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=579&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468593/original/file-20220613-17-sgohui.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=579&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Table sugar and high-fructose corn syrup are two of the culprits that can cause weight gain and obesity.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/sugar-spoon-on-wood-royalty-free-image/681197933?adppopup=true">ATU Images/The Image Bank via Getty Images</a></span>
</figcaption>
</figure>
<p>Since fructose is made from glucose, production of fructose increases when blood glucose levels are high. This process happens when we eat a lot of rice, cereal, potatoes and white bread; those are carbs that rapidly release glucose into the blood rapidly.</p>
<p>And notably, fructose production can also <a href="https://doi.org/10.1074/jbc.RA118.006158">be stimulated by dehydration</a>, which drives fat production. </p>
<h2>Fat provides water</h2>
<p>Fat has two major functions. The first one, which is well known, is to store calories for a later time when food is unavailable. </p>
<p>The other major but lesser-known function of fat <a href="https://doi.org/10.1681/ASN.2015121314">is to provide water</a>. </p>
<p>To be clear, fat does not contain water. But when fat breaks down, it generates water in the body. The amount produced is substantial, and roughly equivalent to the amount of fat burned. It’s so significant that some animals <a href="https://doi.org/10.1681/ASN.2015121314">rely on fat to provide water</a> during times when it’s not available. </p>
<p>Whales are but one example. While they drink some seawater, they get most of their water from the foods they eat. And when they go for extended periods without food, they get their water <a href="https://doi.org/10.1242/jeb.204.11.1831">primarily by metabolizing fat</a>. </p>
<h2>Hold the fries</h2>
<p>The role of dehydration as a contributor to obesity should not be underestimated. It commonly occurs after eating salty foods. Both dehydration and salt consumption lead to <a href="https://doi.org/10.1073/pnas.1713837115">the production of fructose and fat</a>. </p>
<p>This is why salty french fries are especially fattening. The salt causes a dehydration-like state that encourages the conversion of the starch in the french fry to fructose.</p>
<p>What’s more, studies show most people who are overweight or obese <a href="https://doi.org/10.1038/sj.ejcn.1602521">don’t drink enough water</a>. They are far more likely to be dehydrated than those who are lean. Their salt intake is also very high compared with lean people’s. </p>
<p>Research shows that people with obesity frequently <a href="https://doi.org/10.1038/ijo.2012.88">have high levels of vasopressin</a>, a hormone that helps the kidneys hold water to regulate urine volume. </p>
<p>But recent studies suggest vasopressin has another purpose, which is <a href="https://doi.org/10.1172/jci.insight.140848">to stimulate fat production</a>. </p>
<p>For someone at risk of dehydration or starvation, vasopressin may have a real survival benefit. But for those not at risk, vasopressin could drive most of the metabolic effects of excess fructose, like weight gain, fat accumulation, fatty liver and prediabetes. </p>
<h2>Drinking more water</h2>
<p>So does this mean drinking more water can help us lose weight? The medical community has <a href="https://www.nytimes.com/2021/09/17/well/live/how-much-water-should-I-drink.html">often scoffed at the assertion</a>. However, our research team found that giving mice more water slowed <a href="https://doi.org/10.1172/jci.insight.140848">weight gain and the development of prediabetes</a>, even when the mice had diets rich in sugar and fat. </p>
<p>There is also increasing evidence that <a href="https://doi.org/10.3390/nu14102070">most people drink too little water</a> in general, and increasing water intake may help people who are obese <a href="https://doi.org/10.1038/oby.2008.409">lose weight</a>. </p>
<p>That’s why I encourage drinking eight tall glasses of water a day. And eight is likely enough; don’t assume more is better. There have been cases of people drinking so much that “water intoxication” occurs. This is particularly a problem with people who have heart, kidney or liver conditions, as well as those who have had recent surgery or <a href="https://doi.org/10.1056/NEJMoa043901">are long-distance runners</a>. It’s always good to first check with your doctor about water intake. </p>
<p>For the desert sand rat, and for our ancestors who scavenged for food, a high-salt and limited-water diet made sense. But human beings no longer live that way. These simple measures – drinking more water and reducing salt intake – offer cheap, easy and healthy strategies that may prevent or treat obesity.</p><img src="https://counter.theconversation.com/content/184128/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Johnson is a Professor of Medicine at the University of Colorado Anschutz Medical Campus who has received funding from the National Institutes of Health, Veteran's Health Administration, and Department of Defense to understand the role of fructose metabolism in a variety of metabolic disorders. He also has equity with Colorado Research Partners LLC that is developing inhibitors of fructose metabolism. He is also author of Nature Wants Us to Be Fat (Benbella books, 2022) that discusses the science of fructose and its role in obesity and metabolic disorders.</span></em></p>Studies show that most people who are overweight or obese are also chronically dehydrated.Richard Johnson, Professor of Medicine, University of Colorado Anschutz Medical CampusLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1837312022-08-15T02:28:24Z2022-08-15T02:28:24ZWhy do I wake up thirsty?<figure><img src="https://images.theconversation.com/files/477811/original/file-20220805-20-pc80fh.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6230%2C4147&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>If you wake up in the morning feeling thirsty, you might be dehydrated.</p>
<p>There are a few things which might be at play here, including not drinking enough the day before. </p>
<p>The temperature overnight will also impact your hydration levels, with warm conditions meaning you will sweat overnight. </p>
<p>However, even during cold weather, we still lose fluid from breathing, which you’ve probably noticed when your breath becomes visible in the cold.</p>
<p>Often people avoid drinking fluids just before bed to avoid waking in the night to visit the toilet, which may further exacerbate dehydration.</p>
<p>And one of the commonest causes for waking up thirsty is consuming too many diuretics, especially alcohol. Diuretics are things which cause you to lose fluid through urine, but beyond what you would normally lose from the volume you have consumed. </p>
<p>So why is it so important to stay hydrated, and what can we do to ensure we are?</p>
<h2>How do I know if I’m dehydrated?</h2>
<p>Our brains release a hormone called “antidiuretic hormone” when it senses we are becoming dehydrated. It also releases this during the night to help us retain fluid since we can’t drink water while we sleep.</p>
<p>This hormone does two things. It makes us feel thirsty, prompting us to go and drink water, and it tells our kidneys to absorb more water back into the body, rather than turning it into urine. </p>
<p>This response occurs when we are dehydrated by 1-2% of our body weight. So if you weigh 70kg, and you have lost 1.4kg of weight over the day, it is a 2% loss of body fluids. (We know this amount of weight loss is fluids and not body weight, as it would almost be impossible for people to lose this amount of fat and/or muscle in a day).</p>
<p>The colour of your first morning urine is a really good indicator of how hydrated you are. The darker the colour, the more dehydrated you are. You should be aiming for your first morning urine, as viewed in a white toilet bowl, to be the colour of hay. </p>
<p><a href="https://www.healthdirect.gov.au/urine-colour-chart"><img src="http://media.healthdirect.org.au/images/inline/original/urine-colour-chart-v3-8cf049.png" alt="Urine colour chart infographic" width="500"></a></p><p><a href="https://about.healthdirect.gov.au/" target="_blank"></a></p>
<h2>Why is hydration important?</h2>
<p>Staying hydrated is crucial for the <a href="https://pubmed.ncbi.nlm.nih.gov/19724292/">optimal functioning of our body</a>. </p>
<p>Dehydration, even at 2% of body weight, can impact <a href="https://pubmed.ncbi.nlm.nih.gov/17921463/">physical performance</a> – this includes things like fine motor skills, coordination, and strength and endurance when working and exercising. It also makes you feel like you are exerting yourself more than normal, which means you will tire more easily. </p>
<p><a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4207053/">Cognitive performance</a> and ability are also affected at 1-2% dehydration. This includes the ability to concentrate, solve problems and make decisions. </p>
<p>Dehydration also increases your risk of feeling more unwell with heat, and of course in heat you are more at risk of dehydration. Health is further impacted if dehydration goes beyond 2%. At about 10% dehydration (so losing 7kg of fluids in a 70kg person), delirium can set in, as well as renal failure and even death. </p>
<p>Recommendations tell us we need to consume <a href="https://theconversation.com/do-i-have-to-drink-eight-glasses-of-water-per-day-we-asked-five-experts-93025">around two litres of fluid</a> per day, much of which can come from the food we eat, and importantly fluid losses <a href="https://pubmed.ncbi.nlm.nih.gov/15673099/">can be corrected within 24 hours</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1385775531275210754"}"></div></p>
<h2>What are diuretics and why do they make us dehydrated?</h2>
<p>Diuretics are a class of drugs that make the kidneys remove salt and water from the body through urine, usually to treat high blood pressure. But naturally occurring diuretics are also found in our diet.</p>
<p>Alcoholic drinks above 4% alcohol concentration cause our body to turn more fluid into urine than the amount of fluid we’re actually drinking. Given most beers, wines and spirits are above this level, a night with friends having a couple of glasses of alcohol may cause dehydration. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/477812/original/file-20220805-20-q1e9yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bottles of liquor" src="https://images.theconversation.com/files/477812/original/file-20220805-20-q1e9yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/477812/original/file-20220805-20-q1e9yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/477812/original/file-20220805-20-q1e9yc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/477812/original/file-20220805-20-q1e9yc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/477812/original/file-20220805-20-q1e9yc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/477812/original/file-20220805-20-q1e9yc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/477812/original/file-20220805-20-q1e9yc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Alcohol above 4% concentration causes you to lose more fluid than you gain from drinking it.</span>
<span class="attribution"><span class="source">Andreas M/Unsplash</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Coffee is also a diuretic as it contains two chemicals, caffeine and theophylline, which both increase blood flow to the kidneys – this makes them excrete more fluid. Intakes below 450mg of caffeine (about three to four coffees) are unlikely to impact hydration levels, and most people have a lot of milk and water with their coffee which would replenish most of the fluid lost.</p>
<p>Other known diuretics include cranberry juice, ginger, fennel, apple cider vinegar and some teas including green, dandelion and nettle. There are <a href="https://link.springer.com/content/pdf/10.1007/s00345-002-0293-0.pdf">many</a> herbs that are known to be diuretics. However, this does not mean they should be avoided as they offer many other important nutrients, and fluid recommendations account for diuretics in foods consumed in typical serve sizes.</p>
<p>Eating foods high in salt does not lead to total water loss from your body, but it causes fluid loss from your cells. This is problematic for your body and the way cells are regulated. So it’s crucial to drink plenty of fluids when consuming a high-salt meal or diet.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/remind-me-again-why-is-salt-bad-for-you-179768">Remind me again, why is salt bad for you?</a>
</strong>
</em>
</p>
<hr>
<h2>How can I stay hydrated?</h2>
<p>Activities that lead to increased sweating, such as training, playing sport or even gardening, can cause dehydration. So be sure to increase your fluid intake if you have been active, or if the weather is warm. </p>
<p>All fluids contribute to your intake, but water is very effective. </p>
<p>Recently a <a href="https://pubmed.ncbi.nlm.nih.gov/26702122/">group of researchers</a> looked at the potential of different beverages to affect hydration status relative to water. </p>
<p>Sparkling water, sports drinks, cola, diet cola, tea and coffee were equivalent to water. Milk (any fat percentage) from either dairy or soy, milk-based meal replacements, oral rehydration solutions and <a href="https://journals.humankinetics.com/view/journals/ijsnem/23/6/article-p593.xml?rskey=JTFcHB&result=603&utm_source=TrendMD&utm_medium=cpc&utm_campaign=International_Journal_of_Sport_Nutrition_and_Exercise_Metabolism_TrendMD_0">beer</a> under 4% alcohol were superior to water. And of course alcohol above 4% alcohol concentration was inferior to water.</p><img src="https://counter.theconversation.com/content/183731/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Evangeline Mantzioris is affiliated with Alliance for Research in Nutrition, Exercise and Activity (ARENA) at the University of South Australia. Evangeline Mantzioris has received funding from the National Health and Medical Research Council, and has been appointed to the National Health and Medical Research Council Dietary Guideline Expert Committee.</span></em></p>Waking up thirsty might mean you didn’t drink enough the day before, or perhaps you consumed a diuretic such as alcohol.Evangeline Mantzioris, Program Director of Nutrition and Food Sciences, Accredited Practising Dietitian, University of South AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1842362022-06-02T01:52:03Z2022-06-02T01:52:03ZWhy do I need to pee more in the cold?<figure><img src="https://images.theconversation.com/files/466532/original/file-20220601-49081-pmkbqo.jpg?ixlib=rb-1.1.0&rect=0%2C4%2C1000%2C658&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/male-female-distress-having-go-restroom-1882909777">Shutterstock</a></span></figcaption></figure><p>You’re taking a stroll through the park on a cold winter’s morning, when it hits you – the need to find a bathroom, and quick! This didn’t used to happen in summer.</p>
<p>Is there something about winter that makes us need to pee more?</p>
<p>We study the bladder and lower urinary tract. Here are two main explanations for what’s going on.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-are-my-hands-and-feet-always-cold-and-when-should-i-be-worried-184154">Why are my hands and feet always cold? And when should I be worried?</a>
</strong>
</em>
</p>
<hr>
<h2>1. Our lifestyle changes</h2>
<p>In summer, we tend to be outside and more active. We sweat more (to lose heat) and it’s easy to become dehydrated if we don’t drink enough water.</p>
<p>This impacts the amount of free fluid our body is willing to <a href="https://www.nature.com/articles/ejcn2015233">excrete</a>, and our urine volume is often reduced because of this.</p>
<p>In winter, we’re often indoors, around water sources, so we are more likely to be hydrated, less active, and to sweat less. As such, we tend to have more free fluid to excrete via our urine.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-if-our-bodies-are-happy-at-37-why-do-we-feel-so-unhappy-when-its-too-hot-outside-159134">Curious Kids: if our bodies are happy at 37℃, why do we feel so unhappy when it's too hot outside?</a>
</strong>
</em>
</p>
<hr>
<h2>2. Our body wants to avoid losing too much heat</h2>
<p>If we become cold very quickly, the body protects our internal organs in a number of ways.</p>
<p>One is “<a href="https://pubmed.ncbi.nlm.nih.gov/4655205/">cold-induced diuresis</a>”, or an increase in urine excretion in response to the <a href="https://journals.physiology.org/doi/abs/10.1152/ajpregu.1993.264.3.R524">cold</a>.</p>
<p>Initially, blood is diverted away from the skin to avoid losing its heat to the outside air. This means more blood ends up flushing through your internal organs.</p>
<p>In particular, blood rushes to your kidneys in a greater volume and at a higher pressure. This increases the amount the kidneys need to <a href="https://journals.physiology.org/doi/full/10.1152/ajprenal.00430.2005">filter</a>. As a result, your rate of <a href="https://www.frontiersin.org/articles/10.3389/fphys.2022.841181/full">urine excretion</a> increases.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-is-it-so-cold-right-now-and-how-long-will-it-last-a-climate-scientist-explains-184155">Why is it so cold right now? And how long will it last? A climate scientist explains</a>
</strong>
</em>
</p>
<hr>
<h2>What should I do?</h2>
<p>Our diet, age, blood pressure, and personal situation can all impact how much we urinate.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/blVmyrBPves?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Could you have a small bladder? Or an overactive bladder?</span></figcaption>
</figure>
<p>Producing more urine can also be a sign of <a href="https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1365-201X.1998.0314f.x">hypothermia</a>. This is your body responding to the cold as a stressor, so act quickly. Find somewhere away from the cold, and slowly warm up your body. </p>
<p>If the increased urine is also accompanied by <a href="https://www.healthdirect.gov.au/hypothermia">other symptoms</a>, such as extensive shivering, breathing difficulties, or confusion, seek medical attention immediately.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-why-do-some-people-feel-the-cold-more-than-others-37805">Health Check: why do some people feel the cold more than others?</a>
</strong>
</em>
</p>
<hr>
<h2>Keep up the fluids in winter too</h2>
<p>If you’re out in the cold, you may not feel thirsty. Nonetheless, be sure to drink plenty of fluids during the day. Although it may be tempting to avoid drinking so you don’t need to keep rushing to the bathroom, this can lead to dehydration.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/466716/original/file-20220602-18-4l0pci.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Smiling woman wearing yellow puffer jacket holding water bottle" src="https://images.theconversation.com/files/466716/original/file-20220602-18-4l0pci.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/466716/original/file-20220602-18-4l0pci.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/466716/original/file-20220602-18-4l0pci.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/466716/original/file-20220602-18-4l0pci.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/466716/original/file-20220602-18-4l0pci.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/466716/original/file-20220602-18-4l0pci.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/466716/original/file-20220602-18-4l0pci.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">Keep drinking fluids, even in winter.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-hispanic-girl-smiling-happy-drinking-2053295111">Shutterstock</a></span>
</figcaption>
</figure>
<p>If you’re often out in the cold in light gear, and you find this increases your urinary output, there can be impacts over the long term.</p>
<p>Frequent urination can be <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/osmotic-diuresis">detrimental</a> to your body’s natural salt balance (particularly sodium and <a href="https://www.mayoclinic.org/symptoms/low-potassium/basics/causes/sym-20050632">potassium</a>). So be sure to maintain a healthy diet.</p>
<p>It does seem like a bit of a balancing game. The key, however, is to avoid stressing your body this way when it’s cold. To do this, be sure to dress appropriately and keep warm.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/forget-heatwaves-our-cold-houses-are-much-more-likely-to-kill-us-83030">Forget heatwaves, our cold houses are much more likely to kill us</a>
</strong>
</em>
</p>
<hr>
<h2>What if you don’t notice a difference?</h2>
<p>Although the body has mechanisms to make you <a href="https://pubmed.ncbi.nlm.nih.gov/7330607/">urinate more</a> in the cold, not everyone notices peeing more in winter.</p>
<p>If you keep warm, there’s no reason to think your body would often be “shocked” into responding to cold temperatures.</p>
<p>In fact, when tracked in research studies, it has been common for researchers to record no difference in <a href="https://pubmed.ncbi.nlm.nih.gov/7330607/">urinary</a> <a href="https://pubmed.ncbi.nlm.nih.gov/1172/">output</a> between the <a href="https://pubmed.ncbi.nlm.nih.gov/29757578/">seasons</a>.</p>
<h2>What about the urine?</h2>
<p>It’s not just the volume of urine that might be different in winter. The composition can change too.</p>
<p>The body excretes a higher amount of <a href="https://pubmed.ncbi.nlm.nih.gov/29757578/">calcium</a> in the urine during <a href="https://pubmed.ncbi.nlm.nih.gov/7106963/">winter</a>.</p>
<p>This is more likely due to lifestyle during cold seasons rather than anything internal. We tend to be <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2800047/">less active</a> in winter, gain <a href="https://pubmed.ncbi.nlm.nih.gov/31093925/">extra weight</a>, and eat more salty, preserved and processed foods.</p>
<p>This means there can be a higher risk of developing <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6237522/">kidney stones</a> during winter for people who are susceptible.</p>
<p>So as the weather cools down, be sure to maintain a healthy lifestyle, stay warm, and don’t forget to stay hydrated, even when it’s cold.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-why-is-urine-yellow-117747">Curious Kids: why is urine yellow?</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/184236/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>No, you’re not imagining it. You can pee more in winter. Mostly, there’s nothing to worry about. But it could be a sign of hypothermia.Christian Moro, Associate Professor of Science & Medicine, Bond UniversityCharlotte Phelps, PhD Student, Bond UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1774582022-02-28T00:20:06Z2022-02-28T00:20:06ZWater really can provide some relief from anxiety and help us see the glass half full<figure><img src="https://images.theconversation.com/files/448474/original/file-20220225-21-pufn2y.jpg?ixlib=rb-1.1.0&rect=39%2C0%2C6534%2C4376&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/smiling-millennial-biracial-woman-look-distance-1835655406">Shutterstock</a></span></figcaption></figure><p>Many Australians can feel overwhelmed at some stage of their life with feelings of tension, nervousness and fear for the worst. A staggering <a href="https://www.abs.gov.au/statistics/health/mental-health/mental-health/latest-release#:%7E:text=reverse_axis%22%3Afalse%7D%5D-,Anxiety,15.7%25%20compared%20with%2010.6%25">3.2 million Australians</a> have an anxiety-related condition, with the largest increases over recent years witnessed in those between the ages of 15–24 years. </p>
<p>The growing field of <a href="https://academic.oup.com/eurpub/article/31/Supplement_3/ckab164.019/6405367?login=false">nutritional psychiatry</a> focuses on the effects of foods and drinks on our mental health. Despite water constituting 60–80% of the human body, it is often overlooked as a significant nutrient. A recent tweet by <a href="https://twitter.com/healthgovau/status/1492038209181728770">federal health authorities</a> suggesting water could help reduce anxiety was received with some online scepticism. </p>
<p>In fact, the evidence shows water and hydration can play a role in preventing and managing the symptoms of anxiety.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1492038209181728770"}"></div></p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-psychology-of-comfort-food-why-we-look-to-carbs-for-solace-135432">The psychology of comfort food - why we look to carbs for solace</a>
</strong>
</em>
</p>
<hr>
<h2>A well-oiled machine</h2>
<p>We all enjoy the cooling sensation a cold drink of water provides on a sweltering summer day. Our bodies are masterfully programmed to let us know when it’s time to rehydrate. We may be nourishing our brain too. </p>
<p>Several years ago, a group of researchers undertook a <a href="https://pubmed.ncbi.nlm.nih.gov/26290294/">review</a> that focused on the various ways hydration impacts health. The results were promising. </p>
<p>Overall, negative emotions such as anger, hostility, confusion and tension as well as fatigue were found to increase with dehydration. One <a href="https://pubmed.ncbi.nlm.nih.gov/21736786/">trial</a> induced mild dehydration and found increased reports of tension or anxiety and fatigue in participants. </p>
<p><a href="https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC3984246/">Researchers</a> have also found people who usually drink lots of water feel less calm, less content, and more tense when their water intake drops. When researchers increased the participants’ water intake, people in the study felt more happiness, no matter how much water they normally drank. </p>
<p>Another <a href="https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC6147771/">large study</a> found people who drink five cups or more of water per day were at lower risk of depression and anxiety. In comparison, drinking less than two cups per day doubles the risk. This link was less noticeable for anxiety alone (although feelings of depression and anxiety often influence each other). </p>
<p>More recently, <a href="https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC6769552/">researchers</a> found water with electrolytes may prevent anxiety more than plain water, but it was noted that the placebo effect may explain this connection as study participants were aware when they were given the electrolyte drink. </p>
<p>The link between dehydration and anxiety is also observed in <a href="https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC3257694/">children</a>, who are a group at risk of dehydration. Dehydration might also affect how well we <a href="https://pubmed.ncbi.nlm.nih.gov/30395316/">sleep</a>. Poor sleep can exacerbate feelings of anxiety.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/food-as-medicine-your-brain-really-does-want-you-to-eat-more-veggies-74685">Food as medicine: your brain really does want you to eat more veggies</a>
</strong>
</em>
</p>
<hr>
<h2>Water on the brain?</h2>
<p>Almost every bodily function relies on water. Because 75% of brain tissue is water, dehydration reduces energy production in the brain and can change brain <a href="https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC4916775/#:%7E:text=They%20reported%20no%20significant%20effect,et%20al%20found%20no%20changes.&text=Duning%20et%20al13%20showed,0.72%25%20increase%20after%20subsequent%20rehydration.">structure</a>, causing the brain to <a href="https://www.karger.com/Article/Fulltext/463060">slow down</a> and not function properly. </p>
<p>At the molecular level, if water levels are too low, our brain cells cannot function properly, with the brain showing signs of working <a href="https://pubmed.ncbi.nlm.nih.gov/30136401/">harder</a> to complete tasks. </p>
<p>Our cells recognise a state of dehydration as a threat to survival, leading to a state of anxiety. Serotonin is a neurotransmitter (a chemical messenger between brain cells) that stabilises our mood and regulates emotions. During dehydration, we struggle to get the <a href="https://www.tandfonline.com/doi/abs/10.1080/07315724.2007.10719666">chemicals</a> required to produce serotonin into our brain. </p>
<p>Being just half a litre dehydrated may also increase the stress hormone <a href="https://academic.oup.com/nutritionreviews/article/68/8/439/1841926?login=false">cortisol</a>, which has been associated with a range of mental disorders, including anxiety.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/448475/original/file-20220225-23-mriiwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="graphic of water being poured into clear brain structure" src="https://images.theconversation.com/files/448475/original/file-20220225-23-mriiwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/448475/original/file-20220225-23-mriiwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=436&fit=crop&dpr=1 600w, https://images.theconversation.com/files/448475/original/file-20220225-23-mriiwr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=436&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/448475/original/file-20220225-23-mriiwr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=436&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/448475/original/file-20220225-23-mriiwr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=548&fit=crop&dpr=1 754w, https://images.theconversation.com/files/448475/original/file-20220225-23-mriiwr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=548&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/448475/original/file-20220225-23-mriiwr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=548&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Water makes up 75% of brain tissue.</span>
<span class="attribution"><a class="source" href="https://image.shutterstock.com/image-illustration/brain-filled-water3d-illustration-600w-1121751374.jpg">Shutterstock</a></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/want-to-improve-your-mood-its-time-to-ditch-the-junk-food-107358">Want to improve your mood? It's time to ditch the junk food</a>
</strong>
</em>
</p>
<hr>
<h2>The big picture</h2>
<p>So, based on what is currently known and emerging evidence, the <a href="https://twitter.com/healthgovau/status/1492038209181728770">government health communication</a> provides some good advice. Addressing lifestyle factors including your water intake in the context of your overall diet, physical activity levels, and sleep are important foundations that can support a person’s mental health. And there is evidence to suggest dehydration can affect our mood. </p>
<p>But it’s important to note there are a wide range of factors that affect an individual’s level of anxiety. No single thing is likely to be responsible for completely resolving those feelings. This is particularly true in people experiencing significant anxiety, where simply drinking more water is unlikely to be helpful on its own.</p><img src="https://counter.theconversation.com/content/177458/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nikolaj Travica receives funding from Deakin University as a post-doctoral research fellow </span></em></p>Drinking more water can make you feel happier – and not drinking enough may contribute to feelings of anxiety and fatigue.Nikolaj Travica, Postdoctoral research fellow, Deakin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1731342022-02-01T13:14:34Z2022-02-01T13:14:34ZWhy taking fever-reducing meds and drinking fluids may not be the best way to treat flu and fever<figure><img src="https://images.theconversation.com/files/439010/original/file-20211226-36920-246w3v.jpg?ixlib=rb-1.1.0&rect=7%2C0%2C5128%2C3426&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Using fever reducers or drinking too much fluid while battling the flu may upset the body's delicate balancing act. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/sick-woman-taking-her-temperature-royalty-free-image/88689538?adppopup=true">Sam Edwards/OJO Images via Getty Images</a></span></figcaption></figure><p>As flu season progresses, so does the <a href="https://www.cdc.gov/flu/prevent/index.html">chorus of advice</a>, professional and otherwise, to drink plenty of fluids and take fever-reducing medications, like acetaminophen, ibuprofen or aspirin. </p>
<p>These recommendations, <a href="https://doi.org/10.1001/archpedi.1982.03970470017003">well-intentioned and firmly entrenched</a>, offer comfort to those sidelined with fever, flu or vaccine side effects. But you may be surprised to learn the science supporting these recommendations is speculative at best, harmful at worst and comes with caveats. </p>
<p><a href="https://education.wayne.edu/profile/gr7894">I am an exercise physiologist</a> who specializes in studying how the body regulates fluids and temperature. And based on a wide body of evidence, I can tell you that increased fluid intake and taking fever reducers, whether aspirin, acetaminophen or ibuprofen, may not always help in your recovery. In fact, in some cases, it could be harmful.</p>
<p>There’s a reason why people say fevers should be lowered when sick or after a vaccine. Both aspirin and acetaminophen, such as Tylenol, <a href="https://doi.org/10.1016/j.clinthera.2005.06.002">reduce fever, headaches and muscle aches</a>. But at the same time, <a href="https://doi.org/10.1093/infdis/162.6.1277">seminal</a> and <a href="https://doi.org/10.1098/rspb.2013.2570">newer studies</a>, including broad meta-analysis studies, show that <a href="https://doi.org/10.1258/jrsm.2010.090441">these medications</a> may weaken the immune response to infection or <a href="https://doi.org/10.1001/archinte.160.4.449">have unwanted side effects</a>.</p>
<h2>What is a fever?</h2>
<p>First, some background: Fevers are a regulated increase in core body temperature as a response to unwanted microbial invaders.
The more <a href="https://doi.org/10.1016/j.amjms.2021.01.004">severe the infection, the higher the fever</a>. </p>
<p>Having a fever is not all bad; it’s how the body has evolved to recuperate from an infection. For many species, <a href="https://www.racgp.org.au/afp/2015/januaryfebruary/a-is-for-aphorisms/">fevers are advantageous</a> and beneficial for survival. </p>
<p>But fever comes with a cost. A body temperature that’s too high can be deadly. For every increase of 1.8 degrees Fahrenheit, metabolism goes up 10%; the body begins to burn more calories than normal, temperature continues to rise and the <a href="https://doi.org/10.1111/j.1749-6632.2000.tb05376.x">body releases hormones</a> to keep fever under control. </p>
<p>Many studies demonstrate what can happen when fever reducers are thrust into this complex dance. It turns out aspirin or acetaminophen may cause infected people to feel better, but they also spread more virus while suppressing their own immune response to the infection. </p>
<p>In one double-blind, placebo-controlled study, healthy people infected with a cold virus <a href="https://doi.org/10.1093/infdis/162.6.1277">who took aspirin or acetaminophen</a> for a week had a reduced immune response and an increase in viral shedding – meaning producing and expelling virus particles from the nose. Another study showed that taking aspirin effectively reduced fever symptoms but <a href="https://doi.org/10.1001/jama.1975.03240240018017">increased shedding</a>.</p>
<p>Although some of those traditional studies took place decades ago, their results still hold up today. A recent study warned that if everyone took fever suppressants, there would be even <a href="https://doi.org/10.1098/rspb.2013.2570">more flu cases and flu-related deaths</a>. Furthermore, elevated body temperature – or fever – can help fight COVID-19 by reducing the <a href="https://doi.org/10.1371/journal.%20pbio.3001065">growth of the virus within the lungs</a>. In other words, fevers can help the body fight viruses while reducing the rate of death and disease.</p>
<h2>Drinking fluids</h2>
<p>To prevent dehydration, the Centers for Disease Control and Prevention recommends drinking more fluids when one <a href="https://www.cdc.gov/flu/pdf/freeresources/general/influenza_flu_homecare_guide.pdf?web=1&wdLOR=c20031A15-D755-4A4D-B1B2-40CE51B88D3A">has a fever or infection</a>, or has received <a href="https://www.cdc.gov/coronavirus/2019-ncov/vaccines/expect/after.html#relieve_side_effects">a COVID-19 vaccine</a>. But there is <a href="https://www.washingtonpost.com/lifestyle/2021/11/05/what-do-doctors-mean-when-they-say-drink-plenty-fluids/">scant scientific evidence</a> to support this recommendation. </p>
<figure class="align-center ">
<img alt="A teenage girl with flu drinks a glass of water." src="https://images.theconversation.com/files/439558/original/file-20220105-23-18gcely.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/439558/original/file-20220105-23-18gcely.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/439558/original/file-20220105-23-18gcely.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/439558/original/file-20220105-23-18gcely.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/439558/original/file-20220105-23-18gcely.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/439558/original/file-20220105-23-18gcely.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/439558/original/file-20220105-23-18gcely.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">Drinking fluids to excess can lead to overhydration.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/teenager-drinks-water-from-a-glass-indoors-royalty-free-image/1314353664?adppopup=true">Dina Morozova/iStock via Getty Images Plus</a></span>
</figcaption>
</figure>
<p>It’s true that drinking fluids when dehydrated is <a href="https://doi.org/10.1001/archinte.1919.00090240119009">necessary to reduce fever</a>. But not everyone with a fever is dehydrated. For those who aren’t thirsty, forcing fluids <a href="https://doi.org/10.1073/pnas.1403382111">beyond thirst</a>, which is often unpleasant, may not be advisable. </p>
<p>[<em>Get fascinating science, health and technology news.</em> <a href="https://memberservices.theconversation.com/newsletters/?nl=science&source=inline-science-fascinating">Sign up for The Conversation’s weekly science newsletter</a>.]</p>
<p>A study <a href="https://doi.org/10.1002/14651858.CD004419.pub3">that evaluated the advice</a> to “drink plenty of fluids” determined that increasing fluid intake when sick may not offer benefits, and that more high-quality studies are needed. Indeed, there was a potential <a href="https://www.webmd.com/diet/what-is-too-much-water-intake#1">risk from overhydration</a>. For some people, three liters, or about 12 eight-ounce glasses, is too much. Overhydration can cause nausea and vomiting, headaches and cramps; in severe cases, <a href="http://dx.doi.org/10.1136/bcr-2016-216882">excessive fluid intake</a> can cause seizures or coma. </p>
<p>Here’s why this happens. To stop dangerous escalations in fever, the body releases antidiuretic hormones. Urination is diminished, so <a href="https://doi.org/10.2165/11532070-000000000-00000">the body retains water</a> through the actions of the kidneys. So if someone with a fever drinks more water than necessary, water intoxication – or hyponatremia, a potentially fatal medical condition in which a patient’s blood sodium levels are too low – could follow. </p>
<p>One study found that nearly a quarter of patients who came to the hospital with COVID-19 had <a href="https://doi.org/10.1210/clinem/dgab107">hyponatremia upon admission</a>. In that study, hyponatremia increased the need for breathing support in the form of ventilation. And another study showed that the condition can lead to <a href="https://doi.org/10.1007/s40618-020-01301-w">poorer outcomes in COVID-19 patients</a>.</p>
<p>So maybe it’s time to rethink the conventional wisdom. If the fever is mild or moderate, stay warm, even use blankets, rather than try to actively reduce it. Rest, so your body can fight the fever. Conserve energy because your metabolism is already on overdrive. Use fever-reducing medications sparingly. Drink fluids, but only to tolerance, and preferably when thirsty.</p>
<p>And one final suggestion that should be soothing: When fighting a fever or vaccine side effects, consider sipping warm liquids that contain sodium. Broths containing sodium, like bullion, <a href="https://doi.org/10.1097/JSM.0000000000000221">may help avoid hyponatremia</a>. And although the actual scientific evidence is sparse and conflicting, <a href="https://doi.org/10.1016/j.chest.2020.06.062">chicken soup</a> may be a better antidote than water when fending off a fever or flu symptoms.</p><img src="https://counter.theconversation.com/content/173134/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tamara Hew-Butler 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>In some cases, fever reducers and extra fluid intake can weaken the body’s response to infection.Tamara Hew-Butler, Associate Professor of Exercise and Sports Science, Wayne State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1637002021-07-08T12:36:51Z2021-07-08T12:36:51ZKnowing how heat and humidity affect your body can help you stay safe during heat waves<figure><img src="https://images.theconversation.com/files/410012/original/file-20210706-25-13zbvfw.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5593%2C3124&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Record-breaking triple-digit heat in Olympia, Wash., on June 28, 2021.</span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/PacificNorthwestHeatWave/52ee9fd2284b4ac3ab5a0f441da4a08f/photo">AP Photo/Ted S. Warren</a></span></figcaption></figure><p>Less than a month into North America’s official summer, heat waves are blistering much of the West. California and the Southwest are facing <a href="https://www.washingtonpost.com/weather/2021/07/06/california-west-heat-wave/">excessive heat watches</a> for the second time, after a <a href="https://www.climate.gov/news-features/event-tracker/record-breaking-june-2021-heatwave-impacts-us-west">mid-June heat wave</a> pushed temperatures above 100 F (38 C). </p>
<p>And in late June an intense heat dome settled over the <a href="https://www.climate.gov/news-features/event-tracker/astounding-heat-obliterates-all-time-records-across-pacific-northwest">Pacific Northwest</a> for four days, setting all-time temperature records in Oregon, Washington and British Columbia. The effects were most evident in Lytton, British Columbia, which reported a temperature of <a href="https://www.washingtonpost.com/weather/2021/06/27/heat-records-pacific-northwest/">121 F (49.5 C) on June 29</a>, far above its average high for the date of 76 F (24.4 C). A day later, the town was <a href="https://www.cnn.com/2021/07/01/americas/canada-town-evacuation-extreme-heat/index.html">engulfed by a wildfire</a>.</p>
<p>As an <a href="https://scholar.google.com/citations?user=wqDX7PUAAAAJ&hl=en">exercise physiologist</a>, I know that the human body is an amazing machine. But like all machines, it functions effectively and safely only under certain conditions. </p>
<p>People frequently debate whether wet heat in places like Florida or dry heat in desert locations like Nevada is worse. The answer is that either setting can be dangerous. Hot desert climates are stressful due to extreme temperatures, while humid subtropical climates are stressful because the body has trouble removing heat when sweat doesn’t evaporate readily. As recent events have shown, hot is hot.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1412139233565843456"}"></div></p>
<h2>The influence of humidity</h2>
<p>North America has a wide range of climates, but when people talk about heat, they often compare the Southwest and the Southeast. Some communities in the Southwest’s hot desert climates, such as Las Vegas, have average summer high temperatures over 100 F (38 C), with <a href="https://www.ncdc.noaa.gov/ghcn/comparative-climatic-data">relative humidity</a> typically around 20%. This means the air is holding about one-fifth of the maximum amount of moisture it can hold at that temperature and pressure. </p>
<p>In contrast, Southeast locations like Orlando, Florida, typically have average temperatures around 90 F (32.2 C), with humidity regularly approaching 80%. Looking only at temperature, the desert clearly is hotter on average. </p>
<p>However, it’s also important to consider how heat affects the body. Weather reports often do this using the <a href="https://www.weather.gov/ama/heatindex">heat index</a>, which calculates how the human body perceives conditions factoring in humidity as well as heat. </p>
<p>Sweating is your body’s primary way of cooling you off. When sweat evaporates away from your skin, it <a href="https://www.weather.gov/oun/safety-summer-heathumidity">takes heat with it</a>. But when humidity is high, the air already holds a lot of moisture, so the sweat remains on your skin. As it saturates clothing and drips from the body, it can remove only a small amount of heat compared with the cooling that comes with the evaporation of sweat. </p>
<p>As a result, when we account for humidity, the heat exposures people experience in Las Vegas and Orlando are very similar. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Table showing hazardous heat/humidity combinations." src="https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=351&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=351&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=351&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=441&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=441&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410019/original/file-20210706-17-ozucpq.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=441&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 National Weather Service’s Heat Index shows the risk of activity based on heat plus humidity.</span>
<span class="attribution"><a class="source" href="https://dps.mn.gov/divisions/hsem/weather-awareness-preparedness/Pages/severe-weather-heat.aspx">NOAA</a></span>
</figcaption>
</figure>
<h2>Adapting people and places to heat stress</h2>
<p>As people go through their daily lives, their bodies work continuously to maintain a temperature close to a normal level of about 98.6 F (37 C). In regions that regularly experience high heat stress, such as the Southeast and Southwest, most buildings and homes now have air conditioning, which helps people maintain healthy temperatures.</p>
<p>But in areas where heat is unusual, such as the Pacific Northwest, many buildings and residences <a href="https://www.seattletimes.com/seattle-news/health/with-more-heat-waves-expected-in-the-future-seattles-long-term-care-facilities-weigh-the-need-for-air-conditioning/">lack cooling</a>. As a result, people are exposed to higher heat for longer periods of time during events like the region’s late June heat wave than they would be in regions where hot weather is the norm.</p>
<p>Just as buildings and residences in areas chronically exposed to heat are equipped with ceiling fans and air conditioning, bodies that are regularly exposed to heat can <a href="https://www.cdc.gov/niosh/mining/userfiles/works/pdfs/2017-124.pdf">acclimatize</a>, or adapt and improve their ability to cool. This starts to occur with the first heat exposure – for example, the beginning of fall sports practices in August – but take weeks of regular exposure to reach maximal levels. </p>
<p>One of the first things our bodies do in adapting to heat is to <a href="http://dx.doi.org/10.1111/sms.12408">produce more plasma</a> – the watery portion of blood. This enables our circulatory systems to move heat to the skin more effectively so that sweating can remove it from the body.</p>
<p>We also begin sweating earlier than people who are not acclimatized to heat, and our <a href="https://doi.org/10.3390/nu13061807">maximal sweat rate increases</a>. These adaptations improve our bodies’ ability to dissipate heat to the environment. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Workplace flyer with tips for acclimatizing to heat." src="https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=1285&fit=crop&dpr=1 600w, https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=1285&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=1285&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1615&fit=crop&dpr=1 754w, https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1615&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/410017/original/file-20210706-23-1ljbuxh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1615&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Outdoor workers should build up to a full day in the heat to allow their bodies to acclimatize to it.</span>
<span class="attribution"><a class="source" href="https://www.cdc.gov/niosh/topics/heatstress/pdf/NIOSH_HeatStressInfographic_print-508.pdf">CDC</a></span>
</figcaption>
</figure>
<p>Behavior changes are another way of adapting to heat stress. Since midday is typically the hottest part of the day, it makes sense to avoid physical work and exercise then. When people are active, their bodies break down nutrients – carbohydrates, fats and protein – into energy. This powers movement and also generates metabolic heat, which adds to the body’s heat stress.</p>
<p>Taking advantage of shade is another important strategy. Heat radiating from the Sun adds to the stress produced by warm air temperatures. Staying in the shade can significantly reduce the external heat load on <a href="https://blogs.cdc.gov/niosh-science-blog/2021/05/07/heat-stress-2021/">people who have to be outdoors during hot spells</a>.</p>
<p>Many of the <a href="https://doi.org/10.1136/bmj.n1696">hundreds of deaths and hospitalizations</a> that experts have attributed to the recent heat dome in the Northwest probably reflect that buildings there were less equipped to keep people cool than in hotter regions, and residents were less acclimatized to heat.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Q2RQjtucG3M?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">2020 was Phoenix’s hottest year on record, with 53 days reaching at least 110 F.</span></figcaption>
</figure>
<h2>The old and young are most vulnerable</h2>
<p>A healthy adult body can acclimatize to heat, but older people and children are less able to adjust. As people age, their cardiovascular systems change in ways that cause them to <a href="https://www.physio-pedia.com/Cardiovascular_Considerations_in_the_Older_Patient">pump blood less effectively</a>. This reduces the body’s ability to move heat to the skin to be transferred to the environment. </p>
<p>[<em>The Conversation’s science, health and technology editors pick their favorite stories.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-favorite">Weekly on Wednesdays</a>.]</p>
<p><a href="http://dx.doi.org/10.1080/02640414.2015.1055291">Children</a> and <a href="https://www.nih.gov/news-events/news-releases/heat-related-health-dangers-older-adults-soar-during-summer">older adults</a> may also have less active sweat responses, which can reduce their potential to cool off through sweating. </p>
<p>Humans can tolerate most areas of the Earth, but extreme heat requires extra steps. If there’s a heat wave in your local forecast, seek out shade and begin to acclimatize by increasing your activity gradually when things get too hot. Drink more fluids to account for <a href="https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/water/art-20044256">increased fluid loss from sweat</a>, while also making sure <a href="https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/water/art-20044256">not to overhydrate</a>. And avoid outdoor activity during the hottest hours of the day if possible. </p>
<p>Whether heat waves are humid or dry, they are health threats that everyone should take seriously.</p><img src="https://counter.theconversation.com/content/163700/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>JohnEric W. Smith 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>Which is worse, dry heat or wet heat? Both, says an exercise physiologist.JohnEric W. Smith, Associate Professor of Exercise Physiology, Mississippi State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1590202021-04-21T19:40:30Z2021-04-21T19:40:30ZDo you really need to drink 8 glasses of water a day? An exercise scientist explains why your kidneys say ‘no’<figure><img src="https://images.theconversation.com/files/396136/original/file-20210420-19-o81t32.jpg?ixlib=rb-1.1.0&rect=189%2C90%2C5817%2C3827&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Exercising can increase your need to drink water, but there's no need to overdo it. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/happy-female-runner-holding-water-bottle-royalty-free-image/1012617912?adppopup=true">The Great Brigade/Getty Images</a></span></figcaption></figure><p>The warmer weather and longer days have inspired reminders to “stay hydrated” and drink eight glasses of water – or about two liters – a day. </p>
<p>Not to burst anyone’s water bottle, but healthy people can actually <a href="https://www.nbcnews.com/id/wbna16614865">die</a> from drinking too much water. I am an <a href="https://education.wayne.edu/profile/gr7894">exercise physiologist</a>, and my research focuses on <a href="https://doi.org/10.3390/nu11071539">overhydration</a> and how drinking too much water affects the body. Since water – and sodium – balance is essential to life, it is <a href="https://doi.org/10.1097/JSM.0000000000000221">extremely rare</a> for people to die from drinking too much – or too little – fluid. In most cases, your body’s finely tuned molecular processes are unconsciously taking care of you.</p>
<figure class="align-center ">
<img alt="A young football player drinking water." src="https://images.theconversation.com/files/395811/original/file-20210419-19-vcyb4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/395811/original/file-20210419-19-vcyb4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/395811/original/file-20210419-19-vcyb4q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/395811/original/file-20210419-19-vcyb4q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/395811/original/file-20210419-19-vcyb4q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/395811/original/file-20210419-19-vcyb4q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/395811/original/file-20210419-19-vcyb4q.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">A high school football player drinks water during practice. Many coaches have stressed hydration in recent years.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/american-football-players-including-teenagers-in-royalty-free-image/sb10064896w-001?adppopup=true">Darrin Klimek/Getty Images</a></span>
</figcaption>
</figure>
<h2>Water out, water in</h2>
<p>As spring unfolds, hydration challenges take root across <a href="https://wmich.edu/rec/hydrationchallenge">schools</a>, <a href="https://michigansportsalliance.org/hydrationchallenge">sports</a> and <a href="https://documents.ascension.org/communications/benefits2017/SmartHealth_Hydration_Challenge.pdf">workplaces</a>. These heavily marketed hydration challenges serve to cultivate both camaraderie and friendly competition to ensure that we drink compulsory amounts of water throughout the day. </p>
<p>Hydration and “<a href="https://www.fwweekly.com/2016/07/13/the-gym-and-i-water-gallon-challenge/">Gallon Challenges</a>” support the widely held belief that water consumption beyond physiological need – or thirst – is healthy.</p>
<p>But this is not so. Individual body water needs – intake – are primarily based upon how much water people lose. How much water each person needs to drink mainly depends on <a href="https://www.researchgate.net/publication/6928174_Updated_Fluid_Recommendation_Position_Statement_From_the_International_Marathon_Medical_Directors_Association_IMMDA">three factors:</a></p>
<ul>
<li>Body weight. Bigger people need more water.</li>
<li>Environmental temperature. When it’s hotter, people sweat and lose water.</li>
<li>Physical activity levels. Increased exercise intensity increases sweat water losses. </li>
</ul>
<p>Therefore, a “one size fits all” fluid replacement strategy, such as drinking eight glasses of eight ounces of water per day, is inappropriate for everyone.</p>
<p>It remains <a href="https://doi.org/10.1152/ajpregu.00365.2002">unclear where the “8 x 8” water intake recommendation</a> comes from. Perhaps, this two-liter intake threshold is derived from a misinterpretation of original recommendations offered by the <a href="https://doi.org/10.1001/jama.2018.4930">U.S. Food and Nutrition Board in 1945</a> as well as the <a href="https://doi.org/10.2903/sp.efsa.2019.EN-1679">2017 European Food Safety Authority,</a> which states the daily recommended amount of water includes all beverages plus the moisture contained in foods. </p>
<p>This means that the moisture contained in foods, especially fresh fruits, sodas, juices, soups, milk, coffee and, yes, even beer, contributes to this daily recommended water requirement. These guidelines go on to suggest that most of the recommended water content can be accomplished without drinking additional cups of plain water. </p>
<p>And, it is important to note that while <a href="https://doi.org/10.1152/ajpregu.1982.242.5.R522">alcohol has diuretic properties</a> – ethanol acts directly on the kidneys to make us pee more – <a href="https://doi.org/10.1097/jes.0b013e3180a02cc1">caffeinated beverages, like tea and coffee, do not increase urinary water losses</a> above the amount of water contained in these beverages.</p>
<h2>King kidney</h2>
<p>Now, you may be wondering why this is so. After all, you’ve heard from a lot of people that you need to drink more, more, more.</p>
<p>Because total body water balance, or what we exercise scientists call homeostasis, is complicated, mammals survive by making <a href="https://doi.org/10.1056/NEJMra1404726">real-time adjustments at the kidney</a>. That’s why when it comes to hydration, our kidneys are king. </p>
<p>Within each kidney – we need only one (i.e., we are born with a spare, just in case) – is an <a href="https://doi.org/10.1056/NEJMra1404726">undercover network of aquaporin-2 (AQP-2) water channels</a> that respond to a <a href="https://doi.org/10.1016/S1521-690X(03)00049-6">hormone</a> called arginine vasopressin. This is the body’s main anti-diuretic (water retention) hormone. It is secreted by the posterior pituitary gland in response to nerve signals sent from specialized <a href="https://doi.org/10.1038/nrn2400">brain sensors</a> which detect subtle changes in water balance. These specialized sensors are called circumventricular organs. </p>
<p>The kidneys will make molecular adjustments to both underhydration and overhydration within <a href="https://doi.org/10.1152/ajprenal.1992.262.6.F989">40 seconds</a> in response to any upset in the water balance. These adjustments result from the mobilization armies of AQP-2 water channels, numbering about <a href="https://doi.org/10.1152/ajprenal.1997.272.1.F3">12 million per collecting duct cell</a>. </p>
<p>This is why when we drink more water than our body needs – above thirst – we immediately have to pee out any excess water. Or when we forget our water bottle during practice, we stop peeing to conserve body water. This quick coordinated action between the <a href="https://doi.org/10.3390/nu11071539">brain, cranial nerves and kidneys</a> is far more efficient and precise than any phone app, gadget or personalized recommendation available. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/UXUvOIoTUWI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">‘Good Morning America’ hosts took a water challenge. These contests perpetuate the idea that it’s good to drink eight glasses of water a day.</span></figcaption>
</figure>
<h2>Is there anything good to come out of this?</h2>
<p>Data suggests that drinking about two liters of water per day <a href="https://doi.org/10.1152/ajpregu.00365.2002">reduces kidney stone formation</a> in people with a history of kidney stones and decreases the number of <a href="https://doi.org/10.1001/jamainternmed.2018.4204">bladder infections</a> in people with a history of bladder infections. </p>
<p>Improvement in <a href="https://doi.org/10.3390/nu11010070">skin complexion, kidney function</a> and <a href="https://doi.org/10.1016/j.jped.2017.01.005">constipation</a>, with increased water consumption, are not clearly supported by science. Drinking extra water alone <a href="https://doi.org/10.1001/jamapediatrics.2017.0012">does not help kids lose weight</a> unless water intake replaces the ingestion of higher-caloric beverages, such as soda, or makes people feel “<a href="https://doi.org/10.1002/oby.21167">full</a>” before meals. </p>
<p>Drinking water can affect some people’s mental state. Some studies report <a href="https://doi.org/10.1017/S0007114513004455">better cognitive performance</a> after increasing water intake; while females with anxiety report <a href="https://journals.lww.com/jonmd/Abstract/1974/01000/COMPULSIVE_WATER_DRINKING__A_Review_of_the.10.aspx">compulsive water intake makes them feel better</a>, likely from activation of <a href="https://doi.org/10.1016/j.cell.2007.09.018">reward circuits</a> that increase dopamine. Many <a href="https://doi.org/10.1016/j.schres.2014.06.001">schizophrenic patients are compulsive water drinkers</a>, stating that “<a href="https://doi.org/10.1001/archpsyc.1960.03590070102012">voices” tell them to drink</a> and that drinking water suppresses these voices.</p>
<p>[<em>Get facts about coronavirus and the latest research.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=coronavirus-facts">Sign up for The Conversation’s newsletter.</a>]</p>
<p>Of note, brain imaging studies confirm that superfluous drinking is <a href="https://doi.org/10.1073/pnas.1403382111">unpleasant</a> and requires <a href="https://doi.org/10.1073/pnas.1613929113">greater muscular effort</a> than drinking when thirsty. Our brain tries to discourage chronic overdrinking, or polydipsia, because “<a href="https://doi.org/10.1186/1752-1947-6-376">social polydipsia</a>” causes chronic peeing (polyuria), which can lead to internal plumbing modifications such as <a href="https://doi.org/10.1176/ajp.140.7.915">bladder distention, ureter dilation, hydronephrosis and renal failure</a>. </p>
<p>So, do you need to drink eight glasses of water per day? Unless you are thirsty, drinking extra water will probably not offer superior health benefits but probably is not harmful either. However, if kidneys could talk, they would say that hydration challenges represent nothing more than highly marketed peeing contests.</p><img src="https://counter.theconversation.com/content/159020/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tamara Hew-Butler does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>If kidneys could talk, they’d tell you not to overdo the water rule you hear all the time. But since they can’t talk, they do send signals to your body that enough is enough.Tamara Hew-Butler, Associate Professor of Exercise and Sports Science, Wayne State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1490612020-12-29T14:20:18Z2020-12-29T14:20:18ZWhen working out makes you sick to your stomach: What to know about exercise-induced nausea<figure><img src="https://images.theconversation.com/files/375994/original/file-20201218-19-1i1lszk.jpg?ixlib=rb-1.1.0&rect=278%2C0%2C4841%2C3317&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">It's no fun to exercise if you wind up doubled over with gastrointestinal problems.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/fit-woman-having-stomachache-royalty-free-image/1179185150">Goads Agency/iStock via Getty Images Plus</a></span></figcaption></figure><p>You’re doing it! You’re working out, reaping all those <a href="https://www.cdc.gov/physicalactivity/basics/pa-health/index.htm">benefits of exercise</a> that have been drilled into your head.</p>
<p>So you’re pedaling your heart out or running like you’re escaping a zombie horde. You’re feeling accomplished, on cloud nine, until … your stomach starts to churn. You may even feel dizzy. Your feelings of accomplishment have turned to agony as you deal with a bout of nausea.</p>
<p>Exercise-induced nausea is quite common, as are exercise-induced <a href="https://ispyphysiology.com/2020/01/16/spotlight-on-the-digestive-system/">gastrointestinal</a> (GI) problems in general, <a href="https://doi.org/10.1123/ijsnem.2016-0305">affecting perhaps up to 90% of endurance athletes</a>.</p>
<p>So why does this happen and, more important, how can you prevent it?</p>
<h2>The cause: Competing demands</h2>
<p>When you exercise, skeletal muscles in your legs and arms contract. To work most efficiently, they need oxygen. So your heart muscle contracts, too, increasing blood flow through your body. The hemoglobin molecules within your red blood cells carry oxygen to your working muscles.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/375995/original/file-20201218-15-1j5n9ed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="illustration of human cardiovascular system" src="https://images.theconversation.com/files/375995/original/file-20201218-15-1j5n9ed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/375995/original/file-20201218-15-1j5n9ed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=716&fit=crop&dpr=1 600w, https://images.theconversation.com/files/375995/original/file-20201218-15-1j5n9ed.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=716&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/375995/original/file-20201218-15-1j5n9ed.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=716&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/375995/original/file-20201218-15-1j5n9ed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=899&fit=crop&dpr=1 754w, https://images.theconversation.com/files/375995/original/file-20201218-15-1j5n9ed.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=899&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/375995/original/file-20201218-15-1j5n9ed.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=899&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Your body directs oxygen where it’s most needed by sending blood to the most active tissues.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/human-cardiovascular-system-artwork-royalty-free-illustration/478187833">PIXOLOGICSTUDIO/Science Photo Library via Getty Images</a></span>
</figcaption>
</figure>
<p>To maximize the amount of blood being delivered to the active muscles, your body diverts blood away from inactive areas – such as your gut. This diversion is overseen by the “fight or flight” branch of your nervous system. Known as the sympathetic nervous system, it causes some blood vessels to narrow, limiting blood flow. You don’t have conscious control over this process, known as vasoconstriction.</p>
<p>But your contracting skeletal muscles have a special power to preserve blood flow. They’re able to resist the call for vasoconstriction that helps divert blood away from inactive areas. This resistance to the effect of the sympathetic nervous system is called “<a href="https://ecommons.udayton.edu/hss_fac_pub/12">functional sympatholysis</a>.” <a href="https://scholar.google.com/citations?user=uXcM0scAAAAJ&hl=en&oi=ao">Physiologists like me</a> continue to work to <a href="https://doi.org/10.1113/JP274532">understand the specific mechanisms</a> by which this can occur.</p>
<p>So why does limiting blood flow to the gut cause distress?</p>
<p>The relative ischemia, or lack of blood flow, can have different effects. It can change how cells are able to absorb what has been digested and <a href="https://doi.org/10.1007/s40279-014-0153-2">how broken-down food moves through the gut</a>. Taken together, the changes result in an unpleasant feeling you may know all too well. </p>
<p>The lack of blood flow is particularly challenging if the digestive system is actively trying to break down and absorb food, a main reason exercise-induced nausea <a href="https://doi.org/10.1006/appe.2000.0391">can be worse right after you’ve eaten</a>, especially if the pre-workout meal had <a href="https://doi.org/10.1007/s40279-014-0153-2">a lot of fat or concentrated carbohydrates</a>.</p>
<h2>The cure: Moderation and modification</h2>
<p>It’s no fun to exercise if you’re doubled over with stomach cramps or running for the bathroom. So what can you do to limit symptoms or get rid of them when they crop up?</p>
<ul>
<li><p>Moderate your exercise intensity. Nausea is <a href="https://doi.org/10.1097/MCO.0b013e32832e6776">more common with high-intensity exercise</a>, where the competing demands for blood flow are highest. Especially if you’re newer to working out, gradually increasing exercise intensity should help to minimize the likelihood of GI distress.</p></li>
<li><p>Modify your exercise. Some evidence suggests that certain exercises, <a href="https://doi.org/10.1007/s40279-014-0153-2">like cycling</a>, can put the body in a position that’s more likely to cause gut problems. Try different forms of exercise, or combinations of different modes to meet your fitness goals while minimizing discomfort. Be sure to properly warm up and cool down to prevent rapid changes in your body’s metabolism.</p></li>
<li><p>Modify what and when you eat and drink. Stay hydrated! You’ve probably heard it before, but drinking enough is one of the best ways to prevent GI issues during and after exercise, particularly in hot or humid environments. It is possible to overhydrate, though. Aim for <a href="https://doi.org/10.1186/1550-2783-8-12">about half a liter per hour of fluids</a>, including some low-carbohydrate and low-sodium sports drinks for high-intensity exercise. It may take some experimentation with different foods and the timing of ingestion to figure out what works best for you and your training goals. You can also incorporate foods like <a href="https://www.runnersworld.com/nutrition-weight-loss/g20865839/foods-to-prevent-exercise-nausea/">ginger, crackers and coconut water</a> that might help settle your stomach.</p></li>
</ul>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/375996/original/file-20201218-23-147yq8e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="woman in hijab drinks water after sport" src="https://images.theconversation.com/files/375996/original/file-20201218-23-147yq8e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/375996/original/file-20201218-23-147yq8e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/375996/original/file-20201218-23-147yq8e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/375996/original/file-20201218-23-147yq8e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/375996/original/file-20201218-23-147yq8e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/375996/original/file-20201218-23-147yq8e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/375996/original/file-20201218-23-147yq8e.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">Be sure to drink up during and after your workout.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/proud-and-confident-muslim-woman-with-hijab-royalty-free-image/1062308638">Deby Suchaeri/Moment via Getty Images</a></span>
</figcaption>
</figure>
<h2>The caveat: When to seek help</h2>
<p>While exercise-induced nausea is unpleasant to deal with, in general it isn’t a major health concern. Most symptoms should resolve within an hour of finishing exercise. If problems persist either for long periods after exercise or each time you work out, it’s worth having a conversation with your doctor.</p>
<p>Sometimes the GI distress during or after exercise can actually lead to vomiting. If you unfortunately do throw up, you’ll likely feel better but will also need to rehydrate and replenish the nutrition you lost.</p>
<p>[<em>Like what you’ve read? Want more?</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=likethis">Sign up for The Conversation’s daily newsletter</a>.]</p>
<p>If you’re looking to start an exercise regimen or up the intensity of your current workouts, seeking the advice of trained professionals who can tailor a plan to your needs is often a smart approach. <a href="https://www.acsm.org/get-stay-certified/find-a-pro">Exercise physiologists</a> or <a href="https://www.nsca.com/professional-development/professional-areas/personal-trainers/">certified personal trainers</a> can provide exercise programming of appropriate intensity, and <a href="https://www.eatright.org/find-an-expert">registered dietitian nutritionists</a> can discuss individual nutritional needs and strategies. Your <a href="https://www.exerciseismedicine.org/">primary care provider</a> can help to screen for more serious medical issues and should be informed of your exercise routine as well.</p><img src="https://counter.theconversation.com/content/149061/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Anne R. Crecelius 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>You’re working out, feeling great – until your stomach starts to churn and you’re sidelined with a bout of nausea. Here’s what’s happening in your body and how to avoid this common effect of exercise.Anne R. Crecelius, Associate Professor of Health and Sport Science, University of DaytonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1273952020-01-06T13:49:20Z2020-01-06T13:49:20ZIs sparkling water bad for you?<figure><img src="https://images.theconversation.com/files/308421/original/file-20200103-11909-151uacv.jpg?ixlib=rb-1.1.0&rect=38%2C31%2C5137%2C3414&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/pouring-mineral-water-glass-111304484">Hayati Kayhan/Shutterstock</a></span></figcaption></figure><p>For many people, the start of a year is a time for new health resolutions – be it eat more vegetables, consume less sugar or drink more water. </p>
<p>Keeping hydrated <a href="https://www.nutrition.org.uk/healthyliving/hydration.html">is essential</a> for body functions such as temperature regulation, transporting nutrients and removing waste. Water even acts as a <a href="https://www.nutrition.org.uk/healthyliving/hydration/adults-teens.html">lubricant and shock absorber for joints</a>.</p>
<p>But while most people know they should drink more water, it can be a bit boring. So what about sparkling water as an option to liven things up a bit? After all, sparkling water is just as good as normal water, right? Not quite.</p>
<h2>Fizzy fluids</h2>
<p>Sparkling water is made by infusing water with carbon dioxide. This produces carbonic acid with a weak acidic pH of between three and four. That <a href="https://academic.oup.com/chemse/article-abstract/44/5/281/5482222?redirectedFrom=fulltext">“feel good” mouth sensation</a> you get after sipping a carbonated drink is in fact the <a href="https://academic.oup.com/chemse/article-abstract/44/5/281/5482222?redirectedFrom=fulltext">chemical activation of pain receptors</a> on your tongue responding to this acid, giving a moreish taste. And here’s part of the problem, as acid in drinks can harm our teeth.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/308424/original/file-20200103-11919-g3drwb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308424/original/file-20200103-11919-g3drwb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308424/original/file-20200103-11919-g3drwb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308424/original/file-20200103-11919-g3drwb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308424/original/file-20200103-11919-g3drwb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308424/original/file-20200103-11919-g3drwb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308424/original/file-20200103-11919-g3drwb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Tasty to drink but not so great for your teeth.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/healthy-nutrition-drinking-water-lemon-people-359872097">Bignai/Shutterstock</a></span>
</figcaption>
</figure>
<p>The outer layer of our teeth, <a href="https://www.sciencedirect.com/topics/medicine-and-dentistry/tooth-enamel">dental enamel</a>, is the hardest tissue in the body. It is made of a mineral called hydroxyapatite that contains calcium and phosphate. Saliva is mainly water but also contains calcium and phosphate.</p>
<p>There is normally a balance between tooth minerals and the minerals in saliva. The mouth and saliva normally have (<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5966679/">a pH of six to seven</a>), but when this drops below five and a half, calcium and phosphate molecules move out of the teeth and into saliva. This can happen because of the carbonic acid in fizzy drinks.</p>
<h2>Bad for teeth?</h2>
<p>This <a href="https://calcivis.com/publication/demineralisation-new-science/">demineralisation</a> creates tiny pores in the tooth mineral and the enamel starts to dissolve. Initially, the pores are microscopic and can still be plugged by putting calcium or phosphate back in, or by replacing calcium with fluoride – this is how fluoride in toothpaste works to protect teeth. But once the amount of lost tooth mineral reaches a certain level, the pores can no longer be plugged and the tooth tissue is lost for good. </p>
<p>If teeth are <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3432030/#!po=6.25000">bathed in acid from carbonated drinks</a> frequently, more minerals can be dissolved out than get put back in, and there is more risk of <a href="https://www.sciencedirect.com/science/article/pii/B9781845694180500045">tooth wear or erosion</a></p>
<p>So although plain sparkling water is better for your teeth than flavoured sodas (diet or regular) which have a lower pH, still water is best – it has a pH of around seven. Incidentally, club soda is not only carbonated but has some “minerals” added for flavour. These may include sodium, so if you are watching your salt intake you also need to be mindful of this.</p>
<h2>Pure water</h2>
<p>It’s also worth pointing out that sparkling water is not an appetite suppressant. Despite what you <a href="https://www.livestrong.com/article/532893-carbonated-water-and-weight-loss/">might read online </a>, there is no strong scientific evidence to suggest that drinking sparkling water will make you feel fuller or curb your appetite. Yes, drinking carbonated water will fill up your stomach (probably making you belch too) but it won’t stay in your stomach any longer than still water. </p>
<p>Even when sparkling water is drunk alongside food or meals, there is no difference in how quickly <a href="https://www.ncbi.nlm.nih.gov/pubmed/9009113">the stomach will empty compared to still water</a>. Scientifically, it is difficult to measure hunger and fullness, which means that studies investigating these are based on, or influenced by, people’s personal feelings – and naturally us humans are all very different. In fact, the <a href="https://www.sciencedirect.com/science/article/pii/S0924224414002386">European Food Safety Authority</a>, which provides independent scientific advice on food safety, doesn’t endorse any health claims related to foods or drinks said to increase satiety.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/308423/original/file-20200103-11951-f7g8rr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/308423/original/file-20200103-11951-f7g8rr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/308423/original/file-20200103-11951-f7g8rr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/308423/original/file-20200103-11951-f7g8rr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/308423/original/file-20200103-11951-f7g8rr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/308423/original/file-20200103-11951-f7g8rr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/308423/original/file-20200103-11951-f7g8rr.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">Bottled water is big business.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/jeju-south-korea-june-01-2018-1103217548">Toshio Chan/Shutterstock</a></span>
</figcaption>
</figure>
<p>The <a href="https://www.nhs.uk/live-well/eat-well/water-drinks-nutrition/">NHS advises</a> drinking between six to eight glasses of fluid per day. As well as water, this can also include lower fat milk and sugar-free drinks, along with tea and coffee. Water is a healthy and cheap choice for quenching your thirst at any time. It has no calories, is free and contains no sugars that can damage teeth – unlike the myriad of sports, energy and carbonated drinks that flood supermarket shelves.</p>
<p>Of course, if you are swapping sugary soft drinks with sparkling water then this is a step in the right direction. Indeed, soft drinks are estimated to contribute to approximately <a href="https://www.gov.uk/government/publications/sacn-carbohydrates-and-health-report">25% of sugar intake in adults</a> and increase oral acidity. Most sparkling waters do not have added sugars, though some do, so always read the label. </p>
<p>So when it comes to trying to increase your fluid intake, still water is still the preferred option. But if a glass of water is not really your thing, sparkling water can help you stay hydrated and can be a tasty alternative to plain water – but just be mindful of how frequently you drink it for your dental health.</p><img src="https://counter.theconversation.com/content/127395/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>If one of your goals is to drink more water this year, then make sure you read this.Nicola Innes, Professor of Paediatric Dentistry, University of DundeeSuzanne Zaremba, Lecturer in Nutrition, Centre for Public Health Nutrition Research, University of DundeeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1284202019-12-10T13:58:55Z2019-12-10T13:58:55ZOlder people need to stay hydrated – here’s how<figure><img src="https://images.theconversation.com/files/305853/original/file-20191209-90552-95axu2.jpg?ixlib=rb-1.1.0&rect=199%2C544%2C4914%2C2706&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/confirm/722970025?src=5d1b94e7-a6f5-4095-9286-9155ed18e0a7-1-15&size=huge_jpg">Julia Kuznetsova/Shutterstock</a></span></figcaption></figure><p>Dehydration is associated with a higher risk of ill health in older people, from having an <a href="https://clinicalnutritionespen.com/article/S1751-4991(09)00093-6/pdf">infection, a fall or being admitted to hospital</a>. But an appetite for food and drink can diminish as people age, so older people should drink regularly, even when they’re not thirsty. </p>
<p>Older women who don’t have to restrict their fluid intake for medical reasons, such as heart or kidney problems, are <a href="https://www.espen.org/files/ESPEN-Guidelines/ESPEN_GL_Geriatrics_ClinNutr2018ip.pdf">advised to drink</a> eight glasses a day. For older men, it’s ten glasses.</p>
<p>The easiest way to drink more fluids is to build on existing habits. For instance, drinking more fluid as part of everyday routines, such as when taking medication or at mealtimes. If you build this up gradually in small steps, eventually it will become part of your routine. </p>
<p>Keeping up your fluid intake shouldn’t be a chore – drink more of what you enjoy. A common myth is that you have to drink water, but tea, coffee and juices all count. And in some cases, <a href="https://www.espen.org/files/ESPEN-Guidelines/ESPEN_GL_Geriatrics_ClinNutr2018ip.pdf">even beer can be hydrating</a> when consumed within recommended guidelines.</p>
<p>Thirst is seen as a reliable indicator of when you need to drink, but the perception of thirst <a href="https://www.espen.org/files/ESPEN-Guidelines/ESPEN_GL_Geriatrics_ClinNutr2018ip.pdf">can blunt with age</a>. An over-reliance on thirst alone to reach for a drink may increase your risk of dehydration, so it is important to be mindful of drinking fluids regularly even when you’re not thirsty. </p>
<p>Another myth is that avoiding drinking can help urinary incontinence. However, limiting fluid intake <a href="https://www.nhs.uk/conditions/urinary-incontinence/10-ways-to-stop-leaks/">makes incontinence worse</a> because it reduces the bladder’s capacity.</p>
<p>Some people wonder whether hydration benefits our health at all. Many people don’t believe that drinking too little can affect their wellbeing or have serious health consequences. But older people, in particular, are more vulnerable to the effects of drinking too little due to <a href="https://clinicalnutritionespen.com/article/S1751-4991(09)00093-6/pdf">age-related physiological changes or drug side-effects, or both</a>. </p>
<p>By 2046, the percentage of people aged over 65 is <a href="https://www.ons.gov.uk/releases/overviewoftheukpopulationjuly2017">predicted to rise</a> from 18% to almost 25% in the UK. As the climate crisis worsens and heatwaves become more common, the incidence of dehydration-related deaths is also <a href="https://academic.oup.com/eurpub/article/16/6/592/587672">set to increase</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/306078/original/file-20191210-95125-10qiwn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/306078/original/file-20191210-95125-10qiwn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/306078/original/file-20191210-95125-10qiwn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/306078/original/file-20191210-95125-10qiwn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/306078/original/file-20191210-95125-10qiwn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/306078/original/file-20191210-95125-10qiwn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/306078/original/file-20191210-95125-10qiwn.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">Even beer counts.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/group-multiethnic-senior-friends-drinking-beer-754624087?src=194dd965-b8b8-4725-b944-8d15c60eb5ab-1-1&studio=1">LightField Studios/Shutterstock</a></span>
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<h2>Fear of fluids</h2>
<p>Until now, little research has been done on the views on hydration of elderly people who don’t live in residential or care homes. To redress that, we recently <a href="https://t.co/elL2ESlKMC?amp=1">conducted a study</a> to assess older people’s views on hydration. We conducted one-to-one interviews with 24 people aged over 75 who lived at home in London, England. We also interviewed nine carers. </p>
<p>We found that perceptions of the importance of hydration were greatly varied. While interviewees were somewhat aware of public health messages on hydration, many misconceptions existed, such as how much and what to drink. </p>
<p>Some of the greatest barriers to getting the optimal fluid intake was an overwhelming fear of incontinence and difficulty getting to the toilet. In such cases, it is important to drink plenty of fluid to not exacerbate the problem. Opting for decaffeinated tea and coffee can help, as can reducing alcohol intake. </p>
<p>Avoiding constipation by drinking plenty and getting enough fibre in your diet can also help a weak bladder. It can be useful to plan trips ahead of time, locating the nearest toilet and planning for loo breaks. </p>
<p>Another challenge identified in our study was difficulty using kitchen equipment and cups as participants got older, such as the kettle becoming too heavy. If you notice that everyday items are becoming more difficult to use, it is important to discuss this early on with friends, family or carers and explore the options. A lightweight kettle, a straw or tailored cups can make all the difference and are widely available. </p>
<p>Our study concluded that the optimal way of supporting older people to drink more was to acknowledge and address individual barriers to drinking and build on everyday habits, such as drinking with medications and encouraging drinking as a pleasurable, positive experience.</p><img src="https://counter.theconversation.com/content/128420/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cini Bhanu receives funding from National Institute of Health Research School for Primary Care Research (NIHR SPCR)</span></em></p>Just because you’re not thirsty doesn’t mean you’re not dehydrated.Cini Bhanu, GP Clinical Research Fellow, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1235242019-10-22T18:59:45Z2019-10-22T18:59:45ZIs coconut water good for you? We asked five experts<figure><img src="https://images.theconversation.com/files/293520/original/file-20190923-23784-1ivpi9f.jpg?ixlib=rb-1.1.0&rect=0%2C1%2C998%2C664&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Nutritionally, coconut water is OK, but it's healthier to stick to plain water. </span> <span class="attribution"><span class="source">from www.shutterstock.com</span></span></figcaption></figure><p>In recent years coconut water has left the palm-treed shores of tropical islands where tourists on lounge chairs stick straws straight into the fruit, and exploded onto supermarket shelves – helped along by beverage giants such as Coca-Cola and PepsiCo. </p>
<p>Marketed as a natural health drink, brands spout various health claims promoting coconut water. So before we drank the Kool-Aid, we thought we’d check in with the experts whether the nutritional claims stack up. Is coconut water part of a healthy diet or we should just stick to good old water from the tap? </p>
<p>We asked five experts if coconut water is good for you. </p>
<h2>Four out of five experts said no</h2>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/294000/original/file-20190925-51405-pew7xl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/294000/original/file-20190925-51405-pew7xl.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=99&fit=crop&dpr=1 600w, https://images.theconversation.com/files/294000/original/file-20190925-51405-pew7xl.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=99&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/294000/original/file-20190925-51405-pew7xl.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=99&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/294000/original/file-20190925-51405-pew7xl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=125&fit=crop&dpr=1 754w, https://images.theconversation.com/files/294000/original/file-20190925-51405-pew7xl.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=125&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/294000/original/file-20190925-51405-pew7xl.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=125&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>Here are their detailed responses:</em></strong></p>
<p><iframe id="tc-infographic-436" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/436/b66bb4b5e4348a26861976cd570bc1ca019c26dc/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<hr>
<p><em>If you have a “<strong>yes or no</strong>” health question you’d like posed to Five Experts, email your suggestion to: alexandra.hansen@theconversation.edu.au</em></p>
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<img alt="" src="https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em>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, Rijk Zwaan Australia and Greater Charitable Foundation. She has consulted to SHINE Australia, Novo Nordisk, Quality Bakers, the Sax Institute and the ABC. She was a team member conducting systematic reviews to inform the Australian Dietary Guidelines update and the Heart Foundation evidence reviews on meat and dietary patterns. Emma Beckett is a member of the Nutrition Society of Australia, Australian Institute for Food Science and Technology. Her research is funded by the NHMRC and AMP Foundation. She has previously consulted for Kellogg’s. Rebecca Reynolds is a registered nutritionist and the owner of <a href="http://www.therealbokchoy.com">The Real Bok Choy</a>, a nutrition and lifestyle consultancy.</em></p><img src="https://counter.theconversation.com/content/123524/count.gif" alt="The Conversation" width="1" height="1" />
We asked five experts if coconut water is good for you. Four out of five experts said no.Alexandra Hansen, Deputy Editor and Chief of Staff, The Conversation AUNZLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1227612019-09-03T12:33:54Z2019-09-03T12:33:54ZCurious Kids: when fish get thirsty do they drink sea water?<figure><img src="https://images.theconversation.com/files/290552/original/file-20190902-175668-1javyse.jpg?ixlib=rb-1.1.0&rect=97%2C13%2C4399%2C3084&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">I'm parched as. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/nickharris1/6931604669/">Nick Harris/Flickr.</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p><strong>When fish get thirsty do they drink sea water? – Torben, aged nine, Sussex, UK.</strong></p>
<p>This is a great question, Torben, thanks very much for sending it in. </p>
<p>The short answer is yes, some fish do drink seawater – but not all of them. Fish are amazing animals, and have some very cool solutions to living in water. Naturally, different types of fish have evolved different solutions. </p>
<p>The bony kinds of fish that live in the sea – such as cod, herring, tuna and so on – have a few ways of getting water in and out of the body. As well as swallowing and peeing, like humans do, these fish can pass it through their skin and gills.</p>
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<figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a> is a series by <a href="https://theconversation.com/uk">The Conversation</a>, which gives children the chance to have their questions about the world answered by experts. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskids@theconversation.com">curiouskids@theconversation.com</a>. We won’t be able to answer every question, but we’ll do our very best.</em></p>
<hr>
<p>To understand how this works, you first need to know that bony fish have a different <a href="https://www.thoughtco.com/definition-of-concentration-605844">concentration</a> of salt in their bodies to their environment. This means they’re more or less salty than the water they swim in. </p>
<p>The bodies of marine fish (which live in the sea) are less salty than the water they swim in, while the bodies of freshwater fish (which live in rivers and lakes) are more salty than the water they swim in. </p>
<p>Both marine and freshwater fish have to control the amount of water and salt in their bodies, to stay healthy and hydrated. </p>
<h2>Hard to stay hydrated</h2>
<p>Bony marine fish are constantly losing water from their body, through a process called “<a href="https://sciencing.com/osmosis-kids-8650496.html">osmosis”</a>“. During osmosis, water moves through a membrane (like skin), from areas of lower concentration to areas of higher concentration. </p>
<p>Remember, the body of a marine fish is less salty than the seawater it swims in – which means it has a lower concentration of salt. So these fish actually lose water through osmosis: it passes from their body, through their skin and gills, out into the sea. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/290692/original/file-20190903-175714-vntsr7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/290692/original/file-20190903-175714-vntsr7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/290692/original/file-20190903-175714-vntsr7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/290692/original/file-20190903-175714-vntsr7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/290692/original/file-20190903-175714-vntsr7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/290692/original/file-20190903-175714-vntsr7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/290692/original/file-20190903-175714-vntsr7.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">Thirsty work.</span>
<span class="attribution"><span class="source">Sebastian Pena Lambarri/Unsplash.</span>, <a class="license" href="http://artlibre.org/licence/lal/en">FAL</a></span>
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<p>Since they’re constantly losing water this way, these fish have to drink a lot of seawater to stay hydrated. </p>
<p>You might be interested to know that the opposite happens in freshwater fish. Water flows into their body through osmosis, instead of out. This means they don’t generally need to drink – but they do have to pee a lot.</p>
<p>We all know that <a href="http://www.actiononsalt.org.uk/salthealth/children/">too much salt is bad for us</a>. So of course, an animal that drinks seawater must have a way to get rid of excess salt. </p>
<p>Marine fish have kidneys, which pump excess salt into their pee so they can get it out of their bodies. They also have special cells in their gills that pump excess salt out into the sea. Together, these two systems mean that marine fish can stay hydrated. </p>
<h2>Salty sharks</h2>
<p>Sharks have evolved a completely different system. Their bodies have a slightly higher concentration of salt than seawater. This means they don’t have the problem that bony fish have, of losing water through their skin all the time.</p>
<p>Sharks have high levels of waste chemicals – called urea and trimethylamine N-oxide – in their body, which other animals would usually get rid of. Sharks keep them in their body, which keeps them "salty”. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/290693/original/file-20190903-175714-1brmqcm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/290693/original/file-20190903-175714-1brmqcm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=432&fit=crop&dpr=1 600w, https://images.theconversation.com/files/290693/original/file-20190903-175714-1brmqcm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=432&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/290693/original/file-20190903-175714-1brmqcm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=432&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/290693/original/file-20190903-175714-1brmqcm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=543&fit=crop&dpr=1 754w, https://images.theconversation.com/files/290693/original/file-20190903-175714-1brmqcm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=543&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/290693/original/file-20190903-175714-1brmqcm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=543&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">I don’t drink.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/j3Kbs-GcEXs">David Clode/Unsplash.</a>, <a class="license" href="http://artlibre.org/licence/lal/en">FAL</a></span>
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<p>Sharks take in small amounts of water through their gills (by osmosis – because they are slightly saltier than the sea) which means they don’t directly have to drink. </p>
<p>Sharks also have <a href="https://link.springer.com/chapter/10.1007/978-3-662-00989-5_25">a salt gland</a> (in their rectum) to get rid of any excess salt they may have. </p>
<p>The problem of drinking seawater isn’t just for fish. Some seabirds – albatrosses, for example – have to drink seawater too. Like sharks, these seabirds <a href="https://www.sciencedirect.com/topics/immunology-and-microbiology/salt-gland">have a salt gland</a> to get rid of excess salt. But on an albatross it is found at the top of the bird’s beak. </p>
<hr>
<p><em>Children can have their own questions answered by experts – just send them in to <a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a>, along with the child’s first name, age and town or city. You can:</em></p>
<ul>
<li><em>email <a href="mailto:curiouskids@theconversation.com">curiouskids@theconversation.com</a></em></li>
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<p><em>Here are some more <a href="https://theconversation.com/topics/curious-kids-36782?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=CuriousKidsUK">Curious Kids</a> articles, written by academic experts:</em></p>
<ul>
<li><p><em><a href="https://theconversation.com/curious-kids-why-do-some-animals-have-two-different-coloured-eyes-119727?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=CuriousKidsUK">Why do some animals have two different coloured eyes? – George, aged ten, Hethersett, UK.</a></em></p></li>
<li><p><em><a href="https://theconversation.com/curious-kids-how-high-could-i-jump-on-the-moon-120865?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=CuriousKidsUK">How high could I jump on the moon? – Miles, aged five, London, UK.</a></em></p></li>
<li><p><em><a href="https://theconversation.com/curious-kids-why-are-the-bubbles-in-fizzy-drinks-so-small-the-ones-i-blow-are-much-bigger-121513?utm_source=TCUK&utm_medium=linkback&utm_campaign=TCUKengagement&utm_content=CuriousKidsUK">Why are the bubbles in fizzy drink so small? The ones I blow are much bigger - Alison, aged seven, Aberdeen, UK.</a></em></p></li>
</ul><img src="https://counter.theconversation.com/content/122761/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Claire Lacey 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>Fish that live in the sea have found amazing ways to control the amount of water and salt in their bodies, and stay hydrated.Claire Lacey, PhD Candidate in Biology, University of St AndrewsLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1003652018-08-01T10:39:45Z2018-08-01T10:39:45ZOverhydrating presents health hazards for young football players<figure><img src="https://images.theconversation.com/files/229839/original/file-20180730-106514-1k69i9e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Thomas Johnson drinks Gatorade at a 'Beat the Heat' event the company sponsored in Fort Worth, Texas, June 10, 2013.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/inVision-Brandon-Wade-Invision-AP-a-ENT-CPAENT-/ffc008b459e745f1b91f7b8215e0e7dc/3/0">Brandon Wade/Invision for Gatorade/AP Photo</a></span></figcaption></figure><p>With August football practice fast approaching, every coach’s favorite cheer will be to “stay hydrated” and “keep urine clear” during the summer heat. </p>
<p>In 2017, a University of Texas football coach created a urine-based “<a href="https://www.usatoday.com/story/sports/ftw/2017/10/05/herman-explains-logic-texas-hydration-chart/106335964/">Longhorn Football Hydration Chart</a>,” which labeled players with yellow urine as “selfish teammates” and those with brown urine as “bad guys.” This “hydration shaming” practice has permeated high school sports, thereby encouraging a sporting culture which equates <a href="https://usatodayhss.com/2017/true-colors-using-the-texas-longhorns-chart-and-other-hydration-tips">superior performance with superior hydration</a>. </p>
<p>Overzealous obedience to this hydration advice has uncovered a dark underbelly to superior hydration practices: overhydration. When high school football player <a href="http://www.msnewsnow.com/story/26364634/jackson-prep-football-player-dies">Walker Wilbanks</a> died in Mississippi in August 2014 from overhydration, the doctor said that the cause of death was an “<a href="https://www.clarionledger.com/story/prepsreport/2014/08/25/walker-wilbanks-cause-of-death-related-to-over-hydration/14598215/">unpredictable freak occurrence</a>.” </p>
<p>Two weeks prior, another <a href="https://www.ajc.com/news/update-douglas-county-football-player-has-died/G73yyxV1Sxo4N1IMdcibQO/">high school football player from Georgia drank “two gallons of water and two gallons of Gatorade</a>” after football practice to prevent muscle cramps and then died. Thus, over the last four years, two high school football players have died during August football practice from overhydrating - a medical condition known as <a href="https://www.ncbi.nlm.nih.gov/pubmed/26102445">exercise-associated hyponatremia</a>. </p>
<p>Conversely, no football player has ever been known to die from dehydration, although seven died during this same four-year period from <a href="https://nccsir.unc.edu/files/2013/10/Annual-Football-2017-Fatalities-FINAL.pdf">heatstroke</a>, which may be related, but not always. </p>
<p>How do I know about that overhydration kills athletes? I watched runners almost die after <a href="https://www.ncbi.nlm.nih.gov/pubmed/12544163">drinking 100 cups of water during a marathon</a> because they were scared of becoming “dehydrated.” So, I got interested in thirst. </p>
<p>Turns out, the neuroendocrine thirst circuit dates back 700 million years and is found in most animals, including bugs and worms. Thirst activates the same conscious area of the brain that tells us we’re hungry or have to pee. To say we need to stay “ahead of thirst” (or die) is like saying we need to pee every hour to stay ahead of imminent bladder explosion (or die). The molecular and <a href="https://www.ncbi.nlm.nih.gov/pubmed/14657368">neural circuits that govern fluid intake (and micturition) in real-time are absolutely exquisite</a>.</p>
<p>It’s remarkable to think that animals survive without water bottles and urine charts – they drink when they are thirsty, and we should too.</p>
<h2>Too much water, too little salt</h2>
<p>Hyponatremia is caused by drinking too much water or sports drinks, which dilutes blood salt levels below the normal range. Any sudden drop in blood salt levels, from drinking more than the body can excrete, can cause all cells in the body to swell. Brain swelling from hyponatremia can cause headaches and vomiting, while muscle cell swelling can trigger whole-body muscle cramping.</p>
<p>What is most frightening, however, is that these <a href="https://www.ncbi.nlm.nih.gov/pubmed/28902757">symptoms mimic those of dehydration</a> They are often treated by medical staff with more fluids. </p>
<p>So, which hydration imbalance – dehydration and overhydration – is the lesser of two evils? </p>
<p>Dehydration is undeniably harmful to human health and performance. <a href="https://www.ncbi.nlm.nih.gov/pubmed/9480411">Wrestlers have died</a> from trying to “make weight,” through vigorous dehydration practices. A recent meta-analysis of 33 studies verified that more than <a href="https://www.ncbi.nlm.nih.gov/pubmed/29933347">2 percent dehydration impairs cognition</a>. Dehydration can impair performance and increase core body temperature, as per the American College of Sports Medicine’s latest <a href="https://www.ncbi.nlm.nih.gov/pubmed/17277604">position statement</a>. All of these statements underscore the vital importance of staying hydrated. </p>
<p>But I fear that many coaches ignore the finer points that support those conclusions. For example, three wrestlers who died of dehydration rapidly lost about 15 percent of body weight by withholding fluids while exercising in a hot environment in a rubber suit. Similarly, to achieve 3 percent dehydration, which impairs cognition, individuals need to withhold fluids for 24 hours. And that’s without exercise. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/229843/original/file-20180730-106514-1861gwl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/229843/original/file-20180730-106514-1861gwl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/229843/original/file-20180730-106514-1861gwl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/229843/original/file-20180730-106514-1861gwl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/229843/original/file-20180730-106514-1861gwl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/229843/original/file-20180730-106514-1861gwl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/229843/original/file-20180730-106514-1861gwl.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">Dehydration can occur in the desert when one runs out of water, but dehydration is less likely where fluids are readily available.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/man-walking-alone-sunny-desert-he-766046011?src=eM5FT04JqkXAOxNqT6uOEw-1-36">Koldunova Anna/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>These dehydration protocols do not necessarily represent “free-living” situations. When hikers die from dehydration in the desert, most if not all had become lost or had run out of fluids. Thus, thirst – or the “<a href="https://www.ncbi.nlm.nih.gov/pubmed/6727142">deep-seated desire for water</a>” – is rarely “broken” when healthy people die from dehydration. Morbidity and mortality occur when there is no fluid available, fluids are withheld, as in lab studies, or when athletes refuse to drink for other reasons, such as “making weight.” </p>
<h2>When do athletes and others need to drink?</h2>
<p>So how much fluid should football players – and all other humans for that matter – drink? If you ask fluid balance experts who perform basic science research on the <a href="https://www.ncbi.nlm.nih.gov/pubmed/29129925">brain</a> or <a href="https://www.ncbi.nlm.nih.gov/pubmed/25830425">kidney</a>, or <a href="https://www.ncbi.nlm.nih.gov/pubmed/25551526">clinicians who specialize in fluid balance disorders</a>, researchers who perform <a href="https://www.ncbi.nlm.nih.gov/pubmed/29311314">brain scans on dehydrated and overhydrated humans</a>, or even <a href="https://www.ncbi.nlm.nih.gov/pubmed/24058873">worm</a> investigators, they all agree that water balance is tightly regulated and that all land mammals need to drink when thirsty. </p>
<p>Drinking when you are thirsty is not “too late,” because the thirst mechanism is hardwired into the nervous system to protect against scarcity. Thirst represents the highly individualized signal which protects the balance between water and salt regardless of size, activity or ambient temperature and is encoded in <a href="https://www.ncbi.nlm.nih.gov/pubmed/24058873">most invertebrate and all vertebrate DNA</a>. Babies are born with this innate behavioral drive. </p>
<p>Then, what about the need for eight glasses of water per day? There is <a href="https://www.ncbi.nlm.nih.gov/pubmed/12376390">no evidence</a> to support this. What about peeing until our urine is clear? Dark colored urine merely reflects <a href="https://www.ncbi.nlm.nih.gov/pubmed/29464103">water conservation</a> by the kidney, rather than water lack by the body. </p>
<h2>What’s a football player to do?</h2>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/229840/original/file-20180730-106530-177mhi2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/229840/original/file-20180730-106530-177mhi2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=414&fit=crop&dpr=1 600w, https://images.theconversation.com/files/229840/original/file-20180730-106530-177mhi2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=414&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/229840/original/file-20180730-106530-177mhi2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=414&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/229840/original/file-20180730-106530-177mhi2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=521&fit=crop&dpr=1 754w, https://images.theconversation.com/files/229840/original/file-20180730-106530-177mhi2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=521&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/229840/original/file-20180730-106530-177mhi2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=521&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Kirtland, Ohio, football players pour ice over head coach Tiger Laverde after a major playoff win Dec. 6, 2013. Pouring ice or water over their own heads could be a good option to stay cool.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Div-6-Wayne-Trace-Kirtland-Football/6e3833ab0f244ee38e5965f5c0d9fbc8/15/0">David Richard/AP Photo</a></span>
</figcaption>
</figure>
<p>Football players absolutely need water, but they should be warned not to overdo it. </p>
<p>In the modern era, where fluid is widely available, in order to stay adequately hydrated, the following must occur: </p>
<ol>
<li><p>A variety of fluids needs to be freely available to football players, and </p></li>
<li><p>The players should be given the freedom to drink whenever they feel thirsty.</p></li>
</ol>
<p>And when the players get hot, they need the opportunity to pour generous amounts of ice water over their heads instead of into their mouths to promote evaporative cooling, rather than dilute sodium levels. Better yet, they should be allowed to go inside and cool off. </p>
<p>We should recognize who the “true champions” may be with regards to most modern day hydration advice. According to the latest figures, bottled water sales have increased to <a href="https://www.beveragedaily.com/Article/2018/06/01/Bottled-water-takes-top-spot-in-US-in-2017">US$18.5 billion dollars, up 8.8 percent</a> from the previous year. This revenue does not include the vast array of purified, infused, oxygenized, sparkled, distilled, intravenous and reverse osmosis versions that compete for attention on the market. </p>
<p>While we all need water, drinking until our “urine is clear” is money (and water) flushed away. And with the threat of overdrinking high in motivated athletes, I ask coaches/trainers to reconsider before enforcing the urine color chart in athlete locker rooms: Is it worth the risk?</p><img src="https://counter.theconversation.com/content/100365/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tamara Hew-Butler DPM, PhD, FACSM receives royalties from UpToDate, for her ongoing contributions to the topic of Exercise-Associated-Hyponatremia. </span></em></p>Yes, it’s hot outside. And football practice is starting for thousands of kids. But coaches and parents should be careful about tellings kids to drink more water. That has been deadly.Tamara Hew-Butler, Associate Professor of Exercise and Sports Studies, Wayne State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/983132018-06-21T01:56:47Z2018-06-21T01:56:47ZWhy alcohol after sport and exercise is a bad idea<p>Drinking alcohol after sport is a social ritual that has become ingrained in Australian culture, and it seems professional athletes are no exception, despite being paid generously to be in peak physical condition.</p>
<p>Watching many types of professional sport in Australia, we’ll often see players drinking the sponsor’s brand of alcohol on camera after the match. </p>
<p>But given the state our bodies are in after exercise, and what alcohol does to our system, drinking after sport is a bad idea.</p>
<h2>Fatigue and recovery following sport and exercise</h2>
<p>High intensity actions such as running, jumping, tackling and changing direction <a href="https://www.ncbi.nlm.nih.gov/pubmed/2657962">create temporary muscle damage and soreness</a>. If the exercise is of long enough duration, the fuel stored in our muscles for energy (glycogen) <a href="https://www.physiology.org/doi/abs/10.1152/japplphysiol.00860.2016">can become depleted too</a>. </p>
<p>In a hot or humid environment, the body also <a href="https://academic.oup.com/ajcn/article/72/2/564S/4729614">loses a large amount of fluid </a>from sweating, reducing the blood volume (which is important for getting oxygen around to all our muscles and organs), and electrolyte stores (important for muscle contraction).</p>
<p>The body is in a state of dysfunction and repair after vigorous sport and exercise. Athletic qualities such as strength, power and endurance can be depleted for several days after an intense workout. This can be improved with appropriate and timely <a href="https://www.ncbi.nlm.nih.gov/pubmed/26891166">nutrition and hydration</a>.</p>
<h2>Not the drink of champions</h2>
<p>Alcohol ingestion after sport and exercise worsens all major aspects of post-exercise recovery. Alcohol <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0088384">slows down the repair process</a> of exercise-induced muscle damage by <a href="https://www.ncbi.nlm.nih.gov/pubmed/24748461">inhibiting the functions</a> of hormones that usually aid this process (such as testosterone). </p>
<p>For athletes with a soft tissue injury, it’s even worse, as alcohol <a href="https://www.physiology.org/doi/abs/10.1152/japplphysiol.00860.2016">opens up the blood vessels</a> and encourages swelling at the injury site. </p>
<p>It’s unclear if alcohol <a href="https://www.physiology.org/doi/abs/10.1152/japplphysiol.00115.2003">blocks energy storage in the muscles</a>, but when athletes drink large quantities of alcohol, they tend to eat less nutritious foods (especially if they are sick the next day!). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/223970/original/file-20180620-126537-fbbren.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/223970/original/file-20180620-126537-fbbren.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/223970/original/file-20180620-126537-fbbren.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=353&fit=crop&dpr=1 600w, https://images.theconversation.com/files/223970/original/file-20180620-126537-fbbren.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=353&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/223970/original/file-20180620-126537-fbbren.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=353&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/223970/original/file-20180620-126537-fbbren.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=444&fit=crop&dpr=1 754w, https://images.theconversation.com/files/223970/original/file-20180620-126537-fbbren.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=444&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/223970/original/file-20180620-126537-fbbren.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=444&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">After the final siren of the state of origin game 1, the nation watched as the players were handed cans of beer; XXXX Gold for Queensland and Tooheys New for New South Wales, with the colour of the can matched perfectly to the respective jersey.</span>
<span class="attribution"><a class="source" href="https://www.9now.com.au/state-of-origin/2018/episode-3">Screenshot from 9now</a></span>
</figcaption>
</figure>
<p>This indirectly <a href="https://www.physiology.org/doi/abs/10.1152/japplphysiol.00860.2016">slows down the restoration</a> of energy stores in muscle. For those of us trying to shed a few kilos, alcohol is also a bad choice considering it’s highly energy-dense, with little nutritional value.</p>
<p>But if athletes are dehydrated, isn’t drinking something better than nothing? Alcohol is actually a diuretic that <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1393383/">promotes fluid loss</a> and contributes to dehydration. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-check-what-happens-to-your-body-when-youre-dehydrated-50462">Health Check: what happens to your body when you're dehydrated?</a>
</strong>
</em>
</p>
<hr>
<p><a href="https://www.physiology.org/doi/full/10.1152/jappl.1997.83.4.1152">In one study</a>, when drinks containing 4% alcohol were ingested following exercise, there was an increase in urine output and a delay in the recovery rate of blood volume. Drinking nothing at all would be better.</p>
<p>Alcohol consumption is also known to <a href="https://www.ncbi.nlm.nih.gov/pubmed/24820258">decrease sleep duration</a> when consumed after a rugby match, either directly through alcohol’s <a href="https://academic.oup.com/ajcn/article/72/2/564S/4729614">negative influence on falling asleep</a> and staying asleep, or indirectly as a result of a late night on the town.</p>
<p>With poor sleep, impaired muscle repair, energy restoration and delayed rehydration, it’s not surprising drinking alcohol immediately after exercise significantly impairs recovery of both <a href="https://www.ncbi.nlm.nih.gov/pubmed/19230764">strength</a> and <a href="https://www.ncbi.nlm.nih.gov/pubmed/24820258">power</a> in the following days. And we can assume the impact of a hangover on a training session would also be dire.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/got-a-hangover-heres-whats-happening-in-your-body-51027">Got a hangover? Here's what's happening in your body</a>
</strong>
</em>
</p>
<hr>
<h2>What should we drink after sport and exercise?</h2>
<p>With all the negative effects on rehydration and recovery, it’s not surprising the American College of Sports Medicine <a href="https://www.ncbi.nlm.nih.gov/pubmed/20575805">recommends athletes should avoid alcohol</a> altogether.</p>
<p>Instead, <a href="https://www.ncbi.nlm.nih.gov/pubmed/19225360">athletes are recommended</a> to ingest a mixture of carbohydrate, protein and electrolyte immediately after sport and exercise to speed up the recovery process. For example, sports drinks and <a href="https://www.ncbi.nlm.nih.gov/pubmed/16676705">chocolate milk</a> have both been demonstrated to assist muscle repair and rehydration. </p>
<p>A combination of plain water and foods containing these nutrients would also do the trick, but ingestion of large amounts of plain water on its own does not aid muscle repair, and without the addition of electrolytes, much of this water <a href="https://www.physiology.org/doi/10.1152/japplphysiol.00745.2016">can not be stored in the body</a>.</p>
<p>Given the money spent on staff dedicated to nutrition, sports science and medicine within professional sport, it’s hard to believe these messages are not getting through to the athletes. The athletes’ health should come before the demands of alcohol sponsors.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/as-a-matter-of-fact-ive-got-it-now-alcohol-advertising-and-sport-9909">'As a matter of fact, I've got it now': alcohol advertising and sport</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/98313/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Stevens 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>Alcohol has several negative effects on post-exercise recovery and rehydration, and should be avoided after sport and exerciseChristopher Stevens, Lecturer in Sport and Exercise Science, Southern Cross UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/930252018-04-12T19:56:45Z2018-04-12T19:56:45ZDo I have to drink eight glasses of water per day? We asked five experts<figure><img src="https://images.theconversation.com/files/209306/original/file-20180307-146694-f8k2mx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Eight seems like a lot...</span> <span class="attribution"><span class="source">from www.shutterstock.com</span></span></figcaption></figure><p>Everyone knows humans need water and we can’t survive without it. We’ve all heard we should be aiming for eight glasses, or two litres of water per day. </p>
<p>This target seems pretty steep when you think about how much water that actually is, and don’t we also get some water from the food we eat? </p>
<p>We asked five medical and sports science experts if we really need to drink eight glasses of water per day. </p>
<h2>All five experts said no</h2>
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<img alt="" src="https://images.theconversation.com/files/211332/original/file-20180321-165564-zecy2i.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/211332/original/file-20180321-165564-zecy2i.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=191&fit=crop&dpr=1 600w, https://images.theconversation.com/files/211332/original/file-20180321-165564-zecy2i.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=191&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/211332/original/file-20180321-165564-zecy2i.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=191&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/211332/original/file-20180321-165564-zecy2i.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=240&fit=crop&dpr=1 754w, https://images.theconversation.com/files/211332/original/file-20180321-165564-zecy2i.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=240&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/211332/original/file-20180321-165564-zecy2i.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=240&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><strong>Here are their detailed responses:</strong></em></p>
<p><iframe id="tc-infographic-248" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/248/5569e2081efba668022eb859f9f36a24735d7625/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
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<p><em>If you have a “yes or no” health question you’d like posed to Five Experts, email your suggestion to: alexandra.hansen@theconversation.edu.au</em></p>
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<img alt="" src="https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/210303/original/file-20180314-113452-h7un11.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em>Disclosure statements: Toby Mündel has received research funding from the Gatorade Sport Science Institute and Neurological Foundation of New Zealand, which has included research on hydration.</em></p><img src="https://counter.theconversation.com/content/93025/count.gif" alt="The Conversation" width="1" height="1" />
We’ve all hear we should drink eight glasses of water per day, but where did that advice come from, and is it outdated?Alexandra Hansen, Deputy Editor and Chief of Staff, The Conversation AUNZLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/677952016-10-31T14:57:16Z2016-10-31T14:57:16ZYou’ve been sold a myth about sports drinks – and it could be slowing you down<figure><img src="https://images.theconversation.com/files/143907/original/image-20161031-15779-1bav9r7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>From <a href="http://www.nhs.uk/Livewell/Goodfood/Pages/water-drinks.aspx">eight glasses of water</a> a day to <a href="https://theconversation.com/beach-body-row-misses-the-key-points-about-protein-and-weight-loss-40997">protein shakes</a>, we’re bombarded with messages about we should drink and when, especially during exercise. But these drinking dogmas are relatively new. For example, in the 1970s, marathon runners were discouraged from drinking fluids for fear that it would <a href="https://play.google.com/store/books/details?id=3_zPW6FyqgAC&rdid=book-3_zPW6FyqgAC&rdot=1&source=gbs_vpt_read&pcampaignid=books_booksearch_viewport">slow them down</a>.</p>
<p>Now we’re obsessed with staying hydrated when we exercise, not just with water but with specialist drinks that claim to do a better job of preventing dehydration and even improve athletic performance. Yet the evidence for these drinks’ benefits is actually quite limited. They might even be bad for your health in some instances. So how did sports drinks come to be seen as so important?</p>
<p>Much of the focus on hydration can be traced back to the boom in road running, which began with the New York marathon in the 70s. Sports and drinks manufacturers spotted a growing market and launched specialist products for would-be athletes. The first experimental batch of Gatorade sports drink <a href="http://www.bmj.com/bmj/section-pdf/187587?path=/bmj/345/7866/Feature.full.pdf">cost £28</a> to produce but has spawned an industry with sales of around £260m a year in the UK alone. And consumption is increasing steadily, making it the fastest-growing sector in the UK <a href="http://www.britishsoftdrinks.com/write/MediaUploads/Publications/UK_soft_drinks_report_2012.pdf">soft drinks market</a> in recent years. What started life as a mixture of simple kitchen food stuffs has become an “<a href="http://www.bmj.com/bmj/section-pdf/187587?path=/bmj/345/7866/Feature.full.pdf">essential piece of sporting equipment</a>”.</p>
<h2>Marketing victory</h2>
<p>The key behind this huge rise in sports drinks lies in the coupling of science with creative marketing. An investigation by the British Medical Journal has found that drinks companies started sponsoring scientists to carry out research on hydration, which spawned a <a href="http://www.bmj.com/bmj/section-pdf/187587?path=/bmj/345/7866/Feature.full.pdf">whole new area of science</a>. These same scientists advise influential sports medicine organisations, developing guidelines that have filtered down to health advice from bodies such as the European Food Safety Authority and the <a href="https://stillmed.olympic.org/media/Document%20Library/OlympicOrg/IOC/Who-We-Are/Commissions/Medical-and-Scientific-Commission/EN-IOC-Consensus-Statement-on-Sports-Nutrition-2010.pdf">International Olympic Committee</a>. Such advice has helped spread fear about the dangers of dehydration. </p>
<p>One of industry’s greatest successes was to pass off the idea that the body’s natural thirst system is not a perfect mechanism for detecting and responding to dehydration. These include <a href="https://books.google.co.uk/books?id=zJqRB65EsaAC&pg=PA11&lpg=PA11&dq=The+human+thirst+mechanism+is+an+inaccurate+short-term+indicator+of+fluid+needs&source=bl&ots=zro_5VsYoL&sig=ILsoec5uLRDh-_ckaannKfHQTZM&hl=it&sa=X&ved=0ahUKEwji8cL2i4XQAhXKBcAKHb0YCzsQ6AEIHTAA#v=onepage&q=The%20human%20thirst%20mechanism%20is%20an%20inaccurate%20short-term%20indicator%20of%20fluid%20needs&f=false">claims that</a>: “The human thirst mechanism is an inaccurate short-term indicator of fluid needs … Unfortunately, there is no clear physiological signal that dehydration is occurring.”</p>
<p>As a result, healthcare organisations routinely give advice to ignore your natural thirst mechanism. <a href="http://www.diabetes.co.uk/dehydration-and-diabetes.html">Diabetes UK</a>, for example, advises: “Drink small amounts frequently, even if you are not thirsty -— approximately 150 ml of fluid every 15 minutes -— because dehydration dramatically affects <a href="http://www.diabetes.co.uk/training-for-events.html">performance</a>.”</p>
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<img alt="" src="https://images.theconversation.com/files/143908/original/image-20161031-15728-1tmpivg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/143908/original/image-20161031-15728-1tmpivg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/143908/original/image-20161031-15728-1tmpivg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/143908/original/image-20161031-15728-1tmpivg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/143908/original/image-20161031-15728-1tmpivg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/143908/original/image-20161031-15728-1tmpivg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/143908/original/image-20161031-15728-1tmpivg.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">Water – just as good?</span>
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<p><a href="http://www.gssiweb.org/en/Article/sse-122-sodium-ingestion-thirst-and-drinking-during-endurance-exercise">Drinks manufacturers</a> claim that the sodium in sports drinks make you feel thirstier, encouraging you to consume a higher volume of liquid compared with drinking water. They also claim these drinks enable you to retain more liquid once you’ve consumed it, based on the observation that the carbohydrates found in the drinks aid water absorption from the <a href="https://www.virginmoneylondonmarathon.com/en-gb/training/nutrition/lucozade-sports-nutrition-and-hydration-q/">small intestine</a>.</p>
<p>This implies that your thirst mechanism needs enhancing to encourage you to drink enough. But research actually shows natural thirst is a more reliable trigger. A <a href="https://www.ncbi.nlm.nih.gov/pubmed/21454440">review of research</a> on time trial cyclists concluded that relying on thirst to gauge the need for fluid replacement was the best strategy. This “meta-analysis” showed for the first time that drinking according to how thirsty you are will maximise your endurance performance. </p>
<p>On top of this, many of the claims about sports drinks are often repeated without reference to any evidence. A <a href="http://bmjopen.bmj.com/content/2/4/e001702.full">British Medical Journal review</a> screened 1,035 web pages on sports drinks and identified 431 claims they enhanced athletic performance for a total of 104 different products. More than half the sites did not provide any references – and of the references that were given, they were unable to systematically identify strengths and weaknesses. Of the remaining half, 84% referred to studies judged to be at high risk of bias, only three were judged high quality and none referred to systematic reviews, which give the strongest form of evidence. </p>
<h2>More harm than good?</h2>
<p>One of the key problems with many of the studies into the benefits of sports drinks is that they recruit highly trained volunteers who sustain exercise at high intensity for long periods. But the vast majority of sports drink users train for very few hours per week or exercise at a relatively low intensity (for example walking instead of running during a race). This means the <a href="http://bmjopen.bmj.com/content/2/4/e001702.full.pdf+html">current evidence</a> is not of sufficient quality to inform the public about benefits deriving from sport drinks.</p>
<p>Even more importantly, as sports drinks rise in popularity among children, they may be contributing to obesity levels. A 500ml bottle of a sports drink typically contains around 20g of sugar (about five teapsoons’ worth) and so represents a large amount of calories entering the body. But endorsements by elite athletes and claims of hydration benefits have meant sports drinks have shrugged off unhealthy associations in many people’s eyes. <a href="http://blog.journals.cambridge.org/2015/03/11/the-majority-of-parents-believe-some-sugary-drinks-are-good-for-their-children/">One study</a> found more than a quarter of American parents believe that sports drinks are healthy for children.</p>
<p>That’s not to say hydration research into different drinks isn’t useful. For example, it <a href="https://www.researchgate.net/publication/289521168_A_randomized_trial_to_assess_the_potential_of_different_beverages_to_affect_hydration_status_Development_of_a_beverage_hydration_index">could help identify</a> which drinks help the body retain fluids in the longer term. This would be of real benefit in situations where athletes have limited access to fluids or can’t take frequent toilet breaks.</p>
<p>But the current evidence is not good enough to inform the public about the benefits and harms of sports products. What we can be almost sure about is that sports drink are not helping turn casual runners into Olympic athletes. In fact, if they avoided these sugar-laden drinks they would be probably be slimmer and so faster.</p><img src="https://counter.theconversation.com/content/67795/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alberto Dolci does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>There’s not enough evidence that sports drinks are any better at hydrating you than water.Alberto Dolci, Course leader MSc Sport & Exercise Nutrition, Lecturer in Exercise & Environmental Physiology and Exercise Immunology, University of WestminsterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/628542016-07-26T12:24:33Z2016-07-26T12:24:33ZDoes drinking hot tea in summer really cool you down?<figure><img src="https://images.theconversation.com/files/131406/original/image-20160721-32610-1rlsu1f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Refreshing – or a sentence to sweat?</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=tea%20summer&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=247474183">Shutterstock</a></span></figcaption></figure><p>I remember as a child, on the rare warm days that we used to get in Britain, my grandmother telling me to “have a cup of black tea … it will help cool you down”. As a seven-year-old, this seemed like a crazy idea, especially when all I wanted was a cold lemonade and another ice cream. But it appears that this old wives’ tale may actually be more Stephen Hawking than Stephen King.</p>
<p>The idea of drinking hot drinks in warm weather goes back hundreds of years. <a href="http://www.bbc.co.uk/news/magazine-27991440">Tea, or “chai” is one of the most popular drinks in India</a>, and many of the <a href="https://en.wikipedia.org/wiki/List_of_countries_by_tea_consumption_per_capita">leading consumers of tea per capita are in tropical or desert regions</a>. Recently, evidence has begun to emerge that drinking hot drinks may really help to <a href="http://www.ncbi.nlm.nih.gov/pubmed/22574769">cool you down</a>, too.</p>
<p>In 2012, <a href="http://sydney.edu.au/health-sciences/about/people/profiles/ollie.jay.php">Ollie Jay</a> published the <a href="http://www.ncbi.nlm.nih.gov/pubmed/22574769">first of a series</a> of papers to see if drinking a warm drink can actually lower the amount of heat stored by the body compared to a cold drink. In this first study, volunteers were asked to cycle at a relatively low intensity for 75 minutes in around 24°C heat, 23% relative humidity, while consuming water at either 1.5˚C, 10˚C, 37˚C or 50˚C. </p>
<p>The change in core temperature was slightly greater when 50˚C water was ingested compared to 1.5˚C and 10˚C water. However, when the authors considered the effect of drink temperature on body heat storage, which is a better indicator of total body temperature, the results were very different. Following the ingestion of the warm drink, overall body heat storage was actually lower following exercise than with cooler drinks. </p>
<h2>The sweat factor</h2>
<p>An explanation for these findings appears to be related to how sweating may be influenced by drink temperature. Sweating, and more importantly the evaporation of this sweat, is one of the <a href="https://theconversation.com/from-perspiration-to-world-domination-the-extraordinary-science-of-sweat-62753">key avenues for modulating body temperature and maintaining heat balance</a>. </p>
<p>Due to the increased heat load from drinking a warm drink, there is a compensatory increase in overall sweat output, which outweighs the internal heat gain from the warm drink. Consistently, a 50˚C drink results in a higher whole body sweat loss (around 570ml vs about 465ml for 1.5˚C). In practical terms, this means that more sweat is produced which is evaporated from the skin surface, increasing heat loss from evaporation and reducing body heat storage. </p>
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<img alt="" src="https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/131969/original/image-20160726-7041-1mx6fjd.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">Cold water: should he drink it?</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=runner%20hot&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=154131425">Shutterstock</a></span>
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<p>Importantly, however, this study was conducted under conditions that allowed complete evaporation of sweat – in other words dripping sweat was limited by maintaining a good airflow and keeping humidity low. The results would likely be different in conditions where sweat evaporation is limited, such as in hot and humid conditions. In fact, drinking cold drinks may be more favourable in these circumstances, minimising inefficient sweat losses – dripping sweat – and consequently aiding an individual’s hydration status. </p>
<h2>Mouth or stomach?</h2>
<p><a href="http://www.ncbi.nlm.nih.gov/pubmed/24577060">In a second study</a>, Jay aimed to establish the effect of drink temperature on local sweat rate, and to determine the location of thermoreceptors that may influence sweating. They demonstrated that with differing drink temperatures, colder drinks (1.5˚C) resulted in reductions in local sweat rate compared to when warm drinks were ingested (50˚C), despite identical changes in core and skin temperature.</p>
<p>Interestingly, however, differences in the sweat response were found when fluid was either swilled around the mouth or delivered directly to the stomach via a nasogastric tube. The data showed that only when cold drinks were delivered directly to the stomach did they result in reduced local sweat rate. This data indicates that the sensors responsible for influencing the sweat response, and therefore regulation of body temperature, reside somewhere in the abdominal cavity. </p>
<p>In a <a href="http://www.ncbi.nlm.nih.gov/pubmed/?term=Ice+Slurry+Ingestion+Leads+to+a+Lower+Net+Heat+Loss+during+Exercise">third study conducted in their lab</a>, the team asked people to consume either 37˚C fluid or ice during exercise. In agreement with their previous work, they showed that there was a reduction in heat loss following ice ingestion compared to fluid at 37˚C, as a result of reduced sweat evaporation from the skin surface. </p>
<p>This has implications for endurance performance in the heat. In essence, where changes in body temperature are known to <a href="http://www.ncbi.nlm.nih.gov/pubmed/10066720">influence performance, ice ingestion</a> could result in an increase in body heat, negatively influencing endurance capability. The ingestion of an iced drink prior to exercise and in hot and humid environments, however, should be beneficial. </p>
<p>So, depending on your environmental conditions, maybe reaching for that cup of tea isn’t such a crazy idea after all. Plus the moral of the story: listen to your grandmother’s advice – it’s based on years of experience.</p><img src="https://counter.theconversation.com/content/62854/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>Here’s the science.Steve Faulkner, Research associate, Loughborough UniversityKaty Griggs, Research Assistant and PhD student, Loughborough UniversityLicensed as Creative Commons – attribution, no derivatives.