Fact or Myth: Do We Really Need Eight Glasses of Water a Day?

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Fact or Myth: Do We Really Need Eight Glasses of Water a Day?

Water is life. You can survive without food for about a month, but can perish from dehydration in a mere three days. But has our concern for keeping our bodies hydrated led to overconsumption of H2O—and perhaps even pose some health hazards? In extreme circumstances, yes. But the main concern is the purported fallacies associated with how water can benefit our bodies.

The Origins of the Hydration Myth
In 1945, the U.S. Food and Nutrition Board recommended that people drink 2.5 liters of water a day. Evidently, this finding was taken out of context because the following sentence was not considered: “Most of this quantity is contained in prepared foods.” In 1945, the term “prepared” entailed foods that contained water, such as fruits and vegetables. As a result, there was an urge to consume 8 glasses of water (2.5 liters) in addition to food and drinks we were already consuming throughout the day, which added up to this amount.

Today, iterations and (mis)interpretations of these guidelines are still being circulated by organizations such as Hydration For Health, where water is made to be significant in promoting the well-being of the general populace. According to the British Medical Journal, Hydration for Health is an “organization” with vested interests in pushing the public to consume more water; it is sponsored by and was created by French food giant Danone, a major producer of bottled water (e.g. Evian).

Debunking General Claims and Myths
According to Dr. Stanley Goldfarb, Professor of Medicine at the Perelman School of Medicine at the University of Pennsylvania, “The Hydration Myth” is still one of the most pervasive, “good-for-you” pieces of health advice out there. As well, he adds that its enduring popularity is due to it being a cheap resource and catch-all remedy to cure you of general ailments. Unsubstantiated claims of what water can do for the body include “flushing” out toxins, benefiting kidney functions, making skin look healthier and/or wrinkle free and making you feel more energized. Goldfarb also elaborates on why it has so much appeal: “It is the notion that drinking water will fix problems such as headaches, skin blemishes and fatigue, etc. Moreover, it seems intuitive for us to drink water and that a little overconsumption will not pose a threat to our health. I think that is where this train of thought comes from.”

However, the Journal of the American Society of Nephrology states the following: “There is no clear evidence or benefit from drinking increased amounts of water … in fact, there is simply a lack of evidence in general.” Goldfarb agrees with this and adds, “People who have advocated water as having these sorts of amazing healing and holistic properties have no real basis. In fact, there is no scientific basis or data to support such claims.”

As well, organized bodies who write food and nutrition guidelines may not have accurate information—or taken out of context. Goldfarb explains, “Anybody can write a guideline. Any group of individuals can get together and say, ‘this is what we think.’ But the real question should be if those guidelines are correct or not and to heed such advice with caution.”

Despite this body of evidence, these voices have generally been silenced. Goldfarb explains, “Water has become a huge industry—there’s marketing and advertising going on from big corporations. As well, there is a thriving secondary industry. These include the water bottles that people send out as advertising in schools and institutions, etc. So when you put it all together, there’s a lot of profit to be made with water.”

The Consequences of Dehydration
We are told so frequently that dehydration can have adverse effects on our body, but Goldfarb disagrees with this. He surmises from his studies: “We’ve observed water content go down 1 percent in the body—and there is no side effect or dangerous thing that can happen to you. Conversely, if you increase water intake by a percent or more … there is no benefit to be gained either. This defies the experts who do encourage you to drink lots of water.”

Water: Practical Guidelines
Dr. Goldfarb advises us to trust our bodies: “We’re really nicely designed so we won’t get dehydrated significantly. Evolution has ensured that humans with multiples systems will react accordingly at the first sign of thirst. For instance, our kidneys will actually preserve water and prevent excretion of urine before we even have our first sensation of thirst.” So we are always trying to retain water—we’ve been primed for it—perhaps, thanks to our early human ancestors and their ability to survive in arid, harsh conditions with limited access to water.

The Bottom Line
Thirst is your best guide. Dr. Goldfarb explains: “You become thirsty because you lose water throughout the day from your body in two ways: urine via waste the kidneys produce and through your skin via evaporation—in total, about ¾ of a liter. So you will need water—that’s where 2.5 liters come from (the total from food and liquids). And obviously, if you’re engaged in strenuous activities and exercise, you’ll require more water.”

In all this talk of H2O, is there one type that is superior over another? Elitists shun tap water and praise either bottled or filtered. But as Goldfarb explains, this is just another myth. “If we’re talking about where we live—plain water from the tap is good—as long as it is not contaminated by something. But municipal water supplies are checked frequently during the day and considered the safest. Even in instances where the news have reported contamination, it wasn’t actually the water itself that was tainted but rather the conveyance systems of pipes the liquid goes through to reach your home.”

Bonus: The Coffee Dehydration Myth
We’re often told that coffee dehydrates the body. But Goldfarb says that this is an incorrect assumption. “We have studies that measure the amount of urine produced after a person drinks coffee—we discovered that it is the same amount. Therefore, the same amount of fluid goes in as it does out, so to speak.”

Image courtesy of Pixabay

Tiffany Leigh is a Toronto-based food, travel, and science writer.