The water myth?

New research has just been published in the Journal of the American Society of Nephrology that questions the long-held popular belief that drinking eight glasses of water a day benefits our health.

According to Dr. Stanley Goldfarb and Dr. Dan Negoianu of the University of Pennsylvania in Philadelphia, there are four prevalent myths about water intake:

  1. Leads to more toxin excretion
  2. Improves skin tone
  3. Makes one less hungry
  4. Reduces headache frequency

Dr. Goldfarb and Dr. Negoianu reviewed all of the published studies which examined the health benefits of water consumption. They concluded that people in hot, dry climates, athletes or people with certain diseases might do better with increased fluid intake, but for average healthy people, more water did not mean better health.

“There is no clear evidence of benefit from drinking increased amounts of water,” Dr. Goldfarb wrote, but he also added, “There is also no clear evidence of lack of benefit.” In other words, the scientific research doesn’t tell us one way or the other whether there’s a benefit or not.

Fortunately, nature has endowed us with a mechanism that can in fact help us determine how much water we need to be drinking per day. It’s called thirst. If we simply pay attention to our thirst and respond appropriately, it’s likely that we will take in as much water as we need. Four to six glasses per day is probably sufficient for most people; but then again, the evidence indicates there is no harm in drinking more, so if you enjoy drinking a lot of water then knock yourself out!

There is no evidence that increased water consumption helps to excrete toxins. The kidneys perform that function in the body, and as long as they are healthy they do it very well. Dr. Goldfarb: “The kidneys clear toxins. This is what the kidneys do. They do it very effectively. And they do it independently of how much water you take in. when you take in a lot of water, all you do is put out more urine but not more toxins in the urine.”

There is no evidence supporting the other three myths either; namely, that it improves skin tone, reduces hunger and alleviates headaches. But again, if your experience is different and you find that water does help with these conditions – then there is absolutely no reason not to continue what you’re doing now (other than perhaps more frequent trips to the bathroom!) Just don’t go crazy with the water intake, because extremely high levels of water consumption can affect the fluid balance in the body, causing “water intoxication” and even death.

Finally, I’d be remiss if I didn’t emphasize that the quality of the water we drink is much more important than the quantity. My recommendation is that you invest in a high-quality water filter and install it in your home. Avoid bottled water, which is often simply tap water packaged in a plastic bottle that can potentially leach toxins into the water – especially when left in the sun. (You know that “plasticky” smell when you drink water from a plastic bottle that has been around for a while? Not good. Not good at all.) Nalgene bottles should also be avoided as they can leach another unsafe chemical called BPA into your water. Instead, buy a stainless steel water bottle and fill it up with your filtered water at home before you go out.

Also, both tap water and filtered bottled water contain fluoride, a highly toxic bone poison that should be avoided at all costs. Many commercial water filters unfortunately do not remove fluoride, which is present in our water supply because of the gross misconception that it supports dental health. But more on that myth in another article.

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  1. Tracee’s avatar

    My 92 year old grandmother commented at one time about the recommended water consumption. She said if she drinks that much then she has to go to the bathroom every 15 minutes and that can’t possibly be healthy.

  2. Lexicop’s avatar

    Somewhere recently I read that the myth about needing to drink eight glasses of water per day originated from research that indicated that the body’s daily need for water for its various processes was some 2000 ml–two liters,  or about eight glasses. But this figure hopped into the popular domain as the amount we should drink. In fact, the food we eat contains moisture, and much of the water the body needs comes from that source. But there’s another factor, widely unknown–much water is produced by metabolism of carbohydrates. Those foods contain (as the name suggests) carbon and hydrogen. When hydrogen is oxidized (metabolized), one of the results is that hydrogen-oxygen compound we call H2O–water! The body may use eight “glasses” of water per day, but you do not need to drink that much! As the above article suggests, let your thirst be your guide.

  3. Chris Kresser’s avatar

    Thanks for your comment, Lexicop!

  4. Pingback from The Healthy Skeptic · Warning: drinking bottled water could make … | fat animals on April 23, 2010 at 5:13 pm

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