You’ve seen it on the old Food Pyramid. You might have heard it from your doctor. And you’ve certainly heard it countless times in conjunction with just about any diet ever created: if you want to be healthy you need to drink 8 glasses of water daily.
But what would you say if you knew the 8 glasses-a-day recommendation was a myth that actually evolved from a long-forgotten obituary of a doctor who advocated drinking lots of water?
And, what would you say if you I told you that the scientific evidence for needing 8 glasses of water a day just isn’t there?
8 Glasses a Day Not Backed by Science
Water is, of course, essential for your survival. Every day, your body loses water through urine and sweat. This fluid needs to be replenished, for while you can survive for months without food, without water you wouldn't last more than a few days. If you get the fluid/water replacement issue right, then you have made one of the most important and powerful steps you can in taking control of your health.
But just how much water do you need to drink to replenish what you've lost? Writing in the American Journal of Physiology, Heinz Valtin of Dartmouth Medical School notes:i
“Despite the seemingly ubiquitous admonition to “drink at least eight 8-oz glasses of water a day” (with an accompanying reminder that beverages containing caffeine and alcohol do not count), rigorous proof for this counsel appears to be lacking.
This review sought to find the origin of this advice (called “8 X 8” for short) and to examine the scientific evidence, if any, that might support it. The search included not only electronic modes but also a cursory examination of the older literature that is not covered in electronic databases and, most importantly and fruitfully, extensive consultation with several nutritionists who specialize in the field of thirst and drinking fluids. No scientific studies were found in support of 8 X 8.
Rather, surveys of food and fluid intake on thousands of adults of both genders, analyses of which have been published in peer-reviewed journals, strongly suggest that such large amounts are not needed because the surveyed persons were presumably healthy and certainly not overtly ill.”
As for the origins of this now widely accepted dietary dogma, the closest reference Valtin uncovered was a brief mention in the obituary of a well-known nutritionist by the name of Fredrick J. Stare, which said he was an “early champion of drinking at least six glasses of water a day.”
Interestingly, Dr. Stare, who was a professor of nutrition and the head of the Department of Nutrition at Harvard School of Public Health, was a notable friend to industry, notorious for his outspoken support for food additives and water fluoridation. He also had ties to the tobacco industry and was a strong supporter of the sugar industry; he even reportedly earned the moniker “The Sugar King” at Harvard.ii
At one point, sometime during the late ‘50s, early ‘60s, Dr. Stare went so far as to publish an article stating that claims made by the Boston Nutrition Society that white bread was devoid of nutrients and a contributor to disease were “a cruel and reckless fraud.”iii In other words, Dr. Stare believed white bread to be perfectly healthy, and openly criticized those who questioned food additives or excessive sugars in the diet, which isn’t surprising considering his financial ties to Nabisco, Kellogg and the Cereal Institute.
The point is … Dr. Stare is also being credited with perhaps being among the first to promote drinking 6-8 glasses of water a day as healthy, which, given the source, deserves to be questioned.
Also mentioned by Valtin was a 1945 recommendation by the Food and Nutrition Board of the National Research Council, which recommended 2.5 liters of water as a “suitable allowance” of water for most adults. They, however, pointed out that “most of this quantity is contained in prepared foods,” but it could be that people interpreted this to mean that 2.5 liters of water is the right amount to drink each day. The advice was repeated again in 1948, without a scientific backing.
Of course, consuming large quantities of water has been used as a medical therapy since the 19th century, when “hydropathists” advised patients to drink copious amounts of water to cure their ills. People have long been exploring the body’s need for water, as well as what the optimal “dose” appears to be … but to date there’s not much compelling evidence that the “8 8-ounce glasses a day” is the be all and end all in water consumption.
Are Bottled Water Companies Behind the Push to Drink More Water? (read more)
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