Researchers Say Evidence Is Lacking for Benefits of Drinking 8 Glasses of Water a Day
April 2, 2008 -- The health benefits of drinking water, at least for already healthy people, may have been oversold, according to a new report. The findings will likely disappoint water-bottle-toting Americans and relieve those who can never seem to down those eight glasses of water a day, widely recommended for our health.
But there is nothing magical about those eight glasses, at least when it comes to proven health benefits, according to a new report. "There is no clear evidence of benefit from drinking increased amounts of water," writes Stanley Goldfarb, MD, professor of medicine at the University of Pennsylvania, Philadelphia, and the senior author of an editorial on the topic in the Journal of the AmericanSociety of Nephrology.
On the other hand, he adds, "There is also no clear evidence of lack of benefit." There's a general lack of evidence either way.
Those doctors and others who have been recommending drinking eight glasses of water aren't basing it on anything scientific, according to Goldfarb. He concludes that most healthy people don't have to worry about drinking eight glasses every day.
He emphasizes he is talking about healthy people with kidneys that function well. And he points out that people who live in hot, dry climates do need to drink more water to avoid dehydration, as do those who engage in vigorous exercise.
Health Benefits of Drinking Water: Search for Evidence
Goldfarb was curious about where the longstanding recommendation about eight daily glasses of water originated. "In my mind it wasn't that drinking this extra water would hurt you, but that you might not have to."
So he combed through medical literature dating back to the early 1970s, trying to find the science to back up the advice.
Turns out, there is no single study and no single outcome that led to the recommendation becoming popular, he says. Somehow, it took on a life of its own.
Goldfarb and his University of Pennsylvania colleague, Dan Negoianu, MD, next examined some popular claims about the health benefits of drinking water, trying in each case to find scientific evidence.
"We looked at the evidence of some of the so-called urban myths that have grown up about drinking water," Goldfarb says.