I'm glad to see some medical experts have taken the time to write up a review of the lack of evidence for the claims that many glasses of water per day help you stay healthy. The idea that high water consumption delivers a health benefit is just a legend.

Washington, DC (Friday, March 28, 2008) — A recent look at what is known about the health effects of drinking water reveals that most supposed benefits are not backed by solid evidence. The findings indicate that most people do not need to worry about drinking their recommended 8 glasses of 8 ounces (“8x8”) of water per day. The editorial is published in the June 2008 issue of the Journal of the American Society of Nephrology (JASN).

While it is clear that humans cannot survive for longer than several days without water, very little research has assessed how average individuals’ health is affected by drinking extra fluids. Experts have claimed that ingesting water is helpful for everything from clearing toxins and keeping organs healthy to warding off weight gain and improving skin tone.

To investigate the true benefits of drinking water, Dan Negoianu, MD, and Stanley Goldfarb, MD, of the Renal, Electrolyte, and Hypertension Division at the University of Pennsylvania, in Philadelphia, PA, reviewed the published clinical studies on the topic. They found solid evidence that individuals in hot, dry climates, as well as athletes, have an increased need for water. In addition, people with certain diseases benefit from increased fluid intake. But no such data exist for average, healthy individuals. In addition, no single study indicates that people need to drink the recommended “8x8” amount of water each day. Indeed, it is unclear where this recommendation came from.

This scan of the literature included a look at studies related to the notion that increased water intake improves kidney function and helps to clear toxins. A variety of studies reveal that drinking water does have an impact on clearance of various substances by the kidney, including sodium and urea. However, these studies do not indicate any sort of clinical benefit that might result.

I've tried telling co-workers that their water habits were just the stuff of urban legends. But they were thoroughly wedded to their legends and kept on drinking. So just where did this urban legend originate? Maybe in some diet (wash that fat away) for losing weight? Or as part of some 1960s or 1970s fad about body detoxing?