By Laurie Budgar

If trying to down eight glasses of water daily feels more like waterboarding than refreshment to you, researchers have good news for you: It's OK to drink less.

Drs. Dan Negoianu and Stanley Goldfarb of the Renal, Electrolyte and Hypertension Division at the University of Pennsylvania reviewed the published literature on the benefits of drinking large volumes of water. They studied its effects on satiety, headaches, skin tone and on the kidney's ability to clear toxins, and concluded that for healthy individuals "there is no clear evidence of benefit from drinking increased amounts of water."

The origins of the classic "8x8" recommendation to drink eight 8-ounce glasses of water daily remain a mystery. "There is no single study—and therefore no single outcome—that has led to these recommendations," Negoianu and Goldfarb write in their editorial, "Just Add Water," available online ahead of its June publication in the Journal of the American Society of Nephrology.

In their literature review, Negoianu and Goldfarb found that increased water intake does help the kidney clear certain toxins but actually prevents it from clearing others. The clinical significance of the findings was "unclear."

Studies on satiety likewise proffered conflicting results, depending on gender, whether the water was consumed before the meal or during it, and whether the water was drunk or consumed in high-water-content foods. "None of these studies makes clear whether drinking a large volume of fluid over the course of a day will decrease the number of ingested calories," the researchers wrote.

While the researchers found no evidence to support the 8x8 recommendation, they also found none to debunk it. "We concede there is also no clear evidence of lack of benefit. In fact, there is simply a lack of evidence in general." So, chug if you like; otherwise, don't sweat the hydration situation.

Natural Foods Merchandiser volume XXVIII/number 5/p. 1