Fluid approach

Staying well-hydrated requires drinking ample amounts of fluid, but University of Nebraska researchers have found that even caffeinated beverages such as coffee and cola will do.

In the study, 27 healthy men, age 19 to 38, were confined to a heat- and humidity-controlled environment and fed comparable amount of calories, nutrients and fluids, depending on their body weight. But what they drank differed. On one diet, a third of the beverage allowance was plain water. On the other, the water was replaced with diet cola. The remaining two-thirds of the beverage allowance on both diets was equally divided between juice, coffee and caloric, caffeinated cola and noncaloric, noncaffeinated cola. On average, the men drank eight to nine 8-ounce beverages.

There were no differences on either diet in various measures of the men’s hydration, including analysis of 24-hour urine samples. Nor was there any difference between men who consumed more or less caffeine.

Although water has its benefits -- it’s a major source of fluoride, for example -- this study shows that it’s not essential.

“I can now tell people with confidence not to panic if they don’t have water. You can still stay hydrated,” says lead author Ann Grandjean, a consultant to the U.S. Olympic Committee and professor at the University of Nebraska Medical Center.

The study was published in the April issue of the Journal of the American College of Medicine. Although the study was funded by a grant from the Coca-Cola Co., the company had no control of the study design or publication of results.