No Need to Drink Plain Water Daily

Many recommendations are to drink eight 8-ounce glasses of water daily in addition to the fluids included in our food and other drinks. New research indicates that the type of beverage has no impact on hydration status.

In a new study with 27 healthy male volunteers, two diets were evaluated for their effects on several indicators of hydration status over three days in a random, crossover design while physical activity and environment were controlled. One diet provided plain water to drink as part of the beverages served while the second omitted plain water.

Total fluid consumed was about two and a half quarts daily, with the need determined by body weight. About one-fifth of the total fluid was in food and the rest from drinks such as orange juice, coffee and cola drinks. When water was part of the trial, the equivalent of three 8-ounce glasses was included.

Eight different analyses on urine were done and body weight was measured as indicators of hydration status. There were no differences in any values between the two diets. There was also no difference between pre-test values and those after three days of these trials.

Dr. Ann Grandjean, Director of the Center for Human Nutrition at the University of Nebraska Medical Center, and lead author of the study pointed out that the foods in this study provided a relatively low content of water and that the total fluid amount was similar to the eight 8-ounce glasses per day recommendation. Dr. Grandjean said, "People do not need to worry if they do not have access to plain water each day. It is not our intent to imply you don't need water but most beverages will support hydration."

The findings appeared in the April, 2003 issue of the Journal of the American College of Nutrition.