By Sarah Gearhart
See the issue: November 2006

Have you heard the new caffeine buzz? According to a study published in the International Journal of Sport Nutrition and Exercise Metabolism, caffeine doesn’t dehydrate you.

Previous research had suggested that the natural chemical found in cola nuts, coffee beans and tea leaves acts as a mild diuretic, which means it increases urine flow, causing dehydration. New research, however, indicates that an increase in urine production does not equal dehydration.

“Dehydration of total body water is not the same as a temporary increase in urine output,” says the study’s author, Lawrence Armstrong, Ph.D., professor of exercise and environmental physiology at the University of Connecticut.

During the 11-day analysis, those who consumed caffeine in moderation (less than 500mg per day) showed no signs of electrolyte imbalance or dehydration while engaging in moderate exercise.

This doesn’t mean you should gulp down all the coffee you want. Besides increasing your number of trips to the bathroom, too much caffeine can cause restlessness and insomnia, not to mention a slight increase in your blood pressure, according to the American Dietetic Association.

Also noteworthy: guaranÁ, a caffeine-containing extract from a South American plant, is a common ingredient in energy drinks. It’s also on the NCAA list of banned substances when its concentration in urine exceeds 15 micrograms/ml.

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