High-Protein Diets Cause Dehydration

From the WebMD Archives

April 22, 2002 -- Even super-fit endurance athletes can become dangerously dehydrated while adhering to popular high-protein diets, new research shows.

Researchers presented their findings today at the Experimental Biology meeting in New Orleans.

William Forrest Martin, graduate student in the department of nutritional sciences at the University of Connecticut, and colleagues watched what happened to trained athletes when they consumed diets containing low, medium, and high levels of protein.

Based on a 150-pound person, the diets contained 68 grams, 123 grams, and 246 grams of protein, respectively, and were adjusted for each athlete. The athletes remained at each protein level for four weeks.

The researchers tested each athlete periodically for blood urea nitrogen, a measure of proper kidney function that also indicates how well someone is hydrated.

Although all the athletes drank about the same amount of fluids, their hydration level went down significantly as their protein intake went up.

What this all means, the researchers say, is that athletes and regular folk alike should drink plenty of water when they're eating a lot of protein, whether or not they feel thirsty. In fact, most of us could all do with a few more glasses of water each day, they say. Even slight dehydration increases the likelihood of heat illness and other disorders and impairs cardiovascular function.