April 29, 2002

The more protein you eat the more water you should drink, according to a study by UConn's Department of Nutritional Sciences.

William Martin, a second-year graduate student studying with Nancy Rodriguez, an associate professor of nutritional sciences, presented the research last week at the 11th annual Experimental Biology meeting in New Orleans.

As part of the study, five UConn student athletes who are runners consumed low, moderate and high amounts of protein for four weeks at a time. Their meals were carefully planned and scrutinized by Rodriguez, the lead investigator, who worked with University Catering Services to provide the special meals. The hydration status of the athletes was evaluated bi-weekly.

"We found that certain hydration indices tended to be influenced as the amount of protein in their diets increased," says Rodriguez, who also holds joint appointments in kinesiology and allied health.

When the athletes consumed the highest amounts of protein, their blood urea nitrogen (one of several clinical laboratory tests used in evaluating kidney function) reached abnormal ranges. This value returned to normal when protein intake was reduced. Other tests indicated that the high protein diet caused the kidneys to produce more concentrated urine.

The recommended daily protein intake for the average person is set by the U.S. Department of Agriculture and it is dependent on body weight. The recommended daily allowance (RDA) for an individual weighing 150 pounds is 70 grams of protein, which can be easily obtained in a diet including two glasses of milk, three to four ounces of chicken, and a bowl of cereal, rice or pasta. In this study, the low protein diet nearly equaled the RDA. The moderate diet included more than two times the recommended protein intake (which is typical of the general population), and the high protein diet incorporated a little more than four times the suggested level.

"Based on our findings, we believe that it is important for athletes and non-athletes alike to increase fluid intake when consuming a high protein diet, whether they feel thirsty or not, because our study subjects said they did not feel a difference in thirst from one diet to the next," says Rodriguez. She received funding for this study from National Cattlemen's Beef Association and the University of Connecticut's Research Foundation.

For most people, just a 2 percent decrease in body fluid can negatively affect performance and cardiovascular function. Keeping in mind that the average adult should be drinking eight to 10 glasses of water each day, Rodriguez recommends that those who are exercising and/or eating high amounts of protein increase their fluid intake and avoid excessive amounts of caffeine or any other agent that acts as a diuretic.

For this study, Rodriguez and her team worked closely with Carl Maresh and Larry Armstrong, professors of kinesiology who are experts in the fields of thermoregulation and human performance.