ROME -- Trained runners who severely limit the amount of fat in their diets may be suppressing their immune system and increasing their susceptibility to infections and inflammation, a University at Buffalo study has shown.
In findings presented here today (May 22, 1999) at the fourth International Society for Exercise and Immunology Symposium, lead author Jaya T. Venkatraman, Ph.D., reported that running 40 miles per week on a diet composed of approximately 17 percent fat compromised the runners' immune response.
The medium and high-fat diets, composed of approximately 32 and 41 percent fat respectively, left the immune system intact, and enhanced certain components, the findings showed.
"The data suggest that higher-fat diets may lower the proinflammatory cytokines, free radicals and hormones, and may enhance the levels of anti-inflammatory cytokines," Venkatraman said.
Venkatraman is an associate professor of nutrition in the Department of Physical Therapy, Exercise and Nutrition Sciences in the UB School of Health Related Professions.
Earlier studies published by a UB research group headed by David Pendergast, Ed.D., professor of physiology and biophysics, reported that competitive runners who increased the proportion of fat in their diets improved their endurance with no negative effect on weight, body composition, blood pressure, pulse rate or total cholesterol. (See editor's note)
However, since a high level of fat was thought to be immunosuppressive, the researchers sought to determine if increasing dietary fat would compromise various elements of the immune system, while improving performance.
"In general, moderate levels of exercise are known to enhance the immune system," said Venkatraman. "But high-intensity exercise and endurance exercise produce excess levels of free radicals, which may place stress on the immune system.