Natural Healing: Too Much Exercise Bad for Immune System

Runners’ immunity depressed by low-fat diets

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Moderate exercise can enhance immunity, but don’t overdo it: A new study has found that high-intensity and endurance exercise may actually stress the immune system. Part of the reason for the depressed immune systems in the study’s participants—trained runners—was their severely fat-reduced diets, according to the study by University of Buffalo researchers, presented in May 1999 at the International Society for Exercise and Immunology Symposium held in Rome.

Researchers found that running forty miles weekly on a 17 percent fat diet depresses the runners’ immunity. For endurance athletes, a higher-fat diet (45 percent total calories from fat) doesn’t stress the immune system and may lower free radicals, hormones, and compounds that promote inflammation. In runners consuming a higher-fat diet, natural killer cells used to fight infection more than doubled in one month.

Venkatraman, J. T., and D. Pendergast. Medicine and Science in Sports and Exercise, forthcoming Spring 2000.