Background Information
Zinc is an essential trace mineral found in small amounts in all organs, tissues, fluids and secretions of the body. It is a component of many enzymes involved in the metabolism of protien, carbohydrate, and fat. Zinc also influences the activity of several hormones, such as growth hormone, thyroid hormone, and sex hormones. Zinc deficiency causes atrophy of lymphoid tissue and produces abnormalities in both cellular and humoral immunity. In view of the large number of zinc-dependent enzymes, it is understandable how zinc deficiency negatively affects the immune response. Because body stores zinc are limited, a constant steady-state intake of zinc is required. Zinc deficiency can result from disease, malabsorption or inadequate intake. Diets containing large amounts of grains, cereals, unleavened bread, fruits and vegetables, and that are limited in animal products may be inadequate in zinc.

 Effects on Health
Female athletes are more likely to have an inadequate zinc intake because of lower energy intakes and/or lower intakes of meat. The RDA for zinc is 11 mg/d for males and 8 mg/d for females. The Tolerable Upper Intake Level for zinc is 40 mg/d and the Lowest Observed Adverse Effect Level (LOAEL) is 60 mg/d. Chronic daily use of 60 mg of zinc supplements have been found to depress HDL cholesterol levels and 50 mg/d decreases serum ferritin and the copper dependent form of the superoxide dismutase enzyme activity.

 Effects on Performance
Studies have shown that an acute bout of exercise induces an alteration in zinc distribution in the blood. However, more research is needed to examine changes in blood levels of zinc induced by various types of exercise. Even though exercise may result in loss of zinc in sweat, it is not known whether the body can adapt to these loses.