Vitamin E and immune functions.

Vitamin E, the major lipid-soluble antioxidant present in all cellular membranes, is an important nutrient for optimal immune function. When animals are fed nutritionally complete diets lacking vitamin E, immune responses are adversely affected. Supplementation of these diets with higher than nutritionally adequate levels of vitamin E enhances immune responses. High levels of PUFA are immunosuppressive, and vitamin E can partially overcome this immunosuppression. High levels of vitamin C can protect tissue levels of vitamin E and may indirectly contribute to the immunoenhancement by vitamin E. Severe selenium deficiency is immunosuppressive. Vitamin E can protect some aspects of immune responses from the adverse effects of selenium deficiency. These data clearly indicate that nutrients that affect the overall antioxidant status have important effects on immune functions. In addition, antioxidant nutrient interactions can synergize to overcome the adverse effects of polyunsaturated fatty acids on immune functions (Fig 2).