Protective role of vitamin E in biological systems. Vitamin E is well accepted as nature's most effective lipid-soluble, chain-breaking antioxidant, protecting cell membranes from peroxidative damage. Free-radical-mediated pathology has been implicated in the development over time of degenerative diseases and conditions. This paper reviews the current research on the protective role and requirements for vitamin E and the other antioxidants in preventing or minimizing free-radical damage associated with specific diseases and lifestyle patterns and processes, including cancer, aging, circulatory conditions, arthritis, cataract, pollution, and strenuous exercise. While awaiting results of further human studies, research evidence suggests that an adequate intake of vitamin E and the other antioxidants can provide protection from the increasingly high free-radical concentrations caused by air pollutants and current lifestyle patterns. 