Advances in our understanding of vitamin E.

Vitamin E is an essential nutrient for animals and man since it is not synthesized in the body. The level of vitamin E in the lipoproteins of plasma and in the phospholipids of vital mitochondria, microsomes, and plasma membranes in humans depends (as in experimental animals) on the amount of biologically active vitamin E being consumed, the levels of dietary prooxidants and antioxidants, and the adequacy of dietary selenium. Studies with chicks have demonstrated an important mode of action of both vitamin E and selenium in metabolism, and provide a solution to the long-term enigma of the true role of vitamin E in the diet of all animals, including man. The biochemical actions of vitamin E and selenium are concerned with prevention of peroxidative damage to cells and subcellular elements, thereby aiding the body in maintaining its normal defense mechanisms against disease and environmental insult.