ABSTRACT

Vitamin E is one of the most important lipid soluble antioxidants. This chapter reviews its chemistry, absorption, transport, metabolism, and biological function with emphasis on the role of tocopherols and tocotrienols as biological antioxidants. Tocopherols are absorbed from the small intestine and secreted into lymph in chylomicrons produced in the intestinal wall. A major antioxidant function of vitamin E in humans, studied mostly with α-tocopherol, is the inhibition of lipid peroxidation. Tocopherols and tocotrienols and their metabolites appear to have significant and sometimes quite different metabolic effects, which may be independent or only partially related to their function as antioxidants. The active site of both tocopherols and tocotrienols is the 6-hydroxyl group on their chroman ring. The tocopherol binding protein probably plays a major role because its affinity for individual tocopherols is reflected in blood and tissue concentrations. Large doses may exacerbate blood coagulation in persons with vitamin K deficiency or those taking anticoagulant drugs.