Vitamin E

Vitamin E is a fat-soluble vitamin produced by plants. Its absorption requires adequate pancreatic and biliary function, micelle formation, enterocyte absorption, and chylomicron transport. The bioactive isomer is α-tocopherol, which requires specific hepatic protein regulation. Vitamin E is essential to humans for its antioxidant activity and cell-membrane protection. It also inhibits protein kinase C and consequently inhibits platelets aggregation and immune cells proliferation. Alpha-tocopherol directly modulates signal transduction pathways by altering gene expression. Vitamin E deficiency is rare, and occurs mainly in fat malabsorption and in genetic disorders. The clinical phenotype includes progressive ataxia and sensory neuronal degeneration, which can be partially reversed by supplementation.