ABSORPTION, TRANSPORT AND METABOLISM OF VITAMIN-E

Vitamin E includes eight naturally occurring fat-soluble nutrients called tocopherols and dietary intake of vitamin E activity is essential in many species. αTocopherol has the highest biological activity and the highest molar concentration of lipid soluble antioxidant in man. Deficiency of vitamin E may cause neurological dysfunction, myopathies and diminished erythrocyte life span. αTocopherol is absorbed via the lymphatic pathway and transported in association with chylomicrons. In plasma αtocopherol is found in all lipoprotein fractions, but mostly associated with apo B-containing lipoproteins in man. In rats approximately 50% of αtocopherol is bound to high density lipoproteins (HDL). After intestinal absorption and transport with chylomicrons αtocopherol is mostly transferred to parenchymal cells of the liver were most of the fat-soluble vitamin is stored. Little vitamin E is stored in the non-parenchymal cells (endothelial, stellate and Kupffer cells). αTocopherol is secreted in association with very low density lipoprotein (VLDL) from the liver. In the rat about 90% of total body mass of αtocopherol is recovered in the liver, skeletal muscle and adipose tissue. Most αtocopherol is located in the mitochondrial fractions and in the endoplasmic reticulum, whereas little is found in cytosol and peroxisomes. Clinical evidence from heavy drinkers and from experimental work in rats suggests that alcohol may increase oxidation of αtocopherol, causing reduced tissue concentrations of αtocopherol. Increased demand for vitamin E has also been observed in premature babies and patients with malabsorption, but there is little evidence that the well balanced diet of the healthy population would be improved by supplementation with vitamin E. © 1991 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.