POLYUNSATURATED FATTY-ACIDS AND REQUIREMENTS OF VITAMIN-E

The major function of vitamin E is believed to be the protection of cellular membrane lipids against oxygen free-radical attack. In animals, high intakes of polyunsaturated fatty acids without proper antioxidant protection rapidly lead to vitamin E deficiency. Since the peroxidizability of fats increases with the amount and the degree of fatty acid unsaturation, the need for vitamin E increases respectively. Foods high in polyunsaturated fatty acids require, in addition to antioxidant protection to prevent rancidity during storage (technical protection against oxidation), a sufficient amount of vitamin E to physiologically protect against oxidation. The exact requirements of vitamin E needed for compensating the elevated demand caused by polyunsaturated fatty acids can only be estimated from data in the literature. There are no systematic studies in humans, and the requirements depend on the particular parameter chosen to establish vitamin E deficiency. For humans, a reference value of 0.9 mg IU vitamin E per gram linoleic acid may safely be assumed. For polyunsaturated fatty acids of higher degree of unsaturation and mixtures thereof, the minimum elevated vitamin E demand can be calculated by a formula.