Significance and sources of vitamin E Domina Petric, MD

Significance of vitamin E Vitamin E has a fundamental role in the normal metabolism of all cells. Its deficiency can afffect several different organ systems. Its function is related to those of several other nutrients and endogenous factors that, collectively, comprise a multicomponent system that provides protection against the potentially damaging effects of reactive species of oxygen formed during metabolism or that are encountered in the environment. 11/15/2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Significance of vitamin E Both the need for vitamin E and the manifestations of its deficiency can be affected by such nutrients as selenium and vitamin C and by exposure to such prooxidant factors as polyunsaturated fatty acids (PUFAs), air pollution and ultraviolet (UV) light. Vitamin E may also have non antioxidant functions in regulating gene expression and cell signaling. 11/15/2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Significance of vitamin E Supranutritional levels of the vitamin have been useful in reducing the oxidation of low density lipoproteins (LDLs) and thus reducing the risk of atherosclerosis. 11/15/2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Sources of vitamin E 11/15/2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Distribution in food Vitamin E is synthesized only by plants. It is found primarily in plant products, the richest sources being plant oils. All higher plants appear to contain α-tocopherol in their leaves and other green parts. Because α-tocopherol is contained mainly in the chloroplasts of plant cells (whereas the β-, γ- and δ-vitamers are usually found outside of these particles), green plants tend to contain more vitamin E than yellow plants. 11/15/2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Distribution in food Wheat germ, sunflower, and safflower oils are rich sources of α-(RRR)-tocopherol. Corn and soybean oils contain mostly γ-(RRR)-tocopherol. 11/15/2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Distribution in food Animal tissues tend to contain low amounts of α-tocopherol, the highest levels occurring in fatty tissues. Because vitamin E occurs naturally in fats and oils, reductions in fat intake can be expected also to reduce vitamin E intake. A water-soluble metabolite, α-tocopheryl phosphate, has also been idenfied at trace levels in animal tissues. 11/15/2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Vitamin A activity The most biopotent vitamer-the vitamer of greatest interest in nutrition is α-tocopherol, which occurs naturally as the RRR stereoisomer [(RRR)-α- tocopherol]. 11/15/2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Synthetic forms Synthetic preparations of vitamin E are mixtures of all eight diastereoisomers, that is, 2RS, 4′RS, 8′RS-vitamers designated more commonly with the prefix all rac- in both unesterified (all-rac-α-tocopherol) and esterified (all-rac-α-tocopheryl acetate) forms. Other forms used commercially include all-rac- α-tocopheryl succinate and all-rac-α-tocopheryl polyethyleneglycol-succinate. 11/15/2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Dietary sources of vitamin E The important sources of vitamin E in human diets and animal feeds are vegetable oils and, to lesser extents, seeds and cereal grains. The dominant dietary form is γ-tocopherol. Wheat germ oil is the richest natural source, containing 0.9 to 1.3 mg of α-tocopherol per gram, or, about 60% of its total tocopherols. 11/15/2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Dietary sources of vitamin E Animal fats: lard, butter, tallow. Plant oils: soybean, cotton, maize, coconut, peanut, palm, sunflower, safflower and olive. 11/15/2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.

Literature Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008. 11/15/2018 Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc. 2008.