Vitamin E

Vitamin E

Vitamin E consists of two groups of chemical compounds. They are the tocoph-erols and the tocotrienols. There are four types of tocopherols: alpha, beta,delta, and gamma. The most biologically active of these is alpha-tocopherol.

Functions.Vitamin E is an antioxidant. It is aided in this process by vitaminC and the mineral selenium. It is carried in the blood by lipoproteins. When the amount of vitamin E in the blood is low, the red blood cells become vulnerable to a higher-than-normal rate of hemolysis. Vitamin E has been found helpful in the prevention of hemolytic anemia among premature infants. It also may enhance the immune system. Because of its antioxidant properties, it is commonly used in commercial food products to retard spoilage.

Sources. Vegetable oils made from corn, soybean, safflower, and cottonseed and products made from them, such as margarine, are the best sources of vitamin E. Wheat germ, nuts, and green leafy vegetables also are good sources. Animal foods, fruits, and most vegetables are poor sources.

Requirements. Research indicates that the vitamin E requirement increases if the amount of polyunsaturated fatty acids in the diet increases. In general, however, the U.S. diet is thought to contain sufficient vitamin E.

Hypervitaminosis. Although vitamin E appears to be relatively nontoxic, it is a fat-soluble vitamin, and the excess is stored in adipose tissue. Consequently, it would seem advisable to avoid long-term megadoses of vitamin E.

Deficiency. A deficiency of vitamin E has been detected in premature, low-birthweight infants and in patients who are unable to absorb fat normally. Malabsorption can cause serious neurological defects in children, but in adults it takes 5 to 10 years before deficiency symptoms occur.