Nutrition Vitamin E

Vitamin E is a fat soluble vitamin which has a main function of membrane bound antioxidant that prevents oxidative damage by disrupting the free radical chain reactions. Vitamin E also inhibits the intestinal oxidation of vitamin A and thus increases its bioavailability. Vitamin E is the only membrane bound lipid soluble antioxidant thus it plays a key role in preventing cellular injury caused by oxidative stress which is associated with premature aging, cardiovascular diseases, uncontrolled diabetes, cataracts, inflammation and infection. Vitamin E protects and boosts the immune system by preserving the immune cell activity and protecting the cell membranes. Vitamin E also prevents the oxidation of LDL cholesterol thereby inhibiting the initiation of plaque formation in the arteries.

Vitamin E Nutrition
In foods vitamin E occurs as tocopherols and tocotrienols where alpha tocopherol has the highest bioactivity. Naturally vitamin E occurs as d-alpha-tocopherol. The amount of vitamin E required by the body depends on the body size and the intake of polyunsaturated fats in the diet, as vitamin E is required to protect these fats from oxidation. The recommended dietary allowance (RDA) for both the sexes including pregnant women is 15 milligrams; for lactating mothers the RDA is 19 milligrams. Requirements of vitamin E are measured in milligrams but its content is measured in International Units (IU) on food labels (one IU of vitamin E is equivalent to 0.67 milligram).
Sources and Availability
Vitamin E, like most of the nutrients is found in the germ of the grain or seed. Whole wheat and other cereal flours contain more vitamin E compared to refined flours, as most of the nutrients including vitamin E are stripped off during the processing. Other foods which contain vitamin E include vegetable oils like soybean, safflower, olive, canola, corn and cottonseed oil; products made from this oil such as margarine are also good source of vitamin E. Nuts and green leafy vegetables are also a good source of this vitamin. Vitamin E is heat stable but very high temperatures like frying can destroy this vitamin.
Deficiency and Toxicity
Deficiency and toxicity for vitamin E is not common. Vitamin E deficiency at cellular level can promote increased lipid oxidation making the cells vulnerable to oxidative injury. Vitamin E deficiency is usually seen in conditions where fat mal absorption is present like cystic fibrosis. In such cases symptoms like muscle weakness, imbalance, visual impairment, and loss of deep tendon reflexes are seen. Very high intake of vitamin E (more than 100 times of the recommended RDA) can interfere with the utilization or decrease availability of other fat soluble vitamins like vitamin A, D, and K.

Submitted on February 24, 2009