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Vitamin E

Background

Vitamin E is a fat-soluble vitamin with antioxidant properties. Vitamin E exists in eight different forms (isomers): alpha-, beta-, gamma-, and delta-tocopherol; and alpha-, beta-, gamma-, and delta-tocotrienol. Alpha-tocopherol is the most active form in humans.

Dosing and daily allowance recommendations for vitamin E are often provided in alpha-tocopherol equivalents (ATEs) to account for the different biological activities of the various forms of vitamin E, or in international units (IU), which food and supplement labels may use. The conversion factor is 1mg of an ATE=1.5 IU.

Vitamin E supplements are available in natural or synthetic forms. The natural forms are usually labeled with the letter "d" (for example, d-gamma-tocopherol), whereas synthetic forms are labeled "dl" (for example, dl-alpha-tocopherol).

Foods that contain vitamin E include eggs, fortified cereals, fruit, green leafy vegetables (such as spinach), meat, nuts, nut oils, poultry, vegetable oils (corn, cottonseed, safflower, soybean, sunflower), argan oil, olive oil, wheat germ oil, and whole grains. Cooking and storage may destroy some of the vitamin E in foods.

Vitamin E has been proposed for the prevention or treatment of numerous health conditions, often based on its antioxidant properties. However, aside from the treatment of vitamin E deficiency (which is rare), there are a lack of clearly proven medicinal uses of vitamin E supplementation beyond the recommended daily allowance. There is ongoing research on its use in numerous diseases, particularly in cancer and heart disease.

Concerns have been raised about the safety of vitamin E supplementation, particularly in high doses. An increased risk of bleeding has been proposed, particularly in patients taking blood-thinning agents such as warfarin, heparin, or aspirin, and in patients with vitamin K deficiency. Evidence suggests that regular use of high-dose vitamin E supplements may increase the risk of death from all causes by a small amount, although human research is conflicting. Caution is warranted.

Scar prevention is another controversial use for vitamin E. While this use is commonly practiced, there is a lack of evidence for its efficacy. Because of a risk of contact dermatitis, some researchers have advised against the use of this therapy.

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