Vitamin E refers to a group of eight fat-soluble compounds that include both tocopherols and tocotrienols. There are many different forms of vitamin E, of which γ-tocopherol is the most common in the North American diet. γ-Tocopherol can be found in corn oil, soybean oil, margarine and dressings.α-Tocopherol, the most biologically active form of vitamin E, is the second most common form of vitamin E in the North American diet. This variant of vitamin E can be found most abundantly in wheat germ oil, sunflower, and safflower oils. It is a fat-soluble antioxidant that stops the production of reactive oxygen species formed when fat undergoes oxidation.

While it was initially hoped that vitamin E supplementation would have a positive effect on health, research has not supported these conclusions. Vitamin E does not decrease mortality in adults, even at large doses, and may slightly increase it. It does not improve blood sugar control in an unselected group of people with diabetes mellitus or decrease the risk of stroke. Daily supplementation of vitamin E does not decrease the risk of prostate cancer and may increase it. Studies on its role in age related macular degeneration are ongoing as, even though it is of a combination of dietary antioxidants used to treat the condition, it may increase the risk. A Japanese study in 2012 found that vitamin E may contribute to osteoporosis.