is a group of eight lipid-soluble compounds synthesised by plants, tocopherols and tocotrienols. Alpha-tocopherol accounts for 90% of the vitamin E in human tissues. Vitamin E acts as an antioxidant and is required to protect cells against oxidative damage from free radicals, for example oxidation of the lipids in cell membranes. Vitamin E content in food is expressed in terms of mg equivalents based on the biological activities of the tocopherols present.
Existence of dietary vitamin E deficiency is not considered to be a problem even in people consuming a relatively poor diet. Deficiency only occurs in people with severe fat malabsorption and rare genetic disorders.
Vitamin E has very low toxicity and humans appear to be able to tolerate high levels of the vitamin without untoward effects (e.g. between 540-970 mg/day). However, at very high doses vitamin E may have negative effects on other fat-soluble vitamins; it exacerbates the effects of vitamin K deficiency and interferes with the absorption of vitamin A.
Foods containing large amount of polyunsaturated fatty acids will generally contain large amounts of vitamin E, therefore the richest sources of vitamin E are vegetable oils, nuts and seeds. Since vegetable oils are the richest source, deficiency is rare.