Vitamin E, known as the anti-sterility vitamin - from the Greek tokos (child) and pherein (bear), is fat-soluble and is a mixture of alpha-, beta-, gamma- and delta- tocopherols. Although eight chemically similar substances have Vitamin E activity, alpha-tocopherol is the most active of these (100%) with gamma-tocopherol being between 1 and 20% Vitamin E activity. Found in most foods, it is abundant in, amongst other things, whole grain cereals, corn and cottonseed oils, egg yolks, meat and milk. (See also E306, E307 and E309).

It is essential to the life of red blood cells and helps the supply of oxygen to the heart and muscles. Its requirement is increased by high intakes of polyunsaturated fats but, as the body stores about a year's supply, Vitamin E deficiency that produces signs and symptoms is rare. It is possible that generous intakes protect cell membranes from oxidation damage and consequent degenerative diseases.

E308 is an antioxidant for polyunsaturated fatty acids as well as a vitamin. Less effective than alpha-tocopherol (E306 and E307) in animals but not in non-biological matter. It also protects other nutrients, such as Vitamin A, from oxidation but is largely destroyed by freezing.

Commercially it can be produced from cottonseed, maize, rice germ, soya been oil, wheat germ, or green leaves and may, therefore, come from Genetically Modified sources.