Also known as tocopherol. Sometimes referred to as potent fat-soluble antioxidant.
This is a bit of a strange one; its function is not really known. It prevents sterility in rats, but no related disease has been found in humans. However, it has some other uses. It is a good antioxidant, preventing rancidification of cells, and attack by free-radicals, although when used as a food additive, it, like vitamin C is very sensitive to processing and deep freezing. It tends to be used as a short term antioxidant against rapid food degradation. Vitamin E also has some anti-cancer properties, and can protect against some cancer treatments such as radiotherapy and chemotherapy. Its effectiveness is greatly increased when taken in combination with selenium. Recently it has been found that vitamin E may be connected with the functioning some hormones. At very high concentrations (over 800mg per day) vitamin E can operate as an anticoagulant by inhibiting the aggregation of blood platelets. However, there is no known case of an overdose causing harm.
Unlike vitamin D, vitamin E cannot be synthesized by the human body, and so we are entirely dependant on foodstuffs in order to meet our requirements. It is widely available in fresh vegetable and eggs, but especially in broccoli, red cabbage, nuts, vegetable oils and whole wheat.
Vitamin E is widely available, and can be stored by the body, so supplements, are not usually needed. The RDA is 10mg.