HOW SAFE ARE ANTIOXIDANT VITAMINS

Interest in a putative disease-preventive role for the so-called antio xidant nutrients derives from a large body of evidence suggesting that oxidative damage is a contributing cause of many life-shortening dise ases. Since their use is in an otherwise healthy population, it is imp ortant that such agents be virtually free of toxicity. The agents of m ost interest are alpha-tocopherol (vitamin E), ascorbic acid (vitamin C) and beta-carotene, When used for disease prevention, the doses give n are several-fold greater the Recommended Dietary Allowance (RDA), th e latter being based on amounts necessary for the prevention of classi c deficiency conditions recognised decades ago. alpha-Tocopherol, asco rbic acid and beta-carotene are remarkably well tolerated and free fro m toxicity. Consequently, they are well suited for testing as preventi ve agents, since their use does not require any toxicity monitoring ex cept in unusual circumstances. An example of the latter would be in pa tients who are vitamin K deficient, perhaps through anticoagulation wi th drugs such as warfarin, in which case use of high doses of alpha-to copherol may increase the bleeding tendency.