SAFETY OF ANTIOXIDANT VITAMINS AND BETA-CAROTENE

Epidemiologic evidence links high antioxidant status with low risk of degenerative disease. Optimal intakes of antioxidants may not be achie vable by diet alone; supplements may be taken, particularly in subgrou ps of the population at high risk. It is thus necessary to ensure that antioxidant supplements are safe and free from side effects. The toxi city of vitamin E is low; no mutagenic, teratogenic, or carcinogenic e ffects are known and in double-blind studies in which large amounts of vitamin E were used in humans, no side effects occurred. High concent rations are contraindicated in subjects with vitamin K-associated bloo d coagulation disorders, and the toxicity in normal subjects ingesting large amounts of vitamin E over long periods requires additional inve stigation. Toxicity of beta-carotene also is low. Evidence from human toxicity trials is not available but there is much circumstantial evid ence that 15-50 mg/d is without side effects except for hypercarotenem ia in some subjects at high intakes, The finding of more lung cancer i n subjects who smoked and who were given 20 mg beta-carotene/d than in those given a placebo could be influenced by the cancer being well ad vanced before beta-carotene administration, Massive anecdotal evidence exists that vitamin C (at greater than or equal to 1 g/d) is safe. Ex haustive literature searches have failed to reveal a controlled study of vitamin C toxicity in human subjects. Anxiety exists about oxalate stone formation, uricosuria, vitamin B-12 destruction, mutagenicity, a nd iron overload, but the consensus is that adverse effects do not occ ur in healthy subjects ingesting large amounts of vitamin C.