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UNIMPRESSIVE RESULTS FROM TRIALS OF VITAMIN E, BETA CAROTENE.

As compelling as the hypothesis that antioxidant vitamin supplements lower the risk for coronary disease may be, prospective trials have not found strong evidence for such as association. Two new studies give further unimpressive results.

The first trial evaluated whether vitamin E and beta carotene affected the incidence of angina pectoris among 22,269 Finnish male smokers without known coronary disease. The men were randomized to receive either 50 mg/day of vitamin E, 20 mg/day of beta carotene, both vitamins, or placebo. During a median follow-up of nearly five years, 1983 subjects developed angina. There was no evidence of protection against angina associated with beta carotene, and only a modest risk reduction (relative risk, 0.91) was associated with vitamin E. The combination of both supplements was not associated with a significant benefit.

The second study examined the relation between beta carotene use and mortality among 1188 men and 532 women enrolled in a skin cancer prevention trial. The subjects took placebo or beta carotene (50 mg/day) for about four years. Over a median 8.2-year follow-up, there was no reduction in overall risk for death or cardiovascular mortality among those who used beta carotene. However, patients whose initial plasma beta carotene concentrations were in the highest quartile had lower risks of all-cause and cardiovascular death (relative risks, 0.52 and 0.57) than those in the lowest quartile.

Comment: These data offer no convincing evidence that antioxidant supplements lower coronary disease risk. The association between high initial plasma beta carotene and low mortality in the second study might reflect various constituents of diets that are rich in fruits and vegetables.

— TH Lee

Published in Journal Watch General Medicine March 26, 1996

Citation(s):

Rapola JM et al. Effect of vitamin E and beta carotene on the incidence of angina pectoris: a randomized, double-blind, controlled trial. JAMA 1996 Mar 6 275 693-698.

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Greenberg ER et al. Mortality associated with low plasma concentration of beta carotene and the effect of oral supplementation. JAMA 1996 Mar 6 275 699-703.

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