Randomised trial of alpha-tocopherol and beta-carotene supplements on incidence of major coronary events in men with previous myocardial infarction

Abstract

Background: Epidemiological data suggest that the intake of antioxidants such as alpha-tocopherol (vitamin E) and beta-carotene has an inverse correlation with the incidence of coronary heart disease. The results from clinical trials of antioxidant supplementation in people with known coronary heart disease are inconclusive.

Methods: We studied the frequency of major coronary events in 1862 men enrolled in the alpha-tocopherol beta-carotene Cancer Prevention Study (smokers aged between 50 and 69 years) who had a previous myocardial infarction. In this randomised, double-blind. placebo-controlled study, men had received dietary supplements of alpha-tocopherol (50 mg/day), beta-carotene (20 mg/day), both, or placebo. The median follow-up was 5.3 years. The endpoint of this substudy was the first major coronary event after randomisation. Analyses were by intention to treat.

Findings: 424 major coronary events (non-fatal myocardial infarction and fatal coronary heart disease) occurred during follow-up. There were no significant differences in the number of major coronary events between any supplementation group and the placebo group (alpha-tocopherol 94/466; beta-carotene 113/461; alpha-tocopherol and beta-carotene 123/497; placebo 94/438 [log-rank test, p = 0.25]). There were significantly more deaths from fatal coronary heart disease in the beta-carotene (74/461, multivariate-adjusted relative risk 1.75 [95% CI 1.16-2.64], p = 0.007) and combined alpha-tocopherol and beta-carotene groups (67/497, relative risk 1.58 [1.05-2.40], p = 0.03) than in the placebo group (39/438), but there was no significant increase in the alpha-tocopherol supplementation group (54/466, relative risk 1.33 [0.86-2.05], p = 0.20).

Interpretation: The proportion of major coronary events in men with a previous myocardial infarction who smoke was not decreased with either alpha-tocopherol or beta-carotene supplements. In fact, the risk of fatal coronary heart disease increased in the groups that received either beta-carotene or the combination of alpha-tocopherol and beta-carotene; there was a non-significant trend of increased deaths in the alpha-tocopherol group. We do not recommend the use of alpha-tocopherol or beta-carotene supplements in this group of patients.