Q&A

Antioxidant vitamins do not prevent cardiovascular disease

J Fam Pract. 2003 October;52(10):747-769
By
Promita Roychoudhury, MD
Kendra Schwartz, MD, MSPH
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  • BACKGROUND: Oxidized low-density lipoprotein is thought to play an important role in the development of atherosclerosis. Animal studies and studies of various human populations have suggested that dietary supplementation with the antioxidants vitamin E and beta-carotene may reduce cardiovascular disease by inhibiting the atherogenic process.
  • POPULATION STUDIED: In this meta-analysis, 138,113 and 81,788 persons took beta-carotene or vitamin E, respectively, alone or in combination with other antioxidants. The daily dose range for vitamin E was 50–800 IU; for beta-carotene it was 15–50 mg.
  • STUDY DESIGN AND VALIDITY: The authors performed a meta-analysis of antioxidant trials, using studies of 1000 or more patients performed in developed countries without known vitamin deficiencies in their populations.
  • OUTCOMES MEASURED: Four outcomes were measured: all-cause mortality, cardiovascular mortality, cerebrovascular accidents, and combined outcome of cardiovascular death or nonfatal myocardial infarction.
  • RESULTS: For beta-carotene, all-cause mortality and cardiovascular mortality were slightly higher in the actively treated group than in the control group— odds ratio (OR)=1.07 (95% confidence interval [CI], 1.02–1.11) for all-cause mortality (number needed to harm [NNH]=250; 95% CI, 129–714), and OR=1.1 (95% CI, 1.03–1.17) for cardiovascular mortality (NNH=333; 95% CI, 192–1111). Beta-carotene had no effect on the rate of cerebrovascular events. Vitamin E had no effect on any of the measured outcomes.
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PRACTICE RECOMMENDATIONS

This meta-analysis of randomized controlled trials showed that neither beta-carotene nor vitamin E appears to prevent all-cause or cardiovascular mortality in patients with known heart disease or those at risk for heart disease. Similarly, use of these antioxidant vitamins did not affect number of stroke events. The use of beta-carotene and vitamin E should not be recommended for primary and secondary prevention of cardiovascular disease.

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