Beta-carotene supplementation and incidence of cancer and cardiovascular disease: the Women's Health Study

J Natl Cancer Inst. 1999 Dec 15;91(24):2102-6. doi: 10.1093/jnci/91.24.2102.


Background: In observational studies, individuals with high intakes of fruits and vegetables containing beta-carotene experience lower risks of developing cancer. However, the few randomized trials of beta-carotene supplementation show no overall benefits; some even suggest harm. This trial was designed to test the effects of beta-carotene supplementation in women.

Methods: The Women's Health Study is a randomized, double-blind, placebo-controlled trial originally testing aspirin, vitamin E, and beta-carotene in the prevention of cancer and cardiovascular disease among 39 876 women aged 45 years or older. The beta-carotene component was terminated early after a median treatment duration of 2.1 years (range = 0.00-2. 72 years). Statistical tests were two-sided.

Results: Among women randomly assigned to receive beta-carotene (50 mg on alternate days; n = 19 939) or placebo (n =19 937), there were no statistically significant differences in incidence of cancer, cardiovascular disease, or total mortality after a median of 4.1 years (2.1 years' treatment plus another 2.0 years' follow-up). There were 378 cancers in the beta-carotene group and 369 cancers in the placebo group (relative risk [RR] = 1.03; 95% confidence interval [CI] = 0.89-1. 18). There were no statistically significant differences for any site-specific cancer or during years 1 and 2 combined and years 3 and up combined. For cardiovascular disease, there were no statistically significant differences for myocardial infarction (42 in the beta-carotene group versus 50 in the placebo group), stroke (61 versus 43), deaths from cardiovascular causes (14 versus 12), or the combined end point of these three events (116 versus 102; among women with more than one event, only the first was counted). Deaths from any cause were similar in the two groups (59 versus 55). Among smokers at baseline (13% of all women), there were no statistically significant differences in overall incidence of cancer (RR = 1.11; 95% CI = 0.78-1.58) or cardiovascular disease (RR = 1.01; 95% CI = 0. 62-1.63).

Conclusion: Among apparently healthy women, there was no benefit or harm from beta-carotene supplementation for a limited period on the incidence of cancer and of cardiovascular disease.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Cardiovascular Diseases / epidemiology*
  • Cardiovascular Diseases / mortality
  • Cardiovascular Diseases / prevention & control*
  • Dietary Supplements*
  • Double-Blind Method
  • Female
  • Health Personnel / statistics & numerical data
  • Humans
  • Incidence
  • Middle Aged
  • Neoplasms / epidemiology*
  • Neoplasms / mortality
  • Neoplasms / prevention & control*
  • Risk
  • United States / epidemiology
  • Women's Health*
  • beta Carotene / administration & dosage
  • beta Carotene / adverse effects
  • beta Carotene / therapeutic use*


  • beta Carotene