Purpose: To examine the development of age-related cataract in a trial of beta-carotene supplementation in women.
Methods: The Women's Health Study is a randomized, double-masked, placebo-controlled trial originally designed to test the balance of benefits and risks of beta-carotene (50 mg on alternate days), vitamin E, and aspirin in the primary prevention of cancer and cardiovascular disease among 39,876 female health professionals aged 45 years or older. The beta-carotene component of the trial was terminated early after a median treatment duration of 2.1 years. Main outcome measures were visually-significant cataract and cataract extraction, based on self-report confirmed by medical record review.
Results: There were 129 cataracts in the beta-carotene group and 133 in the placebo group (relative risk [RR] = 0.95, 95% CI 0.75-1.21). For cataract extraction, there were 94 cases in the beta-carotene group and 89 cases in the placebo group (RR = 1.04, 95% CI 0.78-1.39). Subgroup analyses suggested a possible beneficial effect of beta-carotene in smokers.
Conclusions: These randomized trial data from a large population of apparently healthy female health professionals indicate that two years of beta-carotene treatment has no large beneficial or harmful effect on the development of cataract during the treatment period.