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March 2003

A Randomized Trial of Beta Carotene and Age-Related Cataract in US Physicians

Author Affiliations

From the Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital (Drs Christen, Manson, Glynn, Gaziano, and Buring), the Departments of Epidemiology (Dr Manson) and Biostatistics (Dr Glynn), Harvard School of Public Health, the Department of Ambulatory Care and Prevention, Harvard Medical School (Dr Buring), and the Massachusetts Veterans Epidemiology Research and Information Center, Department of Veterans Affairs Boston Healthcare System (Dr Gaziano), Boston, Mass; the National Eye Institute, Bethesda, Md(Dr Sperduto); and the Department of Epidemiology and Public Health, University of Miami School of Medicine, Miami, Fla (Dr Hennekens). Dr Hennekens serves as a consultant, including as chairman or a member of data and safety monitoring boards, to Astra Zeneca, Bayer, Bristol-Myers Squibb, Glaxo Smith Kline, McNeil Pharmaceutical, Novartis, Pfizer, and Reliant Pharmaceuticals. The other authors have no relevant financial interest in this article.

Arch Ophthalmol. 2003;121(3):372-378. doi:10.1001/archopht.121.3.372

Objective  To examine the development of age-related cataract in a trial of beta carotene supplementation in men.

Design  Randomized, double-masked, placebo-controlled trial.

Methods  Male US physicians aged 40 to 84 years (n = 22 071) were randomly assigned to receive either beta carotene (50 mg on alternate days) or placebo for 12 years.

Main Outcome Measures  Age-related cataract and extraction of age-related cataract, defined as an incident, age-related lens opacity, responsible for a reduction in best-corrected visual acuity to 20/30 or worse, based on self-report confirmed by medical record review.

Results  There was no difference between the beta carotene and placebo groups in the overall incidence of cataract (998 cases vs 1017 cases; relative risk[RR], 1.00; 95% confidence interval [CI], 0.91-1.09) or cataract extraction(584 vs 593; RR, 1.00; 95% CI, 0.89-1.12). In subgroup analyses, the effect of beta carotene supplementation appeared to be modified by smoking status at baseline (P = .02). Among current smokers, there were 108 cases of cataract in the beta carotene group and 133 in the placebo group (RR, 0.74; 95% CI, 0.57-0.95). Among current nonsmokers, there was no significant difference in the number of cases in the 2 treatment groups (884 vs 881; RR, 1.03; 95% CI, 0.94-1.13). The results for cataract extraction appeared to be similarly modified by baseline smoking status (P = .05).

Conclusions  Randomized trial data from a large population of healthy men indicate no overall benefit or harm of 12 years of beta carotene supplementation on cataract or cataract extraction. However, among current smokers at baseline, beta carotene appeared to attenuate their excess risk of cataract by about one fourth.