Incidence of cataract operations in Finnish male smokers unaVected by á tocopherol or â carotene supplements

Objective—To examine the eVect of á tocopherol and â carotene supplementation on the incidence of age related cataract extraction. Setting—The Alpha-tocopherol Betacarotene (ATBC) Study was a randomised, double blind, placebo controlled, 2×2 factorial trial conducted in south western Finland. The cataract surgery study population of 28 934 male smokers 50–69 years of age at the start. Intervention—Random assignment to one of four regimens: á tocopherol 50 mg per day, â carotene 20 mg per day, both á tocopherol and â carotene, or placebo. Follow up continued for five to eight years (median 5.7 years) with a total of 159 199 person years. Outcome measure—Cataract extraction, ascertained from the National Hospital Discharge Registry. Results—425 men had cataract surgery because of senile or presenile cataract during the follow up. Of these, 112 men were in the á tocopherol alone group, 112 men in the â carotene alone group, 96 men in the á tocopherol and â carotene group, and 105 men in the placebo group. When supplementation with á tocopherol and with â carotene were introduced to a Cox proportional hazards model with baseline characteristics (age, education, history of diabetes, body mass index, alcohol consumption, number of cigarettes smoked daily, smoking duration, visual acuity, and total cholesterol), neither á tocopherol (relative risk, RR, 0.91, 95% confidence intervals, CI, 0.74, 1.11) nor â carotene (RR 0.97, 95% CI 0.79, 1.19) supplementation aVected the incidence of cataract surgery. Conclusion—Supplementation with á tocopherol or â carotene does not aVect the incidence of cataract extractions among male smokers. (J Epidemiol Community Health 1998;52:468–472) Animal studies have shown that deprivation or overprovision of certain vitamins and micronutrients can aVect the development of cataract. Several observational studies in humans have shown an inverse association between cataract development and multivitamin supplementation, vitamin E or C supplementation, and high plasma concentrations of vitamin E, vitamin C or carotenoids while other studies have observed no association. Two double masked controlled clinical trials have been carried out in China to examine the eVect of vitamin and mineral supplements on the prevalence of end of trial cataract. In one the combination of â carotene, vitamin E, and selenium had no eVect on the prevalence whereas in the other multisupplementation with 26 vitamins and minerals including â carotene and vitamin E reduced the prevalence among persons aged 65 to 74 years. Incidence of cataract is strongly associated with age. Various manifestations and diseases of aging are believed to be caused by oxidative damage to tissues mediated by free radicals. In humans complex antioxidative systems protect against this oxidative damage. We present the incidence of age related cataract extractions in the Alpha-tocopherol, Betacarotene Study (ATBC Study), which was originally designed to study the possible protective eVect of á tocopherol or â carotene on the incidence of lung cancer. The study was a joint project of the National Public Health Institute of Finland and the US National Cancer Institute. Methods in ATBC study STUDY DESIGN AND POPULATION Detailed information on study design, methods, randomisation, characteristics of participants, measures of compliance, and overall conduct of the study has been published earlier. The participants (n=29 133) were recruited in 1985–1988 from the entire male population aged 51–69 years of 14 geographical areas in south western Finland. They were respondents to a postal survey (n=224 377) to find eligible participants: smokers of at least five cigarettes per day, and willing to give informed written consent. Before enrollment in the study, potential participants were interviewed by a nurse at one of the 14 local study centres to obtain background information and further evaluate their eligibility. A chest radiograph was taken to exclude prevalent lung cancer cases. Men with a history of cancer or serious disease limiting their ability to participate, taking supplements of vitamin E, vitamin A, or â carotene in excess of predefined doses, or being treated with anticoagulants, were also excluded. At baseline, dietary intakes of á tocopherol and â carotene were estimated from the diet history questionnaire, and height, J Epidemiol Community Health 1998;52:468–472 468 University of Helsinki, Department of Public Health, Helsinki, Finland