Positive Health Online

Abstract

CHRISTEN and colleagues, Department of Medicine, Brigham and Womens Hospital, Harvard Medical School, Boston, MA USA assessed the benefits and risks of supplementation with beta-carotene, vitamin E, vitamin C and multivitamins upon cancer, cardiovascular (CVD) and eye diseases.

Background

Methodology

Physicians Health Study II (PHS II) is a randomized, double-blind, placebo-controlled trial using 15,000 willing and eligible physicians aged 55 years and older. PHS II will test alternate day beta-carotene, alternate day vitamin E, daily vitamin C and a daily multivitamin in the prevention of total and prostate cancer, CVD, age-related eye diseases, cataract and macular degeneration.

Results

PHS I (randomized, double-blind, placebo-controlled trial with 22,071 US male physicians) showed that beta-carotene supplementation (50 mg, alternate days) had no significant benefit or harm on cancer or CVD during more than 12 years of treatment and follow-up. For cancer, there were possible benefits with total and prostate cancer in people with low baseline levels of beta-carotene, a result in line with the Chinese Cancer Prevention Study in a poorly nourished population. For CVD there were apparent benefits of beta-carotene supplementation among a small subgroup of 333 men with prior angina or revascularization. Data from randomized trials of primary prevention are sparse and inconsistent for vitamin E and non-existent for vitamin C and multivitamins. There are no completed large-scale randomized trials of antioxidant vitamins for eye diseases.

Conclusion

PHS II is the only primary prevention trial with apparently healthy men testing for benefits and risks of vitamin E on cancer and CVD, of vitamin C, multivitamins and single antioxidants alone and in combination, on cancer, CVD and eye diseases. Additionally, PHS II is the only trial testing the hypotheses that beta-carotene and vitamin E may reduce the risks of prostate cancer. Therefore, PHS II will add unique and important relevant information to the totality of evidence regarding the benefits and risks of beta-carotene, vitamins E and C and multivitamins alone and in combination on the prevention of cancer, CVD and eye diseases.

References

Christen WG et al. Design of Physicians Health study II a randomized trial of beta-carotene, vitamins E and C, and multivitamins, in prevention of cancer, cardiovascular disease, and eye disease, and review of results of completed trials. Annals of Epidemiology 10(2): 125-34. Feb 2000.