Beta Carotene Ineffective In Lowering Type 2 Diabetes Risk - Study
This article was originally published in The Tan Sheet
Executive Summary
Beta carotene supplementation had no effect on the incidence of type 2 diabetes mellitus in a randomized trial of 21,468 male doctors, Physicians' Health Study researchers report in the Sept. 15 issue of the Journal of the American Medical Association.
|
Beta carotene supplementation had no effect on the incidence of type 2 diabetes mellitus in a randomized trial of 21,468 male doctors, Physicians' Health Study researchers report in the Sept. 15 issue of the Journal of the American Medical Association. " [W]e detected no significant change in risk of type 2 DM associated with 12 years of beta carotene supplementation," Simin Liu, MD, Brigham & Women's Hospital and Harvard Medical School, et al. state. "The large sample size and long duration of the trial allowed for precise estimates with narrow 95% confidence intervals, excluding even a small effect of beta carotene." Three hundred ninety-six cases of type 2 diabetes mellitus were reported in the beta carotene group, compared to 402 cases in the placebo group. A randomized, double-blind, placebo-controlled trial of 22,071 male physicians, the Physicians' Health Study evaluated the roles of aspirin and beta carotene in the prevention of cardiovascular disease and cancer. For this analysis, Liu et al. excluded 603 men who reported a history of diabetes before randomization. A total of 10,756 subjects were assigned to beta carotene and 10,712 received placebo. Begun in 1982, the trial's beta carotene component was terminated on Dec. 31, 1995, by which time 99% of participants were still providing questionnaire information on morbidity, including type 2 DM diagnosis. Incidence rates of type 2 DM were calculated by dividing the number of incident cases by person-years of follow-up and relative risk was estimated by dividing the rate in the beta carotene group by the rate in the placebo group. The lack of association between beta carotene and occurrence of type 2 DM persisted despite multivariate adjustment and there was no evidence of benefit when the period of risk was subdivided into years of follow-up or increasing duration of treatment, the study notes. Liu et al. caution their results should not be interpreted as completely refuting observational study findings that increased intake of vegetables rich in carotenoids and other antioxidants may decrease the risk type 2 DM. "Our trial could not exclude the possibility that some carotenoids or other nutrients other than beta carotene are responsible for the observed association. Other antioxidants such as vitamin E may play a role in the prevention of type 2 DM, but their efficacy still needs to be evaluated in randomized trials." |