Lower ischemic heart disease incidence and mortality among vitamin supplement users.

OBJECTIVE: This study assessed the relationship between vitamin supplement use and the occurrence of ischemic heart disease (IHD).

DESIGN: A cohort study was conducted between 1985 and 1991 in Quebec City. In 1985, 2313 men provided baseline information on vitamin supplement use and IHD risk factors. Incidence of IHD events was ascertained over the first five years of follow-up. Cox regression models were used to assess the relation between vitamin supplement use and occurrence of IHD events while controlling for confounders.

MAIN RESULTS: Vitamin supplement use was consistently associated with a lower incidence of IHD. The adjusted rate ratios and their 95% confidence intervals were: 0.31 (0.09-0.99) for IHD death, 0.53 (0.24-1.11) for MI, 0.76 (0.44-1.65) for angina and 0.73 (0.44-1.22) for a first IHD event. The associations were stronger for IHD death and myocardial infarction, two events assessed with high validity. The inverse association with IHD was more consistent for vitamin E than for any other vitamin.

CONCLUSION: This study suggests that the inverse association between vitamin supplement use and IHD is real. The causal nature of the association can only be demonstrated in the context of a randomised intervention trial such as the HOPE study.