The association of chromium with the risk of a first myocardial infaction in men. The EURAMIC Study.
Background: Chromium, an essential heavy metal, is a cofactor of insulin that increases insulin sensitivity at the receptor level. Chromium has been shown to help control blood glucose and insulin in patients with type 2 diabetes mellitus and glucose intolerance, and it may also improve lipid variables. Although an inverse association between chromium and cardiovascular endpoints has long been hypothesized, no epidemiologic studies have been reported on this association. Objective: To evaluate the association between toenail chromium concentrations and the risk of a first myocardial infarction in men. Setting: The EURAMIC study, a large case-control study conducted in 10 European countries and Israel. Cases (n = 684) were men with a first diagnosis of myocardial infarction recruited within 24 hours of admission to the coronary units of participating hospitals. Controls (n = 724) were men selected to be representative of the populations that originated the cases. Toenail chromium was assessed by instrumental neutron activation analysis. Results: Average concentrations of toenail chromium were 1.10 mg/kg in cases (95% confidence interval [CI] 1.02 - 1.18) and 1.30 mg/kg in controls (1.21 - 1.40). Age and center-adjusted odds ratios (95% CI) of myocardial infarction for quintiles 2-5 of toenail chromium with respect to the first quintile were 0.74 (0.54-1.03), 0.77 (0.56-1.06), 0.53 (0.38-0.75), and 0.65 (0.46-0.91). The p for trend was 0.005. This inverse association was essentially unchanged after further adjustment for smoking, body mass index, HDL cholesterol, diabetes, and history of hypertension. Multivariate adjusted odds ratios for quintiles 2-5 were 0.84 (0.56-1.26), 0.70 (0.46-1.05), 0.56 (0.37-0.87), and 0.65 (0.42-0.99), with a p for trend of 0.049. Conclusions: Toenail chromium was inversely associated to the risk of a first myocardial infarction in men. Further studies are needed to replicate these findings and to elucidate the potential protective mechanisms of chromium on cardiovascular risk.