Dietary iron and coronary heart disease risk: a study from Greece

The authors investigated the association between dietary iron intake and risk of coronary heart disease by means of a case-control study conducted in Athens, Greece, in January 1990 to April 1991. The case series comprised 329 patients with electrocardiographically confirmed first coronary infarct, or a first positive coronary arteriogram, or both, while the controls were 570 patients from the same study base who presented with minor conditions believed to be unrelated to diet. After adjustment by logistic regression for 14 potentially confounding variables of sociodemographic, life-style and nutritional nature, dietary iron intake was found to be positively associated with risk for coronary disease among men aged 60 years or older (odds ratio (OR) for a monthly increment of 50 mg of iron = 1.47, with 95% confidence interval (CI) 1.02-2.12) and particularly women aged 60 years or older (OR for a similar increment of iron = 3.61, with 95% CI 1.45-9.01). Additional adjustment for blood cholesterol, as well as systolic blood pressure and blood glucose level, reduced the iron regression coefficient among older men from 1.47 to 1.36, and among older women from 3.61 to 3.51; however, it is not clear whether the change reflects control of residual confounding or blocking of an intermediate pathway. These data are compatible with the hypothesis that excess dietary iron intake increases the risk of coronary heart disease, particularly among older women and men.