Heme iron intake and acute myocardial infarction: A prospective study of men

BackgroundEpidemiologic studies of heme iron and non-heme iron intake in relation to risk of acute myocardial infarction (AMI) are lacking. Therefore, we examine the associations between heme iron and non-heme iron intake and fatal and nonfatal AMI in men. Moreover, we investigated whether the associations were modified by intake of minerals (calcium, magnesium, and zinc) that decreases iron absorption.MethodsThe population-based prospective cohort of Swedish Men (COSM) included 36 882 men, aged 45-79 years, who completed a self-administered questionnaire on diet and had no history of coronary heart disease, stroke, diabetes, or cancer at baseline.ResultsDuring an 11.7 year follow-up, 678 fatal and 2593 nonfatal AMI events were registered. The hazard ratio (HR) of fatal AMI among men in the highest compared with the lowest quintile of heme iron intake was 1.51 (95%CI: 1.07-2.13, P-trend = 0.02). The association was confined to men with a low intake of minerals that can decrease iron absorption. Among men with combined intakes of calcium, magnesium, and zinc below the medians, the HR of fatal AMI was 2.89 (95%CI: 1.43-5.82) for the highest vs. the lowest quintile of heme iron intake. There was no association between heme iron intake and nonfatal AMI, or between non-heme iron intake and fatal or nonfatal AMI.ConclusionsFindings from this prospective study indicate that a high heme iron intake, particularly with simultaneous low intake of minerals that can decrease iron absorption, may increase the risk of fatal AMI.