Dietary iron intake and risk of death due to cardiovascular diseases: A systematic review and dose-response meta-analysis of prospective cohort studies

Background and Objectives: Many studies have investigated the association between dietary iron intake and death due to cardiovascular disease (CVD), but the results were inconsistent. We performed a dose-response meta-analysis to quantitatively assess the risk of CVD mortality with dietary intake of iron (total iron, heme iron, and non-heme iron). Methods and Study Design: PubMed and Embase databases were searched for articles published up to February 21, 2019. Prospective cohort studies were included if reporting relative risks (RRs) and 95% confidence intervals (CIs) for risk of CVD mortality associated with dietary iron intake. Restricted cubic splines were used to model the dose-response association. Results: We included eight articles (19 studies including 720,427 participants [46,045 deaths due to CVD]) in the meta-analysis. When comparing the highest versus lowest level of dietary heme iron intake, the pooled RR for CVD mortality was 1.19 (95% CI, 1.01-1.39). With a 1-mg/day increase in dietary heme iron intake, the pooled RR for death due to CVD, stroke, coronary heart disease, and myocardial infarction were 1.25 (95% CI, 1.17-1.33), 1.17 (1.04-1.32), 1.25 (0.70-2.22), and 1.17 (0.55-2.50) respectively. The association between dietary iron intake and CVD mortality was linear (p(nonlinearity)>0.05). Conclusions: Higher dietary intake of heme iron was associated with a greater risk of CVD mortality. Reducing consumption of heme iron may help to prevent premature death due to CVD.