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 (pnonlinearity> 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.