Background: Both experimental and observational studies have provided conflicting evidence on the associations of selenium with incidence and mortality of cardiovascular disease (CVD). The aim of this study was to evaluate the association between selenium status in the body and incidence and mortality of CVD by performing a systematic review and meta-analysis of observational studies and randomized controlled trials. Methods: A systematic search for articles in MEDLINE (Ovid), Embase, Web of Science (Thomson Reuters) and Cochrane library (Wiley) was conducted. Thirteen of the 1811 articles obtained from the databases met our inclusion criteria and were considered in the final analysis. The effect sizes were presented as weighted relative risk (RR) and 95% confidence intervals (CIs) using random-effects model. To detect dose-response relationships, we used meta-regression. Results: Overall, there was a reduced risk of CVD incidence (RR = 0.66; 95% CI: 0.40-1.09) and mortality (RR = 0.69; 95% CI: 0.57-0.84) in physiologically high selenium status compared to low selenium status in the body. There was a 15% (RR = 0.85, 95% CI: 0.76-0.94) decreased risk of CVD incidence per 10 µg increment in blood selenium concentration. In addition, a statistically significantly nonlinear dose-response relationship was found between CVD mortality and increased blood selenium concentration with the lowest risk at the 30-35 µg increment in blood selenium. Conclusions: Physiologically high selenium levels in the body are associated with decreased risk for CVD incidence and mortality, however, people should be cautious about the potential harmful effects from excessive intake of selenium.
Keywords: Cardiovascular disease; incidence; meta-analysis; mortality; selenium status.