High Level of Selenium Exposure in the Strong Heart Study: A Cause for Incident Cardiovascular Disease?

Increasing evidence suggests that high selenium (Se) exposure is associated with adverse health effects. However, limited evidence exists on the association of Se exposure with cardiovascular disease (CVD), especially in communities affected by high naturally occurring Se in environmental media. We evaluated the prospective association between urinary Se levels and CVD incidence and mortality for 2727 American Indian adults who participated in the Strong Heart Study, with urinary Se levels measured at baseline (1989-1991) and CVD outcomes ascertained through 2017. The median (interquartile range) of urinary Se was 49.0 (36.7-67.4) μg/g creatinine. The multivariable adjusted hazard ratios (95% confidence interval) of incident CVD, coronary heart disease, and stroke comparing the 75th 25th percentile of urinary Se distributions were 1.11 (1.01-1.22), 1.05 (0.94-1.17), and 1.08 (0.88-1.33), respectively. In flexible dose-response models, increased risk for CVD incidence was only observed when the urinary Se level exceeded 60 μg/g creatinine. For CVD mortality, a nonstatistically significant U-shaped relationship was found across urinary Se levels. There was no evidence of effect modification by other urinary metal/metalloid levels. Our observation leads to the hypothesis that elevated Se exposure is a risk factor for CVD, especially in Se-replete populations. 37, 990-997.