Selenium supplementation for heart health: overlooked, unnecessary, or uncertain?

Selenium isn’t a famous nutrient. There aren’t any major organizations advocating for increased selenium intake and more than 97% of adults in the U.S. meet the estimated average requirement. An essential nutrient, selenium’s main biological role has to do with a variety of proteins called selenoproteins^[1], of which some are major antioxidant enzymes, some are involved in mitigating the inflammatory response^[2], and some playing a role in thyroid hormone^[3] metabolism, to name a few functions. Severe selenium deficiency plays a substantial role in Keshan disease^[4], an often fatal cardiomyopathy characterized by an enlarged heart, cardiac arrhythmias, and congestive heart failure. Some research^[5] points to the role of selenoproteins in protecting heart tissue from oxidative stress as a plausible reason for selenium’s role in preventing Keshan disease, among other functions.

Given these observations and the role that inflammation^[6] and oxidative stress^[7] play in cardiovascular diseases, it’s plausible that selenium could be involved in heart disease prevention and treatment. Some observational studies^[8] have found inverse associations between selenium levels and coronary heart disease risk, although there are some contradictory reports. In particular, NHANES data suggests that serum selenium levels and cardiovascular mortality have a nonlinear relationship, in which cardiovascular mortality decreases as selenium status moves toward about 120 ng/mL and increases thereafter, which may explain some of the inconsistencies in other research.

To help better understand the role that selenium plays in cardiovascular disease and whether supplementation confers any benefits, the study under review was a meta-analysis of randomized controlled trials assessing whether selenium supplementation affects the mortality rates of heart disease patients and several heart disease risk factors.

There’s reason to think that selenium could be relevant in the prevention of cardiovascular diseases, and observational evidence suggests a role for it. The study under review is a new meta-analysis of controlled trials exploring whether the plausible correlation seen in previous research suggests a causal role for supplementation.