Selenium is a trace mineral that has been studied for its role in cardiovascular health. Scientific evidence suggests that selenium is important for heart function primarily because it is a crucial component of antioxidant enzymes, such as glutathione peroxidases, which help protect cells from oxidative damage. Oxidative stress is known to contribute to the development of atherosclerosis and other cardiovascular diseases. Several observational studies have found associations between low selenium status and an increased risk of heart disease, including coronary artery disease and heart failure.

However, clinical trials on selenium supplementation have produced mixed results. While some studies, such as those conducted in regions with low selenium levels, show a potential benefit in reducing cardiovascular risk, larger randomized controlled trials in populations with adequate selenium intake generally do not show a significant reduction in heart disease events with selenium supplementation. The SELECT trial, which tested selenium supplementation for cancer prevention, also monitored cardiovascular endpoints but found no significant benefit. Excessive selenium intake can be harmful, so supplementation is not universally recommended for heart health unless a deficiency is present.

In summary, while selenium is essential for cardiovascular health and deficiency is associated with increased risk, the evidence for supplementation in the general population to support the heart is moderate and context-dependent.