Selenium for Immune Function

Research suggests that selenium plays a meaningful role in supporting immune function, with multiple reviews indicating that deficiency in this trace mineral is associated with weakened immunity, increased susceptibility to infection, and impaired antioxidant defenses that underpin healthy immune responses. Studies indicate that selenium contributes to immune competence across the lifespan, and one 2022 review noted its potential as a cofactor in enhancing immune responses, including to vaccination. The available evidence is largely drawn from narrative and systematic reviews rather than large-scale randomized controlled trials, which limits the strength of conclusions that can be drawn about supplementation specifically. Importantly, several reviews highlight a critical U-shaped relationship between selenium status and health outcomes, meaning that supplementation appears most relevant for individuals with confirmed deficiency, while those with already adequate or high selenium levels may see no benefit and could face increased risk of adverse effects such as elevated diabetes risk — a finding that underscores the importance of assessing individual status before considering supplementation.