What role does Selen play in longevity?

The role of selenium in longevity is not yet fully resolved. Selenium is an essential trace element that acts as a cofactor for selenoproteins (e.g., glutathione peroxidases), which protect against oxidative stress and support thyroid function. An adequate selenium status is associated with reduced oxidative damage and DNA repair – mechanisms that could theoretically slow aging. However, intervention trials show inconsistent results: while correcting a deficiency is beneficial, supranutritional doses can be toxic and may increase the risk of type 2 diabetes. The evidence for a direct lifespan extension in humans is weak and largely based on observational studies. Genetic variants in selenoprotein genes (e.g., GPX1, SEPP1) may modulate individual requirements, but direct-to-consumer DNA tests do not provide clinically actionable guidance. In summary, avoiding deficiency is prudent, but routine supplementation without proven insufficiency is not supported by current evidence. The evidence grade is mixed/unclear.