Myths vs facts: Selen and Sport

Selenium is an essential trace mineral, integral to selenoproteins like glutathione peroxidase, which protect cells from oxidative damage and support thyroid function. In sports, myths often claim that selenium supplements boost performance, reduce muscle soreness, or speed recovery. The evidence is moderate: while adequate selenium is necessary for antioxidant defense, supplementation beyond sufficiency does not enhance athletic performance in well-nourished individuals. Some studies in endurance athletes show modest improvements in oxidative stress markers, but results are inconsistent and effect sizes small. Selenium deficiency (e.g., in vegan diets or low-selenium regions) may impair recovery, but excess intake is toxic (selenosis), with a tolerable upper limit of ~400 µg/day. For most athletes, a balanced diet provides the recommended 55–70 µg/day. DNA tests for selenium-related genes (e.g., SEPP1) have limited predictive value and should not guide supplementation without blood biomarker confirmation. Evidence: human-moderate. Caveat: Do not self-prescribe high-dose selenium; consult a physician if deficiency is suspected.