Is Selen useful for fatigue?

Selenium is an essential trace mineral critical for thyroid hormone metabolism and antioxidant defense. Deficiency can contribute to fatigue, especially in hypothyroidism or certain diseases. However, evidence for selenium supplementation reducing fatigue in generally healthy individuals is limited and inconsistent. Some studies show modest benefits in elderly or specific patient groups, but overall the effect is small. Importantly, excess selenium can be toxic (selenosis), causing hair loss, nail brittleness, and even neurological symptoms. Therefore, supplementation should only be considered after confirming low selenium status via blood tests (serum or whole blood). MyBody-X tests do not directly measure selenium but may report genetic variants in selenoprotein genes (e.g., GPX1, SEPP1); these have weak predictive value for individual needs. In summary, selenium is useful for fatigue only if deficiency exists; otherwise, focus on a balanced diet. Evidence: human-moderate.