Is Selen useful for weight loss?

Selenium is an essential trace mineral crucial for thyroid function and antioxidant enzymes (e.g., glutathione peroxidases). Mechanistically, selenium deficiency could impair thyroid hormone metabolism and thus theoretically slow metabolism, potentially hindering weight loss. However, there is no robust human evidence that selenium supplementation directly promotes weight loss in well-nourished individuals. Existing studies are small, inconsistent, and often confounded by iodine status or overall diet. Consumer DNA tests analyzing selenium-related genes (e.g., GPX1, SEPP1) are not validated for weight management and provide no actionable guidance. Moreover, selenium is toxic in excess (selenosis), causing hair loss, nail brittleness, and neurological damage. Supplementation without confirmed deficiency is not recommended. Evidence: mechanistic plausibility, but no clinical support for weight loss.