Selenium as an adjunctive nutrient in the treatment of hypothyroidism: Evidence-based insights

Background: Selenium plays a vital role in thyroid hormone metabolism and protection from oxidative damage. Interest has grown regarding its role as an adjunctive nutrient in managing hypothyroidism, particularly autoimmune thyroiditis. Objective: To systematically review and synthesize evidence from randomized controlled trials (RCTs), observational studies, and meta-analyses on selenium supplementation in hypothyroidism. Methods: Databases including PubMed, Scopus, and Cochrane Library were searched up to August 2025 using terms “selenium,” “hypothyroidism,” “Hashimoto’s,” and “thyroid autoimmunity.” Results: Twenty-two relevant studies (15 RCTs, 4 meta-analyses, 3 observational) were included. Selenium supplementation (50–300 µg/day) consistently reduced thyroid peroxidase antibodies (TPOAb) in autoimmune hypothyroidism, with mixed effects on thyroglobulin antibodies (TgAb), TSH, and T4/T3 ratios. Benefits were more pronounced in selenium-deficient individuals and those not on levothyroxine. Adverse events were rare at physiological doses. Conclusion: Selenium shows promise as an adjunct therapy in autoimmune hypothyroidism for antibody reduction and possible symptomatic improvement. Evidence is insufficient for universal supplementation; benefits appear subgroup-specific.