https://mayoclinic.elsevierpure.com/en/publications/selenium-and-graves-disease/

Selenium plays a crucial role in thyroid hormone metabolism and immune regulation. This trace mineral supports the conversion of T4 to active T3 and protects thyroid tissue from oxidative stress. In autoimmune thyroiditis, selenium may help reduce thyroid antibody levels and stabilize thyroid function. Learn where selenium occurs in food, the role of selenomethionine, and safe supplementation levels for thyroid support.