Does Selenium Help with Thyroid Function?

Yes, selenium plays a crucial role in thyroid function as an essential cofactor for thyroid hormone metabolism. The thyroid contains more selenium per gram of tissue than any other organ, with selenium-dependent enzymes called deiodinases converting T4 to the more active T3 hormone. Studies show that selenium deficiency can impair thyroid hormone synthesis and increase risk of thyroid disorders. Research indicates that selenium supplementation may reduce thyroid antibodies in people with Hashimoto's thyroiditis by up to 40%. However, excessive selenium intake above 400 mcg daily can be harmful and may actually worsen thyroid function, so proper dosing is essential.