Hashimoto’s Thyroiditis and Selenium Supplementation

Did you know that the thyroid gland has the highest concentration of selenium compared to any organ in your body? Selenium is a powerful and essential trace mineral actually first discovered by the Swedish chemist Berzelius in 1817. Selenium mainly acts as an antioxidant, anti-inflammatory, and it is involved in the production and activation of thyroid hormone. Selenium protects the thyroid from oxidative damage but a deficiency can lead to an increase in the weight of your thyroid which can be compounded by an iodine deficiency. When you’re deficient in selenium, you actually lose iodine more quickly so these two substances must work in perfect balance. This is an interesting adaptation your body has developed because your thyroid has the potential to be damaged when you are deficient in selenium but you have normal iodine levels. Iodine ensures normal thyroid hormone production but the protective effects of selenium may not be there to clean up free radicals produced during hormone synthesis. It has been found that supplementing with selenium if you are deficient in iodine can actually suppress thyroid function. This is why it may be important to have your iodine status checked before supplementing with selenium so we can figure out the best plan forward. The catch is that supplementing with iodine can increase damage to the thyroid gland in patients with Hashimoto’s disease. This is why you should work with an experienced healthcare practitioner to help figure out the right balance for you. Selenium acts as a “thyroid antioxidant” and is vital for the production of thyroid hormone and it is involved in the conversion of T4 (least active thyroid hormone) to T3 (most active form). One clear pattern on you thyroid labs that can indicate selenium deficiency is a high or high/normal Free T4 but low or low/normal Free T3 with a normal TSH. This indicates that your T4 isn’t converting well to T3 possibly due to a selenium deficiency. Selenium protects the thyroid gland from the damaging effects of thyroid peroxidase (TPO-Ab) and anti-thyroglobulin (Tg-Ab) antibodies. Selenium also can protect the thyroid by binding to mercury and making it completely inert. Mercury is a major thyroid disrupting chemical but not as significant when selenium is present. Selenium and iodine are intricately intertwined in the thyroid gland. They are both necessary for thyroid hormone production, but when iodine-deficient subjects were given selenium alone, it made their hypothyroidism much worse. Since iodine deficiency is very rare in industrialized nations, this is usually not something to be concerned about. Can selenium help Hashimoto’s disease? Three separate studies have shown that selenium supplementation suppress TPO-Ab and Tg-Ab levels. A recent study by Wichman et al. Showed that selenium supplementation reduces TPO-Ab levels at 3, 6, and 12 months and Tg-Ab levels at 12 months. This was only in those treated with levothyroxine (T4), not in those who did not take thyroid hormone.