While consuming a generally healthy diet may help reduce the risk of developing many chronic diseases, there are some key nutrients that play important roles in thyroid health such as iodine, selenium, iron, and vitamin D. A deficiency or excessive intake of these nutrients may impact thyroid function and increase the risk for developing Hashimoto’s thyroiditis (HT), also known as autoimmune thyroiditis (AITD).
Iodine plays an important role in thyroid hormones, but there is a small range of beneficial iodine intake, as both excessive iodine intake and deficiency may increase the risk of developing thyroid problems. Iodine deficiency commonly contributes to goiters, while autoimmune conditions, such as HT, are more prevalent in situations of iodine excess. Studies have found a mild-to-moderate amount greater than what is necessary is associated with more frequent occurrence of HT, and even small increases may lead to a higher risk of developing antibodies. Therefore, both those who currently have HT and those at risk should aim for the minimal amounts of the recommended daily intake.
Selenium is not only an important mineral with antioxidant properties, but many selenoproteins play key roles in thyroid health and the production of thyroid hormones. Selenium deficiency impacts thyroid hormone levels by elevating the T4:T3 ratio because the conversion of T4 to T3 requires selenium. Thus, it should come as no surprise that the most selenium-abundant organ in the body is the thyroid. Ensuring adequate selenium can help mitigate some of the inflammatory and oxidative stress associations with autoimmune conditions such as HT.
Studies indicate that a higher serum selenium level has been correlated with reduced odds of developing autoimmune thyroiditis and other thyroid diseases. Some studies show that supplementing with selenium improves antibody levels and could restore thyroid function back to normal. Selenium and iodine also have a close relationship, with a deficiency of one exacerbating the other, especially a selenium deficiency in accelerating the depletion of iodine.
Another essential nutrient vital to thyroid health is iron, as it is required to create thyroid peroxidase, the enzyme that produces the hormones. There is a two-way association between chronic anemia and poor thyroid function. One study also found a relationship between iron levels and iodine levels, with the impact of low iron on the thyroid being dependent on iodine status.
Many studies find that low levels of vitamin D correlate with an increased risk for thyroid autoimmunity, likely due to its effect on the immune system. There are minimal food sources of vitamin D, including cod liver oil and fatty fish such as salmon and sardines. Therefore, safe sun exposure and/or supplementation play larger roles in ensuring sufficient vitamin D levels.
Many patients with HT or those at risk of developing HT may benefit from dietary changes. Focusing on essential thyroid nutrients such as iodine, selenium, iron, vitamin D, and gluten may provide a beneficial component to a treatment protocol.
By Kendra Whitmire, MS, CNS