There isn’t a magic diet for thyroid health, nor is there strong evidence for eliminating entire food groups. Instead, aim for a colourful, varied diet rich in the following essential nutrients:
1️⃣ Iodine
Iodine is a crucial component of thyroid hormones. Deficiency is a common and preventable cause of intellectual impairment, which is why iodine is fortified in salt. However, too much iodine can increase the risk of both hypo- and hyperthyroidism. Supplementation is only recommended during pregnancy and breastfeeding.
2️⃣ Selenium
Selenium is involved in the enzymes (deiodinases) that produce thyroid hormones. Deficiency is linked to an increased risk of autoimmune thyroid disease. Supplementing with selenium for patients with Hashimoto’s has been shown to decrease anti-TPO antibodies but does not change TSH or thyroxine dose. Selenium supplementation has also been shown to improve Graves’ eye disease and may prevent hypothyroidism in pregnant women with positive antibodies. However, supplementation is not recommended for the general population due to the risk of toxicity at doses above 400 µg/day.
3️⃣ Zinc
Zinc plays a role in the production of TRH, TSH, and the enzymes that make thyroid hormones. Zinc deficiency is associated with an increased risk of goitre. Supplementation has been shown to improve hypothyroidism in areas at risk of malnutrition, in people with Down syndrome, and in women with obesity. However, zinc supplementation for the general population and thyroid health has not been extensively studied in large, well-designed trials.
4️⃣ Iron
Iron is required for thyroid hormone production (TPO activity), and deficiency is associated with hypothyroidism and elevated anti-TPO antibodies. This association is partly due to malabsorption, malnutrition, and inflammatory conditions. Thyroxine treatment can improve anemia, and some small studies show that treating iron deficiency can improve hypothyroidism.
5️⃣ Magnesium
Magnesium deficiency has been linked to an increased risk of hypothyroidism, but the impact of routine supplementation is not well studied in randomized controlled trials (RCTs).