Iodine and minerals. Iodine is required by the body to form thyroid hormone, and iodine deficiency can lead to goiter (abnormal enlargement of the thyroid gland) and hypothyroidism. Currently, most cases of iodine deficiency occur in developing nations.
Vegetarians, however, are at risk of developing iodine deficiency, especially if they live in areas where the soil is low in iodine. Vegans, who do not eat iodine-enriched dairy products, are at an even higher risk.
Other minerals, including iron and
zinc, are essential for normal thyroid hormone metabolism. Coexisting deficiencies of these elements can impair thyroid function. The deficiency of iron,
zinc, and
copper can damage thyroid hormone metabolism.
Zinc. Single and multiple deficiencies of iodine,
selenium, and zinc have distinct effects on thyroid metabolism and structure. Zinc deficiency was associated with decreased concentrations of T3 and free thyroxin in serum by approximately 30 percent. Zinc may play a role in thyroid hormone metabolism in patients with low T3 and may contribute to conversion of T4 to T3 in humans.
Selenium is required for appropriate thyroid hormone synthesis, activation, and metabolism. Adequate
selenium supports efficient thyroid hormone synthesis and metabolism and protects the thyroid gland from damage caused by excessive exposure to iodide. Long-term selenium deficiency in experimental animal models led to thyroid cell death and scarring after high iodide loads. Selenium deficiency may seriously influence the generation of free radicals, the conversion of thyroxineT4 to T3, and the autoimmune process.
One study also found that selenium deficiency decreased the inflammation that is associated with autoimmune thyroiditis. During this study, female patients with autoimmune thyroiditis and elevated antithyroid antibodies were given selenium. At the end of the study, researchers found that a significant percentage of the patients had normalized their antibody concentrations.
Vitamins. Newer research has suggested that antioxidant vitamins, such as
vitamin C and
vitamin E, can reduce the oxidative stress caused by hypothyroidism.
Vitamin E was shown to protect animals from increased oxidation and thyroid cell damage. Another study found that
vitamin E reduced proliferation of goiter cells and auto-antibodies. Finally, an antioxidant mix containing vitamins C and E, along with
turmeric extract, reduced hypothyroidism.