Nutrients deficiencies and GMO foods can also be one of the root causes of thyroid conditions. Iodine is a crucial nutrient for thyroid function. Thyroid hormone is rich in iodine, and deficiency of iodine can cause both hypothyroidism and goiter (a swelling of the thyroid gland). Zinc is required for the synthesis of thyroid hormone, and deficiency of zinc has been shown to result in hypothyroidism.
Selenium, a cofactor for iodothyronine deiodinase, is required to convert T4 (the inactive form of thyroid hormone) into T3 (the active form of thyroid hormone). Selenium deficiency exacerbates conditions caused by inadequate iodine intake.