Adequate amounts of nutritional substrates are necessary for the thyroid gland to function efficiently. In addition, T4 must be de-iodinated in peripheral tissues for the thyroid’s infuence to be exerted at the tissue level. Thyrocsin provides nutritional substrates for the initial production of thyroid hormones as well as those cofactors needed for peripheral conversion to the bioactive thyroid hormone T3. Animal studies of the Ayurvedic adaptogen Ashwagandha show improved thyroid function and antioxidant activity.