Dietary supplements and the thyroid—an update on micronutrient supplementation

Abstract

Thyroid hormones regulate many metabolic processes responsible for growth, development, and metabolism. The essential micronutrient iodine is a building block for thyroid hormones and forms a component of the thyroid hormones triiodothyronine (T3) and thyroxine (T4). Austria is considered an iodine-deficient country due to its geographic location. Therefore, iodine supplementation is recommended for pregnant and lactating women due to its importance for the neurodevelopment of the unborn fetus. Selenium is a component of the amino acid selenocysteine, which contributes to thyroid function in the form of deiodinases aiding the conversion of thyroid hormones in active and inactive forms. Clinical studies have so far demonstrated a vast potential for selenium supplementation in hypothyroidism and autoimmune disorders of the thyroid. For other vitamins and minerals such as zinc, magnesium, iron, vitamin D, and vitamin C, current data are insufficient to make a recommendation. In conclusion, selenium supplementation should be evaluated for specific patient populations in future endocrine guidelines.