Which mineral is essential for thyroid hormone production and metabolism?

• A. Calcium
• B. Selenium
• C. Iodine
• D. Copper

Answer: (C)

Iodine is the mineral essential for producing thyroid hormones and for their metabolic effects. In the thyroid gland, iodine atoms are attached to the amino acid tyrosine within thyroglobulin to form the hormones T4 and T3. If iodine is lacking, the gland can’t synthesize enough of these hormones, which slows the body’s overall metabolism and can lead to enlargement of the thyroid (goiter) as the gland tries to compensate. Once made, thyroid hormones regulate the rate at which the body uses energy, affecting carbohydrate, protein, and fat metabolism across many tissues. Adequate iodine intake—through iodized salt, seafood, and dairy—ensures proper production. While other minerals like selenium support related processes (for example, converting T4 to the more active T3 and protecting thyroid cells), iodine is the key mineral required for the actual production of the hormones.