Which dietary component is essential for thyroid hormone production?

Which dietary component is essential for thyroid hormone production?

• A. Iodine
• B. Calcium
• C. Vitamin C
• D. Iron

Answer: (A)

Iodine is the essential substrate for thyroid hormone production. In the thyroid gland, iodide from the diet is taken up and attached to tyrosine residues in thyroglobulin by thyroid peroxidase, forming MIT and DIT, which then couple to form the hormones T3 and T4. Without adequate iodine, the gland cannot synthesize enough thyroid hormone, leading to goiter and hypothyroidism; in fetal development, deficiency can cause serious neurodevelopmental problems. Dietary iodine sources include iodized salt, seafood, and dairy products. Calcium, vitamin C, and iron do not provide the direct building blocks for thyroid hormones, so they do not enable the synthesis of T3 and T4 in the way iodine does.

Iodine is the essential substrate for thyroid hormone production. In the thyroid gland, iodide from the diet is taken up and attached to tyrosine residues in thyroglobulin by thyroid peroxidase, forming MIT and DIT, which then couple to form the hormones T3 and T4. Without adequate iodine, the gland cannot synthesize enough thyroid hormone, leading to goiter and hypothyroidism; in fetal development, deficiency can cause serious neurodevelopmental problems. Dietary iodine sources include iodized salt, seafood, and dairy products.

Calcium, vitamin C, and iron do not provide the direct building blocks for thyroid hormones, so they do not enable the synthesis of T3 and T4 in the way iodine does.