Which mineral is required for production of thyroid hormones that regulate growth, development, and metabolism?

• A. Calcium
• B. Magnesium
• C. Iodine
• D. Fluoride

Answer: (C)

Iodine is the mineral needed to make thyroid hormones. The thyroid gland incorporates iodine into the hormones T4 and T3, which are essential for regulating growth, development (especially brain development in early life), and how the body uses energy. When iodine intake is insufficient, the thyroid can’t produce enough hormones, leading to slower growth, developmental issues in children, and metabolic problems in adults. In pregnancy, adequate iodine supports fetal brain development, so getting enough iodine in the diet is particularly important. Sources include iodized salt, seafood, and dairy products.

Calcium supports bones and teeth and various bodily functions but isn’t used to produce thyroid hormones. Magnesium acts as a cofactor in many enzyme reactions but doesn’t directly enable thyroid hormone synthesis. Fluoride strengthens teeth but does not influence thyroid hormone production.