What is the role of iodine in the body?

• A. Essential for synthesis of thyroid hormones (T3 and T4) that regulate metabolism.
• B. Aids calcium absorption
• C. Primary energy source for cells
• D. Major component of collagen

Answer: (A)

Iodine is required to make the thyroid hormones T3 and T4. These hormones set the body's metabolic rate—how quickly we burn energy—and drive many processes from heat production to protein synthesis. They’re especially important for growth and brain development in the fetus and young children. So without iodine, thyroid hormone production drops, slowing metabolism and affecting development.

Other options point to roles of different nutrients: calcium absorption depends on vitamin D; an energy source for cells comes from carbohydrates, fats, and proteins rather than iodine; collagen is built from amino acids with vitamin C, not iodine.