Which of the following is necessary in the diet for normal functioning of the thyroid gland?

Correct option is C

The correct answer is (c) Iodine

Explanation:

• Iodine is a vital trace element required by the thyroid gland to synthesize its hormones, primarily thyroxine ($T_4$) and triiodothyronine ($T_3$).

• These hormones play a critical role in regulating the body's Basal Metabolic Rate (BMR) and controlling the metabolism of carbohydrates, proteins, and fats.

• If the diet is deficient in iodine, the thyroid gland cannot produce sufficient hormones, which leads to the enlargement of the gland, a condition known as Goitre.

• In children, severe iodine deficiency during pregnancy can lead to stunted growth and mental retardation, a condition called Cretinism.

• According to NCERT Class 10 and 11 Biology, iodised salt is recommended in the diet as a simple way to ensure adequate iodine intake.

Information Booster:

• The production of thyroid hormones is regulated by the Thyroid Stimulating Hormone (TSH) secreted by the pituitary gland.

• Seaweed, seafood, and dairy products are naturally rich sources of iodine, though "iodized salt" is the most common source globally.

Additional Knowledge:

Sodium (Option a)

• Sodium is essential for maintaining fluid balance and the conduction of nerve impulses.

• While it is often consumed as sodium chloride (salt) alongside iodine, it does not directly participate in thyroid hormone synthesis.

Calcium (Option b)

• Calcium is necessary for the formation of bones and teeth, blood clotting, and muscle contraction.

• Its levels in the blood are regulated by the parathyroid glands (located behind the thyroid) and the hormone calcitonin.

Potassium (Option d)

• Potassium is an electrolyte that helps maintain normal cell function, particularly in the heart and nervous system.

• It works in tandem with sodium but is not a raw material for thyroid hormones.