Addition of iodine in the diet is necessary to

The thyroid gland secrete two hormones - tetraiodothyronine or thyroxine (T4) and triiodothyronine (T3). Iodine is essential for the normal rate of hormone synthesis in the thyroid. Deficiency of iodine in our diet results in hypothyroidism and enlargement of the thyroid gland, commonly called goitre. Iodine intake helps in treating hypothyroidism.