At present, one of the basic problems of the contemporary medicine and physiology is the study of the conservation and improvement of human health. The thyroid gland is one of the largest and most important glands of the body. The thyroid controls metabolism, protein synthesis, the overall sensitivity of the body to other hormones action, stimulates the central nervous system, cardiovascular, digestive and muscular; it absorbs the iodine in the body between thyroid hormones and secret, reducing growth in height and weight of the body. Iodine is an essential component of thyroid hormone, and the lack of iodine causes hypothyroidism. So, iodine deficiency is a major public health issue for people all over the world.