Final answer:
Iodine is added to salt to prevent iodine deficiency, which can cause enlargement of the thyroid gland (goitre) and impact the production of thyroid hormones, leading to a variety of development and metabolic disorders.
Step-by-step explanation:
Iodine is added to salt in the United States to prevent iodine deficiency, which can lead to a variety of health problems. Among these problems, the deficiency can cause a significant enlargement of the thyroid gland, a condition known as a goitre. Iodine is an essential component of thyroid hormones, which are necessary for regulating metabolism, growth, and development. Specifically, the lack of adequate iodine intake can lead to hypothyroidism, characterized by insufficient production of thyroid hormones.
For our bodies, iodine is necessary because it's a key element in the synthesis of the thyroid hormones thyroxine (T4) and triiodothyronine (T3). These hormones regulate numerous metabolic functions and are vital for proper growth and development, especially in the fetal stage and early childhood. In regions where natural iodine levels in the soil and food are low, iodized salt serves as the primary source to meet dietary needs.
Iodine deficiency is the foremost cause of preventable intellectual disability worldwide, particularly severe in children, leading to conditions like cretinism. In adults, it causes reversible symptoms related to hypothyroidism, such as a sluggish metabolism and goitre formation. The fortification of salt with iodine has significantly reduced iodine deficiency in many parts of the world, including the United States.