Some salts do carry an undisputed health benefit. Iodized salts include trace amounts of potassium iodide, and thus are a source of a mineral that’s essential for proper functioning of the thyroid gland, which regulates the body’s heat production, protein metabolism, and development of the nervous system. Iodine is a chemical relative of chlorine and readily found in ocean fish, seaweeds, and crops and animals raised near the seacoast. Iodine deficiency was once common in inland areas, and is still a significant problem in rural China. It causes both physical and mental impairment, especially in children.