Natural Factors Iodine from Kelp - Kelp is a sea vegetable and a naturally concentrated source of important minerals, particularly iodine, potassium, calcium, and magnesium, as well as many trace minerals. Iodine is an essential nutrient that the body needs for proper thyroid gland function and making thyroid stimulating hormone. It is important to get enough iodine through the diet. Natural Factors Iodine from Kelp is harvested from kelp beds in the cool waters of the North Atlantic Ocean where the aquatic environment is pure and clean.