Linus Pauling Institute: Micronutrient Information Center: Iodine
Iodine (I), a non-metallic trace element, is required by humans for the
synthesis of
thyroid hormones. Iodine deficiency is an important health problem throughout much of the world. Most of the Earth's iodine, in the form of the iodide ion (I
-), is found in oceans, and iodine content in the soil varies with region. The older an exposed soil surface, the more likely the iodine has been leached away by erosion. Mountainous regions, such as the Himalayas, Atlas, Andes, and Alps; flooded river valleys, such as the Ganges River plain in India; and many inland regions, such as central Asia and Africa, central and eastern Europe, and the Midwestern region of North America are among the most severely iodine-deficient areas in the world
(1).