Iodine

A chemical element, in the periodic table iodine has the symbol I and atom number 53.

One of the halogens, it is an essential trace element; the thyroid hormone molecule, known as thyroxine?, contains iodine atoms. In areas where there is little iodine in the diet -typically remote inland areas where no marine foods are eaten - iodine deficiency gives rise to goitre. In many (but not all) such areas, this is now prevented by the addition of small amounts of sodium iodide to table salt - this product is known as iodised salt