Iodine is a trace mineral which is primarily used for thyroid hormone production and is necessary for appropriate development and growth.
Our body contains between 20 to 30 milligrams of iodine. Of this, about three-quarters is in the thyroid. This is because iodine makes up the thyroid hormones. T4 and T3 are named as such because of the tyrosine amino acid, and then four or three iodine molecules. The rest of the iodine is scattered throughout the body as every single cell uses it.