The only physiological role known for iodine in the human body is in the synthesis of thyroid hormones by the thyroid gland.
The hormone is thyroxin. Thyroxin controls everything from how often the heart beats to the body’s metabolism.
Iodine from the diet is absorb throughout the gastrointestinal tract. Dietary iodine is converted into the iodide ion before it is absorbed.
The iodide is used by the thyroid gland for synthesis of thyroid hormones and the kidneys excretes excess iodine with urine.
People need to eat iodine containing food regularly, however, because only the amount needed by the thyroid gland to make sufficient amounts of thyroxin is absorbed by the body at any one time, excess iodine is not stored.
In the absence of sufficient iodine the gland attempts to compensate for the deficiency by increasing its secretary activity, and this cause the gland to enlarge. This condition is known as goiter.
Iodide found in seafood; however, large differences in iodide content exist between seawater fish and freshwater fish. Other protein rich foods also supply iodide including milk, yoghurt, egg and meat.
An additional source of iodide is breads and grain products made from bread dough.
Iodine in human nutrition
