Iodine is a micro mineral. This means it is a dietary mineral that is required in relatively smaller amounts. Micro minerals are associated with enzymes, and enzymes are required for proper body metabolism. Many enzymes require one or more micro minerals to function properly.
Iodine is needed by the thyroid gland in order to make thyroxin as one of its major functions. Thyroxin is an iodine-containing hormone that controls the rate of body metabolism, or heat production.
When iodine is deficient in the body, goiter, also known as “big-neck”, can occur. Goiter is nature’s way of enlarging the thyroid gland to try and make more thyroxin when there is an insufficient amount present. Other deficiency symptoms include stillbirths and weak young, hairless pigs, and woolless lambs at birth. There is no satisfactory treatment for animals that have developed pronounced iodine deficiency symptoms.
Long-term chronic intake of large amounts of iodine reduces thyroid uptake of iodine. Marked species differences exist in tolerance to intake of iodine. Good sources of iodine are calcium iodate and ethylenediamine dihydriodide (EDDI).
Mature animal bodies contain less 0.00004% iodine. Iodine deficiencies are world-wide. In the United States, the Northwest, the Pacific Coast and the Great Lakes, goiter is an issue.