Iodine is one of the most important elements required for the production of thyroid hormones. The thyroid hormones are one of the most important metabolic hormones produced in the body.
Iodine has largely been deficient in snowbelt. Therefore there was a time when hypothyroidism and goiter were most commonly seen in these regions.
Hypothyroidism can cause many problems. Some noteworthy problems are myxedema coma and cretinism. The latter affects the children due to the involvement of hypothyroidism in mother and child.
And the important fact remains that very small amount of iodine is needed in the body per day. Chiefly because iodine in the body is largely recycled.
Another important fact is that most of the salts in the body are iodinized. And this is supposed to reduce the incidence of iodine deficiency. But the fact remains that the salt that you add during cooking and heating loses its iodine. Iodine has very low boiling point and the average cooking evaporates the iodine.
The best iodine absorption is from the salt added on top.