Iodine is integral to thyroid function. Every cell in our bodies have receptor sites that when the appropriate vitamin, mineral, hormone etc land in the receptor site, the cell will perform its' intended function. When we are deficient in iodine, other elements can fill the receptor site space, (fluoride, chlorine and bromine) and can be detrimental. Thyroid function is affected greatly by iodine deficiency, causing a number of problems with metabolism among other things. Bringing iodine levels up to appropriate levels kicks these other elements out of where they do not belong restoring the possibility of proper cell function.
Again, we have had our iodine levels tested and found our levels to be quite deficient. Our naturopath prescribed 5mg of Iodoral.
To be safe, without being tested, you can get a much smaller dose of iodine, in Organixx Iodine. I have linked that here.