Here is THE best overview of the VITAL roles that iodine plays in human health I've seen anywhere. I however disagree with their buying into our gov'ts RDA of 120 MICROGRAMS as other developed nation's RDAs are EIGHTY THREE times higher!! Coastal Japanese people eating kelp etc. often consume 40 MILLIGRAMS daily and are amazingly free of health issues common in the U.S.

http://lpi.oregonstate.edu/infocenter/minerals/iodine/