Iodine deficiency is frequently observed in indigenous cultures that primarily consume roots and cassava, which are low in iodine and contain goitrogens.

“so we see island deficiency mostly in indigenous cultures who are eating mainly roots and a lot of cassava and stuff that doesn't have much iodine and and they have nitrogens and isothiocyanates that are going to immune consumption or the compounds are going to compete a little thyroid”