some soils are naturally richer in iodine, especially soils near a sea coast the occationaly get 'sea spray', and the iodine is 'picked up by the vegetable grown in such soil--salt water fish, and sea food (fresh, or salted or dried), (and cod liver oil) provide some too, the human body need very little..

carregeen, (a sea weed that i thing we have mentioned once before) called 'irish moss' also provide some..

carreggen is use in many food and 'food like products (toothpaste, ie) is is a thickener.. (check out your yogurt, ice cream, puddings, -- carreggeen is a very pale white sea weed, and almost tasteless. it is commonly used with dairy products to thicken them.. you might some some carreggeen in foods in your house right now (oh yeah, check the egg nog!)

(anyone remember the giant blanc monge from monty python? blanc monge's (and bavarian creams) were commonly made with carreggeen, too)