If you need a lot, then yes, you need to take potassium
iodide. But nobody should take a lot for
very long. As for
hyperthyroidism, if you want to take your chances, be my guest. But iodine speeds up the thyroid's production, which makes it more likely to burn out if one is already overly active. On the other hand, there is no definitive research on anything in the health field, particularly concerning supplementation -- non enough money for good research on things that can't be patented.