Yeah, I'd consider it a dietary supplement. Unfortunately, the stuff I have is marketed as a food because it's essentially just brown seaweed. The bottle I have doesn't break it down to mg of Iodine per tablet. However, from the wiki link above "The main use of bladder wrack (and other types of seaweed) in herbal medicine is as a source of iodine, an essential nutrient for the thyroid gland."

There are more concentrated forms of iodine; I started taking these and a more concentrated form called Iosol the day after the tsunami. Unfortunately, those are what have suddenly become out of stock. The peeps that really need KI are in Japan, buying it for use here in the US for this incident is a waste IMO. We don't have any KI here. If I did I'd donate it.