Every single cell in the body needs iodine. It is essential for human life; the thyroid is made up of Iodine
(it is 65% iodine) and needs to receive Iodine
steadily in order to function; the thyroid, in addition to your metabolism, controls your hormonal balance, and your ability to detox heavy metals. Iodine deficiency wreaks havoc on your body!
Whether you need to supplement forever depends upon whether you can eliminate all iodine-depleting substances from your diet and environment. I.e., most people do get an adequate supply of iodine from their diet. The iodine in iodized salt is not actually bioavailable. However, seafood contains lots of iodine, seaweed and dark green vegetables contain it, beans contain it, many vegetables contain it. If most people receive adequate iodine in their diet, why should we supplement? Because most people are severely iodine deficient *despite* an adequate dietary intake. That is because there are 4 Halides: Fluoride, chlorine, bromide, and iodine. The First 3 are toxic. They should never be in the human body. All 4 halides compete for the same receptor in the human body--a receptor next to the thyroid, where iodine needs to sit. If any one of the 3 toxic halides enter the human body, that halide will push iodine off the receptor--because they are all stronger than iodine. That is, they are of lower atomic weight, which, counter-intuitively, means that they are much stronger. So. As long as their is fluoride in your drinking water, chlorine in your drinking water and in your shower water (you absorb high amounts of chlorine through your pores when you shower, or when you swim in a chlorine-treated pool) and bromine in your diet (it is in white flour products and all 'convetionally grown' produce, via pesticides) you will likely be iodine deficient. Unless, like a Japanese person, you consume 50 mg of iodine each day via seaweed. Bear in mind though, if you eat that much seaweed (or if you supplement iodine via seaweed) you are more than likely to get mercury and arsenic posioning, because these days seaweed is too high in mercury and arsenic to be healthy.
End cap: If you can eliminate fluoride, chlorine, and bromine, completely from your diet and environment, and get an adequate supply of iodine through yr diet, then you don't need to supplement! But it's hard to do the former. You need a reverse osmosis filter to remove fluoride, and ideally that filter contains a remineralization cartridge, so you're not stuck drinking acidic water. A Vitamin-C shower cartridge will remove all the chlorine from your shower. (and it's the only kind that actually does this). You can avoid bromine by eating only organic food. Fluroide is also in black and green tea, in commercial juices, in boxed cereal--see http://www.fluoridealert.com
and go to "sources" for more details. You have to be a super-health nut to avoid it all the time. It's crazy hard. Supplementing with iodine doesn't hurt. Try Lugol's
and just do a drop a day. It's very cheap if you order it offshore. Just google.