I2 is NOT found in nature. it is necessary to combat the halogen imbalance created by man. it is necessary to correct cycsts in breasts, ovaries, prostate and colon, etc. in other words, I2 is therapeutic only. KI is just a dietary supplement and can be taken in massive quantities according to the nutritional needs.
i spot check from time to time using an elemental(lugols, SSKI 2% - any water based mix of KI and I2). i went a very long time without doing that and did get a boost from taking SSKI 2%. 2% of 390mg is about 8mg of I2(magnets on the bottle, of course). you must take it in water to get the full effect. that only lasted a couple of days. i believe it is more of an artifact of the environmental halogens than a real inherent need for elemental iodine.