a little elemental Iodine is ok, but yes Iodide is oxidized in some places in the body to iodine.
put a gram of KI in 100 ml of water and leave open to the air a couple hours. What happens ? What does that tell you ?
How much Iodine do you need ? It depends.... if that is you in the avatar doing a duck face, then you need more than the usual amount because I read ducks need a lot of Iodine :)