Every organ that secretes something needs large amounts of iodine to function normally. See a partial list below. Note that the thyroid glands need the most iodine, but the rest won’t work correctly without iodine. Note that organs that secrete something are the same organs that normally get cancer.
The Japanese that consume large amounts of seaweed (contains iodine) have the least cancer of anyone on the planet! Iodine seems to be protective against cancer.
Iodine kills all single-celled organisms, and they cannot become resistant to it.
The parts of the body exposed to the outside world contain 30 times the amount of iodine as the blood. This effectively creates a shield of iodine around the body, protecting it from infections. Of course this shield cannot exist if you don’t consume enough iodine.
If microorganisms get past your iodine shield, white blood cells create hydrogen peroxide and ozone to kill the “bugs” inside the white blood cells. Thus iodine, hydrogen peroxide and ozone are critical components of a normal immune system.
There are only micrograms of iodine in table salt. The body needs about 1000 times that much to function normally. The soils and foods in the US are depleted of iodine. Unless you normally consume seaweed, you are deficient in iodine and should be taking it as a supplement. You need to take about 12.5 mg per day in tablet form. Do NOT take alcohol-based iodine orally.
I was taught that placing iodine on the skin, as a test for the need for iodine, was valid. It was said that as soon as the body had enough iodine, it would be left on the skin and not absorbed. It has been found that that is not correct!
Dr. David Derry says, "The "test" of putting iodine on the skin to watch how fast it disappears is not an indicator of anything. The iodine disappearance rate is unrelated to thyroid disease or even iodine content of the body. Meticulous research by Nyiri and Jannitti in 1932 showed clearly when iodine is applied to the skin in almost any form, 50% evaporates into the air within 2 hours and between 75 and 80 percent evaporates into the air within 24 hours. A total of 88 percent evaporates within 3 days and it is at this point that the evaporation stops. The remaining 12 percent that is absorbed into the skin has several fates. Only 1-4% of the total iodine applied to the skin is absorbed into the blood stream within the first few hours. The rest of the iodine within the skin (8-11%) is slowly released from the skin into the blood stream. "