It is a required nutrient for human health. Every cell in the human body requires iodine, and has a receptor to absorb iodine. Iodine is also required by our immune system to function properly.
There is a severe Iodine deficiency epidemic in progress where 75% or more of the population is deficient.
Iodine is used by our immune system to kill off defective & cancerous cells (via Apoptosis), bacteria & fungus.