The whole body needs Iodine and the immune system uses it.
I believe most people are deficient enough to cause significant health problems.
I suspect I would not have developed colitis if I was Iodine sufficient.
If you read the articles on http://www.Iodine4health.com
you will get a better idea why this is so. I now take Lugols 8 drops and 10 to 20 drops of reduced Lugols (ie Iodide),that's over a 100mg. Potassium Iodide or SSKI is easy to take in larger amounts and I believe this may be important for colitis and IBD in general. I think the effect on the adrenals is also important.
Iodine is found in high levels in the thyroid, breast, liver, lung, heart, and adrenals and is also accumulated in the skin and mucous membranes