I was recently researching the link between iodine deficiency and anxiety. I didn't find a lot of convincing information, so I decided to try it on myself.
I've had IBS for at least a year now and strangely enough, I found it to be completely anxiety related and not at all to do with the bowels themselves. I also have regular anxiety as well, but I haven't seen any doctors about either condition because I refuse to get on the meds wagon.
Two nights ago, I painted two squares of 2.5% iodine tincture onto my wrists. I could feel the effects of that by the next day, I went the whole day without any symptoms. One important thing I did find in my research, was that selenium deficiency apparently aggravates iodine deficiency, so naturally, I took 200mcg of selenium the next night in addition to painting iodine on my biceps this time. Still no symptoms of anxiety or IBS on the third day now and I'm hoping this is the real deal. Another interesting bit, I used to take selenium regularly as part of my supplement routine and then stopped for a long time without any obvious reason (ran out and forgot to replenish.. ). For informational purposes, I'm 23, smoke regularly, drink on weekends, eat relatively healthy (always home cooked) but not a ton of fruit and vegetables in my diet.
Interesting Fact: The iodine painting deficiency test is not an indication of anything. Most of it evaporates and becomes colorless, and the rate of that is dependent on the environment that you are in. It does absorb into your system, however, in small amounts. To back that up: When you do this so-called test, wait until it disappears, then get some hydrogen peroxide and apply it to the area; you will see that the whole thing is actually still there.
Best of luck!