It's actually seems to be making it's way more and more into feed and food. Not sure about the food you get from the local feed store, but industrial producers (some brands in particular) are feeding higher levels of iodine to chickens and that also is seen in their eggs too. Or at least, I assume they are feeding higher levels since that is what they are advertising. I am sensitive to iodine, and it does do some crappy things to me (not least of which is giving me cystic acne out of nowhere so I look like a 14 year old boy...I get carded a LOT after eating foods that add in extra iodine XD), but not anywhere near as bad as what it does to others. Iodine effects thyroid function, and while too little isn't good, the wrong form or too much can really mess some people up. I don't know if your feed would specifically list iodine or not. I'm not sure what the regulations are on that, or who to ask that could tell you for sure. I'm also not sure how long it takes to leave the body (I hear what isn't taken up by your thyroid gland usually leaves in two days), or if cutting around the thyroid gland would help, or if the hormones it sends out are iodine stuffed to the point where it's already spread out in the body. No idea. XD But, I do think it is really sweet of you to take the time to tailor your birds for her, and bet she will appreciate it immensely!