It is useful to remember that the human body works on the minimum of anything it needs.
Besides "working" with only the minimum amount of any given item, the amazing human body "works" in the virtual absence of items considered essential for proper nutrition. We have lots of backup systems and the ability to compensate for deficiencies and still "work". Just not work as well and not work as long without problems somewhere down the road. I daresay that many of the people who come to this website are here because they have arrived at "somewhere down the road".
It is also useful to remember that the human body often works MUCH BETTER on more than just the minimum amount needed of any given vitamin, mineral or other nutrient. The minimum daily amounts of many items are not at all the same as the optimum daily amounts for general health and an optimum immune system that will help prevent flu, cancer and many other illnesses. For example, the minimum recommended daily amount of vitamin C is merely enough to prevent scurvy. So the body does work on that amount, but it does not get nearly all the benefits it would from larger amounts of vitamin C. Women who have concerns about breast cancer would be better served by much larger amounts of iodine, vitamin C, selenium, Vitamin D3 and others than merely the minimum amounts for the body to function.
There is also often a difference between maintaining adequate amounts for every day well being and the use of therapeutic amounts to resolve specific conditions. Imo, the amount that a person should be taking of many items will vary widely according to the purpose for which the items are intended and the conditions, if any, being addressed. And that is true for iodine and many other items.
I don't mean to suggest that anyone needlessly take mega-doses of vitamins and minerals and such, but a healthy diet, adequate sunshine and wise supplementation are all musts for optimum health. Most of us are woefully deficient in having even the minimum RDA of many vital vitamins and minerals (magnesium for example), and almost none of us get all the trace minerals we need. And that is true even for those who largely avoid our SADS diet, thanks to our depleted soils, factory produce and over-processed foods on our grocers shelves.