Not yet investigated
What we have so far
It saturates the thyroid so radioactive iodine cannot enter, and it protects that one organ from that one isotope. Nothing else.
This star is on the map because the show intends to take the question apart properly — the trials, how it is actually tested, whether the thing sold is the thing studied. That work is not done yet, and nothing here should be read as a conclusion. When the investigation is published it will appear on this page.