I'm shocked to learn just how widespread iodine deficiency is among people eating a "normal" diet (I would have guessed less than 10% prevalence).

The worst part is, a lot of that decline is from people trying to eat 'healthy' - and cut out as much salt as possible. Guess what the main source of iodine for people who can't afford seafood for every meal is? Iodized salt.

(If you want US figures for deficiency, you can find some cites in my iodine page, or simply search for papers related to the long-running NHANES survey which is the main source of evidence.)