In Raising the World’s I.Q., the Secret’s in the Salt (2006)
> In many places, like Japan, people get iodine from seafood, seaweed, vegetables grown in iodine-rich soil or animals that eat grass grown in that soil. But even wealthy nations, including the United States and in Europe, still need to supplement that by iodizing salt.<p>Where did Western people get iodine before it was necessary to add it to salt? Has our soil been so depleted that iodine is no longer present in the vegetables grown in it?