Probably also caused by other aspects of American wheat (many "sensitive" people notice they can eat bread in Europe just fine), such as higher glyphosate content, fortification with nasty stuff like vitamin A, possibly others.
>nasty stuff like vitamin A
Pardon?
People get far too much of it (IIRC there even was a Polish study that kids already have a way too high intake), large parts of the population in most Western countries are liver toxic avoiding to analysis of accident victims, it significantly increases your osteoporosis risk, many people (anecdotally, including me) experience lots of health improvements after reducing their intake, and so on.