Someone once told me allergic reaction to soy may actually be allergic reaction to GMO soy, not soy per se.

There may be very different stats from one country to another on how much GMO soy gets used.

This is where i think science has been failing us. I have a couple similar stories where I have various reactions to one product but not a very similar product from another vendor. When that happens it would be really helpful if there were a research lab/etc where one could show up with both products and basically say, product A does the following to me, while product B doesn't.

The first time I really noticed this was ~15 years ago I was on a spinach salad kick that started when I purchased an organic pre-packaged salad kit (as In I was almost exclusively eating just spinach salad for a couple weeks because I really liked it and my kitchen was being remodeled). Anyway, those kits were quite expensive, so I switched to a cheaper non organic spinach and my own dressing. I started to have some pretty severe intestinal distress over a couple days, and swapped the spinach for a 3rd organic brand and the problem went away. But because the no organic brand was cheaper I bought a couple other bags assuming it was probably just a bad batch and I had gotten hit by a bacterial infection/whatever and it returned.

So I've had similar issues with coffee (gotten ichy all over when I changed brands and couldn't figure it out for a couple months), and a few other products. My Dr describes me as "allergy prone" but its not as simple as I'm allergic to spinach, or coffee. I seem to have a low grade allergy to something that is sometimes present across multiple food sources. I suspect without any proof at this point its a pesticide or herbicide, since I seem to have far fewer reactions if I'm tending to stick with organic leafy vegetables, and away from crops which have traditionally used more industrial farming processes.

If you look at the pesticide/herbicide studies what is abundantly clear in the US, that just like e-coli its hard to predict/track which foods are affected at any given point . The food growing and distribution system is to complex. So while a farmer may be following all the rules, he may be downwind (or whatever) of another farmer growing and spraying a different crop. Then his crop gets mixed into a larger batch and it goes complexly undetected because in low doses many of these products are considered non-harmful.