Well in terms of engineering, the US is the largest manufacturer of soy in the world because in order to grow lots of corn, you need to grow lots of soy. Corn depletes the soil, Soy replenishes. Of course to get as much soy/corn as we do, it has to be genetically modified. Both are actually fed to livestock and then other surplus goes into processed foods. Which is one reason it is good to avoid processed foods.
Also, what concerns me is what isn't on the labels of our food. Food manufacturers lobby heavily to keep information off our labels including foods that are genetically modified. It is another reason to eat organic foods when possible is to avoid GMO products.
I've increased a lot of my organics in the past few years and I've talked directly to farmers about their growing practices. Of course, you can look at a label and see that the food comes outside of the US but some non organic stuff from in the US is pretty scary, to me at least.
You can't out-exercise poor eating habits.