You could try digestive enzymes, or beano--some of us find it effective with "challenging foods." I use enzymes and I personally find them helpful and effective, although WARNING, it doesn't work on broccoli or cabbage or onions for me, but it does with beans and soy is a bean. Sometimes the sugars cause digestive distress until your body adjusts to metabolizing them/processing them. A fair trial run of soy in your diet sounds like a fair shot.