Casein is a milk product which, of corse, is an IBS no-no! Ironically (as far as I know) all soy and rice "cheeses" contain casein. Heather includes these cheeses in some of her recipes. She has said the small amount of casein in these cheeses should be tolerable for IBS people. However, I don't know. Basically you would have to try it to see if you could tolerate it. Personally I stay away from anything containing casein.