It's not IBS safe because if you replace the amount of butter in that recipe (it calls for 12 tablespoons) with another form of fat such as smart balance light (not even sure if that would work), it would still be much to fatty. Add in the egg yolks and the chocolate chips (which are about 50%+ fat, yes even non-dairy ones) and these cookies will most certainly trigger an attack. The challenge with making cookies IBS friendly is replacing the butter with something else. Butter is what gives cookies their form and texture. You would need something equally fatty, like margarine or shortening to replace it for the cookies to come out as if they were made with butter. This is problematic because an IBS safe diet requires that no more than 25% of the calories from something you eat be from fat. That's why IBS safe cookies have to be reformulated - thus the recipe I gave you.