I have often wondered about this as well. I just found out that I was misdiagnosed with UC, and that I actually have IBS. What threw my doctor off was the severity of the attacks and the rectal bleeding, but he is now positive it is IBS. I know that often if I eat ice cream, particularly the soft serve type, I will suffer for it, but not always. When he told me to avoid dairy, I asked if it was possible for it to only be a trigger when I was in a flare, and not at times when I was not in a flare. He said it was more likely that it was a permanent type of intolerance or aversion, but that it had to build up or had an accumulative affect. So eating it today might be okay, tomorow too, but eventually it would build up and cause an attack. It sounds plausible, as I know that this is how honey bothers me. I can get away with eating a bit once in a while, but too much or too many days with just a nibble and I will be very ill.
fibromyalgia, Irritable Bowel, restless legs, polycystic ovarian syndrome.