an intolerance does not have to be global like you suggest. you can have an allergy to pollen, but it only affects your sinus, or your eyes, not your lungs ... etc
you are also assuming the intolerance (and it can be just a sensitivity, which complicates things further) is causing the UC or CD, and it is mostly clear that it is the other way around. Excepting some cases where severe intolerance may have seriously disturbed gut flora to contribute to IBD, the IBD generally makes sensitivities that normally don't bother us suddenly give distressful symptoms. When UC is active in the colon, the normal activity of food and antigens and mucosal permeability can result in some foods causing problems that would not happen if UC was not active. Similar reasoning for areas where Crohn's is active.
Also, if someone's intolerance/sensitivity were causal, it just means that sometimes it caused a problem with Th1 cells and other times it caused a problem with Th2 cells. Then the kind of immune problem determined which IBD and where it effects.
Also, while a person has an "intolerance" the actual problem is located in some tissue or organ. By your logic, why would the effect of intolerance be limited to the GI tract? Why not every cell of the body? Different tissues and organs are very different. For example, pH of colon is different form pH of small intestine. Different kind of cells line each organ.
Your analogy is more apt to fire or draino than allergens. All tissue is hurt by fire and draino, and if we had draino running through the GI tract, we would expect all tissues to blister. But not all tissues are equally sensitive to allergens, and not all tissues are cabpble of the same responses.
I see what you are saying, but the model you invoke is too simplistic.
Post Edited (DBwithUC) : 4/23/2012 10:30:37 AM (GMT-6)