I started taking Asacol when I was first dxed in '06. Never had a flare until I stopped taking it, and I tapered down. There are only a few meds that I'd stop cold turkey and not expect some negative effect, and Asacol is not in that category.
I don't believe diet triggers a flare, but it certainly contributes to how I'm feeling physically. Certain foods make me gassy, certain foods make me go to the bathroom alot, but no food itself makes me bleed or gives me near-constant diarrhea for weeks on end.
Hope you get your flare under control soon. If you end up on the Asacol again, you might want to consider taking it awhile after you are feeling better, and then do a slow taper off. Some people are able to maintain remission without meds.
36 y.o. male
Diagnosed w/ moderate UC in May '06
Meds & supplements:
Asacol, Florastor, VSL#3, Wellbutrin XL, Prozac, multi-vitamin, Allegra, Lialda, Colocort, Prednisone, flaxseed oil, L-glutamine.