I have not personally taken this drug. Below is what may be some helpful information, though.
A family member has been battling ulcerative colitis for more than 10 year now. Her gastro doc prescribed Asacol
to regularize the gut function as well as a major change in her diet. She is now eating significant amounts of fish and chicken with very light seasonings. Breakfasts are lightly toasted breads like Saloio or Sourdough. Lunch is usually chicken, salmon, or tuna salad with either a light seasoning of dill or salt and pepper. In the mornings, she will also mix a 12 or 16 oz. glass of water with acacia to help soothe the stomach and intestinal lining. She has also found a lot of information about IBS and colitis at Heather's Tummy Care
Hope this helps.