hi, thank you for your query. ulcerative colitis causes swelling of the inner lining of your colon and rectum (large intestine). It damages the lining, causing it to bleed or ooze mucus or pus. this is a common occurance with ulcerative coloitis. i would advise you- 1.To eat a well-balanced, healthy diet. 2.Avoid foods that make your symptoms worse. 3.Avoid foods that are known to cause gas, such as beans, spicy food, cabbage, broccoli, cauliflower, raw fruit juices, and fruits -- especially citrus fruits. 4.Avoid or limit alcohol and caffeine. They may make your diarrhea worse. 5.Eat smaller meals, and eat more often. Drink plenty of liquids. these should keep your symptoms under check. thank you, wishing you good health