Inclusion Criteria:  Ulcerative colitis patients over the age of 19 with mild to moderate symptoms using 5-ASA (Mayo score 3-9) Patient who signed the consent form  Exclusion Criteria:  The extent of ulcerative colitis is limited to proctitis History of bowel resection History of using other medication than 5-ASA such as immunomodulators, steroid or biologics within 3months history of using antibiotics or probiotics within 2 weeks Pregnant or lactating woman Requiring hospitalization and imminent need for surgery