Ulcerative colitis is a chronic inflammatory disease primarily involving the colon and has long been considered to be due to a dysregulated immune response targeting the colon, and involves unknown environmental factors. Currently, no effective therapy targets the microbiota or its interaction with the colonic epithelium. Diet has a significant impact on the composition of the microbiota; however, no dietary intervention to date has proven effective for induction of remission. The primary objective of this study is to determine whether the Ulcerative Colitis Diet (UCD) can induce remission or response in pediatric UC patients with active mild to moderate UC on a stable medication.