This study aims to examine patient tolerability of personalized dietary fibre consumption recommendations (high-pectin diet versus high-B-fructan diet based on personalized responses), provided by an IBD dietician, based on our novel translational research findings.

Inclusion Criteria:

• Children (age 6-17) or young adults (age 18-39).
• Known or suspected UC or IBDU [there will be 2 control group: non-IBD (undergoing colonoscopy but found not to have IBD; and healthy (no GI symptoms, so not required to have colonoscopy; could be family members)]
• For UC: Remission-mild-moderate disease: Mayo score <10
• Clinical indication for sedated colonoscopy
• Disease location: E2-E4
• Stable treatment (not on steroids; biologics or immunomodulator not changed in last month)
• High likelihood that patients will be able to collect all samples and provide all data

Exclusion Criteria:

• Use of antibiotics for a week or more over the last 3 months
• Use of probiotics or prebiotics at pharmacological doses (adding fibre sources to food or probiotics in yogurt, for example, are allowed)
• History of abdominal surgery, including appendectomy
• Documented enteric infection during the 3 months prior to endoscopy
• Presence of non-IBD bowel conditions (e.g., celiac), anatomical or mucosal abnormalities, motility disorder
• Presence of a systemic disease requiring treatment (cancer, ischemic heart disease, kidney failure, etc)
• Proctitis (E1)
• Systemic steroids (above 10 mg/day of Prednisone)
• Topical therapy within 1 week of endoscopy
• Recent change in IBD treatment (started biologics or IM over the last month)
• Pregnancy or planning to become pregnant during the study
• Inability to understand or sign the consent