Nicotinamide Riboside in Ulcerative Colitis

Inclusion Criteria: * Pediatric patients (≤18yo); * Diagnosis of mild to moderate ulcerative colitis as determined by Pediatric Ulcerative Colitis Activity Index (PUCAI) and endoscopic scoring (Mayo) at the time of colonoscopy; * Although the investigators will target newly diagnosed patients (therefore, treatment naïve), patients with established disease will also be enrolled. Exclusion Criteria: * Patients with acute severe ulcerative colitis; * Concurrent gastrointestinal infection (ie. Clostridium difficile, Cytomegalovirus, etc.); * A diagnosis of Crohn's disease; * Indeterminate colitis/IBD-U; * In general, patients that have been treated with steroids or antibiotics in the past three months. Patients on Biologic medications may be enrolled if their dose has been stable for at least three months. Final determination of eligibility will be at the discretion of the treating investigator. After the initiation of the study, subjects may receive any medication to treat their disease as dictated by their care providers; * Patients who have other chronic inflammatory/autoimmune disorders or prior malignancy; * Pregnant women (All women of childbearing age will be required to use contraception at the time of inclusion). * Patients with existing renal or hepatic dysfunction; * Per standard of care guidance, subjects with platelets \<50,000 do not undergo endoscopy and, therefore, are not eligible.