We are planning a series of studies in individuals with ulcerative colitis, primary sclerosing cholangitis and pouchitis to determine if hydroxocobalamin is an effective therapy to treat these conditions. For these indications we are submitting INDs to the FDA as well as protocols to the IRB. Hydroxocobalamin, referred to as vitamin B12a has been approved by the FDA for treatment of cyanide toxicity in up to 5 grams intravenously over 15 minutes twice in a brief period. This has been tested and used in intravenous doses as high as 15 grams in a day. We will be utilizing its pharmacokinetic and safety profile to treat several subsets of patients. We are testing this initially in a healthy population to assess tolerability.

Patients will be recruited at Brigham and Women's Hospital (BWH), at both the main campus and 850 Boylston Street locations. Healthy subjects may be identified as family members of patients who are picking them up from colonoscopy procedures or through the Mass General Brigham Rally system. Flyers and emails will inform interested subjects of the trial and will assist with recruitment.

Patients may be identified by their physician or by a research coordinator with physician permission. Patients identified by their healthcare providers who may meet entry criteria would be approached by a study team member to explain about the trial in more detail and to offer participation. In collaboration with their physician, the patient will decide whether to consent and participate.

We aim to enroll up to 10 individuals for the study. Individuals will be requested to maintain their diets in their usual intake and avoid those foods which they are aware that may induce diarrhea or looser stools for them.

Patients will be given different oral doses of hydroxocobalamin to assess tolerability.

Inclusion Criteria:

• Ages 18-70
• Ability to give consent

Exclusion Criteria:

• Patients who are pregnant or breastfeeding
• Use of chronic medications
• History of hypersensitivity to hydroxocobalamin
• History of chronic constipation or diarrhea
• History of IBS or other GI illness which causes symptoms of diarrhea or constipation