Vitamin D Regulation of Gut Specific B Cells and Antibodies Targeting Gut Bacteria in Inflammatory Bowel Disease

Inclusion Criteria: * Adult patients (18 years or older) with inflammatory bowel disease (ulcerative colitis or Crohn's disease) * Low serum vitamin D (25(OH)D ≤ 25 ng/mL * Not currently on high dose vitamin D supplementation * No prior bowel resections * No antibiotic use in past 3 months. Exclusion Criteria: * Patients less than 18 years old * No diagnosis of IBD * Serum 25(OH)D \> 25 ng/mL * Patients already on vitamin D supplementation * Prior history of bowel surgery (colectomy or small bowel resections) * Recent antibiotic use in past 3 months * Renal Dysfunction * History of Hypercalcemia * History of HIV * History of IgA deficiency * History of Common Variable Immunodeficiency (CVID) * Active C. diff infection