Vitd and Barrier Function in IBD (VIP)

Inclusion Criteria:

• All patients must fulfill the clinical criteria for diagnosis of CD as defined by Lennard-Jones et al. (1976)
• All patients must be in clinical remission for at least 1 month at study entry as defined by a Crohn's Disease Activity Index (CDAI) of <150
• 18-65 years
• Patients on stable drug therapies for at least 1 month pre-enrolment
• Sufficient English language ability to carry out the study requirements

Exclusion Criteria:

• Symptomatic CD at study entry including CDAI >150
• Pregnancy
• Previous extensive small bowel resection (less than 200 cm of viable small bowel or a loss of 50% or more of the small intestine)
• Presence of an ileostomy or colostomy
• Known hypersensitivity to vitamin D
• Hypercalcaemia (corrected serum calcium > 2.66 mmol/L)
• Those currently using supplemental vitamin D >800 IU/D
• Diagnosis of any of the following: active tuberculosis, sarcoidosis, hyperparathyroidism, renal failure, pseudohyperparathyroidism, malignancy, active, lymphoma, short bowel syndrome
• Antibiotic use in the 4 weeks prior to enrolment
• Current use of bisphosphonates
• Renal Impairment, Diabetes Mellitus
• Patients participating in a concurrent RCT
• Alcohol dependency