Vitamin D Repletion and Maintenance in IBD: How Much and How Often

Inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease
(CD), are chronic relapsing inflammatory conditions of the gastrointestinal tract. IBD is
thought to result from a complex interaction between genetic, immune, microbial and
environmental factors. The role of vitamin D in bone health and calcium homeostasis is well
documented. However, emerging data suggests that vitamin D may also regulate immune
responses, which may play a role in the pathogenesis and disease activity of IBD.

The investigators seek to identify CD or UC patients with mild disease or in clinical
remission who have vitamin D levels <30 ng/ml and not on any type of vitamin repletion
therapy. The investigators will randomize the participants into one of four arms: (1) Oral
50,000 vitamin D IU every week for 12 weeks (2) Oral 50,000 vitamin D weekly for 12 weeks
than oral 800 vitamin D IU/d (3) Oral 50,000 vitamin D IU weekly for 12 weeks then 5,000
vitamin D IU/d (4) Oral 5,000 vitamin D IU/d and check vitamin D levels and inflammatory
markers as part of standard of care follow- up every 3 months for nine months. Every
participant will receive dietary counseling throughout the study duration. Our aim is to
identify an optimal dosing strategy for repletion and maintenance of vitamin D levels in the
subset of IBD patients. Based on clinical experience, doses higher than the recommended doses
for bone health are needed to achieve and maintain optimal levels of Vitamin D in IBD
patients, even patients are in remission or do not have small bowel (malabsorption)
involvement.

Inclusion Criteria:

1. Diagnosis of Crohn's disease or Ulcerative colitis

2. In clinical remission or with mild disease activity as determined by the Harvey
Bradshaw Index (CD) ≤7 or Ulcerative Colitis disease activity index ≤6.

3. 25(OH)D level <30 ng/ml within three months of study enrollment

4. Provided verbal consent

5. 18 years of age or older

Exclusion Criteria:

1. Unwilling to provide consent or lack capacity

2. Moderate to severe disease activity (Harvey Bradshaw index >7 or UCDAI >6)

3. Current pregnancy or attempting to conceive

4. Known coexisting hyperparathyroidism

5. Already on vitamin D supplementation, calcium supplementation or a multivitamin

6. BMI >30 kg/m²

7. History of kidney stones

8. Subjects <18 years of age - pediatric population with different recommended dosing
than adults (10).

9. Non-english speakers