Background: The north–south geographical gradient of inflammatory bowel disease (IBD) prevalence, its epidemiology, the genetic association of vitamin D receptor polymorphisms, and results in animal models suggest that vitamin D plays an important role in the pathogenesis of IBD.
Aims: The purpose of this review was to critically appraise the effectiveness and safety of vitamin D therapy in patients with IBD.
Methods: MEDLINE, Scopus and Google Scholar were searched from inception to May 20, 2014 using the terms ‘Crohn’s disease’, ‘ulcerative colitis’ and ‘vitamin D’. Results: Vitamin D deficiency is common in patients with IBD. Limited clinical data suggest an association between low vitamin D concentration and increased disease activity in both ulcerative colitis (UC) and Crohn’s disease (CD). To date, only two small open label trials and one randomized controlled trial have shown a positive effect of vitamin D supplementation on disease activity in patients with CD; no effect has been shown for UC. An optimal vitamin D supplementation protocol for patients with IBD remains undetermined, but targeting serum 25-hydroxy vitamin D [25(OH)D] levels between 30 and 50 ng/mL appears safe and may have benefits for IBD disease activity. Depending on baseline vitamin D serum concentration, ileal involvement in CD, body mass index, and perhaps smoking status, daily vitamin D doses between 1800–10,000 international units/day are probably necessary.
Conclusion: Increasing preclinical and clinical evidence suggests a role for vitamin D deficiency in the development and severity of IBD. The possible therapeutic role of vitamin D in patients with IBD merits continued investigation.