Review Article

Vitamin D and Inflammatory Bowel Diseases

V. P. Mouli; A. N. Ananthakrishnan

Disclosures

Aliment Pharmacol Ther. 2014;39(2):125-136. 

In This Article

Abstract and Introduction

Abstract

Background Vitamin D is traditionally associated with bone metabolism. The immunological effects of vitamin D have increasingly come into focus.

Aim To review the evidence supporting a role of vitamin D in inflammatory bowel diseases.

Methods A comprehensive search was performed on PubMed using the terms 'crohn's disease' 'ulcerative colitis' and 'vitamin D'.

Results Vitamin D deficiency is common in patients with inflammatory bowel diseases (IBD) (16–95%) including those with recently diagnosed disease. Evidence supports immunological role of vitamin D in IBD. In animal models, deficiency of vitamin D increases susceptibility to dextran sodium sulphate colitis, while 1,25(OH)2D3 ameliorates such colitis. One prospective cohort study found low predicted vitamin D levels to be associated with an increased risk of Crohn's disease (CD). Limited data also suggest an association between low vitamin D levels and increased disease activity, particularly in CD. In a large cohort, vitamin D deficiency (<20 ng/mL) was associated with increased risk of surgery (OR 1.8, 95% CI 1.2–2.5) in CD and hospitalisations in both CD (OR 2.1, 95% CI 1.6–2.7) and UC (OR 2.3, 95% CI 1.7–3.1). A single randomised controlled trial demonstrated that vitamin D supplementation may be associated with reduced frequency of relapses in patients with CD compared with placebo (13% vs. 29%, P = 0.06).

Conclusions There is growing epidemiological evidence to suggest a role for vitamin D deficiency in the development of IBD and also its influence on disease severity. The possible therapeutic role of vitamin D in patients with IBD merits continued investigation.

Introduction

Ulcerative colitis (UC) and Crohn's disease (CD) constitute chronic idiopathic inflammatory bowel diseases (IBD). The key underlying pathogenic mechanisms for both diseases is a dysregulated host immune response to commensal intestinal flora in genetically susceptible individuals.[1,2] Known genetic variants incompletely explain the variance in disease incidence, suggesting a strong role for environmental factors, supported by epidemiological evidence.[3,4]

Vitamin D has long been recognised as a major regulator of calcium and phosphorus metabolism and key in maintaining bone health.[5–7] However, several recent studies have yielded new insights into the role of vitamin D in various other physiological processes. In particular, vitamin D appears to play important roles in immune regulation, particularly involving the innate immune system, cardiovascular and renal physiology, and development of cancer.[6] Importantly, an increasing body of literature supports an important role of vitamin D in the pathogenesis as well as potential therapy of IBD.[8–13] The current review examines the evidence linking vitamin D to IBD, both through its effect on bone health and association with pathogenesis and natural history of these diseases.

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