Association Between Inflammatory Bowel Disease and Vitamin D Deficiency

Abstract

Background—Vitamin D plays a role in several immune-mediated diseases, but its association with inflammatory bowel disease (IBD) is unclear. We conducted a systematic review and meta- analysis to assess the association between IBD and vitamin D deficiency. Methods—We searched electronic databases from inception to December 2014 for observational studies reporting the presence of vitamin D deficiency (defined as serum 25- hydroxycholecalciferol [25(OH)D] level of 20 ng/ml) in IBD patients and having a control group without IBD. Odds ratios (OR) were combined using a random effects model. Meta-regression was performed using latitude as a moderator. Study quality was assessed using the Newcastle- Ottawa scale. Results—Out of 816 citations, 14 eligible studies were identified, comprising 1891 participants (938 IBD cases and 953 controls). Meta-analysis showed that patients with IBD had 64% higher odds of vitamin D deficiency when compared to controls (OR = 1.64; 95% CI: 1.30, 2.08; I2 = 7%; p < 0.0001). UC patients had more than double the odds of vitamin D deficiency when compared to normal controls (OR = 2.28; 1.18, 4.41; I2 = 41%; p=0.01). Latitude did not influence the association between IBD and vitamin D deficiency (p = 0.34). Generalizability of our results might be limited as we summarized unadjusted ORs, due to non-availability of adjusted ORs in individual studies. Conclusions—IBD is significantly associated with having higher odds of vitamin D deficiency. Well-designed RCTs and longitudinal studies are needed to further clarify the role of vitamin D in IBD pathogenesis and its therapy. Keywords Meta-analysis; Inflammatory Bowel Disease; Crohn’s Disease; Ulcerative Colitis; Vitamin D