Factors affecting vitamin D deficiency in active inflammatory bowel diseases.

Background: Hypovitaminosis D is prevalent in inflammatory bowel disease (IBD) and may be associated with disease activity.

Aim: This study evaluated vitamin D (VitD) status in an Italian cohort of IBD patients, not taking VitD supplementation. We investigated risk factors for VitD deficiency and its correlation with disease activity.

Methods: VitD levels were measured in 300 consecutive outpatients (42% with Crohn's Disease (CD) and 58% with ulcerative colitis (UC), 56% male) from a tertiary referral center. Data from the IBD cohort were compared with those of 234 healthy controls, matched by sex, age, and the month in which VitD levels were measured.

Results: The mean VitD level in IBD patients was significantly lower than in controls (18.9 ng/ml vs. 25 ng/ml, p < 0.001) when accounting for gender, age, and season. VitD deficiency was present in 62% of IBD patients. Risk factors for deficiency were: age <40 and ≥60 years, winter, previous surgery, C-reactive protein (CRP) ≥0.5 mg/dl, and erythrocyte sedimentation rate ≥20 mm/h. In multivariate analysis, VitD levels were negatively influenced by disease location and CRP in UC.

Conclusions: Although VitD deficiency was more prevalent than expected in healthy controls living in a Mediterranean country not at high risk of hypovitaminosis D, it was more common and severe in IBD patients. This study also found an association between VitD status and disease activity.