The importance of vitamin D levels in patients with inflammatory bowel disease

The possible role of vitamin D (VD) in the pathogenesis of inflammatory bowel disease (IBD) and the associations between VD levels and IBD activity remain unclarified. We aimed to assess VD levels in IBD patients and their associations with IBD activity. We evaluated VD levels in Greek patients aged 18-75 years old with Crohn's disease (CD) or ulcerative colitis (UC). Patients were ineligible under the following conditions: history of enterectomy/right colectomy, receiving VD or agent(s) interfering with VD metabolism during the last three months and any comorbidities that influence VD levels. Epidemiologic characteristics, clinical course, laboratory investigations, endoscopic and histologic findings were recorded. In total, 122 patients with CD and 71 with UC were included. Most of them had low levels of VD (90% of CD and 91.5% of UC patients). Patients with clinically active CD or UC had lower levels of VD compared to those in remission (p = 0.009 and p = 0.033, respectively).CD patients with low levels of VD had higher CRP and stool calprotectin compared to those with normal levels of VD (P = 0.032 and P = 0.002, respectively). In UC, patients with pancolitis had lower VD levels compared to patients with proctitis (P = 0.036). In conclusion, the majority of Greek IBD patients have low levels of VD. Clinical activity is related to lower levels of VD. Low compared to normal levels of VD in CD patients are associated with higher CRP and calprotectin levels, so VD levels might serve as an activity marker.