Vitamin D Status Is Associated with Intestinal Inflammation as Measured by Fecal Calprotectin in Crohn's Disease in Clinical Remission

Background Vitamin D, as potential immune modulator, has been implicated as an environmental risk factor for Crohn's disease (CD). Vitamin D status may be associated with disease risk, severity, activity, and progression. While associations between circulating 25OHD and markers of disease activity and inflammation in CD have been reported, the results are inconsistent. Aim To determine the association between vitamin D status and markers of disease activity and inflammation in CD. Methods One hundred and nineteen CD patients' active and inactive diseases were enrolled in the cross-sectional study. Subject demographics and clinical data were collected. A serum sample was collected for 25OHD and CRP analysis, and a stool sample was collected for fecal calprotectin (FC) measurement. Results The mean serum 25OHD concentration of the group was 59.8 (24.9) nmol/L. After controlling for confounding variables, serum 25OHD inversely correlated with FC (r=-0.207, P=0.030), particularly among those in clinical remission (r=-0.242, P=0.022). The association between FC and 25OHD was further confirmed by linear regression (r=31.3 %, P<0.001). FC was lower in patients with 25OHD levels >= 75 nmol/L compared with levels <25 nmol/L [FC: 32.2 (16.3-98.2) vs 100.0 (34.4-213.5) mu g/g, P=0.004]. In the current study, however, 25OHD was not significantly associated with either CRP or CDAI. Conclusion Circulating 25OHD was significantly inversely associated with intestinal inflammation as determined by FC in CD. Subgroup analysis confirmed the association among those in clinical remission, but not in those with active disease. 25OHD was not associated with disease activity score (CDAI) or systemic inflammation (CRP). Vitamin D intervention studies are warranted to determine whether raising serum 25OHD levels in patients with CD may reduce intestinal inflammation as measured by FC.