Objective: Bone mineral density (BMD) is usually normal at the time of inflammatory bowel disease (IBD) diagnosis. The purpose of this study was to evaluate the role of vitamin D metabolism in recently diagnosed IBD.

Methods: Adult subjects with recently diagnosed IBD (median 4 yr) were recruited from the University of Manitoba IBD Research Registry into the Manitoba IBD Cohort Study. Baseline BMD and serum 25-hydroxy vitamin D (25OHD) were measured in a nested subgroup of 101 subjects of whom 94 had repeat BMD measurements 2.3 +/- 0.3 yr later.

Results: Only a minority (22 [21.8%]) of recently diagnosed IBD participants had optimal serum 25OHD levels (75 nmol/L or greater). Serum 25OHD was positively correlated with baseline BMD for the lumbar spine, total hip, and total body (all P < 0.05). MANOVA confirmed significant between-group differences in baseline T-scores when vitamin D status was categorized according to serum 25OHD quartile (P < 0.05). Gain in total body BMD between the baseline and follow-up DXA scans was positively correlated with 25OHD (r = 0.20, P < 0.05).

Conclusions: Poorer vitamin D status correlates with lower baseline BMD at all measurement sites and better vitamin D status is correlated with a gain in total body BMD. Early optimization of vitamin D may play an important role in preventing IBD-related bone disease.