Vitamin D status and bone density in recently diagnosed inflammatory bowel disease: the Manitoba IBD Cohort Study

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.

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.

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).

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.