The effect of two doses of vitamin D3 (400 IU vs. 2000 IU/d) on serum 25‐hydroxyvitamin D in children with Crohn's disease

Vitamin D is crucial for Crohn's disease (CD) patients to maximize bone mineral density and because vitamin D insufficiency has been linked to increased disease activity. We tested whether 2000 IU/d ( vs . 400 IU/d) of vitamin D 3 yields a higher proportion of children with CD with serum 25‐hydroxyvitamin D (25OHD) concentration ≥ 50 or ≥ 75 nmol/L. 83 patients (8–18 yr) with quiescent CD (Pediatric Crohn's Disease Activity Index (PCDAI) ≤ 10) were randomized to either 400 or 2000 IU/d for 6 months. Clinical and biochemical data were collected at baseline, 3 months and 6 months. Using an intention to treat analysis, at 6 months subjects receiving 2000 IU ( vs . 400 IU) were more likely to achieve 25OHD ≥ 75 nmol/L (75% vs. 34%; χ 2 =13, P<0.001), but proportions ≥ 50 nmol/L did not differ (94% vs. 91%). After adjustment for baseline 25OHD, mean (95% CI) serum 25OHD was higher in the 2000 IU group than the 400 IU group, 90 (84–96) vs. 67 (60–73) nmol/L (p<0.001), respectively. Disease activity assessed by the PCDAI, and serum bone specific alkaline phosphatase concentrations, were similar between groups. Vitamin D supplementation of 2000 IU/d allows most children with quiescent CD to reach serum 25OHD concentrations of ≥ 75 nmol/L, while 400 IU/d is associated with concentrations ≥ 50 nmol/L. Funding: University of British Columbia Vitamin Research Fund