Maintenance of optimal vitamin D status in children and adolescents with inflammatory bowel disease: a randomized clinical trial comparing two regimens.

CONTEXT: Vitamin D promotes bone health and regulates the immune system, both important actions for pediatric patients with inflammatory bowel disease (IBD). The supplementation dose that would maintain optimal serum 25-hydroxyvitamin D concentration (25OHD ≥ 32 ng/mL) is unknown. OBJECTIVE: The objective of the study was to compare two supplementation regimens' efficacy and safety in maintaining optimal 25OHD in children with IBD. DESIGN: This was a randomized, not blinded, controlled trial. SETTING: The trial was conducted in the Boston Children's Hospital Clinical and Translational Study Unit. PARTICIPANTS: Sixty-three patients, aged 8-18 years with IBD and baseline 25OHD greater than 20 ng/mL were enrolled; 48 completed the study, and one withdrew for adverse events. INTERVENTION: Arm A received 400 IU of oral vitamin D2 daily (n = 32). Arm B received 1000 IU daily in the summer/fall and 2000 IU in the winter/spring (n = 31). MAIN OUTCOME: The main outcome was the probability of maintaining 25OHD of 32 ng/mL or greater in all trimonthly visits for 12 months. RESULTS: Three participants in arm A (9.4%) and three in arm B (9.7%) achieved the primary outcome (P = .97). The incidence of adverse events, all minor, did not differ. More participants in arm A developed C-reactive protein level of 1 mg/dL or greater (31% vs 10%, P = .04) and IL-6 greater than 3 pg/mL (54% vs 27%, P = .05). CONCLUSIONS: Daily oral vitamin D2 doses up to 2000 IU were inadequate to maintain optimal 25OHD but were well tolerated. The finding of lower incidence of elevated inflammatory markers and cytokines among participants receiving higher vitamin D2 doses merits further study.