BACKGROUNDVitamin D deficiency is highly prevalent in children with inflammatory bowel disease (IBD). This may contribute to an increased risk of poor bone health and may also influence the course of disease. An optimal treatment strategy of vitamin D therapy in children with IBD has not yet been established.AIMTo analyse the published intervention studies of vitamin D therapy in children with IBD.METHODSA systematic review was conducted of clinical studies involving children with IBD (including Crohn disease or ulcerative colitis) who had received vitamin D therapy. Studies up to March 31st 2018 were identified through MEDLINE, PubMed, EMBASE and the Cochrane Library. Search terms included synonyms of the following terms: vitamin D, paediatric, supplementation, IBD. References of included articles based on abstract were searched for other relevant articles. All relevant articles were accessed and reviewed in full text. Studies fitting the set criteria were included and the remainder were excluded.RESULTSTwo hundred and seventy-seven discrete articles were identified. Following assessment of these articles included in the initial search and application of inclusion and exclusion criteria, ten published studies were included in this review. The included studies showed a heterogeneity in study design, inclusion and exclusion criteria, baseline demographics and treatment strategies. Treatment regimens differed in length, supplemented form of vitamin D and factors based upon which dosage was adjusted. Each of the reports included in this review concluded their vitamin D regimens to be safe and well-tolerated. Few of the included studies reported secondary outcomes on the efficacy of vitamin D treatment upon the clinical course of disease or markers of inflammation. The majority of included trials were not sufficient in raising serum vitamin D levels to an adequate level (30 ng/mL) in children with IBD with vitamin D deficiency.CONCLUSIONThe included trials featured diverse treatment regimens that were predominantly insufficient in correcting vitamin D deficiency or maintaining adequate levels in children with IBD. Better treatment regimens are required for the management of vitamin D deficiency in children with IBD.

Background: High-dose oral vitamin D (stoss) is a novel treatment in children with inflammatory bowel disease (IBD). Vitamin D supplementation may have benefits in IBD beyond bone health including reduced disease activity and improvements in inflammatory markers. The aim of this study was to retrospectively assess the efficacy, safety and impact on disease activity of single oral high-dose vitamin D3 therapy in New Zealand (NZ) children with IBD and vitamin D deficiency. Methods: In this retrospective chart review, children with IBD and vitamin D deficiency [serum 25-OH vitamin D level (25-OHD) <50 nmol/L] in Christchurch, NZ, who were managed with single highdose vitamin D3 therapy were identified. Measurements of serum 25-OHD, calcium and standard serum inflammatory markers prior to and up to 6 months following stoss therapy were extracted from patient records. Disease activity was also defined using the Pediatric Crohn's Disease (CD) Activity Index (PCDAI) at time points before and 3 months following stoss. Results: Twenty-eight doses of stoss were given to 23 children, aged 3-16 years. Mean 25-OHD levels