Vitamin D has been proven in studies to have immunomodulatory effects on both the innate and adaptive immune systems. Although there have been reports of associations between vitamin D deficiency and the development or progression of inflammatory bowel diseases (IBDs), a cause-and-effect relationship between pretreatment 25 hydroxyvitamin D [25(OH)D] levels and response to anti-tumor necrosis factor (anti-TNF) therapy has not been established. This study looked at paediatric IBD patients who had their 25(OH)D levels drawn within three months of starting infliximab and/or adalimumab medication. Demographic information, the Paris classification, baseline 25(OH)D levels, disease activity, and laboratory findings were gathered before and after 3 months of anti-TNF medication. At 3 months, the association between vitamin D deficiency at induction and lack of response to anti-TNF medication was studied.

The inclusion criteria were met by 76 of the 383 patients. Sixty-five patients  had Crohn’s disease (CD), whereas 11 had ulcerative colitis. Seven individuals had 25(OH)D levels measured during both infliximab and adalimumab induction, for a total of 83 subjects. A 25(OH)D concentration of 30 ng/mL was reported in 55 of 83 of the individuals. In CD, proximal gastrointestinal tract inflammation was linked to vitamin D deficiency. Patients with vitamin D deficiency had a significantly greater rate of early cessation of anti-TNF medication. Inadequate vitamin D prior to anti-TNF medication may result in a poor response to induction therapy.