A recent study published in the UnitedEuropeanGastroenterologyJournal showed that vitamin D supplementation in patients with Crohn’s disease (CD) in remission correlates with short-term maintenance of intestinal permeability and improvement in markers of disease activity, compiled as follows: “The study presents a number of new insights into the mechanisms by which vitamin D may exert beneficial effects on Crohn’s disease. This will stimulate further research on the role of vitamin D in the intestinal barrier and immune function.” Lead author Professor Tara Raftery (St. James Hospital, Dublin, Ireland) noted in an email that while vitamin D supplementation appears to be beneficial for Crohn’s disease, few studies have explored possible mechanisms for this outcome, Prof. Raftery and colleagues noted. To investigate further, the group randomly selected 27 CD patients in remission to be given 2,000 IU of vitamin D or placebo daily for three months. At the end of that study, 25-hydroxyvitamin D (25(OH)D) concentrations were significantly higher in the active treatment group. And this group of patients also showed stable maintenance of intestinal permeability. In contrast, patients in the placebo group showed a significant increase in both small bowel and gastro-duodenal permeability. However, despite changes within the group, there were no significant differences in intestinal permeability measurements between groups at three months. Human-derived bactericidal peptide (LL-37) promoted intestinal epithelial cell wound healing, and other beneficial effects that were increased in the active treatment group but not significantly altered in patients in the placebo group. However, there were no significant between-group differences in LL-37 concentrations at three months. Overall, patients with high levels had significantly lower C-reactive protein, higher quality of life scores, and non-significantly lower Crohn’s Disease Activity Index scores compared to patients with 25(OH)D levels maintained at or below 75 nmol/L. Thus, senior author Maria O’Sullivan (St. James Hospital) believes that “while the study is exciting and may translate into improved treatment of Crohn’s disease, we also need to recognize that there is insufficient evidence to recommend vitamin D as an adjunctive therapy and further randomized controlled trials are needed. In addition, it appears, at least for now, that we are committed to preventing vitamin D deficiency in the Crohn’s patient population.” Commenting on the study, gastroenterologist Professor Helen Pappa (St. Louis University School of Medicine) said in an email, “Despite the study’s limitations, such as the small number of participants, the short duration of follow-up, the relatively low dose of vitamin D, and the inability to account for confounding factors due to the small number of participants, it is still an important study because it investigated the role of vitamin D, a known modulator of the immune system, in Crohn’s disease where the immune system link is affected. In addition, this is a population-based prospective study. The promise of these preliminary findings will inspire larger studies to uncover the enormous potential of vitamin D for the treatment of IBD (inflammatory bowel disease), adding a new, less toxic drug to the IBD treatment catalog.”