In a new study entitled “Effects of vitamin D supplementation on intestinal permeability, cathelicidin and disease markers in Crohn’s disease: Results from a randomized double-blind placebo-controlled study,” researchers revealed how Vitamin D supplementation contributed to intestinal epithelia permeability and reduced inflammation in Crohn’s Disease patients. They found that patients on vitamin D supplementation have increased protection against inflammation and are capable of maintaining intestinal permeability. The study was published in the United European Gastroenterology journal.

Crohn’s disease (CD) is a type of inflammatory bowel disease (IBD), which is estimated to affect 1.6 million Americans. The second most common type of IBD is ulcerative colitis. CD is a long-term condition characterized by chronic inflammation occurring in any part of the gastrointestinal tract. It is established that a series of genetic and environmental cues contribute to CD development, however, recent studies with animal models as well as clinical data suggest that Vitamin D deficiency is a risk factor for CD. As a result, Vitamin D supplementation is a potential therapy for treating CD, as previous studies showed how vitamin D suppressed the development of IBD. However, while these studies demonstrated the effect of vitamin D on inflammation, how it impacts the permeability of the intestinal wall remains unknown (the barrier function of the intestinal epithelia and its permeability are key features implicated in CD development).

In this new study, a research team investigated how Vitamin D supplementation impacted intestinal permeability, as well as its effects on the immune system response (they measured the concentration of antimicrobial peptides, such as LL-37) and the expression of markers for CD. Authors performed a double-blind randomized placebo-controlled study. Specifically, the team enrolled 27 patients with confirmed diagnosis of CD but that were in a state of disease remission who were at least 18 years old. Patients were then randomly assigned to receive either 2000 IU (IU is the International Unit used in measuring fat soluble vitamins) of Vitamin D or placebo control. The treatment was delivered daily as one tablet and lasted for 3 months. The team measured a series of parameters, including intestinal permeability, markers of inflammation and immune system response (including the LL-37 marker, a molecule of the innate immune system that is secreted by the gastrointestinal epithelium and reduces intestinal inflammation), disease activity (Crohn’s Disease Activity Index (CDAI)), Quality of Life (QoL), and Vitamin D (by measuring the amount of 25-hydroxy vitamin, 25(OH)D) at baseline (month 0) and at the end of treatment (month 3).

The authors observed that 2000 IU Vitamin D/day during 3 months significantly increased patients 25(OH)D concentration. While in the placebo group, patients exhibited increased intestinal permeability, vitamin D supplementation resulted in a stable permeability in the treated group, suggesting that Vitamin D can effectively maintain intestinal permeability in CD. The Vitamin D supplemented group exhibited decreased levels of inflammatory markers and higher levels of LL-37 concentration accompanied by an increase in patients’ quality of life.

The team highlights that although their findings need further conformation, they suggest that 2000 IU/day Vitamin D was sufficient to raise 25(OH)D concentration which helped maintain patients gastrointestinal wall permeability and increase the concentration of circulating LL-37, shown to decrease intestinal inflammation. Future studies testing different dosages and treatment durations will further explore the effects of Vitamin D therapy in CD.