Background: Vitamin D (vitD) supplementation may prolong remission in Crohn's disease (CD); however, the clinical efficacy and mechanisms are unclear. Aim: To determine changes in intestinal permeability (IP), antimicrobial peptide (AMP) concentrations and disease markers in CD, in response to vitD supplementation. Methods: In a double-blind randomised placebo-controlled study, we assigned 27 CD patients in remission to 2000 IU/day vitD or placebo for 3 mos. We determined IP, plasma cathelicidin (LL-37 in ng/mL), human-beta-defensin-2 (hBD2 in pg/mL), disease activity (Crohn's Disease Activity Index (CDAI)), C-reactive protein (CRP in mg/L), fecal calprotectin (mg/g), Quality of Life (QoL) and serum 25-hydroxyvitamin D (25(OH)D in nmol/L) at 0 and 3 mos. Results: At 3 mos., 25(OH)D concentrations were significantly higher in those whom were treated (p < 0.001). Intra-group analysis showed increased LL-37 concentrations (p ¼ 0.050) and maintenance of IP measures in the treated group. In contrast, in the placebo group, the small bowel (p ¼ 0.018) and gastro-duodenal permeability (p ¼ 0.030) increased from baseline. At 3 mos., patients with 25(OH)D 75 nmol/L had significantly lower CRP (p ¼ 0.019), higher QoL (p ¼ 0.037), higher LL-37 concentrations (p < 0.001) and non-significantly lower CDAI scores (p ¼ 0.082), compared to those with levels <75 nmol/L. Conclusion: Short-term treatment with 2000 IU/day vitD significantly increased 25(OH)D levels in CD patients in remission and it was associated with increased LL-37 concentrations and maintenance of IP. Achieving 25(OH)D 75 nmol/l was accompanied by higher circulating LL-37, higher QoL scores and reduced CRP. Registered at ClinicalTrials.gov (NCT01792388).

Background and aims: Obesity and overweight are major public health issues. Although traditionally associated with weight loss, there is now evidence that increasing Body Mass Index (BMI) and overweight are emerging features of Crohn's disease (CD) and may be associated with more severe disease course. The aim of the study was to determine the prevalence of overweight and obesity in patients with CD compared with matched healthy controls and to identify disease-specific and generic factors associated with current BMI in this group. Methods: This was a prospective case-control study (n=200), comprising 100 CD outpatients and 100 age-, sex-and socioeconomically-matched healthy controls. BMI, Crohn's disease activity index (CDAI), clinical and lifestyle factors and circulating inflammatory markers were assessed. Results: Overall, 40% of patients with CD were overweight/obese (BMI ≥25 kg/m 2 ) compared with 52% of controls (P =0.206). On regression analysis, higher current BMI was significantly associated with disease specific factors, namely lower disease activity (CDAI) and lower white cell count, suggesting stable disease, as well as older age and lower physical activity. BMI was not significantly associated with the need for surgery or the need for corticosteroids. We identified a novel association between higher BMI and higher CRP, a marker linked both with obesity in the general population and with CD. Conclusions: Overweight was common in out-patients with CD and appeared to reflect current wellness, older age and sedentary lifestyles. The potential long-term implications of high BMI for CRP and inflammatory load merit further study.

Circulating 25OHD was significantly inversely associated with intestinal inflammation as determined by FC in CD. Subgroup analysis confirmed the association among those in clinical remission, but not in those with active disease. 25OHD was not associated with disease activity score (CDAI) or systemic inflammation (CRP). Vitamin D intervention studies are warranted to determine whether raising serum 25OHD levels in patients with CD may reduce intestinal inflammation as measured by FC.

Habitual physical activity of all intensities is associated with reduced arterial stiffness among adults with hypertension.

Vitamin D deficiency is common among patients with Crohn's disease. Serum 25-hydroxyvitamin D (25(OH)D) is the best measure of an individual's vitamin D status and current cut-off ranges for sufficiency are debatable. Several factors contribute to vitamin D deficiency in Crohn's disease. These include inadequate exposure to sunlight, inadequate dietary intake, impaired conversion of vitamin D to its active metabolite, increased catabolism, increased excretion and genetic variants in vitamin D hydroxylation and transport. The effects of low 25(OH)D on outcomes other than bone health are understudied in Crohn's disease. The aim of the present review is to discuss the potential roles of vitamin D and the possible levels required to achieve them. Emerging evidence suggests that vitamin D may have roles in innate and adaptive immunity, in the immune-pathogenesis of Crohn's disease, prevention of Crohn's disease-related hospitalisations and surgery, in reducing disease severity and in colon cancer prevention. The present literature appears to suggest that 25(OH)D concentrations of ≥75 nmol/l may be required for non-skeletal effects; however, further research on optimal levels is required.