Vitamin D deficiency in Crohn's disease: prevalence, risk factors and supplement use in an outpatient setting.

BACKGROUND AND AIMS: Vitamin D deficiency impacts on bone health and has potential new roles in inflammation. We aimed to determine the prevalence of and risk factors for vitamin D deficiency and to explore vitamin D supplement usage in patients with Crohn's disease (CD) in an outpatient setting, compared with controls. METHODS: Serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured by radioimmunoassay in 151 participants, comprising 81 CD patients and 70 age-, sex- and socio-economic status-matched healthy controls. Levels of 25(OH)D <50 nmol/L were classed as deficient. Data on vitamin supplement usage were recorded for all participants at interview. RESULTS: Vitamin D deficiency was common in patients with CD (63%) and significantly higher in winter than summer (68% v 50%; p<0.001, χ(2)). Notably, the deficiency rate remained high even in summer (50%). On regression analysis, 25(OH)D levels were inversely associated with winter season. Disease-specific factors for lower serum 25(OH)D levels were longer disease duration and smoking. Overall, 43% of patients reported using a vitamin D-containing supplement, primarily at low dosages (200-400 IU/d); however, this level of supplement did not prevent deficiency. For the majority of CD patients, 25(OH)D remained below optimal levels proposed to confer bone and immune health benefits. CONCLUSIONS: Vitamin D deficiency was common in patients with CD and associated with longstanding disease, smoking and winter. While over 40% of patients used a vitamin D-containing supplement, the dosages were inadequate to prevent deficiency. Appropriate vitamin D screening and supplementation should be considered in the context of health promotion of outpatients with CD.

Vitamin D status and cytokine levels in patients with Crohn's disease.

OBJECTIVE: There is growing evidence that vitamin D may have immunomodulatory properties in Crohn's disease (CD). The aim of this study was to determine if serum 25-hydroxy-vitamin D [25(OH)D] was associated with inflammatory cytokines, IL-10, and TNF-alpha levels in patients with inactive CD. METHODS: This was a prospective study of 75 adults with quiescent CD. Serum 25(OH)D was measured by radioimmunoassay and serum IL-10 and TNF-alpha by ELISA. Disease activity was assessed by the Crohn's disease activity index (CDAI) and C-reactive protein (CRP). RESULTS: IL-10 levels were significantly lower in patients with vitamin D insufficiency compared with the vitamin D replete group (mean and SE 2.48 ± 0.51 v 6.77 ± 2.49 pg/mL, p < 0.001). There were, however, no differences in serum TNF-alpha or CRP levels based on vitamin D status. The use of a vitamin D supplement at a low dose (200 IU) did not significantly influence IL-10 levels. CONCLUSION: Circulating levels of IL-10, but not TNF-alpha, were significantly lower in CD patients with inadequate serum 25(OH)D. This suggests that poor vitamin D status may be linked to reduced anti-inflammatory capacity in this group.