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.

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).

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.

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.