The Effect of Vitamin D on Intestinal Inflammation and Faecal Microbiota in Patients with Ulcerative Colitis

J Crohns Colitis. 2018 Jul 30;12(8):963-972. doi: 10.1093/ecco-jcc/jjy052.


Background and aims: Vitamin D may be immunomodulatory and alter faecal microbiota, but results from clinical studies in humans to date have been inconclusive. This study aimed to assess the effect of vitamin D replacement in vitamin D-deficient patients with and without ulcerative colitis [UC] on inflammation and faecal microbiota.

Methods: Vitamin D was replaced over 8 weeks in patients with active UC [defined by faecal calprotectin ≥ 100 µg/g], inactive UC [faecal calprotectin < 100 µg/g] and non-inflammatory bowel disease [IBD] controls with baseline serum 25[OH] vitamin D <50 nmol/l, and markers of inflammation and faecal microbiota were analysed.

Results: Eight patients with active UC, nine with inactive UC and eight non-IBD controls received 40000 units cholecalciferol weekly for 8 weeks. Mean baseline 25[OH] vitamin D increased from 34 [range 12-49] to 111 [71-158] nmol/l [p < 0.001], with no difference across the groups [p = 0.32]. In patients with active UC, faecal calprotectin levels decreased from a median 275 to 111 µg/g [p = 0.02], platelet count decreased [mean 375 to 313 × 109/l, p = 0.03] and albumin increased [mean 43 to 45 g/l, p = 0.04]. These parameters did not change in patients with inactive UC or non-IBD controls. No changes in overall faecal bacterial diversity were noted although a significant increase in Enterobacteriaceae abundance was observed in patients with UC [p = 0.03].

Conclusions: Vitamin D supplementation was associated with reduced intestinal inflammation in patients with active UC, with a concomitant increase in Enterobacteriaceae but no change in overall faecal microbial diversity.

MeSH terms

  • Adult
  • Aged
  • Case-Control Studies
  • Cholecalciferol / therapeutic use*
  • Colitis, Ulcerative / blood
  • Colitis, Ulcerative / complications
  • Colitis, Ulcerative / drug therapy*
  • Enterobacteriaceae / drug effects
  • Feces / chemistry
  • Feces / microbiology*
  • Female
  • Gastrointestinal Microbiome / drug effects
  • Humans
  • Leukocyte L1 Antigen Complex / analysis
  • Male
  • Middle Aged
  • Pilot Projects
  • Platelet Count
  • Prospective Studies
  • Serum Albumin / metabolism
  • Vitamin D / analogs & derivatives
  • Vitamin D / blood
  • Vitamin D Deficiency / blood
  • Vitamin D Deficiency / complications
  • Vitamin D Deficiency / drug therapy*
  • Vitamins / therapeutic use*


  • Leukocyte L1 Antigen Complex
  • Serum Albumin
  • Vitamins
  • Vitamin D
  • Cholecalciferol
  • 25-hydroxyvitamin D