The Effect of Various Doses of Oral Vitamin D3 Supplementation on Gut Microbiota in Healthy Adults: A Randomized, Double-blinded, Dose-response Study

Anticancer Res. 2020 Jan;40(1):551-556. doi: 10.21873/anticanres.13984.


Background/aim: To investigate the effects of vitamin D3 supplementation on gut microbiota.

Patients and methods: Twenty adults with vitamin D insufficiency/deficiency [25(OH)D <30 ng/ml] were enrolled and given 600, 4,000 or 10,000 IUs/day of oral vitamin D3 Stool samples were collected at baseline and 8 weeks for identifying gut microbiota using 16S rRNA gene amplification and sequencing.

Results: Baseline serum 25(OH)D was associated with increased relative abundance of Akkermansia and decreased relative abundance of Porphyromonas (p<0.05). After the intervention, we observed a dose-dependent increase in relative abundance of Bacteroides with a significant difference between the 600 IUs and the 10,000 IUs groups (p=0.027), and Parabacteroides with a significant difference between the 600 IUs and the 4,000 IUs groups (p=0.039).

Conclusion: Increased serum 25(OH)D was associated with increased beneficial bacteria and decreased pathogenic bacteria. A dose-dependent increase in bacteria associated with decreased inflammatory bowel disease activity was observed after vitamin D3 supplementation.

Keywords: 25-hydroxyivitamin D; Vitamin D3; Vitamin D3 supplementation; gut microbiota; randomized clinical trial.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Administration, Oral
  • Adult
  • Bacteria / drug effects
  • Cholecalciferol / administration & dosage*
  • Cholecalciferol / pharmacology*
  • Dietary Supplements*
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Gastrointestinal Microbiome / drug effects*
  • Humans


  • Cholecalciferol