Prevention of urinary tract infections with vitamin D supplementation 20,000 IU per week for five years. Results from an RCT including 511 subjects

Infect Dis (Lond). 2016 Nov-Dec;48(11-12):823-8. doi: 10.1080/23744235.2016.1201853. Epub 2016 Jun 30.


Background: In observational studies vitamin D deficiency is associated with increased risk of infections, whereas the effect of vitamin D supplementation in randomized controlled trials is non-conclusive.

Methods: Five hundred and eleven subjects with prediabetes were randomized to vitamin D3 (20,000 IU per week) versus placebo for five years. Every sixth month, a questionnaire on respiratory tract infections (RTI) (common cold, bronchitis, influenza) and urinary tract infection (UTI) was filled in.

Results: Mean baseline serum 25-hydroxyvitamin D (25(OH)D) level was 60 nmol/L. Two hundred and fifty-six subjects received vitamin D and 255 placebo. One hundred and sixteen subjects in the vitamin D and 111 in the placebo group completed the five-year study. Eighteen subjects in the vitamin D group and 34 subjects in the placebo group reported UTI during the study (p < 0.02), whereas no significant differences were seen for RTI. The effect on UTI was most pronounced in males. The effect of vitamin D on UTI was unrelated to baseline serum 25(OH)D level.

Conclusion: Supplementation with vitamin D might prevent UTI, but confirmatory studies are needed.

Keywords: Diabetes; respiratory infection; urinary tract infection; vitamin D.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Aged
  • Chemoprevention / methods*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Placebos / administration & dosage
  • Respiratory Tract Infections / prevention & control
  • Treatment Outcome
  • Urinary Tract Infections / prevention & control*
  • Vitamin D / administration & dosage*


  • Placebos
  • Vitamin D