Reduction of bacteriuria and pyuria after ingestion of cranberry juice

JAMA. 1994 Mar 9;271(10):751-4. doi: 10.1001/jama.1994.03510340041031.


Objective: To determine the effect of regular intake of cranberry juice beverage on bacteriuria and pyuria in elderly women.

Design: Randomized, double-blind, placebo-controlled trial.

Subjects: Volunteer sample of 153 elderly women (mean age, 78.5 years).

Intervention: Subjects were randomly assigned to consume 300 mL per day of a commercially available standard cranberry beverage or a specially prepared synthetic placebo drink that was indistinguishable in taste, appearance, and vitamin C content but lacked cranberry content.

Outcome measures: A baseline urine sample and six clean-voided study urine samples were collected at approximately 1-month intervals and tested quantitatively for bacteriuria and the presence of white blood cells.

Results: Subjects randomized to the cranberry beverage had odds of bacteriuria (defined as organisms numbering > or = 10(5)/mL) with pyuria that were only 42% of the odds in the control group (P = .004). Their odds of remaining bacteriuric-pyuric, given that they were bacteriuric-pyuric in the previous month, were only 27% of the odds in the control group (P = .006).

Conclusions: These findings suggest that use of a cranberry beverage reduces the frequency of bacteriuria with pyuria in older women. Prevalent beliefs about the effects of cranberry juice on the urinary tract may have microbiologic justification.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Bacteriuria / diet therapy
  • Bacteriuria / prevention & control*
  • Beverages*
  • Double-Blind Method
  • Female
  • Fruit*
  • Humans
  • Pyuria / diet therapy
  • Pyuria / prevention & control*
  • Urinalysis