BACKGROUND AND PURPOSE:

• Cranberries for prevention of urinary tract infections (UTIs) is thought to be effective because they contain proanthocyanidins (PACs) which inhibit binding of some bacteria to cells lining the bladder
• Williams et al. (Cochrane Database of Systematic Review, 2023) provide an update on the efficacy of cranberries for preventing UTIs

METHODS:

• Systematic review and meta-analysis
• Study inclusion criteria
  • Randomized or quasi-randomized controlled trials
  • Studies that compared cranberry products with placebo, no specific treatment, or other intervention (antibiotics, probiotics) for the prevention of UTIs
• Study design
  • Study quality was assessed using the Cochrane risk of bias assessment tool
  • Confidence in the evidence was assessed using GRADE criteria
• Primary outcomes
  • Incidence of symptomatic UTIs
  • Positive culture results
  • Side effects
  • Adherence to therapy

RESULTS:

• 50 total studies (26 new studies added) | 8857 participants
  • The risk of bias was generally low

Cranberry Products vs Placebo or No Treatment

• 45 studies (26 studies included in meta-analysis)
• There is moderate certainty evidence that cranberry products reduced the risk of UTIs
  • Risk ratio (RR) 0.70 (95% CI 0.58 to 0.84) | I2=69% | 6211 participants
• Cranberry products probably reduced the risk of symptomatic, culture-verified UTIs in
  • Women with recurrent UTIs
    • RR 0.74 (95% CI, 0.55 to 0.99) | I2=54%
    • 8 studies | 1555 participants
  • Children
    • RR 0.46 (95% CI, 0.32 to 0.68) | I2=21%
    • 5 studies | 504 participants
  • People with a susceptibility to UTIs due to an intervention
    • RR 0.47 (95% CI, 0.37 to 0.61) | I2=0%
    • 6 studies | 1434 participants
• However, with low-certainty evidence, there may be little or no benefit of cranberry products among
  • Elderly institutionalized men and women
    • RR 0.93 (95% CI, 0.67 to 1.30) | I2=9%
    • 3 studies | 1489 participants
  • Pregnant women
    • RR 1.06 (95% CI, 0.75 to 1.50) | I2=3%
    • 3 studies | 765 participants
  • Adults with neuromuscular bladder dysfunction with incomplete bladder emptying
    • RR 0.97 (95% CI, 0.78 to 1.19) | I2=0%
    • 3 studies | 464 participants
• The number of participants with gastrointestinal side effects probably does not differ between those taking cranberry products and those receiving placebo or no specific treatment
  • RR 1.33 (95% CI, 1.00 to 1.77) | I2=0%
  • Moderate certainty evidence | 10 studies | 2166 participants

Cranberry Products vs Antibiotics

• 6 studies
• Compared to antibiotics, cranberry products may make little or no difference to the risk of
  • Symptomatic, culture-verified UTIs
    • RR 1.03 (95% CI, 0.80 to 1.33) | I2=0%
    • 2 studies | 385 participants
  • Clinical symptoms without culture
    • RR 1.30 (95% CI, 0.79 to 2.14) | I2=68%
    • 2 studies | 336 participants

Cranberry Products vs Probiotics

• 3 studies
• Compared to probiotics, cranberry products may reduce the risk of symptomatic, culture-verified UTIs
  • RR 0.39 (95% CI, 0.27 to 0.56) | I2=0%
  • 3 studies | 215 participants

Cranberry Tablets vs Juice

• 1 study
• It is unclear whether efficacy differs between cranberry juice and tablets as the certainty of the evidence was very low

Different Doses of PACs

• 2 studies
• It is unclear whether efficacy differs between different doses of PACs as the certainty of the evidence was very low
• No difference in the risk for UTIs could be demonstrated between low, moderate and high doses of PACs

CONCLUSION:

• Cranberry products reduce the risk of UTIs in women with recurrent UTIs, children, and those at risk due to a procedure
• The use of cranberry products is not supported in the elderly, pregnant women, or adults with neuromuscular bladder dysfunction

Learn More – Primary Sources:

Cranberries for preventing urinary tract infections