A recent report provided evidence supporting the use of cranberry juice for preventing urinary tract infections (UTIs). The study found that cranberry juice consumption was associated with a significant reduction in infection rates and antibiotic use compared to placebo or no treatment.

Researchers from Bond University and collaborating institutions conducted a systematic review and network meta-analysis of 20 trials, including 18 randomized and 2 nonrandomized controlled trials, involving 3,091 participants. The study, published in European Urology Focus, primarily examined UTI occurrence rates, with secondary outcomes of UTI symptoms and antibiotic use.

The researchers searched PubMed, Embase, and Cochrane CENTRAL databases from inception to September 25, 2023. They included randomized controlled trials comparing cranberry products (juice or tablets) to placebo, other liquids, or no treatment. The network meta-analysis was performed using a contrast-based frequentist random-effect method. The GRADE approach was used to assess the certainty of evidence.

Key Findings

Cranberry juice intake resulted in a 54% lower rate of UTIs compared to no treatment (very low–certainty evidence) and a 27% lower rate compared to placebo liquid (moderate-certainty evidence).

Cranberry juice use was associated with a 49% lower rate of antibiotic use compared to placebo liquid and a 59% lower rate compared to no treatment.

Cranberry compounds reduced the prevalence of UTI symptoms.

For the primary outcome of UTI rate, the rate ratio for cranberry juice vs placebo liquid intake was 0.73 (95% confidence interval [CI] = 0.59-0.91; P = .005). The rate ratio for cranberry juice vs no treatment was 0.46 (95% CI = 0.31-0.68; P < .0001).

Regarding antibiotic use, cranberry juice showed a rate ratio (RR) of 0.51 (95% CI = 0.30-0.87; P = .014) compared to placebo liquid and 0.41 (95% CI = 0.17-1.02; P = .055) compared to no treatment.

The study also found that use of cranberry tablets was associated with a higher likelihood of being UTI symptom–free compared to control groups (RR = 5.22; 95% CI = 1.26-21.55; P = .02).

Additional Analysis Details and Findings

Fifteen studies (75%) of the 20 in the meta-analysis evaluated cranberry in liquid form, while 5 studies (25%) evaluated cranberry in tablet form. 

Duration of intake ranged from 2 weeks to 12 months, with 6 months being the most common.

Sixteen of the 20 studies were comprised a large majority of female participants—the total analysis population included 2,745 (88.8%) females and 346 (11.1%) males. Four studies were performed in children. Mean or median participant age ranged from 4 to 87 years.

The detailed network meta-analysis results showed:

• Cranberry tablet vs placebo liquid intake: RR = 1.04 (95% CI = 0.62-1.73; P = .89)
• No treatment vs placebo liquid: RR = 1.58 (95% CI = 1.07-2.35; P = .022)
• Cranberry tablet vs no treatment: RR = 0.65 (95% CI = 0.42-1.03; P = .068)
• Cranberry juice vs cranberry tablet: RR = 0.70 (95% CI = 0.42-1.17; P = .18).

Pairwise meta-analysis results for UTI rate were:

• Cranberry juice vs placebo liquid (14 randomized controlled trials [RCTs], 2,400 participants): RR = 0.74 (95% CI = 0.60-0.91; P = .004)
• Cranberry tablet vs placebo liquid (1 RCT, 100 participants): RR = 0.56 (95% CI = 0.25-1.22; P = .16)
• No treatment vs placebo liquid (3 RCTs, 189 participants): RR = 1.44 (95% CI = 0.83-2.48; P = .19)
• Cranberry juice vs no treatment (3 RCTs and 1 controlled clinical trial, 234 participants): RR = 0.31 (95% CI = 0.18-0.54; P < .0001).

A likelihood ratio test comparing treatment effects for adults and children showed no evidence of interaction (P = .21).

Seven studies reported on urinary symptoms, with three being meta-analyzable. One study found significantly lower mean episodes of dysuria, painful urination, and frequent urination in the cranberry group compared to no treatment after 3 months.

Six studies contributed to the analysis of antibiotic use:

• Cranberry tablet vs placebo liquid: RR = 0.47 (95% CI = 0.07-3.17; P = .44)
• No treatment vs placebo liquid: RR = 1.25 (95% CI = 0.53-2.94; P = .62)
• Cranberry tablet vs no treatment: RR = 0.38 (95% CI = 0.07-2.08; P = .26).

GRADE assessment showed evidence certainty ranged from very low to moderate across different comparisons; reasons for downgrading included risk of bias, inconsistency, and imprecision.

For the meta-analysis of UTI symptoms, heterogeneity among included studies was low (I² = 36%)

Limitations

The authors noted several limitations, including variability in the definition of recurrent UTIs across studies and potential confounding in some cranberry tablet studies that also provided educational interventions. Additionally, the majority of participants were female, limiting generalizability to males.

The study authors concluded, "The evidence supports the use of cranberry juice for the prevention of UTIs. While increased liquids benefit the rate of UTIs and reduce antibiotic use, and cranberry compounds benefit symptoms of infection, the combination of these, in cranberry juice, provides clear and significant clinical outcomes for the reduction in UTIs and antibiotic use, and should be considered for the management of UTIs."

The authors declared having no competing interests.