By Cole Petrochko, Associate Staff Writer, MedPage Today
Published: July 09, 2012
Reviewed by
Zalman S. Agus, MD;
Emeritus Professor, Perelman School of Medicine at the University of
Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner
Drinking
cranberry juice or taking cranberry capsules or tablets was associated
with a protective effect against urinary tract infection, a systematic
review found.
The pooled data from 10 studies comparing
cranberry-product consumers against nonusers showed cranberry
consumption had a risk ratio protective against UTI at 0.62 (95% CI 0.49
to 0.80), according to Chien-Chang Lee, MD, of the National Taiwan
University Hospital, and colleagues.
A subgroup analysis found the
cranberry products were more effective in women with recurrent UTI,
female populations, children, regular cranberry juice drinkers, and
those who used cranberry products more than twice daily, Lee and
co-authors wrote in the July 9 issue of
Archives of Internal Medicine.
"Cranberry-containing
products have long been used as a folk remedy to prevent UTIs," the
authors explained. Cranberry is thought to interfere with the attachment
of bacteria to uroepithelial cells, potentially preventing infection.
The
meta-analysis evaluated randomized controlled trials that compared the
effectiveness of cranberry containing products, such as juices and
pills, with placebo and non-placebo control groups at preventing UTIs.
The review included data from 10 trials of 1,494 patients, with 794 in
the cranberry group versus 700 in the control group.
In pooled
trials, there was an association with protective effects for the
cranberry group and significant heterogeneity between the trials (RR
0.68, 95% CI 0.47 to 1.00), but the results were nonsignificant, Lee and
colleagues wrote.
They added that sensitivity analyses "showed
that the protective effect of cranberry containing products was stronger
in nonplacebo-controlled trials" and suggested that expectations of
efficacy had an effect on outcomes.
When broken down by subgroup,
there was a nonsignificant trend for protection in certain groups
consuming cranberries, including:
- Women with recurrent UTI (RR 0.53, 95% CI 0.33 to 0.83)
- Female patients (RR 0.49, 95% CI 0.34 to 0.73)
- Children (RR 0.33, 95% CI 0.16 to 0.69)
- Cranberry juice drinkers (RR 0.47, 95% CI 0.30 to 0.72)
- Patients consuming cranberry products more than twice daily (RR 0.58, 95% CI 0.40 to 0.84)
The
authors noted that patients who drank cranberry juice versus other
forms of cranberry may have been better hydrated, and additives in juice
may have offered additional protective benefits not seen in cranberry
tablets or capsules.
However, the high sugar content in most
cranberry drink products may cause gastrointestinal problems or raise
concerns about sugar control in diabetic patients, the authors warned.
They
concluded that although their meta-analysis showed an association
between cranberry product consumption and protection against UTI, "this
conclusion should be interpreted with great caution" due to the
"substantial heterogeneity across trials."
The authors said that
their review was limited by absent searches for conferences,
proceedings, and clinical trial registries; inability to reach some
study authors to acquire missing data; and missing proanthocyanidin
content for cranberry products in several trials. Proanthocyanidins are
compounds that may potentially inhibit the adherence of
Escherichia coli to urological mucosa, they wrote.
The authors declared no conflicts of interest.
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