Cranberry extracts—frequently used as a home remedy to treat and prevent urinary tract infection—have been shown in a meta-analysis to reduce significantly the incidence of symptomatic urinary tract infections in women.
An analysis of four randomized controlled trials, comprising 665 participants, showed that cranberry products—such as juice, tablets, or capsules—significantly reduced the incidence of symptomatic UTI at 12 months, compared with a placebo (relative risk 0.65).
Within these studies, cranberry products were most effective in women with recurrent UTIs, investigators reported in a review published Jan. 23 in the Cochrane Library.
The investigators, led by Ruth Jepson, senior research fellow at the University of Stirling, Scotland, searched medical databases to identify studies that used cranberry juice or tablets to prevent recurrences of UTI.
Ten studies, comprising 1,049 patients, met the data-quality standards set by the reviewers (Cochrane Database Syst. Rev. 2008 Jan. 23 [doi:10.1002/14651858.CD001321.pub4]).
The evidence was “inconclusive” regarding whether cranberry products are effective in older men and women, the investigators wrote.
In one Scottish study that focused on 376 men and women aged 60 years or older, there was no significant difference in the number of symptomatic UTIs between patients drinking 300 mL/day of cranberry juice and those drinking a placebo beverage.
In a second study of 192 elderly women in the United States randomized to a group drinking 300 mL/day of cranberry juice or a placebo, those in the intervention group were at a reduced risk of asymptomatic infections indicated by bacteriuria with pyuria (odds ratio 0.42).
The authors added, however, that asymptomatic infections are “a condition which does not normally need treating in certain populations.”
Of two randomized controlled trials that focused on women with symptomatic recurrent lower UTI or with a current UTI, subjects in the intervention arm were at a reduced risk of subsequent infections than were those in the placebo group (RR 0.61).
With catheterized patients, no statistical difference was found between patients in intervention groups or placebo arms either for symptomatic or asymptomatic infections.
In a Canadian study of 40 children who had been intermittently catheterized, 89% (17 of 19) of the subjects in the intervention group drinking 15 mL/kg per day of a cranberry beverage dropped out, 9 of whom cited taste as a factor.
In addition, the researchers said, “the large number of dropouts/withdrawals from some of the studies indicates that cranberry juice may not be acceptable over long periods of time.”
The investigators noted that their analysis provided no clear evidence as to the amount and concentration of cranberry juice that needs to be consumed to be most effective in preventing UTIs.
In four trials, cranberry products such as juice, tablets, or capsules reduced the incidence of UTI. ©Kerioak/Fotolia.com