The potential UTI risk reduction was found to be higher for women (51% reduction), children (67% reduction), and people who consumed cranberry products at least twice a day, according to findings published in the Archives of Internal Medicine.
The link between cranberries and urinary tract health is well established, and linked to its proanthocyanidin (PAC) content. In 2004 France became the first country to approve a health claim for the North American cranberry (Vaccinium macrocarpon) with at least 36mg of proanthocyanidins (PAC) to “help reduce the adhesion of certain E. coli bacteria to the urinary tract walls”, and subsequently fight urinary tract infections (UTIs).
Researchers from National Taiwan University Hospital and Harvard School of Public Health report, however, that only three of the ten clinical trials considered for their analysis presented data on PAC contents, making it “difficult to effectively compare outcomes among the trials without this information”.
Safe and effective natural alternative
Commenting independently on the review’s conclusions, Amy Howell, PhD, from the Marucci Center for Blueberry Cranberry Research at Rutgers University told NutraIngredients-USA: “The results of this latest meta-analysis of clinical trials in a highly regarded journal provide further convincing support for the use of cranberry in the prevention of recurrent UTI in susceptible populations.
“Results indicate that despite the challenges of utilizing cranberry in different formulations, dosages, and target populations, overall positive outcomes were obtained in many cases.
“Since this analysis, an additional study on cranberry effectively preventing UTI recurrences in children has been published (Salo et al., Cranberry juice for the prevention of recurrences of urinary tract infections in children: a randomized placebo-controlled trial. Clin Infect Dis. 2012, Vol. 54, pp. 340-346).
“Given the increasing rates of antibiotic resistance development when low-dose antibiotics are prescribed for UTI prevention, cranberry should be considered as a safe and effective natural alternative for maintenance of urinary tract health.”
Study details
The Taiwan and Harvard researchers identified 10 trials for inclusion in their meta-analysis. These trails provided data for 1,494 people.
While a general reduction in risk was observed for all the data, further analysis revealed that cranberry-products were more effective in specific sub-groups, including women with recurrent UTIs, women in general, children, regular cranberry juice drinkers, and people who consumed cranberry-containing products at least twice a day.
“A better preventive effect from cranberry-containing products was noted with dosing frequency more than twice daily,” wrote the researchers.
“Because in vitro data have suggested that the anti-adhesion activity of cranberry juice on fimbriated E coli lasts for approximately 8 hours after ingestion, dosing more frequently than twice daily may be a reasonable choice.”
“The PAC content should be specified in future trials to allow differentiation of the effects of PACs on clinical response. Also, consumers of cranberry-containing products should have access to this information when they buy products touted for prevention of UTI.”
Source: Archives of Internal Medicine
Volume 172, Number 13, Pages 988-996
“Cranberry-Containing Products for Prevention of Urinary Tract Infections in Susceptible Populations - A Systematic Review and Meta-analysis of Randomized Controlled Trials”
Authors: C-H. Wang, C-C. Fang, N-C. Chen, S.S-H. Liu, et al.