“UTIs can be distressing, and people often take a self-care approach rather than seeking professional advice,” said Ruth Jepson, a senior research fellow at the University of Stirling, who led the review. “It is a common problem that a great deal of health care time and resources are spent on.”

A diagnosis of a urinary tract infection refers to a presence of a large amount of bacteria in the urine that can cause pain during urination and can lead to more severe infections of the bladder and kidneys.

The aim of the systematic review was to determine whether taking cranberries is an effective way to prevent urinary tract infections.

The review appears in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates research in all aspects of health care. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing trials on a topic.

According to the American Urological Association, UTIs are among the most common medical conditions and are responsible for more than 7 million doctor office visits each year. The association reports that about 40 percent of women and 12 percent of men will experience at least one urinary tract infection during their lifetime.

People have used cranberries, especially cranberry juice, for decades to prevent and treat UTIs. The fruit contains organic substances, such as quinic acid and citric acid, which act as antibacterial agents to help eliminate bacteria from the bladder.

The Cochrane reviewers analyzed 10 studies including 1,049 participants of all ages who received either cranberry products (juice or cranberry capsules), placebo juice or water for at least one month.

Of the studies evaluated, there was no consistent dosage or concentration of cranberries given to the participants, but according to Jepson, there was a “typical amount” given daily.

“The most common amount recommended is one glass twice a day,” Jepson said. “Trouble is, there is no general rule as to how long you have to drink that much in order for you to prevent one UTI.”

Jepson and her colleague found that cranberry products significantly reduced UTIs over 12 months compared to the placebo/control groups. The cranberry treatment was more effective for women who suffered from recurrent UTIs. For example, in one study, after six months, eight women in the cranberry group had a least one recurring UTI, compared with 19 women in the lactobacillus group and 18 in the control group.

The Cochrane reviewers pointed to a high number of participant withdrawals within some of the studies, and suggested it was due to the taste of cranberry juice or the juice’s high cost. Jepson, however, could not recommend that a woman with recurrent UTI use cranberry capsules as an alternative treatment if taste or cost became prohibitive.

“The trouble with capsules is that there is no standardized preparation,” said Jepson. “What we don’t know is if the active ingredient is as effective when taken in the capsule or tablet form.”

Roger Dmochowski, a professor of urology at Vanderbilt University Medical and the American Urological Association’s expert on this topic, and said the association has no official policy toward cranberry juice or products.

“Most urologists recommend urine acidification for certain types of infections of the urine,” he said. “However not all UTIs are due to non-acid urine. Therefore, it is reasonable to use cranberry extract, but certainly this does not pertain to all UTI indications. This strategy [cranberries] remains an option for women bothered by recurrent infections but only one of many strategies, which include hydration and judicious use of antibiotics.”

FOR MORE INFORMATION:
Health Behavior News Service: hbns-editor@cfah.org or (202) 387-2829.

The Cochrane Collaboration is an international nonprofit, independent organization that produces and disseminates systematic reviews of health care interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions. Visit http://www.cochrane.org for more information.

Jepson RG, Craig JC. Cranberries for preventing urinary tract infections (Review). Cochrane Database of Systematic Reviews 2008, Issue 1.