Can Cranberries Fight Urinary Tract Infections?

By Charlene Laino
WebMD Health News

Reviewed by Louise Chang, MD

Sept. 11, 2012 (San Francisco) -- Early research suggests cranberries, vitamin C, acupuncture, and other alternative treatments may help to prevent urinary tract infections (UTIs) in some women, according to a Dutch infectious diseases specialist.

While the treatments don't appear to work as well as antibiotics, they also will not contribute to the growing problem of antibiotic resistance, says Suzanne Geerlings, MD, of the Academic Medical Center in Amsterdam.

But other experts say the evidence for alternative treatments is weak, and they point out that studies of such treatments often show conflicting results.

Speaking here at the annual infectious diseases meeting of the American Society for Microbiology, all agree that further study is needed before cranberries or other alternative treatments can be recommended as standard UTI fighters.

Urinary tract infections are the second most common type of infection in the body, accounting for about 8.1 million visits to health care providers each year, according to the National Kidney and Urologic Diseases Information Clearinghouse. Women are especially prone to UTIs; their lifetime risk is more than 50%. UTIs are not as common in men but can be serious when they occur.

Many women have frequent UTIs. About 20% of young women with a first UTI will have a recurring infection. And with each UTI, the risk of repeat UTIs further rises.

Cranberry Juice, Capsules

A review of 10 studies involving more than 1,000 women showed that taking cranberry juice or cranberry capsules cut by one-third the number of UTIs over a year compared with placebo, Geerlings says. Younger women and those with repeat UTIs benefited most.

However, many of the women in the cranberry group dropped out of the studies early. Geerlings believes that's because many dropouts were assigned to drink the concentrated cranberry cocktails, "which are not very palatable." She suggests future research use capsules.

Her team recently performed a study pitting cranberry capsules against antibiotics in more than 200 premenopausal women who had an average of seven UTIs a year. Over 12 months, antibiotics lowered the average number of UTIs to two vs. four for the cranberry capsules.

"Still, the cranberries again reduced the number of UTIs by about one-third. Moreover, 85% of the women taking antibiotics [showed signs of] resistance after only one month of treatment," Geerlings says.

So what's a person to do? Talk to your doctor, Geerlings advises. "If getting rid of the UTI is your priority, you are probably better off with antibiotics, as long as you realize their downside. But some women have already had antibiotic-resistant UTIs, which are more difficult to treat."

Another reason to talk with your doctor is that while generally safe, cranberry products can react dangerously with certain medications; mixed with the blood thinner warfarin, for example, they can cause excessive, potentially fatal bleeding, Geerlings says.

Some doctors say it's too soon to even think about taking cranberry products to ward off UTIs. "Until long-term studies are done, I do not think cranberries can be recommended for prevention of UTIs," says Lindsay Nicolle, MD, professor of internal medicine and medical microbiology at the University of Manitoba in Winnipeg, Canada.

She says most of the studies that have been done are not well designed. Also, some studies have shown no benefit to cranberry products; in one such study, cranberry capsules did not reduce bladder infections in people in long-term care facilities.

These findings were presented at a medical conference. They should be considered preliminary, as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.


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SOURCES: Interscience Conference on Antimicrobial Agents and Chemotherapy 2012, San Francisco, Sept. 9-12, 2012. Suzanne Geerlings, MD, infectious diseases specialist, Academic Medical Center, Amsterdam. Lindsay Nicolle, MD, professor of internal medicine and medical microbiology, University of Manitoba, Winnipeg, Canada.

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