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Cranberry and UTIs

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Updated September 18, 2012

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Cranberry has long been a popular remedy for urinary tract infections (or "UTIs"), a common condition typically caused by bacteria that enter the urethra and then the bladder. Available in a number of different natural products, cranberry is often consumed in juice or supplement form. While cranberry is not known to treat existing infections, there's some evidence that boosting your cranberry intake may help fend off future UTIs.

The Science Behind Cranberry and UTIs

Lab research shows that certain compounds in cranberry can help stop bacteria from sticking to cells in the walls of the urinary tract. While clinical trials on cranberry and UTI have yielded mixed results so far, some studies suggest that cranberry may be effective when it comes to preventing UTIs.

For a report published in Cochrane Database of Systematic Reviews in 2008, researchers analyzed 10 clinical trials (with a total of 1,049 patients) that tested the use of cranberry products for the prevention of UTIs. Overall, cranberry products (including cranberry juice and cranberry supplements) proved more effective than placebo when it came to decreasing the number of UTIs experienced over a 12-month period. Cranberry appeared to be particularly effective for women with recurring UTIs, according to the report's authors.

In another research review (published in the journal Drugs in 2009), investigators noted that trials testing the use of cranberry for UTIs tend to have high dropout rates (with up to 55 percent of participants withdrawing before the study's end). It's possible that participants may drop out due to certain adverse effects associated with long-term use of cranberry products, including stomach upset and weight gain (mostly likely caused by the increase in caloric intake resulting from adding cranberry juice to the diet).

Should You Use Cranberry to Fight Off UTIs?

More research is needed before cranberry can be recommended for prevention of UTIs. While cranberry may be of some benefit for UTI prevention, regular intake of cranberry products may also lead to side effects like gastrointestinal upset or diarrhea. Furthermore, cranberry may interact with some medications (including blood-thinning drugs, aspirin, and medicines that affect the liver). If you're considering the use of cranberry for UTI prevention, talk to your doctor to weigh the benefits and risks (and to check for any underlying health problems).

Sources:

Jepson RG, Craig JC. "Cranberries for preventing urinary tract infections." Cochrane Database Syst Rev. 2008 Jan 23;(1):CD001321.

Guay DR. "Cranberry and urinary tract infections." Drugs. 2009;69(7):775-807. doi: 10.2165/00003495-200969070-00002.

National Center for Complementary and Alternative Medicine. "Cranberry [NCCAM Herbs at a Glance". NCCAM Publication No. D291. Created September 2005. Updated July 2010.

National Institutes of Health. "Urinary tract infection – adults: MedlinePlus Medical Encyclopedia". December 2010.

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