This folk remedy may be for real: A new study finds that cranberry products really do help prevent urinary tract infections.
The benefit of cranberry juice and other cranberry products in staving off urinary tract infections (UTIs) has long been debated. In 2011, a study showed that among a group of college-age women, those consuming more cranberry products were 43% more likely to develop a UTI. Yet, other studies, including one conducted by the Cochrane Review in 2008, have hinted that cranberry products can help reduce the risk of these infections by as much as 34%. Those results were backed up by molecular analyses showing that compounds in cranberries could block the ability of the bacteria that cause UTIs to attach themselves to the membranes of the urinary and genital tracts.
Despite the lack of consensus, however, many doctors have continued to advise their patients to try cranberry products for infection, since the alternative treatment — antibiotics — can lead to drug resistance, which makes bacterial infections harder to treat.Some 50% of all women will have UTI at least once in their lives, and 30% of women will have recurrent infections.
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Now, in a new report published in the Archives of Internal Medicine, researchers led by Dr. Chih-Hung Wang of the department of emergency medicine at National Taiwan University Hospital aim to clarify the conflicting data. They note that previous studies may have suffered from methodological problems, since many included participants who drank cranberry juice, which can be high in sugar, and sugar is known to promote bacterial growth.
To get a better idea of where the majority of the data lie on this issue, Wang and his colleagues collected data from 13 different trials involving 1,616 participants. The studies investigated consumption of cranberries and cranberry products, including juices and pills, and its effect on risk of UTIs. Overall, the evidence, which compared UTI rates between those consuming more or less cranberry products, showed that people eating more cranberry were 38% less likely to develop UTIs.
When the scientists broke down the data by subgroups, they found that some people had even lower risk: women who experienced recurrent infections were 47% less likely to have a UTI if they consumed more cranberry. Those who drank cranberry juice, versus other forms of cranberry or cranberry supplements, had a 53% drop in infections, possibly because they were better hydrated or because juice contains other beneficial additives, the researchers said. Children consuming cranberry products had the greatest drop in risk of all; youngsters who consumed more cranberries had a 67% lower risk of UTIs, compared with those who ate less.
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The researchers could not determine how cranberry may protect against infection, but suggest that future studies focus on a compound called A-type proanthocyanidins, which are known to block the ability of E. coli, a common cause of UTI, to stick to mucosal walls.
Alice Park is a writer at TIME. Find her on Twitter at @aliceparkny. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.