Cranberries ‘unlikely’ to prevent UTIs, says Cochrane

By Nathan Gray contact

- Last updated on GMT

Cranberry juice is ‘unlikely’ to prevent UTIs, however supplements may have some promise, says the Cochrane review
Cranberry juice is ‘unlikely’ to prevent UTIs, however supplements may have some promise, says the Cochrane review

Related tags: Cranberry juice, Urinary tract infection

Cranberry juice does not appear to have a significant benefit in preventing urinary tract infections and may be 'unacceptable' to consume in the long term, according to the findings of a new systematic review by the Cochrane Collaboration.

The updated review – initially published in 1998 and last updated in 2008 – analyses the most up-to-date evidence from clinical trials investigating the usefulness of cranberry products for prevention of urinary tract infections (UTIs).

Led by Ruth Jepson from the University of Stirling, UK, the new review contrasts its 2008 findings that cranberry products have some benefit for UTIs, by now concluding that any benefit, if present at all, is likely to be small and only for women with recurrent UTI.

“Prior to the current update it appeared there was some evidence that cranberry juice may decrease the number of symptomatic UTIs over a 12 month period, particularly for women with recurrent UTIs,”​ write the researchers.

“The addition of 14 further studies suggests that cranberry juice is less effective than previously indicated.”
Jepson commented that she does not see ‘a particular need’ for more studies investigating the effects of cranberry juice, “as the majority of existing studies indicate that the benefit is small at best, and the studies have high drop-out rates."

The lead researcher noted that in many studies where participants were given juice, there were large numbers of drop-outs – suggesting that a daily juice might not be acceptable to drink over long time periods.

She added that a common problem with research evaluating cranberry tablets or capsules was that they rarely reported the levels of active ingredient, meaning it is unclear whether levels would have been high enough to have any effect.

"More studies of other cranberry products such as tablets and capsules may be justified, but only for women with recurrent UTIs, and only if these products contain the recommended amount of active ingredient,"​ she added.

Review update

For the updated systematic review, the team gathered together evidence from 24 studies – involving a total of 4,473 people. This includes data from 14 more studies than the 2008 update.

The analysis revealed although some studies showed small benefits for women suffering from recurring infections, women would have to consume two glasses of cranberry juice per day for long periods to prevent one infection.

“Although some of small studies demonstrated a small benefit for women with recurrent UTIs, there were no statistically significant differences when the results of a much larger study were included,”​ says the review.

“Given the large number of dropouts/withdrawals from studies (mainly attributed to the acceptability of consuming cranberry products particularly juice, over long periods), and the evidence that the benefit for preventing UTI is small, cranberry juice cannot currently be recommended for the prevention of UTIs,”​ they conclude.

"Looking to future trials, we recommend no further trials of the juice should be done because it's probably not effective,"​ said Jepson. "Instead research needs to evaluate properly standardised tablets or capsules to test whether they do have an effect and to provide clear insights into the dosage."

 Supplements less affected

Doug Klaiber, C.E.O. of Decas Botanical Synergies (now part of Naturex), said while the review was not good news for juice, it's a different picture for supplements.  Decas supplies PACran, a standardized cranberry supplement ingredient.

”The Cochrane report highlighted the deficiencies in the current published clinical research for cranberry juice but also  presented the merits of cranberry supplements which are standardized in the active ingredient. The focus of our business and clinical research has been on standardized cranberry supplements," ​he said.

Marc Roller, Scientific Director of Naturex  said delivering the active cranberry compounds via a supplement improves compliance.

"The daily PACran  dose necessary to reach efficacy in UTIs si not as constraining as juices. This has been confirmed in all clinical trials performed with PACran , where dropouts were much lower than what was reported in other trials with cranberry juice," ​he said. 

 

Source: The Cochrane Library
Published online, doi: 10.1002/14651858.CD001321.pub5
“Cranberries for preventing urinary tract infections”
Authors: Ruth G Jepson, Gabrielle Williams, Jonathan C Craig

Related topics: Research, Polyphenols

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2 comments

juice or juice drink

Posted by Donald Thomas,

Aloha,
I wonder how many ladies were drinking pure cranberry juice as compared to juice drink made with sugar and watered down. I would think that cranberry powder and pure supplements would produce a greater benefit. Whole cranberries have been shown to be beneficial to UTI's.

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Cranberry still recommended

Posted by Amy Howell,

I have been doing research at Rutgers University for the past 20 years and have found that cranberries prevent bacteria from sticking to bladder cells, which is the initial step in the urinary tract infection process. I think we need to keep these latest findings in perspective with the totality of cranberry research that has been done over the last 100 years. This latest review analyzed results from some of the clinical trials, using criteria that apply to studies on drug treatments. Cranberry is a food that comes in different forms (juices, powders, dried, etc.) making it difficult to compare results from different trials because the same form and dosage of cranberry were not used in each study.

Interestingly, three new UTI clinical studies, published after this report was prepared, have shown significant benefits in children, with as much as a 65% reduction in UTIs and reduced use of antibiotics. Cranberries in many forms are enjoyed by millions of people globally on a daily basis. If women are currently consuming cranberry products, the results of this one review do not provide a reason for them to change their current practices. It is important that cranberry continue to be regarded and researched as a viable means to help address the public health challenge that UTIs and their treatment presents to antibiotic resistance. The effects of the studies are clinically important to the 15 million women in the US with UTIs each year. - Amy Howell, PhD

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