Posted by: Chris Maloney | March 14, 2013

Cranberries Don’t Help Urinary Tract Infections?

English: cranberries

English: cranberries (Photo credit: Wikipedia)

Just when I thought it was safe to assume that the sun rises in the east, the Cochrane meta-analysis of all studies found that “cranberry juice cannot currently be recommended for the prevention of UTIs.”  This is a reversal of two previous analyses, as well as decades of herbal folklore.

What happened?  Well, they didn’t see a robust effect in the newer studies, so they concluded that cranberry juice didn’t work.  Did it hurt anyone?  No.  “There was no significant difference between gastrointestinal adverse effects from cranberry product compared to those of placebo/no treatment.”

So why not recommend cranberry juice?  Well, it just doesn’t work according to studies.

How did cranberry juice do compared to taking antibiotics?  “The effectiveness of cranberry was not significantly different to antibiotics for women and children.”

Wait a second, did I just read that cranberry juice was pretty much the same as antibiotics for urinary tract infections?  Yes.

So the headline should read:  neither antibiotics nor cranberry juice help urinary tract infections?  Nope.   Because everyone knows antibiotics work.

What we have here is a case of a group of  researchers reversing both a scientific and traditional medical treatment, and doing so selectively without raising the question of what is going on when neither established treatment is as effective as it should be.

Is e. coli becoming more resistant?  That’s worth pursuing.  Don’t waste time pointing the finger at a harmless treatment with a long history of effective use.

Here’s the Cochrane study:

Cochrane Database Syst Rev. 2012 Oct 17;10:CD001321. doi: 10.1002/14651858.CD001321.pub5.

Cranberries for preventing urinary tract infections.

Source

Department of Nursing and Midwifery, University of Stirling, Stirling, UK. ruth.jepson@stir.ac.uk.

Abstract

BACKGROUND:

Cranberries have been used widely for several decades for the prevention and treatment of urinary tract infections (UTIs). This is the third update of our review first published in 1998 and updated in 2004 and 2008.

OBJECTIVES:

To assess the effectiveness of cranberry products in preventing UTIs in susceptible populations.

SEARCH METHODS:

We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL in The Cochrane Library) and the Internet. We contacted companies involved with the promotion and distribution of cranberry preparations and checked reference lists of review articles and relevant studies.Date of search: July 2012

SELECTION CRITERIA:

All randomised controlled trials (RCTs) or quasi-RCTs of cranberry products for the prevention of UTIs.

DATA COLLECTION AND ANALYSIS:

Two authors independently assessed and extracted data. Information was collected on methods, participants, interventions and outcomes (incidence of symptomatic UTIs, positive culture results, side effects, adherence to therapy). Risk ratios (RR) were calculated where appropriate, otherwise a narrative synthesis was undertaken. Quality was assessed using the Cochrane risk of bias assessment tool.

MAIN RESULTS:

This updated review includes a total of 24 studies (six cross-over studies, 11 parallel group studies with two arms; five with three arms, and two studies with a factorial design) with a total of 4473 participants. Ten studies were included in the 2008 update, and 14 studies have been added to this update. Thirteen studies (2380 participants) evaluated only cranberry juice/concentrate; nine studies (1032 participants) evaluated only cranberry tablets/capsules; one study compared cranberry juice and tablets; and one study compared cranberry capsules and tablets. The comparison/control arms were placebo, no treatment, water, methenamine hippurate, antibiotics, or lactobacillus. Eleven studies were not included in the meta-analyses because either the design was a cross-over study and data were not reported separately for the first phase, or there was a lack of relevant data. Data included in the meta-analyses showed that, compared with placebo, water or not treatment, cranberry products did not significantly reduce the occurrence of symptomatic UTI overall (RR 0.86, 95% CI 0.71 to 1.04) or for any the subgroups: women with recurrent UTIs (RR 0.74, 95% CI 0.42 to 1.31); older people (RR 0.75, 95% CI 0.39 to 1.44); pregnant women (RR 1.04, 95% CI 0.97 to 1.17); children with recurrent UTI (RR 0.48, 95% CI 0.19 to 1.22); cancer patients (RR 1.15 95% CI 0.75 to 1.77); or people with neuropathic bladder or spinal injury (RR 0.95, 95% CI: 0.75 to 1.20). Overall heterogeneity was moderate (I² = 55%). The effectiveness of cranberry was not significantly different to antibiotics for women (RR 1.31, 95% CI 0.85, 2.02) and children (RR 0.69 95% CI 0.32 to 1.51). There was no significant difference between gastrointestinal adverse effects from cranberry product compared to those of placebo/no treatment (RR 0.83, 95% CI 0.31 to 2.27). Many studies reported low compliance and high withdrawal/dropout problems which they attributed to palatability/acceptability of the products, primarily the cranberry juice. Most studies of other cranberry products (tablets and capsules) did not report how much of the ‘active’ ingredient the product contained, and therefore the products may not have had enough potency to be effective.

AUTHORS’ CONCLUSIONS:

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. The addition of 14 further studies suggests that cranberry juice is less effective than previously indicated. 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. Cranberry products were not significantly different to antibiotics for preventing UTIs in three small studies. 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. Other preparations (such as powders) need to be quantified using standardised methods to ensure the potency, and contain enough of the ‘active’ ingredient, before being evaluated in clinical studies or recommended for use.

PMID:
23076891

 

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  1. […] Cranberries Don’t Help Urinary Tract Infections? […]


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