Cranberry offers alternative to antiobiotics for the prevention of urinary tract infections

Less than a month ago I wrote about one specific hazard associated with the taking of antibiotics, specifically their capacity to disturb the ‘ecosystem’ within the gut. In the short term this may lead to symptoms such as diarrhoea, but theoretically there may be longer-term consequences too, in the form of chronic digestive symptoms such as bloating, wind and altered bowel habit. One way to insure against such problems is to take probiotics (health gut organisms) during and/or after a course of antibiotics. My blog of last month focused on the research which has found this to be a generally worthwhile strategy for the prevention of gut upset in the short term.

Urinary tract infections (UTIs) are typically treated with antibiotics, and are much more common in women. Over the years I have seen many women who seem to be especially prone to UTIs. Quite often the picture is one of repeated UTIs interspersed with bouts of vaginal thrush (yeast infection) as a result of taking antibiotics. What is likely to be happening here is that the antibiotics are leading to the yeast overgrowth in the body (including the vagina) which then manifests as thrush. The ability for antibiotics to alter the ‘ecosystem’ in the vagina may be especially relevant, because this may make it more likely that unhealthy organisms (including the bacterium E. coli) will be able to colonise the area in numbers sufficient to make their way up the urethra (the pipe from the bladder to the outside) and into the bladder to set up an infection here.

How to break this cycle? Well, I believe probiotics have a role to play here in helping to establish the better ecosystem in the gut and elsewhere, including the vagina.

The other major strategy is to try and do without antibiotics, of course. In a previous post here I wrote about the potential use of cranberry in this regard, as well as including some other strategies in the form of a previous piece. Cranberry has the ability to inhibit the attachment of E. coli organisms to the bladder wall, and so makes it less like that this organism will set up camp here can cause a full-blown infection.

I was interested to read of a recent study where the effectiveness of cranberry was tested in terms of its ability to prevent UTIs in women [1]. In this study, 137 women prone to UTIs were treated either with cranberry (500 mg of extract each day) or the antibiotic trimethoprim (commonly used in the treatment or prevention of UTIs) at a dose of 100 mg per day. There was no statistically significant different in the average time it took to the next UTI between the two groups. Also, trimethoprim led to more side-effects, and the drop-out rate from the study was about twice that in the group taking cranberry.

This study, I think, is hampered by not having a control group taking placebo (inactive medication). However, what it does show is that cranberry offers a viable alternative to long-term antibiotics for women suffering from recurrent UTIs. The authors of the study were suitably impressed, and concluded Our findings will allow older women with recurrent UTIs to weigh up with their clinicians the inherent attractions of a cheap, natural product like cranberry extract whose use does not carry the risk of antimicrobial resistance or super-infection with Clostridium difficile or fungi.


1. McMurdo ME, et al. Cranberry or trimethoprim for the prevention of recurrent urinary tract infections? A randomized controlled trial in older women. J Antimicrob Chemother 2008 Nov 28 [Epub ahead of print]

4 Responses to Cranberry offers alternative to antiobiotics for the prevention of urinary tract infections

  1. Anna 8 January 2009 at 1:31 am #

    I used to be one of those women “prone to UTIs”, with repeated infections from age 19-late 30s, lots of PCP and urologist appts, and eventually prophylactic low dose Macrodantin (nitrofurantoin) for a year. I also got a lot of vaginal yeast overgrowths, though not generally due to the UTI treatment (nitrofurantoin isn’t one of those antibiotics that kills off all the good bacteria, too). I never traveled without a Rx for Macrodantin or antifungal treatment, just in case.

    I was told birth control pills were a likely factor, but the infections occurred whether I took BCPs or not. And the infections occurred both when I was naturally quite skinny and when I gained about 25 pounds in my 30s. Most of that time, I was eating a high carb diet (per the common dietary advice), probably with too much sugar, and definitely too many PUFA oils and not enough natural fats. I became very sick of drinking cranberry juice.

    Interestingly, the UTIs and yeast infections stopped when I started a low carb diet. I’ve been sticking to a whole foods, low carb diet for a number of years now and nary an infection. And I now know I have impaired glucose regulation, with very high BG levels if I consume common high carb foods, unprocessed or not. I suspect I was running high glucose levels for years before, and this was triggering the infections. My diet keeps my glucose levels steady and normal and I suspect that prevents the conditions that promote infections.

    This isn’t proof of course, but I’m not about to test it by chowing carbs to raise my BG to see if I get a UTI or yeast infection. But frequent UTIs and yeast infections are also symptoms of diabetes, which of course, no one thought to check back then.

  2. Jeff 8 January 2009 at 8:00 pm #

    I second Anna’s comment regarding diet. My wife and I changed to a Paleo/low carb diet in Feb 2008 and she has not had a UTI since. Are there any studies on this? At least 3 women in my family had recurring UTI’s and this may effect a lot of people.

  3. Hilda Glickman 9 January 2009 at 11:53 pm #

    There is a huge amount of literature on the effect of sugar on yeast infections which are related to this. See web on candida.

  4. Samantha 20 February 2009 at 4:12 am #

    The diet thing is so very true. I suffered from both UTI and yeast infections for years. About 3 months ago I came across a site. The lady had the same problems as me, but started low carb and it went away. I followed the diet she had listed and haven’t had one in 3 months since i started. is her site. Good info.

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