• Don’t bother with the cranberry juice

    Surely you’ve heard that cranberry juice will prevent urinary tract infections. There are even some old studies that seem to support this belief. A new systematic review has made that much less clear:

    Urinary tract infections (UTIs) affect the bladder, as in cystitis, and sometimes the kidneys. Cranberries and cranberry juice have been used to prevent UTIs for decades, although it is not clear how they might help protect against infection. According to one theory, certain sugars and flavanol compounds in cranberries prevent bacteria sticking to cells lining the walls of the urinary tract. Several systematic reviews have been published on the subject in The Cochrane Library, each time incorporating more evidence. In the last review in 2008, it was concluded that cranberries offer a small benefit in preventing recurring UTIs in women.

    In the current review, the researchers gathered together evidence from 24 studies that involved a total of 4,473 people. These studies included 14 added since the 2008 update. Those in treatment groups were given cranberry juice, tablets or capsules, while those in control groups were given placebo cranberry products, water, methenamine hippurate, antibiotics, lactobacillus or nothing. Although in some studies there were 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. The researchers conclude that current evidence does not support cranberry juice as a means of preventing UTIs.

    No one is going to drink two glasses of cranberry juice a day for a long time for a very, very small chance of preventing a urinary tract infection. In fact, it appears that there were large numbers of women dropping out of studies requiring that much cranberry juice consumption.

    This all warms my mythbusting heart. I can’t find the link to the systematic review yet. When I do, I’ll post it.


    • We were taught in our medical training that acidifying the urine during treatment for UTI was helpful. For instance Mandelamine and ascorbic acid. Cranberry juice simply acidifies the urine. I am sorry that I have no concrete data for you, however.

      Antibiotic treatment these days is so simple, cheap and effective, that we rarely make a specific recommendation for cranberry juice other than maybe with women with recurrent urinary tract infections.

    • This should cause us to question much more of what we think we know about nutrition but it won’t.

    • I had a neighbor in grad school in the mid seventies. He was paraplegic as a consequence of a bad auto accident. He had been prescribed cranberry juice, and he drank great quantities of it. I went to the grocery store for him one night, and I came back with the wrong stuff — cranberry apple. It would not do.

    • Which cranberry juice? The one that everybody enjoys or the unfiltered, unsweetened kind? the studies that I have read don’t stipulate. The women I know who have benefited from cranberry are those with recurrent UTI who consume unsweetened unfiltered cranberry juice and it only takes about 1/4 c per day. I posit that part of the benefit is increased fluid consumption — either a lot of the sweetened juice or a lot of water to wash down the other. Many women (the only kind of patients I know) fail to drink enough water daily to effectively flush their bladder regularly.