UTIs and cranberry juice

Patient question of the day: how much cranberry juice do I have to drink to prevent a UTI? Notice the question is NOT: will drinking cranberry juice prevent a UTI? It is assumed that it will, and that I have the secret formula to give. Let’s see if I do …

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I think we can all agree that the first question should be: Can cranberry juice help prevent UTIs?

The short answer: yes. With some qualifications: You have recurrent UTIs and you’re premenopausal (meaning you still get your period every month).

Some basic stats first:

  • 50-70% of women will have a UTI during their life. You’re not alone with that exquisite burning when you pee!
  • 20-30% of these women will have recurrent UTIs. Recurrent UTIs is defined as having 3+ UTIs in the previous year, or at least 2 UTIs in the previous 6 months. If you’re one of these women, you should be evaluated by your doctor. They’ll check that you’re just unlucky with UTIs versus some underlying cause or problem.


This seems weird. How can a berry prevent UTIs?

  • Current theory: cranberries contain proanthocyanidins, an antioxidant. It may keep certain types of bacteria from adhering to lining of the bladder, thus preventing a UTI!


Cranberry juice is actually studied on patients? Tell me more:

  • Women with recurrent UTIs were put into 1 of 3 groups: drink cranberry- lingonberry juice or take lactobacillus supplements or do nothing at all. At the end of 6 months, the juice group had the fewest number of UTIs (16% versus 38% vs 36%, respectively)
  • Another study showed cranberry juice and /or cranberry supplements were better at preventing UTIs than placebo (about 20% compared to 32%).
  • Yet another one: cranberry supplement versus placebo, in college age women who had had one previous UTI. Repeat UTIs were similar in both groups. This study tells us that cranberry won’t necessarily work for women with a single UTI (that’s why I used “recurrent UTIs” as a qualification above).


So now to my patient’s question: how much cranberry juice do I have to drink?

The studies usually use several glasses of juice daily. Several women in the studies dropped out because they couldn’t / didn’t want to drink that much cranberry juice. I don’t blame them. It’s not my fav.

So this is the secret formula? Yes! A few glasses daily. Sporadic chugging won’t help. It’s the consistency that seems to be the key.


Isn’t there an alternative to the juice itself?

  • Yes! Cranberry supplements have been studied too, as you can see above. But supplements are tricky. They are not FDA regulated so the amount and concentration of proanthocyanidins varies from supplement to supplement. The studies used 2 tablets daily. The most important thing is to take them consistently.


This all satisfied my patient … hope it satisfies the internet too.


Source: Geerlings et al. Prevention of recurrent urinary tract infections in women. Infect Dis Clin N Am 28 (2014) 135-147.

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