Sunday, August 7, 2011

Does cranberry really help prevent urinary tract infection?

Cranberry juice and drinks and pills with cranberry extract have been promoted to prevent urinary tract infections in women.

But does taking cranberry in one form or another really work?
If so, how much should you take?

First, keep in mind that no studies have shown that cranberry can be used to treat an infection that has already occurred.

But many studies, although not all, show that cranberry can be helpful for prevention of urinary tract infection.

But cranberry for prevention in those with urinary catheters does not seem to work.

In a study published last month, 221 women who had suffered from at least 3 urinary tract infections each year were given either a cranberry pill supplement twice daily or an antibiotic (trimethoprim with sulfamethoxazole abbreviated TMP-SMX) once a day.

This was a randomized study. That means patients were assigned randomly to one treatment or the other. There was no placebo group; that means all the participants had some form of treatment. In this case, cranberry extract or the antibiotic was given.

Over the next 12 months of the study, there were more infections in the cranberry users than those on the antibiotic. Obviously, that's not good news.

But those taking cranberry had less than they had had the year before the study: down from around 7 to 4 infections per year.
And the dose of cranberry given in this study was probably much too low.

Most of the women who took the antibiotic developed bacteria that became resistant to that antibiotic, TMP-SMX. There was more than 3 times the antibiotic resistance in those on the daily antibiotic as compared to those on the cranberry pills.

And resistance to other antibiotics besides the TMP-SMX was also more common in the group on the antibiotic.

Getting resistant bugs is not good. That’s for sure.

So what should you do if you are a woman who tends to gets more than 2 urinary tract infections each year?

Urinating after sexual intercourse can be helpful. 
Many urinary tract infections occur after sex. 
Emptying your bladder after can be a simple effective measure.

And talk to your doctor to get evaluated and consider use of cranberry.

Cranberry appears to be safe and if you take enough it probably helps reduce your chances of another urinary tract infection.

The active chemical substances in the cranberry are probably proanthocyanidins  that reduce the ability of the bacteria to stick to the lining of the urinary tract.

But it is not clear how much cranberry you need to take.

Also not clear: should you use pills with cranberry extract or drink cranberry juice or cranberry cocktail?

I suggest getting pure cranberry juice such as that made by Lakewood or R.W. Knudsen. You can add non-caloric sweetener or dilute it with water or other beverage.

You can’t drink straight cranberry juice! Wow, it’s tart!

If your infections are mostly after sex you might drink the juice around that time.
But if you get infections at any time not related to sex, you could drink juice daily or take daily pills. 
You will note that I am assuming you're not having sex daily.

More studies on cranberry are underway.

In the meantime, I hope this update was of help.

Has cranberry worked for you?


  1. Cranberry juice has health benefits other than preventing the infection.

  2. Those claims for other benefits of cranberry are not supported by any compelling clinical trials.
    We all await such trials with a randomized placebo controlled prospective design.
    Thanks for the post.