Cranberry for UTIs: What's the evidence?

If you’ve ever had a urinary tract infection (UTI), there’s a good chance you have tried to treat it yourself with cranberry.

Cranberry juice and supplements (these may be capsules and tablets) have long been promoted as a “natural” way to deal with a UTI. The idea is they can stop a UTI before it really gets started or treat the symptoms once you have it.

The thing is, when you look at all the scientific research, the evidence cranberry products work just doesn’t stack up.

What does the research tell us?

A lot of people swear cranberry works for them.

And lab studies have found chemicals called proanthocyanidins in cranberries can stop E. coli (the bug that causes most urinary infections) from sticking to the lining of the urinary tract.

But consider the human studies and the story gets more complicated. Some smaller and older studies found cranberry products can be useful for UTIs, but others found no benefit.

The biggest review of studies to date, published in 2012, found neither the juice nor supplements were effective in preventing UTIs. However, the reviewers suggested it might be because supplements did not contain enough of the “active ingredient”.

In the latest research, infectious disease physician Associate Professor Manisha Jutani-Mehta and colleagues at Yale University studied the effect of cranberry capsules containing a higher dose of active ingredient in older women.

One hundred and eighty-five nursing home residents were put into two groups. Half were given two cranberry capsules a day and the other half were given a placebo.

Over a 12-month period, the researchers tested the women’s urine every two months to check levels of bacteria that cause UTIs, and white blood cells — a common sign of infection. They found no differences in these markers between the groups.

The researchers concluded cranberry supplements were no more effective than the placebo when it comes to preventing UTIs.

This was disappointing given they were hoping cranberry might be an alternative to antibiotics, which are often given to nursing home residents, but which can impact on their health as well as the health of the wider community.

“Nursing home residents are exposed to antibiotics so frequently and they are at risk for infection, so much so that I was hoping that a non-antimicrobial method would be possible at preventing UTIs in these women,” Associate Professor Manisha Jutani-Mehta said.

What about juice?

This study looked specifically at cranberry supplements, so what about juice?

The 2012 review concluded ‘cranberry juice does not appear to have a significant benefit in preventing UTIs’. Again, other studies have had mixed results.

One reason why so many women might feel cranberry juice helps is because it has a ‘flushing effect’. Women are told to drink plenty of water and other fluids to flush out the urinary system to prevent UTIs.

So rather than the cranberry have an effect, it’s probably the ‘juice’ that’s helping, Associate Professor Jutani-Mehta says.

So what next?

Despite a lack of scientific support for cranberry, she wouldn’t tell women to stop drinking cranberry juice.

Women report that it reduces the burning sensation they have when they are developing a UTI, she says.

She believes cranberry juice may have an anti-inflammatory effect, or work in a way we don’t yet understand.

“Many women will tell me that it works for them. And for those who tell me that, I say continue using it. There is little downside to doing that,” she said.

But cranberry capsules and tablets means are a different matter, Dr Jutani-Mehta said.

While drinking cranberry juice may be an enjoyable thing to do, supplements have no proven benefits.

“I think [these] are a different category of product because this is really an unregulated industry … which has great financial potential for companies.”

Get the right treatment.

If you think you have a UTI, don’t ignore it and hope it will go away. Go to your GP. An untreated UTI can become a full blown kidney infection, which is much more serious.

But there are some measures you can take that can help prevent UTIs. The women’s health organisation Jean Hailes recommends the following:

Drink plenty of water to flush out the urinary system
Go to the toilet as soon as you feel the need so bacteria does not have the chance to collect
Wipe from front to back after going to the toilet to avoid transfer of bacteria from the anus to the urethra
Go to the toilet immediately after sex to reduce the movement of bacteria into the urethra and drink plenty of water so that you need to go again in a few hours

This post originally appeared on ABC News.