New evidence suggests cranberry products can prevent urinary tract infections for women. 

Drinking cranberry juice has long been a mythical prevention strategy for women who develop a urinary tract infection - but new medical evidence shows consuming cranberry products is an effective way to prevent a UTI before it gets started. 

A global study looking at the benefits of cranberry products published in Cochrane Reviews has determined cranberry juice, and its supplements, reduce the risk of repeat symptomatic UTIs in women by more than a quarter, in children by more than half, and in people susceptible to UTI following medical interventions by about 53 per cent.

It is a surprising finding, given that the most recent review in 2012, with evidence from 24 trials, showed no benefit from the products.

The medical scientists behind this updated review from Flinders University and The Children’s Hospital at Westmead aimed to update these findings, as an important step in determining the effectiveness of cranberry products by looking at 50 more recent trials that included almost 9,000 participants.

“This incredible result didn’t really surprise us, as we’re taught that when there’s more and better evidence, the truth will ultimately come out. UTIs are horrible and very common; about a third of women will experience one, as will many elderly people and also people with bladder issues from spinal cord injury or other conditions,” says the study lead author Dr Gabrielle Williams.

“Even back in 1973, my mum was told to try cranberry juice to prevent her horrible and frequent UTIs, and for her it’s been a saviour. Despite me niggling in her ear about evidence, she’s continued to take it daily, first as the nasty sour juice and in recent years, the easy to swallow capsules. As soon as she stops… the symptoms are back. As usual, it turns out that mum was right! Cranberry products can help some women prevent UTIs.”

Flinders University epidemiologist Dr Jacqueline Stephens, a co-author of the study, says if the UTI persists untreated it can move to the kidneys and cause pain and more complications, including sepsis in very severe cases, so prevention is the most effective way to reduce risks.

“Most UTIs are effectively, and pretty quickly, treated with antibiotics, sometimes as little as one dose can cure the problem. Unfortunately, in some people UTIs keep coming back,” she said. 

“Without being sure if or how it works, some healthcare providers began suggesting it to their patients.  It was a harmless, easy option at the time. 

“Even centuries ago, Native Americans reportedly ate cranberries for bladder problems, leading somewhat more recently, to laboratory scientists exploring what it was in cranberries that helped and how it might work.”

The studies we looked at included a range of methods to determine the benefits of cranberry products. The vast majority compared cranberry products with a placebo or no treatment for UTI and determined drinking cranberries as a juice or taking capsules reduced the number of UTIs in women with recurrent cases, in children and in people susceptible to UTIs following medical interventions such as bladder radiotherapy.

The experts say it is also important to consider that few people reported any side effects with the most common being tummy pain based on the results. 

They also did not find enough information to determine if cranberry products are more or less effective compared with antibiotics or probiotics in preventing further UTIs.

Additionally, the data also does not show any benefit for elderly people, pregnant women or in people with bladder emptying problems.

The full study is accessible here.