A new study suggests cranberry juice has gone beyond a mythical urinary tract infection (UTI) prevention to the real deal — for some people.
The global review by medical scientists from Flinders University in South Australia and The Children's Hospital at Westmead in New South Wales found cranberry juice or supplements can reduce the risk of repeat symptomatic UTIs in some women by more than a quarter, and in children by more than half.
For people susceptible to UTIs following medical interventions, such as bladder radiotherapy, that risk drops by around 53 per cent.
But the review did not show any benefit for elderly people, pregnant people or in people with bladder-emptying problems.
A UTI is a bacterial infection in the bladder, kidneys or urethra and affects one in two women in their lifetime, with many people suffering from more than one infection.
The researchers said the review is the first since 2012, which showed no benefit from the products.
The Cochrane Review update includes 50 more recent trials of cranberry products, spanning close to 9,000 participants.
Senior author and executive dean of the College of Medicine and Public Health at Flinders University, Jonathan Craig, said the benefits of cranberry products became clear when the scope of the review was expanded.
"The earlier versions of this review didn't have enough evidence to determine efficacy and subsequent clinical trials showed varied results, but in this updated review the volume of data has shown this new finding," he said.
Researchers said the anecdotal benefits of cranberries span back centuries.
Lead author Gabrielle Williams said she was not surprised by the result — and the cranberry legend had been passed down in her own family.
"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," she said.
"Despite me niggling in her ear about evidence, she's continued to take it daily … as usual, it turns out that mum was right."
Co-author and Flinders University epidemiologist Jacqueline Stephens said UTI prevention was crucial to avoid the risks associated with untreated infections, including sepsis in extreme cases.
"Most UTIs are effectively and pretty quickly treated with antibiotics, sometimes as little as one dose can cure the problem," she said.
"Unfortunately, in some people, UTIs keep coming back."
Dr Stephens said the review did not look at the use of cranberry for UTI treatment.
"This is not about cure, this is about prevention. If you do have a current UTI, you still need to seek medical attention from your healthcare provider," she said.
Dr Stephens said the majority of studies examined in the review compared cranberry products with a placebo or with no treatment for UTIs.
"They might still get UTIs, but it would be less than what they'd normally get if they did nothing," she said.
She said the researchers also found no difference in the result of studies done by juice companies or manufacturers of cranberry products, and those done by academic institutions or hospitals.
"As researchers doing these reviews, we always look at who has a vested interest in the findings," Dr Stephens said.
"It's really important to look at who funds those projects and research trials — more and more scrutiny is put on those now."
The review did not find enough information to determine if cranberry products are more or less effective when compared to antibiotics or probiotics in preventing more UTIs.
