London - It’s a popular treatment for bladder infections but researchers say cranberry juice is less effective than previously thought.

The researchers said the juice could help women who suffer from recurrent cystitis but they would have to drink two glasses a day and over months to gain any benefit.

The team from the University of Stirling gathered evidence from 24 studies involving a total of 4,473 people.

In the studies, participants had been treated with a variety of products, from cranberry juice to tablets and antibiotics, or placebos such as water or nothing.

Selected research showed the juice prevented some infections in women suffering from recurring cystitis.

But the Stirling researchers said these women would have to consume two glasses of cranberry juice every day over months to prevent just one infection.

Previous research has found cranberry juice can fight infections because it contains sugars and plant pigments called flavonoids which help flush away bacteria.

But the researchers, whose work is published in the Cochrane Library collection of research, concluded that current evidence does not support cranberry juice as a means of preventing urinary tract infections.

Lead researcher Ruth Jepson said: “We can’t see a particular need for more studies of the effect of cranberry juice, as the majority of existing studies indicate that the benefit is small at best.

“More studies of other cranberry products such as tablets and capsules may be justified but only for women with recurrent UTIs, and only if these products contain the recommended amount of active ingredient.” - Daily Mail