Cranberry juice provides no meaningful protection against cystitis, contrary to the belief of large numbers of women, say Scots scientists.

A review of findings from 24 studies involving 4473 participants found no evidence that cranberry juice, or supplements, can be used to prevent bladder and kidney infections.

Cystitis is a stinging inflammation of the bladder usually caused by a urinary tract infection (UTI). It can also be triggered by irritation during sexual intercourse, leading to its nickname the "honeymoon disease".

For decades women have used cranberry juice to treat mild cystitis or prevent recurring infection. Experts have suggested that compounds in cranberries may stop bacteria sticking to cells lining the walls of the urinary tract.

Numerous websites and many GPs encourage women troubled by cystitis to try the cranberry treatment on the basis it might help and will do them no harm.

In 2008, a review of 10 trials found that women who drank the juice or took cranberry supplements had fewer UTIs than those who did not.

Like the latest review, it was published in the Cochrane Library that specialises in assessing medical evidence to inform guidelines and health policy.

Some of the studies looked at in the new review showed "small benefits" for women suffering from recurrent infections. However, the authors stressed these were not statistically significant. Women would have to consume two glasses of cranberry juice every day over long periods to prevent one infection, they pointed out.