Q. Does drinking cranberry juice really help with bladder infections?

A. Yes. Cranberry juice and cranberry extract have been shown to be quite effective in preventing and treating bladder infections in several clinical studies. In one study, 16 ounces of cranberry juice per day produced beneficial effects in 73% of the subjects with active urinary tract infections. Furthermore, withdrawal of the cranberry juice in the people who benefited resulted in recurrence of bladder infection in 61%.

Although many people believe the action of cranberry juice is due to acidifying the urine and the antibacterial effects of a cranberry component hippuric acid, these are probably not the major mechanisms of action. Recent studies have shown that components in cranberry juice reduce the ability of bacteria to adhere, or stick to, the tissue that lines the bladder and urethra. In order for bacteria to infect they must first adhere to this tissue. By interfering with adherence, cranberry juice greatly reduces the likelihood of infection. This is the most likely explanation of cranberry juice’s positive effects in bladder infections.

If cranberry extract is used instead of cranberry juice, the amount taken should be equivalent to 16 ounces of cranberry juice daily. There is no known toxicity as a result of cranberry ingestion.