Cranberries for Preventing Urinary Tract Infections

Cranberries have been used widely for several decades for the prevention and treatment of urinary tract infections (UTIs). This is the third update of our review first published in 1998 and updated in 2004 and 2008.

Objectives – To assess the effectiveness of cranberry products in preventing UTIs in susceptible populations.

This updated review includes a total of 24 studies with a total of 4473 participants. Thirteen studies (2380) participants) evaluated cranberry juice/concentrate; nine studies (1032) participants) evaluated cranberry tablets or capsules; one study compared cranberry juice and tablets; and one study cranberry capsules and tablets.

Many studies reported low compliance and high withdrawal/dropout problems which they attributed to palatability/acceptability of the products, primarily the cranberry juice. Most studies of the other cranberry products (tablets and capsules) did not report how much of the ‘active’ ingredient the product contained, and therefore the products may not have had enough potency to be effective.

Prior to the current update, it appeared there was some evidence that cranberry juice may decrease the number of symptomatic UTIs over a 12-month period, particularly for women with recurrent UTIs. The addition of 14 further studies suggests that cranberry juice is less effective than previously indicated. Although some of the small studies demonstrated a small benefit for women with recurrent UTIs, there were no statistically significant differences when the results of a much larger study were included. Given the large number of dropouts/withdrawals from studies and the evidence that the benefit for preventing UTI is small, cranberry juice cannot currently be recommended for the prevention of UTIs. Other preparations (such as powders) need to be quantified using standardized methods to ensure the potency and contain enough of the ‘active’ ingredient, before being evaluated in clinical studies or recommended for use.

Cranberry Juice for Urinary Tract Infection?

Contrary to popular belief, cranberry juice does not cure a urinary tract infection, a doctor says.
Many people drink cranberry juice in an attempt to ease their symptoms, but it will do nothing to help them, said Dr. Timothy Boone, vice dean of the Texas A&M Health Science Center College of Medicine, Houston campus.

“Cranberry juice, especially the juice concentrates you find at the grocery store, will not treat a UTI [urinary tract infection] or bladder infection,” he said in a center news release.

“It can offer more hydration and possible wash bacteria from your body more effectively, but the active ingredient in cranberry is long gone by the time it reaches your bladder,” Boone said.

Each year, more than 3 million Americans have a urinary tract infection – an infection in any part of the urinary system, kidney, bladder or urethra, according to the news release.

The active ingredient in cranberries – A-type proanthocyanidins (PACs) – is effective against UTI causing bacteria, but is found only in cranberry capsules, not in cranberry juice, Boone said.

“It takes an extremely large concentration of cranberry to prevent bacterial adhesion,” Boone said. “This amount of concentration is not found in the juices we drink. There’s a possibility it was stronger back in our grandparents’ day, but definitely not in modern times.”