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Cranberry Compounds Fight Urinary Tract Infection.

NEW YORK, Oct 07 (Reuters) -- Drinking cranberry juice is a common home remedy for a urinary tract infection, but just how it works was not understood. A group of researchers believe they have found the answer: "The effect is due not to the highly acidic nature of cranberries but to specific compounds in cranberries that inhibit the adherence of Escherichia coli (bacteria) to uroepithelial cells" -- cells lining the urinary tract, report Dr. Amy Howell of Rutgers University, New Brunswick, New Jersey, and colleagues in a letter in the October 8th issue of The New England Journal of Medicine.

Escherichia coli, or E. coli, is a bacterium found normally in the digestive tract. However, if certain strains of the bacteria gain access to the normally sterile environment of the bladder and urinary tract, the bacteria can trigger an infection, with symptoms including a frequent, painful urge to urinate and blood in the urine. The condition can be readily treated with antibiotics, but recurs in 25% of cases.

In a new study, the researchers tested the ability of cranberry extracts to inhibit the binding of certain, disease-causing strains of E. coli to cells taken from the lining of the urinary tract. This binding process is thought to be an early step in the initiation of an infection.

During the course of the 5-year study, the team found that extracts containing compounds called "condensed tannins" or "proanthocyanidins," which are found in cranberries and blueberries, could inhibit the binding process.

"We have identified condensed tannins (proanthocyanidins) as the compounds in cranberries that are responsible for preventing... E. coli from adhering to the urinary tract," they conclude.

"We found that the condensed tannins in cranberries were capable of preventing the bacteria from attaching to the urinary tract, which would promote flushing of bacteria from the bladder into the urine stream, resulting in the prevention or reduction of symptoms," said Howell in a statement released by Rutgers.

Howell estimates that the amount of condensed tannins in a 10-ounce glass of cranberry juice taken on a daily basis could help prevent urinary tract infections, which are more common in women than in men.

The study was funded by Ocean Spray Cranberries, Inc.

SOURCE: The New England Journal of Medicine 1998;339:1085-1086.  
 

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