Drinking 8 ounces of cranberry juice works on the bacteria that cause most urinary tract infections (UTI)

Cranberry juice has long been recommended to ward off bladder infections. Now there's evidence that more of the tart drink may be better than less.

Drinking 8 ounces of the juice works better than 4 ounces on the bacteria that cause most urinary tract infections (UTI), according to preliminary research presented at the 42nd Annual Meeting of the Infectious Diseases Society of America on September 30, 2004.

A specific type of tannin found only in cranberries and blueberries interacts with the little projections on the Escherichia coli bacteria (the most common cause of UTI), preventing them from sticking to the walls of the bladder and causing infection.

A UTI is an infection anywhere in the urinary tract, including the kidneys, the bladder, and the urethra. Due to anatomy, women have a higher risk of UTIs than men, and people who experience three or more in 1 year are considered to have recurrent infections.

"There is no evidence that drinking or eating cranberry products can cure a UTI once the bacteria have established infection," said Kalpana Gupta, MD, principal investigator of the University of Washington study. "The next step is to evaluate our findings in a larger group of women, and then conduct a trial to help determine if the laboratory findings translate into clinical differences in the rate of UTI depending on the dosage of cranberry consumed."

Theoretically, blueberries may prevent UTIs as well, but they need to be further tested in a laboratory and clinical trials, she said.

"Cranberry is one of North America's few native fruits, and Native Americans used it for its antibacterial properties," said Amy Howell, PhD, coauthor of the study and a research scientist at the Marucci Center for Blueberry and Cranberry Research at Rutgers University, Chatsworth, New Jersey. "They even mention it for urinary disorders."

In the study, urine was collected from three volunteers before and 4 to 6 hours after consumption of 27% cranberry juice cocktail. E. coli were incubated in the urine samples and combined with human bladder cells.

The amount of bacteria sticking to the bladder cells was significantly reduced after the bacteria were incubated in urine from women who drank the cranberry juice cocktail, and that effect was two-fold greater after 8 ounces of cranberry juice cocktail was consumed than after 4 ounces was consumed, the researchers reported.

"It is unlikely that regularly consuming a glass of cranberry juice has a downside, but this will be formally evaluated in future clinical trials," she said.

Women who feel symptoms (including a frequent need to urinate, and pain or burning after urination) should see their healthcare providers, and if diagnosed with a bladder infection, should receive antibiotics, Gupta recommended. Untreated, a bladder infection can become a more serious kidney infection.

Combinations of cranberry and other fruit juices (such as apple, grape, and raspberry) contain a smaller percentage of cranberry juice and may be less effective for UTI prevention, but have not been adequately studied, Dr. Gupta noted.

Cranberry tablets also may vary in the percentage of the effective, and therefore may or may not help prevent UTIs. Tablets that include spray-dried cranberry juice include the tannin, while those that are derived from various extracts may not, said Howell. Initial studies suggest that single-serving sizes of dried cranberries and cranberry sauce contain as much of the tannin as a serving of cranberry juice cocktail, and may be just as effective as the juice.

This article is courtesy of http://www.coastalurology.com and http://www.newsrx.com.