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Cranberry Juice May Fight Intestinal Bugs

Laboratory study found immediate effect, but more research needed

TUESDAY, June 7, 2005 (HealthDay News) -- Cranberry juice, a long-standing home remedy to help prevent urinary tract infections, may also work against gastrointestinal viruses, new research suggests.

So far, the results have been achieved only in the laboratory, and more study is needed to see if those results bear out, said study co-author Patrice Cohen, a undergraduate researcher at St. Francis College in Brooklyn.

But if they do, the cranberry juice solution theoretically could make a big difference, she said. "Hundreds of thousands of children die from gastroenteritis each year in the world."

The study was funded by St. Francis College, the Cranberry Institute and the Wisconsin Cranberry Board.

Working with cell cultures in the laboratory, Cohen and her team focused on an intestinal monkey rotavirus (which causes diarrhea) called SA-11 and a pool of goat intestinal reoviruses (which cause inflammation of the small intestine). They exposed both of the cultures to cranberry juice.

Cranberry juice prevented the SA-11 virus from attaching to red blood cells or infecting host cells, the researchers report. When they looked at the SA-11 cell cultures under high-magnification microscopes, there were no viral particles in those treated with juice. "It was an immediate effect," Cohen said.

"We also tried to determine if there was a dose response," she said. "A dose of 1:16, cranberry juice to virus, was effective."

To determine if the effect had something to do with the pH of cranberry juice, they looked at two samples, one of virus exposed to cranberry juice; the other with virus exposed to an equivalent amount of liquid with the same pH as cranberry juice.

"In the one with the virus and cranberry juice, there was a 100 percent reduction in infectivity," she said. "In the one with the liquid with the same pH [as cranberry juice] you saw only a 34 percent reduction. That means pH was not a factor. It was some other component."

In other studies finding cranberry juice effective for prevention of urinary tract infections in women, researchers have found that substances in the juice help prevent the adhesion of certain bacteria to the urinary tract wall.

Another expert, Dr. Prabhakar Swaroop, an assistant professor of internal medicine at St. Louis University Hospital, called the new research "a very interesting study investigating the antiviral properties of cranberry juice."

He agrees more study is needed, asking: "How can we translate this study to be of use in daily life? In clinical practice, rotavirus, one of the studied viruses, causes a self-limited diarrheal syndrome in infants and children," he said. So it would be important to study whether the course of diarrhea is shortened after drinking cranberry juice, he said.

Identification of the active ingredient which produces the anti-viral activity would be important, too, he added.

While Cohen stops short of suggesting anyone drink cranberry juice to ward off GI ailments, "it won't hurt to drink cranberry juice," he said.

More information

For more on diarrhea, head to the American Academy of Family Physicians.

SOURCES: Patrice Cohen, student researcher, St. Francis College, Brooklyn, N.Y.; Prabhakar P. Swaroop, M.D., assistant professor, department of internal medicine, Division of Gastroenterology and Hepatology, St. Louis University Hospital, St. Louis; June 6, 2005, presentation, American Society for Microbiology annual meeting, Atlanta
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