Berries battle bladder bugs.

Drinking cranberry juice has long served as a popular home remedy for mild urinary tract infections. Scientists have uncovered hints that its infection-fighting prowess is real (SN: 9/17/88, p.187), but the drink's mode of action remained elusive until 1989, when Israeli researchers discovered that cranberry juice contains a compound that prevents bacteria from anchoring themselves in the bladder.

Now, the tangy red berry faces some competition. Preliminary studies by the same research team indicate that blueberry juice also contains the as-yet-unidentified compound.

Researchers led by Nathan Sharon of the Weizmann Institute of Science in Rehovot, Israel, found that the compound inhibits the sticking ability of Escherichia coli bacteria, a common culprit in urinary infections. E. coli normally live quietly in the gut, but can cause an annoying infection if they take hold in the urinary tract, where they use tiny, hair-like appendages to adhere to bladder cells.

Both blueberries and cranberries grow on shrubs of the genus Vaccinium. The researchers tested a variety of juices, including grapefruit, mango, guava, orange and pineapple, but only blueberry and cranberry contained this compound, they report in the May 30 NEW ENGLAND JOURNAL OF MEDICINE.

While the findings lend credence to the cranberry's role in folk medicine, scientists at Ocean Spray Cranberries, Inc., of Lakeville-Middleboro, Mass., note that laboratory studies alone cannot prove that either juice flushes E. coli from the bladder. "We absolutely are not making any claims for this," says Lawrence N. Kuzminski of Ocean Spray.