Research has previously shown that the juice is beneficial for urinary tract health, but scientists have been uncertain why. Now, researchers at Rutgers University say they have discovered the secret behind the little red fruit.
In the current New England Journal of Medicine, scientists explain that a chemical compound in cranberries helps deter the infection.
Most cases of UTI are caused by E. coli bacteria that attach to the urinary tract wall and spread. But 10 ounces of cranberry juice a day can stop the bacteria from ever attaching to the wall.
Researchers also found that eating a bowl of blueberries will have the same effect.
However, the scientists do not advise that people treat their UTIs with cranberry juice alone. They advise that those suffering from the infection see a doctor, and take prescribed antibiotics to fight the UTI.
If approved by a physician, drinking cranberry juice while taking antibiotics may be helpful, researchers say. The scientists also strongly recommend continuing to drink the juice after the infection is gone to reduce the chances of the problem recurring.
The research was partially sponsored by Ocean Spray, a manufacturer of cranberry juice.