* There is evidence that cranberry can help to prevent urinary tract infections; however, the evidence is not definitive, and more research is needed. Cranberry  treatment for an existing urinary tract infection.
* Research shows that components found in cranberry may prevent bacteria, such as E. coli, from clinging to the cells along the walls of the urinary tract and causing infection. There is also preliminary evidence that cranberry may reduce the ability of H. pylori bacteria to live in the stomach and cause ulcers.
* Findings from a few laboratory studies suggest that cranberry may have antioxidant properties and may also be able to reduce dental plaque (a cause of gum disease).
* NCCAM is funding studies of cranberry, primarily to better understand its effects on urinary tract infection. The Office of Dietary Supplements and other NIH agencies are also supporting cranberry research; for example, the National Institute on Aging is funding a laboratory study of potential anti-aging effects.

Side Effects and Cautions

* Cranberry appears to be safe, although excessive amounts could cause gastrointestinal upset or diarrhea.
* There are some indications that cranberry should be used cautiously by people who take blood-thinning drugs (such as warfarin), medications that affect the liver, or aspirin.