There is some evidence that cranberry can help to prevent urinary tract infections; however, the evidence is not definitive, and more research is needed. Cranberry has not been shown to be effective as a treatment for an existing urinary tract infection.
Research shows that components of cranberry may prevent bacteria, such as E. coli, from clinging to 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 antioxidantantioxidanta chemical substance that prevents cellular damage from free radicals 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 National Institutes of Health (NIH) agencies are also supporting cranberry research; for example, the National Institute of Aging is funding a laboratory study of potential antiaging effects.
Drinking cranberry juice products appears to be safe, although excessive amounts could cause gastrointestinal upset or diarrhea.
People who think they have a urinary tract infection should see a health care provider for proper diagnosis and treatment. Cranberry products should not be used to treat infection.
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.
Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health products you may be taking.