What is it?
Cranberry juice or extracts may be helpful for urinary tract infections (UTIs) in limited populations, but there is not enough evidence to recommend it for UTI prevention.
Cranberries contain compounds called proanthocyanidins that may prevent bacteria from attaching to the bladder wall, which could cause UTIs. Human studies suggest possible benefit in some populations including prostate cancer patients, but overall evidence is conflicting. Cranberry may also prevent bacteria from attaching to the stomach lining and areas in the mouth. Although lab studies suggest activity against several types of cancer cells, these properties have yet to be evaluated in human studies.
In patients who are prone to kidney stones, regular use of cranberry should be avoided as it contains oxalates, a compound found in the most common form of kidney stones.
What are the potential uses and benefits?
- Urinary tract infections
The evidence for prevention or treatment of UTIs is mixed. - Anticancer effects
Lab studies suggest cranberry juice extract and isolated compounds may inhibit various types of cancer cells, but these observations have not been studied in humans. - Stomach ulcers
Studies suggest cranberry juice may help prevent or suppress H. pylori infection. - Atherosclerosis
Evidence on whether cranberry juice can help reduce cardiovascular disease risk factors are limited and unclear. - Gum disease/cavities
Lab studies suggest cranberry juice prevents bacteria from attaching, thereby slowing plaque formation, but additional studies are needed.
What are the side effects?
- Nausea, vomiting and diarrhea with large amounts of cranberry juice (3 cups daily)
Case reports
- Increased International Normalized Ratio (INR) and/or bleeding: Several cases due to suspected interactions between cranberry juice and warfarin.
- Internal hemorrhage resulting in death: In 2 patients, following concurrent use of warfarin and cranberry juice.
What else do I need to know?
Do Not Take if:
- You are taking tacrolimus: Serum levels of tacrolimus dropped when taken with cranberry extract. Levels returned to the desired range after stopping cranberry intake.
- You are taking warfarin: Because data is mixed on whether cranberry juice may increase bleeding, usage of cranberry juice should be monitored by a healthcare professional, if not avoided. Case reports of bleeding and death in 2 elderly patients who used cranberry juice and warfarin have occurred.
- You are taking CYP450 substrate drugs: Cranberry may increase blood levels of these drugs or their adverse effects.
- You are taking UGT substrate drugs: Cranberry may increase the risk of side effects for these drugs.
- You have a history of kidney stones: Cranberry contains high concentrations of oxalates, a component common to kidney stones.