For Patients & Caregivers
Cranberry juice has not been shown to treat or prevent cancer.
Cranberries contain compounds known as proanthocyanidins that have been shown to inhibit E. coli from attaching to the bladder wall, thus preventing the development of an infection. Cranberry juice has also been shown to inhibit the attachment of oral bacteria in the laboratory setting, suggesting that it may slow the development of dental plaque and offer some protection from plaque-related diseases.
- Prevention and treatment of urinary tract infections (UTIs)
The evidence for this claim is mixed.
- Anticancer effects
Lab studies have shown that cranberry juice extract has anti-proliferative effects on cancer cells such as prostate, liver, breast, colon, and oral. But such effects have not been confirmed by clinical trials.
- Anti aging
There is no scientific evidence to support this use.
- Prevention of stomach ulcers
A study done in China has shown cranberry juice to be effective for the prevention of H. pylori infection.
- Prevention of Atherosclerosis
This use is not backed by clinical data.
- Prevention of Gum Disease/Cavities
Laboratory studies have shown that cranberry juice prevents bacteria from attaching to one another thereby slowing down plaque formation.
- You are taking warfarin (cranberry juice may increase bleeding).
- • You are taking drugs that are substrates of CYP450 (cranberry may increase the blood level and the risk of adverse effects of these drugs).
- You are taking drugs that are substrates of UGT (Uridine 5’-diphospho-glucuronosyltransferase) enzymes (cranberry may increase the risk of side effects of these drugs).
For Healthcare Professionals
Cranberry is an evergreen shrub that is grown in North America and in Europe. The processed fruit and juice, which are rich in vitamin C, are widely consumed as food. The juice extract is marketed as a dietary supplement for urinary tract health. Cranberry is thought to have antibacterial, anti-inflammatory, and antioxidant activities. It is used for oral and gastrointestinal infections, cardiovascular diseases, and against cancer. The proanthocyanidins in cranberries inhibit the adherence of E. coli fimbriae to uroepithelial cells (1) in vitro.
Clinical studies demonstrate that cranberry extracts can help prevent urinary tract infections (UTI) in adults (2) (3), in children (4) and in prostate cancer patients undergoing radiation therapy (5). However, regular consumption of cranberry juice did not confer protection against UTIs (6). While cranberry is not as effective as trimethoprim-sulfamethoxazole in preventing UTI, patients using cranberry are also less likely to develop antibiotic resistant bacteria (7) (8). But conclusions from a meta-analysis indicate that there is not enough evidence to recommend cranberry juice for the prevention of UTIs (9).
In studies of cancer prevention and treatment, cranberry extracts demonstrated anti-proliferative effects against prostate (10) (11) (12), liver (13), breast (14), ovarian (15), colon (12,16), and oral (12) cancer cell lines in vitro. However, cranberry juice consumption did not lower oxidative status in humans suggesting lack of protective effect against cancer or heart disease (17).
Cranberry juice also inhibited the adhesion of H. pylori to human gastric mucosa (18). Regular consumption of cranberry juice can suppress H. pylori infection (19) (20), a major factor in peptic ulcer disease and gastric cancer. When used with standard treatment, cranberry juice helps to eradicate H. pylori in women (21).
Proanthocyanidins found in cranberries inhibit P-fimbriated E. coli from adhering to the uroepithelial cells, thus preventing the development of infections (25) (26) (27) (28). Research suggests that the high number of A-type linkage proanthocyanidins found in cranberries may enhance in vitro and urinary bacterial anti-adhesion activities that prevent UTIs (27). A constituent of cranberry juice inhibits adhesion of H. pylori to immobilized human mucus, human erythrocytes, and cultured gastric epithelial cells, suggesting that cranberry juice may also prevent stomach ulcers caused by H. pylori via preventing the adhesion of bacteria to the stomach lining (18) (29). Cranberry juice was also shown to decrease adherence of oral streptococci strains to saliva-coated hydroxyapatite (23), glucan-coated hydroxyapatite, and impaired biofilm formation (22) (30) indicating that cranberry juice may slow the development of dental plaque and offer protection from plaque-related diseases.
A proanthocyanidin from cranberry has been shown to arrest ovarian cancer cell growth by inhibiting vascular endothelial growth factor and by generating reactive oxygen species (15). Cranberry extract inhibits prostate cancer cell growth by decreasing the expression of cyclin-dependant kinase and cyclins (10). It also decreases matrix metalloproteinase activity (31).
Several cases of increased INR (36) (37)and/or bleeding due to suspected interactions involving warfarin and cranberry juice have been reported. Two patients suffered internal hemorrhage following concurrent use of warfarin and cranberry juice that resulted in their deaths (38,39).
Cranberry products can increase urine oxalate excretion and may promote the formation of kidney stones (32) (33) (40).
- Warfarin: Cranberry juice may potentiate warfarin-induced anticoagulation, but data are conflicting (34) (41).
- Cyclosporin: A randomized controlled trial has shown that 240 mL of cranberry juice had no clinically significant effect on the disposition of a 200 mg dose of cyclosporin (42).
- UGT (Uridine 5’-diphospho-glucuronosyltransferase) substrates: Cranberry modulates UGT enzymes in vitro and can increase risk of side effects of drugs metabolized by them (35).
- Cytochrome P450 substrates: Cranberry inhibits enteric CYP3A activities and may interfere with the absorption of substrate drugs (43). Cranberry inhibits CYP2C9 in in vitro studies, but this activity was not observed in humans (44).