There is some human evidence supporting the use of cranberry juice and cranberry supplements to prevent urinary tract infection (UTI), although most available studies are of poor quality. There are no clear dosing guidelines, but given the safety of cranberry, it may be reasonable to recommend the use of moderate amounts of cranberry juice cocktail to prevent UTI in non-chronically ill individuals.
Cranberry has not been shown effective as a treatment for documented UTI. Although cranberry may be used as an adjunct therapy in some cases, given the proven efficacy of antibiotics, cranberry should not be considered a first line treatment.
Cranberry has been investigated for numerous other medicinal uses, and promising areas of investigation include prevention of H. pylori infection, which causes gastrointestinal ulcers and dental plaque.
American cranberry, Arandano Americano, Arandano trepador, bear berry, black cranberry, bog cranberry, Ericaceae (family), European cranberry, grosse moosebeere, isokarpalo, Kranbeere, Kronsbeere, large cranberry, low cranberry, marsh apple, mountain cranberry, moosebeere, mossberry, Oxycoccus hagerupii, Oxycoccus microcarpus, Oxycoccus macrocarpus, Oxycoccus palustris, Oxycoccus quadripetalus, pikkukarpalo, preisselbeere, ronce d'Amerique, trailing swamp cranberry, Tsuru-kokemomo, Vaccinium edule, Vaccinium erythrocarpum, Vaccinium hageruppi, Vaccinium microcarpum, Vaccinium occycoccus, Vaccinium plaustre, Vaccinium vitis.
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Urinary tract infection (prevention)
There are multiple studies of cranberry (juice or capsules) for the prevention of urinary tract infections in healthy women and nursing home residents. While no single study convincingly demonstrates the ability of cranberry to prevent UTIs, the sum total of favorable evidence combined with laboratory research tends to support this use. It is not clear what dose is best.
Study results of cranberry as an antibacterial in other conditions show conflicting results. Further study is needed before a conclusion can be drawn.
Limited laboratory research has examined the antifungal activity of cranberry. There are no reliable human studies supporting the use of cranberry in this area.
Based on laboratory study, cranberry may have antioxidant properties. However, human study is lacking. Further study is needed before a recommendation can be made.
Limited laboratory research has examined the antiviral activity of cranberry. There are no reliable human studies supporting the use of cranberry in this area.
B12 absorption in people using antacids
Preliminary research suggests that cranberry juice may increase vitamin B12 absorption in patients taking drugs that reduce stomach acid, such as proton pump inhibitors like lansoprazole (Prevacid®). However, this effect may be due to the acidity of the juice rather than an active component of cranberry itself. Further study is needed before a recommendation can be made.
Based on a small amount of laboratory research, cranberry has been proposed for cancer prevention. Study is needed in humans before a recommendation can be made.
Because of its activity against some bacteria, cranberry juice has been proposed as helpful for mouth care. However, many commercial cranberry juice products are high in sugar, and may not be suitable for this purpose. There is not enough research in this area to make a clear recommendation.
Based on preliminary research, it is not clear if drinking cranberry juice increases or decreases the risk of kidney stone formation. Cranberry juice is reported to decrease urine levels of calcium, increase levels of urine magnesium and potassium, and increase urine levels of oxalate.
Preliminary study results show that cranberry juice may increase overall ability to remember. Further well-designed clinical trials are needed to confirm these results.
Stomach ulcers caused by H. pylori bacteria
Based on early research, cranberry may reduce the ability of
Reduction of odor from incontinence/bladder catheterization
There is preliminary evidence that cranberry juice may reduce urine odor from incontinence or bladder catheterization. Further study is needed before a recommendation can be made.
In large quantities, cranberry juice may lower urine pH, making it more acidic. Contrary to prior opinion, urine acidification does not appear to be the way that cranberry prevents urinary tract infections.
Urinary tract infection (treatment)
There are no well-designed human studies of cranberry for the treatment of urinary tract infections. Laboratory research suggests that cranberry may not be an effective treatment when used alone, although it may be helpful as an adjunct to other therapies such as antibiotics.
It is proposed that skin irritation at urostomy sites may be related to urine pH. Cranberry juice can lower urine pH, and has been tested for this purpose. Further study is needed before a recommendation can be made.
Chronic urinary tract infection prevention: children with neurogenic bladder
There is preliminary evidence that cranberry is not effective in preventing urinary tract infections in children with neurogenic bladder.
Radiation therapy side effects (prostate cancer)
There is preliminary evidence that cranberry is not effective in preventing urinary symptoms related to pelvic radiation therapy in patients with prostate cancer.