Cranberry : Scientific and Traditional Uses

by MedlinePlus

Cranberry is widely used to prevent urinary tract infection (UTI). It was initially believed to function by acidifying urine. However, the mechanism is now thought to be inhibition of adhesion of bacteria to uroepithelial cells by proanthocyanadin, a compound present in cranberry.

There is preliminary clinical evidence in support of the use of cranberry juice and cranberry supplements to prevent UTI, although most available studies are of poor methodologic quality. Most evidence has focused on effects against E. coli , although in vitro research suggests activity against Proteus , Pseudomonas and other species. 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 a viable adjunct therapy in a time when antimicrobial resistance of concern, given the proven efficacy of antibiotics, cranberry should not be considered a first line agent.

Cranberry has been investigated for numerous other medicinal uses, and promising areas of investigation include prevention of H. pylori infection and dental plaque.

Synonyms

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.

Evidence

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.

Uses based on scientific evidence

Urinary tract infection (UTI) 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. Most research has focused on the bacteria E. coli , although laboratory research suggests possible effects against other bacteria such as Proteus or Pseudomonas .Cranberry seems to work by preventing bacteria from sticking to cells that line the bladder. Contrary to prior belief, urine acidification does not appear to play a role. Notably, many studies have been sponsored by the cranberry product manufacturer Ocean Spray®. Additional research is needed in this area before a strong recommendation can be made.

Antioxidant

Based on laboratory study, cranberry may have antioxidant properties. However, human study is lacking. Further study is needed before a recommendation can be made.

Antiviral and antifungal

Limited laboratory research has examined the antiviral and antifungal 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.

Cancer prevention

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.

Dental plaque

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.

Stomach ulcers caused by H. pylori bacteria

Based on early research, cranberry may reduce the ability of H. pylori to live in the stomach. Further research is needed to confirm these results.

Kidney stones

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.

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.

Urinary tract infection (UTI) 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.

Urine acidification

In large quantities, cranberry juice may lower urine pH. Contrary to prior opinion, urine acidification does not appear to be the way that cranberry prevents urinary tract infections.

Urostomy care

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.

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Anorexia, antibacterial, anti-inflammatory, bladder conditions, bladder infections, blood disorders, cancer prevention, cancer treatment, decontamination (of meats), diuresis (increasing urine flow), gall bladder stones, improving brain function, influenza, liver disorders, plaque, recurrent cystitis, rheumatoid arthritis, scurvy, stomach ailments, vomiting, wound care.

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