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.

Key to grades

A
Strong scientific evidence for this use
B
Good scientific evidence for this use
C
Unclear scientific evidence for this use
D
Fair scientific evidence against this use (it may not work)
F
Strong scientific evidence against this use (it likely does not work)

Grading rationale

Evidence gradeCondition to which grade level applies
C

Achlorhydria and B12 absorption

Preliminary research suggests that cranberry juice may increase vitamin B12 absorption in patients taking antacids (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 research is needed before a recommendation can be made.
C

Antibacterial

Research results of cranberry as an antibacterial show conflicting results. Further research is needed before a conclusion can be drawn.
C

Antioxidant

According to laboratory research, cranberry may have antioxidant properties. However, human research is lacking. Further research is needed before a recommendation can be made.
C

Antiviral and antifungal

Limited laboratory research has examined the antiviral and antifungal activity of cranberry. There is a lack of reliable human studies supporting the use of cranberry in this area.
C

Cancer prevention

Based on a small amount of laboratory research, cranberry has been proposed for cancer prevention. Research is needed in humans before a strong recommendation can be made.
C

Cardiovascular disease

In preliminary human research on patients with coronary artery disease, consumption of cranberry juice reduced the carotid femoral pulse wave velocity, a measurement of arterial stiffness. Further research is required.
C

Chronic urinary tract infection prophylaxis (in children with neurogenic bladder)

There is preliminary evidence that cranberry may be effective in preventing urinary tract infections in children with neurogenic bladder.
C

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.
C

Diabetes

According to a single trial from a systematic review, effects of cranberry on blood sugar levels in patients with diabetes are lacking. Further research is required.
C

H. pylori infection

Based on early research, cranberry may reduce the ability of Helicobacter pylori bacteria to live in the stomach and cause ulcers. Further research is needed to confirm these results.
C

Kidney stones

According to 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.
C

Lipid lowering effects

The lipid-lowering effects of cranberry were observed in individuals with obesity or diabetes. At this time evidence in support of these effects is lacking. Further research is required.
C

Memory improvement

Preliminary research results show that cranberry juice may increase overall ability to remember. Further well-designed clinical trials are needed to confirm these results.
C

Metabolic syndrome

In early research, cranberry juice lacked effect on cardiovascular disease risk factors in patients with metabolic syndrome. Further research is required.
C

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.
C

Reduction of odor from incontinence/bladder catheterization

There is preliminary evidence that cranberry juice may reduce urine odor from incontinence or bladder catheterization. Further research is needed before a firm recommendation can be made.
C

Stress

The effect of a cranberry supplement in female surgeons with stress-related disorders has been studied. Although there is evidence of benefit, further research is required.
C

Urinary tract disorders (LUTS)

Cranberry fruit powder improved International Prostate Symptom Score (IPSS) and quality of life in men with lower urinary tract symptoms (LUTS) and presenting with elevated levels of prostate-specific antigen (PSA) and/or benign prostatic hyperplasia (BHP). Further well-designed research is required.
C

Urinary tract infection (prevention)

There are multiple studies of cranberry (juice or capsules) for the prevention of urinary tract infections (UTIs) in healthy women, pregnant women, individuals with spinal cord injuries, 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.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 firm conclusion can be drawn.
C

Urinary tract infection (treatment)

There is a lack of 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.
C

Urine acidification

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. More research is needed in this area.
C

Urolithiasis

Although cranberry consumption may increase urinary excretion of oxalate, possibly predisposing to calcium oxalate stone formation, it also increases magnesium and potassium excretion, which may decrease the rate of stone formation. Cranberry juice of unspecified amounts has been found to decrease urinary calcium by 50% in patients with renal stones. The clinical significance and net outcome of these findings in various subgroups has not been elucidated.
C

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 research is needed before a recommendation can be made.

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.

Alzheimer's disease, anorexia, anticoagulant, anti-inflammatory, antiparasitic, atherosclerosis, bladder disorders, blood disorders, brain injuries (improves brain function), cancer treatment, cholecystitis, cystitis (recurrent), decontamination (of meats), degenerative diseases, diuresis, food uses, gallbladder disease, hypercholesterolemia, ischemic stroke, liver disorders, neurodegenerative diseases, nutritional support (unclogging feeding tubes), periodontitis/gingivitis, prostate cancer, rheumatoid arthritis, scurvy, stomach ailments, vomiting, wound care (poultice).

This evidence-based monograph was prepared by The Natural Standard Research Collaboration

www.naturalstandard.com