Cranberry is a small, evergreen shrub grown throughout North America. Cranberry has a long history of use among native American Indian tribes, primarily for treating urinary conditions. Juice and extracts from the fruit (berry) are used as medicine.
Cranberry is most commonly used for prevention and treatment of urinary tract infections (UTIs). Cranberry JUICE seems to help prevent UTIs, but so far it doesn’t seem to be effective in treating UTIs.
Cranberry is also used for neurogenic bladder (a bladder disease), as well as to deodorize urine in people with urinary incontinence (difficulty controlling urination). Some people use cranberry to increase urine flow, kill germs, speed skin healing, and reduce fever.
Some people use cranberry for type 2 diabetes, chronic fatigue syndrome (CFS), scurvy, inflammation of the lining around the lung (pleurisy), and cancer.
In foods, cranberry fruit is used in cranberry juice, cranberry juice cocktail, jelly, and sauce. Cranberry juice cocktail is approximately 26% to 33% pure cranberry juice, sweetened with fructose or artificial sweetener.
How does it work?
People used to think that cranberry worked for urinary tract infections by making the urine acidic and, therefore, unlikely to support the growth of bacteria. But researchers don’t believe this explanation any more. They now think that some of the chemicals in cranberries keep bacteria from sticking to the cells that line the urinary tract where they can multiply. Cranberry, however, does not seem to have the ability to release bacteria which are already stuck to these cells. This may explain why cranberry is possibly effective in preventing urinary tract infections, but possibly ineffective in treating them.
Cranberry, as well as many other fruits and vegetables, contains significant amounts of salicylic acid, which is an important ingredient in aspirin. Drinking cranberry juice regularly increases the amount of salicylic acid in the body. Salicylic acid can reduce swelling, prevent blood clots, and can have antitumor effects.
Possibly Effective for:
- Preventing urinary tract infections (UTIs). Most research shows that drinking cranberry juice or taking certain cranberry extracts can lower the risk of repeated UTIs in some people. Evidence suggests that taking cranberry products can reduce the occurrence of UTIs in women, most children, and people who are hospitalized. It is not clear if drinking cranberry juice or taking supplements of cranberry extract is more effective. Although most research shows that cranberry is beneficial for UTIs, there is some evidence that it might not benefit children with a history of UTIs. Also, there is no strong evidence that cranberry can treat an existing UTI.
Possibly Ineffective for:
- Diabetes. Research shows that taking cranberry supplements by mouth does not lower blood sugar in people with diabetes.
- Benign prostatic hyperplasia (BPH). Early research shows that taking dried cranberry capsules, three times daily for 6 months, might improve urinary symptoms and reduce levels of certain biomarkers associated with BPH.
- Clogged arteries (coronary artery disease). Early evidence suggests that drinking cranberry juice daily for 4 weeks does not improve blood flow in people with clogged arteries.
- Stomach ulcers caused by Helicobacter pylori (H pylori) infection. There is inconsistent evidence regarding the ability of cranberry juice to eliminate a certain bacteria (H. pylori) in the stomach that can cause stomach ulcers. Some research suggests that drinking cranberry juice daily for 90 days can help eliminate H. pylori more quickly. However, other early research shows that drinking cranberry juice while taking conventional medication used to treat H. pylori infection s does not improve healing time compared to taking the medication alone.
- Kidney stones (nephrolithiasis). There is inconsistent evidence on the use of cranberry to lower the risk of kidney stones. Some early evidence suggests that drinking cranberry juice might lower the risk of kidney stones forming. However, other early evidence suggests that drinking cranberry juice or taking cranberry extracts might actually increase the risk of kidney stones.Memory. Some early evidence suggests that drinking cranberry juice twice daily for 6 weeks does not improve memory.
- Metabolic syndrome. Early research suggests that drinking cranberry juice (Ocean Spray) twice daily does not appear to affect blood pressure, blood sugar, or cholesterol levels in people with metabolic syndrome.
- Urine odor. Early research shows that drinking cranberry juice might reduce the odor of urine.
- Skin healing.
- Chronic fatigue syndrome (CFS).
- Other conditions.
Side Effects & Safety
Cranberry is LIKELY SAFE for most people when taken by mouth. Cranberry juice and cranberry extracts have been used safely in people. Cranberry juice is LIKELY SAFE for children. However, drinking too much cranberry juice can cause some side effects such as mild stomach upset and diarrhea. Drinking more than 1 liter per day for a long period of time might increase the chance of getting kidney stones.
Special Precautions & Warnings:Pregnancy and breast-feeding: Cranberries and cranberry juice are safe to consume during pregnancy and breast-feeding. However, do not use dietary supplements that contain cranberry products. It is not known if these are safe to use during pregnancy and breast-feeding.
Aspirin allergy: Cranberries contain significant amounts of salicylic acid. Salicylic acid is similar to aspirin. Avoid drinking large quantities of cranberry juice if you are allergic to aspirin.
Inflammation of the stomach lining (Atrophic gastritis): Cranberry juice might increase how much vitamin B12 the body absorbs for people with atrophic gastritis.
Diabetes: Some cranberry juice products are sweetened with extra sugar. If you have diabetes, stick with cranberry products that are sweetened with artificial sweeteners.
Low stomach acid (hypochlorhydria). Cranberry juice might increase how much vitamin B12 the body absorbs for people with low levels of stomach acid.
Kidney stones: Cranberry juice and cranberry extracts contain a large amount of a chemical called oxalate. In fact, there is some evidence that some cranberry extract tablets can boost the level of oxalate in the urine by as much as 43%. Since kidney stones are made primarily from oxalate combined with calcium, healthcare providers worry that cranberry might increase the risk of kidney stones. To be on the safe side, avoid taking cranberry extract products or drinking a lot of cranberry juice if you have a history of kidney stones.
Moderate Interaction Be cautious with this combination
- Warfarin (Coumadin) interacts with CRANBERRY
Warfarin (Coumadin) is used to slow blood clotting. Cranberry might increase how long warfarin (Coumadin) is in the body, and increase the chances of bruising and bleeding. Be sure to have your blood checked regularly. The dose of your warfarin (Coumadin) might need to be changed.
Minor Interaction Be watchful with this combination
- Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates) interacts with CRANBERRY
Some medications are changed and broken down by the liver.
Cranberry might decrease how quickly the liver breaks down some medications. Taking cranberry along with some medications that are broken down by the liver can increase the effects and side effects of some medications. Before taking cranberry, talk to your healthcare provider if you take any medications that are changed by the liver.
Some medications that are changed by the liver include amitriptyline (Elavil), diazepam (Valium), zileuton (Zyflo), celecoxib (Celebrex), diclofenac (Voltaren), fluvastatin (Lescol), glipizide (Glucotrol), ibuprofen (Advil, Motrin), irbesartan (Avapro), losartan (Cozaar), phenytoin (Dilantin), piroxicam (Feldene), tamoxifen (Nolvadex), tolbutamide (Tolinase), torsemide (Demadex), warfarin (Coumadin), and others.
The following doses have been studied in scientific research:
- For preventing urinary tract infections (UTIs): Cranberry juice 1-10 oz per day has been used. However, the ideal dose has not yet been determined.
- For preventing UTIs in children: 15ml/kg daily as 30% cranberry concentrate has been used.
- For use as a urinary deodorizer for incontinent patients: 3-6 oz per day of cranberry juice.
- For type 2 diabetes: Six capsules (equivalent to 240 mL cranberry juice cocktail) daily for 12 weeks. Encapsulated formulations are often taken in doses of 300-400 mg twice daily.