Cranberry

Cranberries are fruit that can be consumed whole or made into food products such as jellies and juices. Cranberry supplements are available as pills.

(See also Overview of Dietary Supplements Overview of Dietary Supplements Dietary supplements are used by about 75% of Americans. They are the most common therapies included among integrative medicine and health (IMH) and complementary and alternative medicine (CAM)... read more .)

People most often take cranberries to help prevent and relieve the symptoms of urinary tract infections Overview of Urinary Tract Infections (UTIs) In healthy people, urine in the bladder is sterile—no bacteria or other infectious organisms are present. The tube that carries urine from the bladder out of the body (urethra) contains no bacteria... read more (UTIs).

Some people take cranberry juice to reduce fever and treat certain cancers, specifically stomach cancer caused by the bacterium Helicobacter pylori. Proponents claim cranberry has an antioxidant effect. Antioxidants Antioxidants The human body needs various vitamins and minerals in order to thrive. Many of these nutrients can be found in whole, non-processed foods such as fruits and vegetables. However, most modern... read more protect cells against damage by free radicals, which are highly chemically active by-products of normal cell activity.

Evidence suggests that cranberry juice or extract can help prevent UTIs from recurring during the following 12 months, but this effect is small. Cranberry cannot treat active UTIs. However, evidence has been somewhat inconsistent. Natural unprocessed cranberry juice contains anthocyanidins, which prevent Escherichia coli (the bacteria that usually cause urinary tract infections) from attaching to the urinary tract wall.

There is no evidence that cranberry is effective for reducing fever or treating certain cancers.

No side effects are known. However, because most cranberry juice is highly sweetened to offset its tart taste, people with diabetes should not consume cranberry juice unless it is artificially sweetened or unsweetened. People can also avoid the extra sugar by using cranberry pills instead of food products.

People who have kidney stones should consult their doctor before taking cranberry products.

Cranberry products taken with warfarin, an anticoagulant, may increase the risk of bleeding; therefore, people taking warfarin should avoid cranberry products. Cranberry may increase the effect of atorvastatin, used to lower cholesterol, as well as nifedipine, an antihypertensive (blood pressure–lowering drug).

People with recurring UTIs can consider taking cranberry to reduce the risk. However, they should consult their doctor about possible drug interactions before taking cranberry products.