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

Medicinal Claims: People most often take cranberries to help prevent and relieve the symptoms of urinary tract infections. The effectiveness of cranberries in preventing urinary tract infections has been documented. 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.

Some people take cranberry juice to reduce fever and treat certain cancers. However, there is no scientific proof that it is effective for these uses.

Possible Side Effects: 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. People who have kidney stones should consult their doctor before taking cranberry products. Cranberry products may increase the effects of drugs that prevent blood clots (such as the anticoagulant warfarin), causing severe bleeding. Therefore, people who take warfarin should not consume cranberry juice at the same time.

Last full review/revision February 2009 by Ara DerMarderosian, PhD