Cranberries are fruit that can be consumed whole or made into food products such as jellies and juices.
People most often take cranberries to help prevent and relieve the symptoms of UTIs. The effectiveness of cranberries in preventing UTIs has been documented. Natural unprocessed cranberry juice contains anthocyanidins, which prevent Escherichia coli 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.
No adverse 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. Because cranberry increases urinary acidity, it may promote stone formation in patients with uric acid kidney stones. Cranberry products may increase the effects of warfarin.
Last full review/revision May 2009 by Ara DerMarderosian, PhD
Content last modified August 2013