[Cranberries for prevention of recurrent urinary tract infections]

Cranberries have been used for prevention and treatment of urinary tract infections for decades. The berries contain proanthocyanidins that may reduce the susceptibility to infection by preventing bacteria from attaching to uroepithelial cells. Several clinical trials have been published during recent years. This article reviews documentation of cranberries on clinical effect, adverse events, drug interactions and use during pregnancy and lactation.

Clinical effects of cranberries have been assessed based on the Cochrane review from January 2007 and literature on clinical trials retrieved from a systematic search of PubMed and Embase (from 1 January 2007 to 29 October 2008) with the search terms "cranberry", "Vaccinium macrocarpon", "Vaccinium oxycoccus".

Some evidence exists on cranberries' preventive effect on recurrent symptomatic urinary tract infections in women. The evidence is inconclusive for children, men and older people (both men and women). Studies of people with neuropathic bladder are contradictory. Most of the clinical trials published have several flaws and have not used standardised products. More evidence is needed to determine the optimum dosage, method of administration and the minimum length of treatment. Cranberries should not be used during pregnancy and lactation due to lack of safety data. Further, properly designed studies with standardised products and relevant outcomes are needed.