Cranberry is a low-growing evergreen shrub with leathery leaves and bright red berries. This member of the heath family main grows in mountains, forests and damp bogs in north-east of China, America and Canada. Cranberries are distinguished by their extremely sour taste, due to their low sugar and high acid content. Cranberries are rich in citric, malic, quinic and other acids. They also contain flavonoids, anthocyanins, ellagic acid, and vitamin C. Because of their tannin content, the berries possess a natural astringency. Recent research supports the notion that cranberries contain substances that prevent the adhesion of E coli and other bacteria to the lining of the urinary tract.