The cranberry is a member of the Ericaceae or Heath family, genus Vaccinium, subgenus Oxycoccus. Closely related species include the blueberries, rhododendrons and azaleas (Rhododendron), mountain laurel (Kalmia latifolia), heather (Calluna), heath (Erica), and leatherleaf (Leucothoe). Cranberry is a small evergreen shrub containing dark pink flowers and cranberries. Cranberry grows both in damp bogs and in mountain forests from Tennessee to Alaska and blooms from late spring until the end of the summer. The shrub’s small red fruits are produced in the fall, which explains their prevalence during the Thanksgiving season.
Cranberry offers its users a number of benefits. In addition to being a good source of vitamin C, cranberry juice often is recommended for its positive effects on the urinary tract. Cranberry is a good source of iodine, a trace mineral that is essential for the proper function of the thyroid. The most likely mechanism of action for cranberry is its ability to inhibit bacterial adhesion to the urinary tract lining (Escherichia coli is the most common culprit in causing UTIs). Cranberries contain several organic acids and fatty acids that act to keep bacteria from sticking to urinary tract cells. Cranberry ingestion also lowers the acidity of urine, thereby making conditions for bacterial growth less favorable. In addition, another constituent of cranberry, parasorbic acid, has been found to give plants some protection from fungal attack.
Cranberries and their juice have long been regarded as folk treatments for urinary infections. In early American medicine, the crushed berries were applied to tumors and poulticed on wounds. The berries were recognized as a treatment for scurvy (a vitamin C deficiency) and dysentery. Recently, however, scientists discovered that cranberry juice and extracts prevent adhesion of E. coli bacteria to linings of the bladder and the gut, inhibiting their ability to colonize and cause infection. A recent study of elderly patients found that drinking 4 to 6 ounces of cranberry juice daily had a preventative, rather than curative, effect on urinary tract infections. In other studies the juice was effective as a urinary deodorant in bedridden patients with high levels of white blood cells and bacteria in the urine.