Herbs for Health: Cranberry Benefits

Enlarge Image Image Gallery Cultivated cranberries.

A supplement to the Herb Companion from the American Botanical Council and the Herb Research Foundation.  

Cranberry: An Ounce of Prevention

In addition to being a tangy, refreshing beverage, cranberry juice cocktail is a time-honored American folk remedy for urinary tract infections, a disorder that is especially common in women. Its reputation has been upheld, at least in part, by a host of scientific studies.

The native American cranberry (Vaccinium macrocarpon) is a mat-forming evergreen shrub of the heath family (Ericaceae) that grows in bogs from Newfoundland to Manitoba south to Virginia, Ohio, and northern Illinois. Most Americans are familiar with its glossy red fruits, up to 3/4 inch across, that seem to materialize in grocery stores just before Thanksgiving. This species is cultivated on thousands of acres of artificial bogs in Massachusetts, Michigan, Wisconsin, and British Columbia.

Several other species are also known as cranberries. The closely related European cranberry (V. oxycoccos), which occurs in northern North America and Asia as well as in Europe, has much smaller, brownish red berries. It is not cultivated. Mountain cranberry (V. vitis-idaea), or lingonberry, is cultivated to a limited extent in Europe, and its small fruits are also collected from the wild. The bark of highbush cranberry (Viburnum trilobum and V. opulus), medium-sized shrubs of the honeysuckle family (Caprifoliaceae) with small, extremely astringent red fruits, has been used by herbalists and Native Americans to treat menstrual cramps.

An array of medicinal uses

Early white settlers valued cranberries as a refreshing, invigorating food that was easily dried for winter storage. They also discovered that eating the fruits prevented scurvy (vitamin C deficiency) and relieved dropsy (fluid accumulation in connective tissue) by promoting urination. Fevers, diarrhea, and many other disorders were treated by ingesting cranberries, and the crushed berries were poulticed on tumors and wounds.

German physicians in the mid–nineteenth century observed that ingesting European cranberries increased the excretion of hippuric acid in the urine. Further, a 1923 study reported that the urine of a subject given 305 g (more than 10 ounces) of cooked cranberries became more acidic, with a sixfold increase in the concentration of hippuric acid, whereas that of a subject given prunes didn’t change. Because acid inhibits the growth of bacteria, this finding was thought to indicate that eating cranberries would inhibit the growth of bacteria in the urinary tract (the bacterium Escherichia coli, which is found in the intestinal tract of even healthy individuals, is the cause of most urinary tract infections).