The cranberry bush (Vaccinium macrocarpon) is a low-growing evergreen shrub with leathery leaves and bright-red berries. This member of the heath family grows in mountains, forests, and damp bogs within the United States from Alaska to Virginia. However, most of the commercial berries are produced in Massachusetts and Wisconsin.
Native Americans used cranberries for both food and medicine. The berries were enjoyed either raw or sweetened with maple sugar. In addition, they used them in sauces, breads, and puddings. Cran-berries were also used in poultices for treating wounds. Cranberry leaves were typically used for diarrhea and urinary disorders. The sailors during Colonial days used cranberries to prevent scurvy.
Today the cranberry is available in a variety of products, such as frozen cranberries, cranberry juice and juice cocktails, cranberry sauce, and capsules containing cranberry powder. The most popular form of cranberries is the sweetened cranberry cocktail that contains about 30 percent cranberry juice. Apple cranberry and other cranberry drinks contain only about 10 percent juice.
Cranberries are distinguished by their extremely sour taste, because of 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.
Help for Infections
Cranberries have long been considered valuable for maintaining the health of the urinary tract. The juice has been widely used for the prevention, treatment, and symptomatic relief of urinary tract infections.
It was commonly believed that cranberry juice was effective because it acidified the urine. The high acidity was believed to prevent bacterial growth. However, recent research supports the notion that cranberries contain substances that prevent the adhesion of Escherichia coli and other bacteria to the lining of the urinary tract. The bacteria adhere to the urinary tract by way of many fimbriae, hairlike projections on the surface of the bacteria. This allows the bacteria to colonize in large numbers and produce an infection. Recently researchers identified proanthocyanidins in cranberry juice that inhibit the E. coli from adhering to the lining.
Common Infections
Urinary tract infections (UTIs) pose a serious health problem affecting millions of Americans every year. UTIs are more prevalent among women than men, and many women will develop several UTIs in their lifetime. The risk of a UTI increases with advancing age and is greatest among institutionalized older women. In addition, people with diabetes are at higher risk for UTIs.
Symptoms commonly experienced with a UTI include painful urination, the need to urinate frequently, a cloudy urine, and lower back pain. If a UTI is untreated, more serious complications may develop. If they occur during a pregnancy, the infection may cause a preterm delivery.
Clinical Studies
A group of 153 elderly women living in a nursing home experienced on average a 50 percent reduction in the bacterial load and white blood cell count in their urine after daily consuming 10 ounces of cranberry juice cocktail for six months. The elderly women also had a greater possibility of being free of the infection than similar women not using the cranberry juice. Capsules containing cranberry concentrate can also be effective. Women who took two 400-milligram capsules of cranberry powder daily or 3 months experienced a significant decrease in risk of UTIs.
Cranberry juice is also effective in reducing urinary odors in bedridden patients who have urinary infections and are incontinent. Nursing home personnel have observed a decrease in urine odor in the geriatric wards of a nursing home following the regular drinking of two glasses of cranberry juice by the patients. In addition, patients complained less about a burning sensation when they urinated.
What About Other Fruits?
The blueberry (Vaccinium corymbosum), a close relative of the cranberry, is also a good source of the proanthocyanidins that inhibit the colonization of certain bacteria. On the other hand, orange, grapefruit, pineapple, guava, and mango juices do not possess any antiadhesion properties.
Other Protective Effects
The cranberry appears to possess other benefits for human health. Helicobacter pylori is the major cause of gastric and duodenal ulcers. This bacterium penetrates the mucous lining of the gastrointestinal system and adheres to the underlying epithelial layer. Recently it was found that a cranberry fraction disabled some strains of Helicobacter pylori so that they could not stick to the epithelial surface. Through this mechanism cranberries could help prevent ulcers. A cranberry mixture also reduces the stickiness of oral bacteria and may be useful for delaying the development of dental plaque and gum disease.
Cranberry juice may also prevent the formation of certain types of kidney stones. A glass or two of cranberry juice every day for one to two weeks will increase the acidity of the urine and decrease the risk of a kidney stone forming. In addition, cranberry juice does not contain high levels of oxalate, a substance that can promote the formation of kidney stones.
Protection Against Chronic Disease
Cranberries are rich in polyphenolic antioxidants that protect against cancer and cardiovascular disease. The proanthocyanidins and other compounds inhibit the oxidation of LDL cholesterol, while cranberry powder has been observed to decrease the LDL cholesterol levels of animals with elevated blood cholesterol levels. The proanthocyanidins in cranberries and blueberries are known to inhibit tumor growth.
Safe Dosage
For the prevention or treatment of UTIs a daily glass of cranberry juice, one to three cups of cranberry juice cocktail, or 10 to 12 capsules of cranberry powder are recommended. Generally, there are no side effects. However, drinking 3 or more liters of cranberry juice per day can produce diarrhea and other gastrointestinal effects. Lesser amounts may increase the frequency of bowel movements. It is important that a patient with a UTI see their physician.
Remember: Herbal products and dietary supplements can have pharmacological effects, may produce adverse reactions in some people, and could interact with over-the-counter and prescription medications you may take. Discuss with your physician your decision to use any herbal product. Anything mentioned in this article is not intended to diagnose, prescribe, or treat any ailment.
Winston J. Craig, Ph.D., R.D., is a professor of nutrition at Andrews University, Berrien Springs, Michigan.
