Cranberry

Botanical name(s):

Vaccinium macrocarpon. Family: Ericaceae

Other name(s):

bearberry, craneberry

General description

The cranberry is an evergreen plant native to the northeastern United States. The red berries on the plant are used in foods, beverages, and in herbal products. It has been used traditionally for the prevention and treatment of urinary tract infections. Although it has fallen in and out of favor in medicine, cranberry is currently recognized as an effective agent to help prevent uncomplicated urinary tract infections, particularly in older women.

Cranberries are considered a foodstuff and are used in commercial quantities for cooking. They are most notably recognized as a garnish for salad and used in gelatin salad, cranberry sauce and jelly, and cranberry cocktail. Cranberry cocktail is most often used as a source of cranberry to prevent urinary tract infections. However, potent cranberry extracts are available and can be taken as pills by those who do not like the tartness or flavor of cranberry juice.

Cranberry contains a variety of constituents (anthocyanin, catechin, triterpenoids, quinic acid) that have been shown to decrease the adherence of bacteria to the bladder walls, therefore decreasing the likelihood of urinary tract infections.

Medically valid uses

There is some evidence that cranberry can help to prevent urinary tract infections; however, the evidence is not definitive, and more research is needed. Cranberry juice prevents bacteria from clinging to the bladder walls and increases the acidity of the urine. Cranberry is most useful as a preventive measure rather than a cure for an existing urinary tract infection. However, its use, along with standard treatment for a urinary tract infection, can hasten improvement. Constituents in cranberries have the following properties:

  • They inhibit certain chemicals necessary for E. coli (a common urinary infectious agent) to attach to the bladder wall.

  • They increase the acidity of urine (decrease the pH).

  • There is some evidence that cranberry may help prevent stomach ulcers caused by the bacteria H. pylori

  • A few lab studies have suggested that cranberry may decrease dental plaque. 

Unsubstantiated claims

Please note that this section reports on claims that have NOT yet been substantiated through scientific studies.

Cranberry juice is also claimed to help cure yeast infections. When consumed regularly, it is claimed to help prevent recurrences of yeast infections.

The high levels of vitamin C in cranberry juice may help reduce the frequency and severity of upper respiratory infections. In addition, cranberry may help relieve postnasal drip.

Cranberry juice may also help prevent kidney stones by reducing the amount of calcium in the urine and decreasing the pH (increasing the acidity) of the urine. High levels of urinary calcium have been linked to the development of kidney stones, as has consistently high pH (alkaline) urine.

Dosing format

Cranberry is found in the form of berries, capsules (concentrated cranberry extracts), juice, and tea. For over-the-counter cranberry concentrates, follow the instructions on the package. Cranberry juice is generally recommended in amounts ranging from 6 to 10 ounces per day, usually divided between meals.

Side effects, toxicity, and interactions

People on blood thinners or aspirin should use cranberry products with caution.

Additional information

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