What Are the Benefits of Cranberry Juice?

In addition to being high in vitamin C and often fortified with calcium, cranberry juice is commonly used to prevent cystitis, or urinary tract infections, in women. Cranberries are also being studied for their possible role in fighting arterial heart disease, dental plaque, gastrointestinal infections, and herpes simplex, and the results appear promising. More in-depth research must be completed, however, before any definitive statements can be made about the role of cranberries in preventing any condition other than UTIs.

How it Works

Astringent substances found in cranberry juice, known as tannins, prevent several types of E. coli bacteria from adhering to the walls of the urinary tract and, in essence, washes the bacteria out of the bladder and into the urine for disposal from the body. This is especially significant when cranberry juice dislodges bacteria that are resistant to antibiotic treatment.

Cranberry juice's protective effect begins within two hours of drinking a glass of cranberry juice and lasts for up to 10 hours afterward. On its own, however, cranberry juice is not an effective treatment once a urinary tract infection is established, though you may want to drink it as an adjunct to antibiotic therapy.

How to Get the Most Benefits

If you are prone to UTIs, drink 3 to 16 oz. of cranberry juice cocktail twice a day, every day.
If you use pure unsweetened cranberry juice, drink 1/2 to 1 oz. daily. Most people prefer to dilute pure cranberry juice in a large glass of water.

Warnings and Side Effects

For some people, there are potential side effects from drinking cranberry juice.
As with most fruit juices, large amounts of cranberry juice can cause stomach upset and diarrhea.
Although claims are sometimes made that cranberry juice can help prevent kidney stones, at least one study showed that cranberry juice could actually be responsible for the formation of a rare type of stone.
Speak to your doctor before drinking cranberry juice if you take antacids, prescription blood thinners or aspirin on a regular basis.