Health Tips / Cranberry

What Is It?

Generations of American women have known that the bitter native cranberry isn’t just the basis of a Thanksgiving relish. In fact, these small, dark red berries have a long medical history in addition to a colorful culinary one. Specifically, cranberry juice and cranberry extract appear to help prevent and even eliminate urinary tract infections. Most women develop this type of problem at least once in their lives, and some suffer from constant recurrences.

The name “cranberry” evolved from “craneberry” (a common name for the low-growing shrub Vaccinum macrocarpon) because the plant’s flowers resemble the heads of cranes frequently spotted in the bogs where cranberries thrive.

Health Benefits

Early American physicians successfully applied crushed cranberries to tumors and wounds. They also used cranberries as a remedy for the age-old malady known as scurvy, a disease caused by a lack of vitamin C. It wasn’t too surprising, therefore, when modern scientists discovered that cranberries contain plentiful stores of this common antioxidant vitamin.

Recently, Israeli researchers discovered that a compound in cranberry juice is effective against various plaque-forming bacteria that can bind to teeth and cause gingivitis and gum disease. If you’re considering using cranberry juice for this purpose, however, stick with the natural (and unsweetened) variety. Commercial cranberry juice cocktails are very high in sugar, a gum-disease culprit in its own right.

Researchers have also found that cranberry juice may deodorize urine, a real boon for individuals who suffer from incontinence. In fact, the most popular medicinal uses by far for cranberry relate to urinary tract conditions.

Specifically, cranberry may help to:

Prevent and relieve symptoms of urinary tract infections (UTIs). Over the decades, countless women have used pure cranberry juice or cranberry juice cocktail to self-treat their UTIs. This common infection typically causes a burning sensation while urinating as well as a frequent and often intense urge to do so. For a long time, cranberries were thought to directly fight the infection by acidifying the urine to such an extent that bacteria such as Escherichia coli would languish or die. Today, the prevailing theory is that cranberry juice inhibits microorganisms from adhering to the mucosal cells lining the urinary tract, making it a less hospitable environment for the proliferation of E. coli and other infection-causing bacteria.

Several clinical trials now corroborate that this folk remedy does indeed work. In one of the best-designed studies, published in the prestigious Journal of the American Medical Association in 1994, Harvard researchers reported that regular consumption of cranberry juice led to reduced amounts of potentially infectious bacteria in 153 older women. The number of white blood cells–markers of the body’s response to infection–were also less. And over a six-month period, the participants who drank 10 ounces of cranberry juice daily developed significantly fewer cases of UTIs. Studies in younger women have been similarly positive.

In addition, when taken at the same time as prescription antibiotics for a UTI, cranberry juice or cranberry extract in supplement form may lessen the duration of the infection and help to ease such symptoms as itching, burning, and pain. In general, however, this herbal remedy is better taken to prevent recurrent UTIs than to treat a potentially serious infection that has already developed.

Reduce the risk for kidney stones. Anecdotal reports indicate that cranberry may help to reduce the risk of infection when you have this painful condition, also commonly referred to as urinary stones and “bladder gravel.”


fresh herb
dried herb/tea

Dosage Information

Special tips:

–Be aware that many major brands of cranberry juice cocktail are only 30% cranberry juice, with water and sweeteners making up the difference. If you want to drink a smaller amount of juice, try a high-quality, full-strength cranberry juice product, often sold at health-food stores. Add apple juice, if you find the taste too tart.

–A cup of cooked fresh cranberries is roughly equivalent to a 400 mg cranberry capsule, but the tangy flavor may require the addition of a sweetener.

To prevent UTIs: Drink three or more fluid ounces of cranberry juice cocktail (containing at least 30% juice) daily. Alternatively, take four to six 500 mg capsules of dried cranberry powder; the milligram dosage should come out to at least 2,000 mg daily.

To treat UTIs: Take 6,000-8,000 mg standardized extract a day, divided into three or four doses (such as four 500 mg capsules, three or four times a day). Alternately, drink 12 to 32 fluid ounces of cranberry juice cocktail daily.

Guidelines for Use

Drinking lots of water or other fluids, in addition to taking cranberry, will speed recovery from a UTI.

Taking vitamin C (2,000 mg three times a day) will further acidify the urine and improve the effect of cranberry.

General Interaction

If you use medication that affects your kidneys or urinary tract, consult your doctor before using cranberry.

Cranberry’s acidifying effect on urine lessens the impact of an herb called uva ursi (or bearberry) that is also taken for urinary tract infections. Choose either uva ursi or cranberry; don’t use them together.

Possible Side Effects

Drinking cranberry juice in large quantities can cause diarrhea and stomach upset.

No serious side effects have been associated with the use of moderate amounts of cranberry in supplement form. Some people develop loose stools as a result of treatment with cranberry supplements, however; stop taking them if this occurs.


If you suspect you have a UTI, try cranberry for 24 to 36 hours. But if such symptoms as burning, pain, or a frequent urge to urinate persist after that time, consult your doctor. Antibiotics may be necessary to prevent serious complications.

Keep in mind that cranberries may not eliminate or wash away all bacteria, which is why prescription antibiotic treatment may be needed to knock out a UTI completely. After you have self-treated a bladder infection, checking with your doctor and obtaining a follow-up urinalysis is strongly advised, even if your symptoms have completely cleared. If this isn’t done, recurrent infections might cause infections in the upper urinary tract that could harm the kidneys. Signs and symptoms of this potentially serious complication include low back pain, fever, chills, and the presence of blood in the urine. Seek professional care.


Kidney Stones Acute: 2 300-500 mg capsules twice a day or drink 6 oz. of cranberry juice 4 times a day
Urinary Tract Infections 400 mg 4 times a day

Be well,
David Edelberg, MD