The cranberry is a member of the plant family Ericaceae, which includes
a number of edible berries such as blueberries, huckleberries, and
bilberries. The plant is an evergreen, fruit-bearing vine found in bogs
and swamps throughout much of Europe, Asia, and North America. Most
commercially grown cranberries are produced in bog fields in New
England, Wisconsin, Washington, Oregon, and Eastern and Central Canada.
The primary cultivated species, Vaccinium macrocarpon, is a woody vine
that produces stems or runners which can reach lengths of six feet or
more. From these runners grow short upright branches (about two to three
inches long) which bear the flowers and fruit. The small (7-13 mm long
and 2-6 mm wide), oval-shaped leaves stay on the plant about two years
and vary in color from dark, glossy green during summer to a dull,
reddish brown during the dormant winter months. The plant flowers from
June through July, producing small, pale-rose colored blossoms. The
bitter-tasting fruit, which are bright red in color and nearly spherical
in shape, are used widely as a food and are also used for medicinal
purposes.
Health applications
Urinary tract health
Antioxidant support
History and traditional use
Cranberries have been used as a food since ancient times. As far back as
the Bronze age, an early Scandinavian form of beer was being made from
wheat, cranberries, myrtle, and honey. The early European explorers of
America found cranberries growing abundantly and noted that the fruit
was used widely by native tribes. Native Americans used cranberries in
foods such as pemmican and succotash, to make dyes for blankets and
rugs, and in poultices for wounds. Cranberries remain popular to this
day as an ingredient in beverages, sauces, jellies, salads, and
stuffings. Cranberry juice and concentrated cranberry supplements are
used in folk medicine for urinary tract infections.
Chemical composition
Most of cranberry's activity in the body is attributed to its
concentration of proanthocyanidins, a group of antioxidant flavonoids
found in red, blue, and purple colored berries. Cranberry also contains
vitamin C and (in trace amounts) a variety of other essential vitamins
and minerals.
Urinary tract infections
Herbalists have long recommended cranberry juice for the prevention and
treatment of recurrent urinary tract infections (UTIs), and modern
clinical studies appear to support this use. Research indicates that
women who consume cranberry juice daily can reduce their risk of UTIs by
50 percent or more.1-3 The results of one study
suggest that cranberry juice may be more effective in treating than
preventing UTIs,3 but it appears to useful for both
purposes. The method of action by which cranberry inhibits UTIs has been
the subject of much debate. Cranberry has shown the ability to increase
the acidity of the urine,4-5 and this action was
initially thought to be responsible for the herb's protective role
against UTIs. More recent studies indicate that cranberry inhibits the
ability of bacteria cells to adhere to the lining of the urinary tract
and cause infection.6,7
Dosage/toxicity
The optimum dosage of cranberry juice for UTIs has yet to be determined.
Because many commercial cranberry drinks (cranberry juice cocktails)
contain less than 30 percent cranberry juice, and most are heavily
sweetened with sugar, many herbalists recommend using concentrated
(10:1) cranberry capsules or tablets in doses equivalent to 1,600 mg per
day. Cranberry juice has no known toxicity and appears to be very safe,
with no negative side effects reported at this dosage. Increasing intake
of fluids is often recommended for people taking cranberry supplements.
Cranberry should not be used as a substitute for antibiotics during
acute urinary tract infection. Because acute urinary tract infections
can be dangerous, even lethal, they should be diagnosed and treated by a
physician.
Cranberry Compounds Fight Urinary Tract Infection
(From New England Journal of Medicine)
Drinking cranberry juice is a common home remedy for a urinary tract
infection, but just how it works was not understood.
A group of researchers believe they have found the answer: The effect
is due not to the highly acidic nature of cranberries but to specific
compounds in cranberries that inhibit the adherence of Escherichia coli
(bacteria) to uroepithelial cells.
Escherichia coli, or E. coli, is a bacterium found normally in the
digestive tract. However, if certain strains of the bacteria gain access
to the normally sterile environment of the bladder and urinary tract,
the bacteria can trigger an infection, with symptoms including a
frequent, painful urge to urinate and blood in the urine.
The condition can be readily treated with antibiotics, but recurs in
about 60% of cases.
In a new study, the researchers tested the ability of cranberry
extracts to inhibit the binding of certain, disease-causing strains of
E. coli to cells taken from the lining of the urinary tract which would
promote flushing of bacteria from the bladder into the urine stream,
resulting in the prevention or reduction of symptoms.
This binding process is thought to be an early step in the initiation
of an infection. During the course of the 5-year study, the team found
that extracts containing compounds called "condensed tannins"
or "proanthocyanidins," which are found in cranberries and
blueberries, could inhibit the binding process.
The New England Journal of Medicine October 8,1998;339:1085-1086.
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