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© Steven Foster
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Botanical name: Vaccinium macrocarpon
Parts used and where grown
Cranberry is a member of the same family as bilberry and
blueberry. It is from North America and grows in bogs. The ripe fruit is used medicinally.
Cranberry has been used in
connection with the following conditions (refer to the individual
health concern for complete information):
Historical or traditional use (may
or may not be supported by scientific studies)
In traditional North American herbalism, cranberry has been used to prevent kidney stones and “bladder gravel” as well as
to remove toxins from the blood. Cranberry has long been recommended by herbalists as well as
doctors to help prevent urinary tract infections (UTIs).
Active constituents
In test tube studies, cranberry prevents E. coli, the most common bacterial cause
of UTIs, from adhering to the cells lining the wall of the bladder. This anti-adherence action
is thought to reduce the ability of the bacteria to cause a UTI.1 2 The
proanthocyanidins in the berry have exhibited this
anti-adherence action.3 Cranberry has been shown to reduce bacteria levels in the
urinary bladders of older women significantly better than placebo, an action that may help to
prevent UTIs.4 A small double-blind trial with younger women ages 18–45 years
with a history of recurrent urinary tract infections, found
that daily treatment with an encapsulated cranberry concentrate (400 mg twice per day) for
three months significantly reduced the recurrence of urinary tract infections compared to
women taking a placebo.5 Other preliminary trials in humans suggest cranberry may
help people with urostomies and enterocystoplasties to keep their urine clear of mucus buildup
and possibly reduce the risk of UTIs.6 However, one trial found that cranberry did
not reduce the risk of UTIs in children with neurogenic bladder disease (a condition that does
not allow for proper flow of urine from the bladder) who were receiving daily
catheterization.7
How much is usually taken?
One capsule of concentrated cranberry juice extract (400 mg) can be taken two times per
day.8 Several 16-ounce (500 ml) glasses of high-quality unsweetened cranberry juice
from concentrate each day approximate the effect of the cranberry extract. Cranberry tincture,
1/2–1 teaspoon (3–5 ml) three times per day, can also be taken.
Are there any side effects or interactions?
Cranberry concentrate has not been reported to cause side effects and has no known
contraindications to use during pregnancy and breast-feeding. According to one report,
supplementation with an unspecified number of cranberry tablets for seven days increased the
urinary excretion of oxalate by 43%, suggesting that long term use of cranberry supplements
might increase the risk of developing a kidney
stone.9 On the other hand, in the same study, urinary excretion of magnesium
and potassium (which are inhibitors of stone formation) also increased. Until more is known,
individuals with a personal or family history of calcium-oxalate kidney stones should consult
a doctor before using cranberry supplements for long periods of time (e.g., more than a week).
Cranberry should not be used as a substitute for
antibiotics during an acute urinary tract infection,
except under medical supervision.
Are there any drug
interactions?
Certain medicines may interact with cranberry. Refer to drug interactions for a list of those medicines.
References
1. Sobota AE. Inhibition of bacterial adherence by cranberry juice:
Potential use for the treatment of urinary tract infections. J Urol
1984;131:1013–6.
2. Zafriri D, Ofek I, Adar R, et al. Inhibitory activity of cranberry
juice on adherence of type 1 and type P fimbriated Escherichia coli to eucaryotic
cells. Antimicrob Agents Chemother 1989;33:92–8.
3. Howell AB, Vorsa N, Der Maderosian A. Inhibition of the adherence of
P-fimbriated Escherichia coli to uroepithelial—all surfaces by proanthocyanidin
extracts from cranberries. New Engl J Med 1998;339:1005–6.
4. Avorn J, Monane M, Gurwitz JH, et al. Reduction of bacteriuria and
pyruria after ingestion of cranberry juice. JAMA 1994;271:751–4.
5. Walker EB, Barney DP, Mickelsen JN, et al. Cranberry concentrate: UTI
prophylaxis. J Family Pract 1997;45:167–8 [letter].
6. Leaver RB. Cranberry juice. Prof Nurse 1996;11:525–6
[review].
7. Schlager TA, Anderson S, Trudell J, Hendly JO. Effect of cranberry
juice on bacteriuria in children with neurogenic bladder receiving intermittent
catheterization. J Pediatr 1999;135:698–702.
8. Brown DJ. Herbal Prescriptions for Better Health. Rocklin,
CA: Prima Publishing, 1996, 57–61.
9. Terris MK, Issa MM, Tacker JR. Dietary supplementation with cranberry
concentrate tablets may increase the risk of nephrolithiasis. Urology
2001;57:26–9.
Copyright © 2004 Healthnotes, Inc. All rights reserved.
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The information presented in Healthnotes is for informational
purposes only. It is based on scientific studies (human, animal, or in vitro),
clinical experience, or traditional usage as cited in each article. The results reported may
not necessarily occur in all individuals. For many of the conditions discussed, treatment with
prescription or over-the-counter medication is also available. Consult your doctor,
practitioner, and/or pharmacist for any health problem and before using any supplements or
before making any changes in prescribed medications. Information expires March 2005.
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Reliable and relatively consistent scientific data showing a substantial health benefit.
For an herb, supported by traditional use but
minimal or no scientific evidence. For a supplement, little scientific support and/or minimal
health benefit.
