Date Last Updated: 24/02/06
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Do cranberries help prevent urinary tract infections?
Treatment in brief
Cranberry (Vaccinium macrocarpon) to prevent urinary tract infection
Urinary tract infection
Urinary tract infections are caused by bacteria in the urinary tract,
usually in the bladder (cystitis). They are very common, especially in
women. The most common symptoms of urinary tract infections are a frequent
or urgent need to pass urine, or a burning sensation when passing urine. The
diagnosis is confirmed by a urine test, which measures the concentration of
bacteria (most commonly Escheria coli) in the urine.
Cranberries
Cranberry
juice has traditionally been used for preventing urinary tract infections.
Its effect may be due to its ‘anti-adhesive’ properties, as it has been
demonstrated that cranberries contain compounds that prevent bacteria from
sticking to the lining of the bladder (Zafriri
1989). Cranberry can also be taken as a capsule.
The evidence
There is
level 1 evidence from a systematic review that taking cranberry products for
twelve months reduces the number of urinary tract infections in women who
have a problem with recurrent urinary tract infections. When taken over one
year, cranberry prevents recurrent infections for about one in six women.
It is not
clear whether cranberry products are also effective for other groups who
commonly get urinary tract infections, such as older men and children with
bladder problems.
Cranberries do not seem to have any serious side effects for most people and
there is
evidence (level 2) that cranberry juice is generally well accepted and
tolerated by older people. Some children find the taste unpleasant.
There is
no evidence as to what form of cranberry treatment (eg, juice or tablets) is
most effective, what dose is best or for how long it should be taken.
Other
important issues
There is
evidence suggesting that cranberry products may interfere with the action of
the drug warfarin (level 4 evidence). People taking warfarin may wish to
limit their intake of cranberries, or carefully monitor their warfarin
levels (INR test).
Key
messages
|
There is evidence
that cranberry products may reduce the number of recurrent urinary tract
infections for women. |
1 |
|
|
|
|
The evidence
suggests that cranberry products may interfere with the action of
warfarin. |
4 |
|
|
|
|
There is no evidence
that cranberry products prevent urinary tract infections in children or
men. |
No study
evidence |
|
|
|
|
|
There is no evidence
for deciding the dose required to reduce infection, or whether juice or
capsules are better. |
No study
evidence |
Key:
Levels of evidence
The information in
this summary was developed by assessing:
The
Cochrane review: Cranberries for preventing urinary tract infections – 2004
http://www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD001321/frame.html
Date 27 Jan
2006 Last updated 7 Feb 2006
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