cranberries
by Jenny Bryan
Cranberries are the reddish-black fruits found on the evergreen cranberry shrub, Vaccinium macrocarpon. They have been used to treat a variety of ailments since the 17th century and are available today as fresh or frozen berries, juice, concentrate, dried capsules and tablets.
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why are cranberries good for you?
The cranberry's main health-giving claim is in the treatment and prevention of urinary tract infections. Up to 60% of women have a urinary tract infection at some time in their life and a third of these will experience a recurrence during the following year – especially if they are 25-29 or over 55 years of age.
A common bacterial cause of urinary tract infection is Escherichia coli – a microbe which can spread from the intestine to the urethra (the tube which drains urine from the bladder) during bowel movements. Cranberries, blueberries and their relatives contain chemicals which prevent E. coli and some other bacteria from sticking to cells, so it is harder for them to infect bowel and urinary tissues.
what's the evidence?
Cranberries have been used to treat recurrent urinary tract infection since the 1920s, and several studies have demonstrated their anti-bacterial properties. In a US study in elderly women with urinary tract infection, those who drank 300ml/day of cranberry juice for several months had significant reductions in levels of bacteria in their urine. But other studies, for example in children, have failed to show benefits.
A recent review by the respected worldwide Cochrane Collaboration examined data from five trials of cranberry juice or capsules in the prevention of urinary tract infections and concluded that there was no reliable evidence in favour of cranberries. They also suggested that the large number of people who dropped out of the trials could mean that treatment was unpalatable over long periods. A similar review by the same group of the evidence in favour of using cranberries to treat (rather than prevent infections) produced even less evidence.
promising new data
In June 2001, Finnish doctors reported much more promising evidence of the benefits of cranberry juice in preventing recurrent urinary infections in women. In a study of 150 women with urinary tract infection caused by E.coli, drinking 50ml of a cranberry-lingonberry juice concentrate every day for six months was associated with a significant reduction in recurrences. By six months, 16% of women in the cranberry group had had a recurrence compared with 36% of those who had no treatment and 39% of those who had a drink of 'friendly bacteria' (lactobacillus) to try and improve the bacterial environment in their bowel.
how much cranberry juice?
In the Finnish study, 50ml/day of juice concentrate seemed to provide a beneficial effect while in the earlier US study in elderly women, it was 300ml/day which seemed to reduce the bacterial content of the urine.
Whatever dose you choose, be sure to stick with low sugar brands, or you may just be swapping one health problem for another!
when should I drink it?
The strongest evidence in favour of cranberries is in the prevention of recurrent urinary tract infection, particularly when there is E.coli infection.
People with symptoms of urinary tract infection (eg: needing to pee a lot and painful pee-ing) are likely to be prescribed antibiotics. Some will be asked to provide a urine sample, particularly if they have had previous infections or symptoms do not begin to clear up within a few days of starting treatment. Lab tests on the sample will show whether E. coli or other organisms are present.
A daily drink of cranberry juice is one way of trying to prevent recurrent urinary infections. Others include:
- wiping 'front to back' after bowel movements to prevent the spread of bacteria from the bowel to the urinary tract
- drinking plenty of fluids to 'flush out' bacteria from the bladder
- wearing loose fitting cotton underwear and, for women, avoiding tights and tight fitting trousers
- eating live yoghurts containing friendly bacteria (eg: lactobacilli) which may help to replace harmful bacteria in the intestines, such as E. coli.
help and info
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organisations
The Cochrane Collaboration
PO Box 726
Oxford OX2 7UX
Tel: 01865 310138
E-mail: secretariat@cocharane.org
Website: www.cochrane.org
Provides up-to-date, accurate, evidence-based information about the effects of healthcare. Website features information about the Cochrane Collaboration and details about its activities.
The Cranberry Institute
3203-B Cranberry Highway
East Wareham, Massachusetts 02538
USA
E-mail: cinews@earthlink.net
Website: www.cranberryinstitute.org
A US-based organisation providing research and education about the cranberry. Website contains information about cranberries, the health aspects, recipes, and a range of cranberry-related links.
NHS Direct
Helpline: 0845 46 47 (24 hours)
Website: www.nhsdirect.nhs.uk
The 24-hour NHS service provides expert health advice from trained nurses. An extensive database of medical information is available on their website. They can also advise you if you wish to make a complaint about the NHS.
websites
Cystitis
www.netdoctor.co.uk/diseases/facts/cystitis.htm
Outlines what cystitis is, its causes, symptoms, treatments, plus practical preventative advice.
Marilyn Glenville
www.marilynglenville.com/general/cystitis.htm
This natural health website for women explains the symptoms of cystitis and outlines which supplements, herbs and foods can help to combat the infection.
What Really Works
www.whatreallyworks.co.uk/ ..
An article on cystitis which introduces a 'pink punch' of juices that can be effective in combating the disease. Also offers alternative ways to take cranberry if you find the juice unpalatable.
reading
'Randomised Trial of Cranberry-Lignonberry Juice and Lactobacillus GG Drink for the Prevention of Urinary Tract Infections in Women' by T Kontiokari et al, British Medical Journal, vol 322 (30 June 2001), pages 1571-1573. http://bmj.bmjjournals.com/ .. |
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Cranberry Cooking for All Seasons by Nancy Cappelloni (Spinner Publications, 2002) |
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Blueberries, Cranberries and Other Vacciniums by Jennifer Trehane (Timber Press, 2004) |
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(December 2001, resources updated March 2005)
