Fighting urinary tract
infections with cranberry juice
For nearly ninety years, the American cranberry (Vaccinium macrocarpon) has
been used by countless women to prevent and treat urinary tract infections (UTI).
Originally, scientists believed drinking cranberry juice cocktail acidified
the urine, hindering bacterial proliferation. At the time, this practice was
one of the few effective treatments for women with recurrent UTI.
A 1967 study shows consumption of commercial cranberry juice cocktail did not
acidify the urine as was previously believed.(1) Despite this, UTI sufferers
continued to use cranberry juice with beneficial results. A second study,
published in The Journal of the American Medical Association (JAMA) in
1994, confirmed the beneficial effects of regular consumption of cranberry
In this study 153 female
subjects were randomized into two groups, cranberry juice drinkers (10 ounces
daily) and placebo, using a cranberry flavored beverage with no cranberry
juice. After six months the results conclusively demonstrated that the
drinkers of cranberry juice experienced fewer bacterial infections. Those with
bacteria counts indicating an increased likelihood of infection diminished in
the cranberry group as reflected by a 25% decrease in positive bacterial urine
samples relative to the controls.(2)
Because no assessment was made
as to urinary tract infection symptoms, the study did not enable researchers
to determine if cranberry actually cured full blown infections. Nevertheless,
the evidence to support regular use of cranberry to prevent recurrent or
chronic UTI is compelling to say the least.
Modern research has now led us to the discovery that cranberry helps relieve
UTI not by any process of acidification, but rather due to its ability to
prevent microorganisms from adhering to the epithelial cells that line the
urinary tract. Escherichia coli, the most common UTI-causing bacteria,
produces chemicals known as adhesions, enabling the organism to cling to
epithelial cells where they proliferate and cause infection. Cranberry juice
was found to contain two substances which inhibit the adhesion activity of
bacteria: fructose and an, as yet, unidentified polymeric compound.
It is now known that cranberry
can reduce the bacteria responsible for UTI. However, cranberry's effects on
full blown UTI infections have not been studied, so persons experiencing UTI
or UTI symptoms should still seek medical intervention in addition to
supplementing their diets with cranberry.
Because of the high sugar and
moderate calorie content of cranberry juice, coupled with the amount required
each day for optimum effect, some people prefer to take a cranberry extract
instead of juice.