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There have been a number of scientific studies performed
regarding the use of cranberry juice for UTI prevention. Below is a list of
papers involving this theory, along with the results and conclusions that have
been determined based on this experimentation.
Mechanism of
Action Studies (in vitro)
Clinical Studies (in vivo)
Mechanism of Action Studies
Howell, Amy B, PhD, Ara Der Marderosian, PhD, and Lai
Yeap Foo, PhD. “Inhibition of the Adherence of P
Fimbriated Escherichia coli to Uroepithelial-Cell Surfaces by Proanthocyanidin
Extracts from
Cranberries.” NEJM.
339:15, 1085-1086, 1998.
While the fructose in cranberry juice has been found to
inhibit the adherence of E. coli with Type 1 fimbriae to uroepithelial cells,
the mechanism of inhibition of P fimbriated E. coli was not known. This study
found that the condensed tannins (proanthocyanidins) in cranberry juice are
responsible for the inhibition of adherence of P fimbriated E. coli to uroepithelial cells. This property was noted at concentrations of
proanthocyanidins of only 10 to 50 micrograms per milliliter. The
characteristic was also noted with blueberries and other members of the
vaccinium species.
Ofek, Itzhak, PhD, Janina Goldhar, MD, Dina Zafriri,
PhD, Helina Lis, PhD, Rivka Adar, PhD, Nathan
Sharon, PhD.
“Anti-Escherichia Coli Adhesin Activity of Cranberry and Blueberry Juices.
NEJM.
324:1599-1599, 1991.
E. coli strains that lead to UTIs are able to adhere to uroepithelial cells due to the presence of two adhesins, MS and MR on their
fimbriae. Fructose is known to inhibit the MS adhesion component, but the
mechanism of inhibition of the MR component was unknown, other than it is a
polymeric structure. In this study seven fruit juices were tested for their
ability to inhibit hemagglutination of E. coli isolates containing the MR
adhesin. Only cranberry juice and blueberry juice were found to contain this
inhibitor. The inhibitory action was found to be more active on urinary, rather
than fecal E. coli isolates. The MR inhibitor was found to be heat-stable,
resistant to trypsin, and nondialysable, although its exact identification was
not made.
Sobota, A.E. “Inhibition of Bacterial Adherence by
Cranberry Juice: Potential Use for the Treatment of
Urinary Tract
Infections.” The Journal of Urology. 131: 1013-1016, 1984.
In this study 77 isolates of E. coli were exposed to
cranberry juice cocktail. The cocktail inhibited adherence of the bacteria by
75% or more in 60% of the bacterial samples. Researchers also gave cranberry
juice cocktail to mice in their normal water supplies for fourteen days. It was
found that the urine collected from the mice following this consumption, was
able to inhibit the adherence of E. coli to uroepithelial cells by 80% in
vitro. The same experiment was performed on human urine from twenty-two
participants, which found that 15 of the 22 samples had significant
anti-adherence properties one to three hours following consumption of fifteen
ounces of cranberry juice cocktail.
Zafriri, Dina, Itzhak Ofek, Rivka Adar, Marisol Pocino,
and Nathan Sharon. “Inhibitory Activity of
Cranberry
Juice on Adherence of Type 1 and Type P Fimbriated Escherichia coli to
Eucaryotic Cells.”
Antimicrobial Agents and Chemotherapy. 33:1, 92-98, 1989.
This in vitro study found that cranberry juice cocktail
“inhibited the adherence of urinary isolates expressing Type 1 fimbriae and P
fimbriae. The drink was also found to inhibit yeast agglutination caused by
purified Type 1 fimbriae. The mechanism of inhibition for the Type 1 fimbriated
E. coli was attributed to the fructose component of the cocktail. The
inhibitory effect of the P fimbriated E. coli was detected only after preincubation of the bacteria with the cocktail. The study also illustrated
that cranberry juice, orange juice, and pineapple juice also inhibit the
adherence of Type 1 fimbriated bacteria due to their high fructose content, but
these juices were not found to inhibit P fimbriated bacteria.
Clinical Studies
Avorn, Jerry, MD, Mark Monane, MD, MS, Jerry H. Gurwitz,
MD, Robert J. Glynn, PhD, Igor Choodnovskiy,
Lewis A.
Lipsitz, MD. “Reduction of Bacteriuria and Pyuria After Ingestion of Cranberry
Juice.” JAMA.
271:10,
751-754, 1994.
This study was a randomized, double-blinded study that
involved giving 153 women (average age of 78.5 years) either 300 ml of a typical
store bought cranberry juice, sweetened with saccharin, for six months or a
placebo juice that was similarly sweetened, but contained no cranberry
byproducts. The participant’s urine was sampled every month for bacteriuria and
leukocytes. The results showed that the women who drank cranberry juice daily,
had a risk of developing bacteriuria that was only 42% that of the control
group. Also, after becoming bacteriuric, the test group had only 27% the odds
of the placebo group of remaining bacteriuric in the upcoming month.
.
Kontiokari, Tero, Kaj Sundqvist, M Nuutinen, T Pokka, M
Koskela, and M Uhari. “Randomised Trial of
Cranberry-Lingonberry
Juice and Lactobacillus GG Drink for the Prevention of Urinary Tract
Infections in
Women.” British Medical Journal. 322:1571-1573, 2001.
In this study 150 women with documented Escherichia coli
UTIs were separated into three groups. The first group received 50 ml of
cranberry-lingonberry juice every day for six months. The second group was given 100
ml of lactobacillus drink five days a week for one year. The final group
underwent no treatment. While the lactobacillus and no treatment group
experienced no change in recurrence of UTI, the cranberry-lingonberry juice
group developed 20% fewer UTIs than the control and lactobacillus group.
Kunzminski, L.N., PhD, M.B.A. "Cranberry Juice and
Urinary Tract Infections: Is There a Beneficial
Relationship." Nutrition Reviews. 54:11, S87-S90, Nov 1996.
This article provides an informative review and case study
of the cranberry, itself, UTIs, UTI prevention, data from a prior study
performed regarding UTI prevention, and suggestions for areas of research on
this topic.
Lowe, Franklin C. and Elliot Fagelman. “Cranberry Juice
and Urinary Tract Infections: What is the
Evidence?”
Urology. 57:407-413, 2001.
This paper is an excellent review article that explains
the mechanism of cranberry juice’s action to prevent UTIs, along with a summary
of the clinical studies that have been performed regarding this theory.
The paper contains the findings of several studies, which are not included in this list.
A case study by Moen of a 66-year-old woman with chronic pyelonephritis who was
not responsive to antibiotic therapy, revealed an improvement in the patient’s
pyuria after nine months of consuming cranberry juice. Another study by Pappa,
gave sixty patients already suffering from UTIs cranberry juice and found that
53% improved significantly, 20% responded moderately, and 27% experienced no
change in their bacteriuria. In a study undertaken by Haverkorn and Mandigers
seven in-patient participants were given cranberry juice regularly and a
decrease in the expected cases of bacteriuria was found. A final study by
Foxman revealed that drinking cranberry juice decreased the incidence of UTIs in
sexually active women.
Schlager, Theresa A., MD, Susan Anderson, MD, Julie
Trudell, RN, and Joseph O. Hendley, MD.
“Effect of
cranberry juice on bacteriuria in children with neurogenic bladder receiving
intermittent
catheterization.” Journal of Pediatrics. 135:698-702, 1999.
Symptomatic and asymptomatic bacteriuria are common
problems for children who require catheterization for neurogenic bladder. In
this study 15 children received either cranberry concentrate or placebo for 6
months (3 months of treatment, followed or preempted by 3 months of placebo).
Weekly urine samples were collected from the participants and analyzed.
Unfortunately, the results revealed no difference in the occurrence of bacteriuria in both groups, with 70% of patients in both groups developing
bacteriuria.
Walker, Edward B. PhD, D. Paul Barney, MD, Jennifer N.
Mickelson, Ruth J. Walton, Richard A.
Mickelson,
Jr. “Cranberry Concentrate: UTI Prophylaxis.” The Journal of Family
Practice.
45:2,
167-168, 1997.
This randomized, double-blinded,
cross-over, placebo-controlled study involved ten sexually active females
between the ages of 18 and 45 who were in good health other than suffering from
recurrent UTIs. Each participant received a solid nutritional cranberry
supplement containing 400 mg of cranberry product daily for three months,
followed or preempted by a daily placebo
for three months. In total, the participants experienced twenty-one
UTIs throughout the study period and only six of those UTIs occurred while the
women were taking the test product. This number was statistically significant
to illustrate that cranberry supplements do have a statistically significant
chance of reducing the reoccurrence of UTIs.
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