• Prevention and Possibly Treatment:
• Prevention and Treatment:
• Prevention Only:
The cranberry plant is a close relative of the common blueberry. Native Americans used it both as food and for the treatment of bladder and kidney diseases. The Pilgrims learned about cranberry from local tribes and quickly adopted it for their own use. Subsequent physicians used it for bladder infections, for "bladder gravel" (small bladder stones), and to remove "blood toxins."
In the 1920s, researchers observed that drinking cranberry juice makes the urine more acidic. Since common urinary tract-infection bacteria such as E. coli dislike acidic surroundings, physicians concluded that they had discovered a scientific explanation for the traditional uses of cranberry. This discovery led to widespread medical use of cranberry juice for treating bladder infections. Cranberry fell out of favor with physicians after World War II, but it became popular again during the 1960s—as a self-treatment.
What Is Cranberry Used for Today?
Cranberry is widely used today to prevent bladder infections
Just as cranberry seems to prevent adhesion of bacteria to the bladder, preliminary evidence suggests that it might also help prevent the adhesion of the ulcer-causing bacteria
to the stomach wall.
On this basis, it has been proposed for preventing or treating ulcers, with mixed results as described
Other preliminary evidence suggests that the same actions of cranberry juice might make it useful for treating or preventing
Cranberry has also been investigated as a possible aid in reducing the risk of
What Is the Scientific Evidence for Cranberry?
Probably the best evidence for the use of cranberry juice for preventing bladder infections comes from a 1-year, double-blind, placebo-controlled
A double-blind study of 376 hospitalized seniors attempted to determine whether a low dose of cranberry juice (as cranberry juice cocktail, 10 ounces daily—a very low dose compared to the previous study) would help prevent acute infections.
Another double-blind study evaluated cranberry juice cocktail for the
of chronic bladder infections.
A review of 10 studies investigated the benefits of cranberry juice or tablets compared to a placebo control in patients susceptible to urinary tract infections. Among 1,049 participants, the researchers found the cranberry products reduced the incidence of urinary tract infections by 35%, a statistically significant amount, over a 12-month period. The effect was most notable in those with recurrent infections. However, many subjects dropped out of the studies early, suggesting that continuous consumption of cranberries is not well tolerated.
On the negative side, 3 other double-blind, placebo-controlled studies evaluated the effectiveness of cranberry extract for eliminating bacteria in the urine of people with bladder paralysis (neurogenic bladder).
plays a major role in the initiation and maintenance of
, ulcers in the stomach and duodenum. A 90-day, double-blind, placebo-controlled study performed in China tested the effects of daily consumption of cranberry juice in individuals who were chronically infected with
(but who did not necessarily have ulcers).
While this was a promising finding on a theoretical level, it did not directly address treatment or prevention of ulcers. A more practical study evaluated the use of cranberry as a support to standard therapy.
The results were somewhat promising. In the study group at large, OAC plus cranberry was no more effective than OAC plus placebo or OAC alone. However, among female participants in the study, use of cranberry was associated with a significantly increased rate of helicobacter eradication as compared to placebo or no treatment.
Does this mean that women undergoing ulcer treatment may benefit from cranberry? Perhaps, but not necessarily. When a treatment fails to produce benefit in the entire group studied, researchers may, after the fact, go on a hunt for a subgroup who did benefit. The laws of chance alone ensure that they can almost always find one. Therefore, it is not clear whether cranberry actually did provide benefit, or whether this finding was merely a statistical fluke.
The usual dosage of dry cranberry juice extract is 300 mg to 400 mg twice daily or 8 to 16 ounces daily of pure cranberry juice (not cranberry juice cocktail.)
As a widely eaten food, cranberry is thought to have a generally good safety profile.
However, several case reports suggest that cranberry could interact with the drug warfarin (Coumadin), potentially leading to internal bleeding.
Two formal studies have failed to find evidence of such an interaction,
In addition, cranberry juice might allow the kidneys to excrete weakly alkaline drugs more rapidly, thereby reducing their effectiveness. This would include many antidepressants and prescription painkillers.
Interactions You Should Know About
If you are taking:
3. 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;33:92-98.
5. Howell AB, Vorsa N, Der Marderosian A, et al. Inhibition of the adherence of P-fimbriated Escherichia coli to uroepithelial-cell surfaces by proanthocyanidin extracts from cranberries [letter]. N Engl J Med. 1998;339:1085-1086.
6. Habash MB, Van der Mei HC, Busscher HJ, et al. The effect of water, ascorbic acid, and cranberry derived supplementation on human urine and uropathogen adhesion to silicone rubber [abstract]. Can J Microbiol. 1999;45:691-694.
9. Stothers L. A randomized trial to evaluate effectiveness and cost effectiveness of naturopathic cranberry products as prophylaxis against urinary tract infection in women. Can J Urol. 2002;9:1558-1562.
12. Kontiokari T, Sundqvist K, Nuutinen M, et al. Randomised trial of cranberry-lingonberry juice and Lactobacillus GG drink for the prevention of urinary tract infections in women. BMJ. 2001;322:1-5.
19. Weiss EI, Kozlovsky A, Steinberg D, et al. A high molecular mass cranberry constituent reduces mutans streptococci level in saliva and inhibits in vitro adhesion to hydroxyapatite. FEMS Microbiol Lett. 2004;232:89-92.
21. Waites KB, Canupp KC, Armstrong S, et al. Effect of cranberry extract on bacteriuria and pyuria in persons with neurogenic bladder secondary to spinal cord injury. J Spinal Cord Med. 2004;27:35-40.
23. Di Martino P, Agniel R, David K, et al. Reduction of Escherichia coli adherence to uroepithelial bladder cells after consumption of cranberry juice: a double-blind randomized placebo-controlled cross-over trial. World J Urol. 2006 Jan 6. [Epub ahead of print]
25. Duthie SJ, Jenkinson AM, Crozier A, et al. The effects of cranberry juice consumption on antioxidant status and biomarkers relating to heart disease and cancer in healthy human volunteers. Eur J Nutr. 2005 Jul 20. [Epub ahead of print].
26. Crews WD, Harrison DW, Griffin ML, et al. A double-blinded, placebo-controlled, randomized trial of the neuropsychologic efficacy of cranberry juice in a sample of cognitively intact older adults: pilot study findings. J Altern Complement Med. 2005;11:305-309.
27. McMurdo ME, Bissett LY, Price RJ, et al. Does ingestion of cranberry juice reduce symptomatic urinary tract infections in older people in hospital? A double-blind, placebo-controlled trial. Age Ageing. 2005;34:256-261.
28. Linsenmeyer TA, Harrison B, Oakley A, et al. Evaluation of cranberry supplement for reduction of urinary tract infections in individuals with neurogenic bladders secondary to spinal cord injury. A prospective, double-blinded, placebo-controlled, crossover study. SCI Nurs. 2005;22:20-25
29. Greenblatt DJ, von Moltke LL, Perloff ES, et al. Interaction of flurbiprofen with cranberry juice, grape juice, tea, and fluconazole: In vitro and clinical studies. Clin Pharmacol Ther. 2006;79:125-133.
33. Shmuely H, Yahav J, Samra Z, et al. Effect of cranberry juice on eradication of Helicobacter pylori in patients treated with antibiotics and a proton pump inhibitor. Mol Nutr Food Res. 2007 May 9. [Epub ahead of print]
36. Hess MJ, Hess PE, Sullivan MR, et al. Evaluation of cranberry tablets for the prevention of urinary tract infections in spinal cord injured patients with neurogenic bladder. Spinal Cord. 2008 Apr 8.
Last reviewed April 2009 by EBSCO CAM Review Board
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