Cranberry is a slender-stemmed shrub with leathery leaves, white-to-pink flowers, and glossy red fruit. Also known as “low bush cranberry,” this trailing evergreen is native to North America and commercially cultivated in northern and central Europe. The pungent juice produced from the fruit is extensively marketed in the United States, with Massachusetts as the major producer of both the fruit and the juice.1 During the past decade cranberry has become increasingly popular as a dietary supplement, ranking 5th in total sales of single herbal supplements in the mainstream channel of trade in 2005.2
History and Cultural Significance
The Iroquois and the Cherokee tribes viewed the cranberry as a symbol of peace and friendship.3 Historically, cranberries were used by American settlers in poultices for treating wounds and blood poisoning and were eaten to prevent scurvy (a disease caused by vitamin C deficiency).4 Cranberries and their leaves were used for treating various conditions including stomach ailments, liver problems, fever, swollen glands, and mumps.
Traditionally, the fruit has also been used to treat urinary tract infections3 and as a urinary deodorizer for people with incontinence.5 In foods, cranberries are used widely in fruit juice, jelly, and sauce.
At least 21 studies have been conducted on a total of more than 1700 subjects demonstrating cranberry’s positive effects on urinary tract health. Of these, 9 studies supported the use of cranberry juice or capsules for the prevention of urinary tract infections (UTI).6,7,8,9,10,11,12,13,14 Two of the studies found cranberry juice to be effective in the treatment of UTIs,15,16 while 2 additional studies on elderly subjects examined cranberry juice as a treatment for bacteriuria (bacteria in the urine, with or without UTI) and pyuria (pus or white blood cells in the urine).17,18 Eight studies investigated the effect of fresh cranberry juice on urinary pH and kidney stones.19,20,21,22,23,24,25,26
Early research suggested that cranberry juice acidified the urine through the excretion of hippuric acid, thus inhibiting the growth of bacteria.27 However, later studies showed that cranberry’s effectiveness in treating UTIs is due to its inhibition of the adhesion of
E. coli bacteria to the walls of the urinary tract, thereby preventing colonization of the bacteria and subsequent infection.28,29,30,31 The authors of a 2007 study investigated the effects of 2 cranberry products on bladder epithelial cells as well as vaginal epithelial cells.27 (Note: The brand of one of the cranberry products used in the study was not identified and the other was a purified cranberry extract prepared in a laboratory.) These are the first published results on the ability of cranberry to inhibit E. coli adhesion to vaginal epithelial cells. The results suggest that cranberry has the potential to inhibit adherence to both vaginal epithelial cells and bladder epithelial cells, thus preventing UTIs before colonization in the bladder.27
Recent case reports suggest the possible adverse interaction of cranberry with the anticoagulant drug warfarin (aka Coumadin®, Bristol-Myers Squibb).32,33,34,35,36 Based on these reports, the United Kingdom’s Committee on Safety of Medicines alerted clinicians to advise patients to avoid the concurrent use of cranberry and warfarin.33,37 Patient education materials in US pharmacies have also recommended that patients limit intake or avoid cranberry consumption while taking warfarin.37 However, some sources consider this a dubious interaction.38,39 David Greenblatt, MD, of Tufts University Medical School reviewed all the case reports and stated that “not a single one of these cases plausibly demonstrated that loss of anticoagulant control was caused by cranberry juice.”39 Also, Greenblatt did a clinical study on patients taking cranberry juice and flurbiprofen and found no effect of cranberry on the metabolism of flurbiprofen, suggesting no interaction between cranberry and warfarin.39,40 (Note: Flurbiprofen is a drug that is metabolized by the CYP2C9 enzyme, which also plays a major role in warfarin metabolism.)
As recently as June 2001, overproduction had diminished the price of cranberries.41 However, due to its increasingly well-documented health benefits, cranberry has attracted widespread media and industry attention in recent years. Moving from beverages and mineral waters into dairy and confectionary products, cranberry is now also recognized as a key ingredient in the dietary supplement market.2,42 Because of the increased awareness on the importance of healthy nutrition, the future of cranberry as a food and dietary supplement appears certain, and it may eventually become a recognized medicinal product.
- Leung AY, Foster S. Encyclopedia of Common Natural Ingredients. 2nd ed. New York: Wiley Inter-Science Publication. 1996.
- Blumenthal M, Ferrier GKL, Cavaliere C. Total sales of herbal supplements in United States show steady growth. HerbalGram. 2006;71:64 66.
- Eck P. The American Cranberry. New Brunswick: Rutgers University Press. 1990.
- Blumenthal M, Hall T, Goldberg A, Kunz T, Dinda K, Brinckmann J, Wollschlaeger B, eds. The ABC Clinical Guide to Herbs. Austin, TX: American Botanical Council; 2003.
- Jellin JM, Gregory PJ, Batz F, et al. Pharmacist’s Letter/Prescriber’s Letter Natural Medicines Comprehensive Database. 5th ed. Stockton, CA: Therapeutic Research Faculty; 2003.
- Walker E, Barney D, Mickelsen JN, et al. Cranberry concentrate: UTI prophylaxis. J Fam Pract. 1997;45(2):167–168.
- Kontiokari T, Sundquvist K, Nuutinen M, et al. Cranberry-Lingonberry Juice and Lactobacillus GG Drink for the Prevention of urinary tract infections in women. British Medical Journal. 2001;322:1–5.
- Dignam R, Ahmed M, Kelly K, et al. The effect of cranberry juice on urinary tract infection rates in a long-term care facility. Ann Long-Term Care. 1998;6(5):163–167.
- Gibson L, Pike L, Kilbourn JP. Clinical Study: Effectiveness of cranberry juice in preventing urinary tract infections in Long-Term Care Facility patients. J Naturopathic Med. 1991;2(1):45–47.
- Bailey D, Dalton C, Daugherty FJ, Tempesta MS. Can a concentrated cranberry extract prevent recurrent urinary tract infections in women? A pilot study. Phytomed. 2007;14:237-241.
- Zhang L, Ma J, Pan K, Go VLW, Chen J, You W. Efficacy of Cranberry Juice on Helicobacter pylori Infection: a Double-Blind, Randomized Placebo-Controlled Trial. Helicobacter. 2005;10(2):139-145.
- Di Martino P, Agniel R, David K, et al. Reduction of Escherichia coli adherence to uroepithelial bladder cells after consumption of cranberryjuice: a double-blind randomized placebo-controlled cross-over trial. World J Urol. 2006;24:21–27.
- McMurdo MET, Bissett, LY, Price RJG, Phillips G, Crombie IK. Does ingestion of cranberry juice reduce symptomatic urinary tract infections in older people in hospital? A double-blind, placebocontrolled trial. Age and Ageing. 2005;34:256–261.
- Greenberg JA, Newmann SJ, Howell AB. Consumption of sweetened dried cranberries versus unsweetened raisins for inhibition of uropathogenic Escherichia coli adhesion in human urine: a pilot study. J Altern Complement Med. October 2005;11(5):875-878.
- Papas P, Brusch C, Ceresia GC. Cranberry juice in the treatment of urinary tract infection. Southwest Med J. 1966;47(1):17–20.
- Rogers J. Clinical: Pass the cranberry juice. Nursing Times. 1991;27(87):36–37.
- Avorn J, Monane M, Gurwitz J, et al. Reduction of bacteriuria and pyuria after ingestion of cranberry juice. JAMA. 1994;271(1):751–754.
- Haverkorn M, Mandigers J. Reduction of bacteriuria and pyuria using cranberry juice [letter]. JAMA. 1994;272(8):590.
- Jackson B, Hicks L. Effect of cranberry juice on urinary pH in older adults. Home Healthcare Nurse. 1997;15(3):198–202.
- Schultz A. Efficacy of cranberry juice and ascorbic acid in acidifying the urine in multiple sclerosis subjects. J Community Health Nursing. 1984a;1(3):139–169.
- Kinney A, Blount M. Effect of cranberry juice on urinary pH. Nursing Res. 1979;28(5):287–290.
- Nickey KE. Urinary pH: effect of prescribed regimes of cranberry juice and ascorbic acid [Academy/Congress Abstracts]. Arch Phys Med Rehabil. 1975;56:556.
- Fellers C, Redmon B, Parrott E. Effect of cranberries on urinary acidity and blood alkali reserve. J Nutrition. 1933;6(5):455-463.
- Bodel P, Cotran R, Kass E. Cranberry juice and the antibacterial action of hippuric acid. J Lab Clin Med. 1959;54:881–888.
- Light I, Gursel E, Zinnser HH. Urinary ionized calcium in urolithiasis. Effect of cranberry juice. Urology. 1973;1(1):67–70.
- Kahn DH, Panariello VA, Saeli J, Sampson JR, Schwartz E. Effect of cranberry juice on urine. J Am Dietetic Assoc. 1967;51(3):251-254.
- Gupta K, Chou MY, Howell A, et al. Cranberry products inhibit adherence of P-fimbriated Escherichia coli to primary cultured bladder and vaginal epithelial cells. J Urol. June 2007;177, 2357-2360.
- Sobota AE. Inhibition of bacterial adherence by cranberry juice: potential use for the treatment of urinary tract infections. J Urol. May 1984;131:563-568.
- Schmidt DR, Sobota AE. An examination of the anti-adherence activity of cranberry juice on urinary and nonurinary bacterial isolates. Microbios. 1988;55:173-181.
- Ahuja S, Kaack B, Roberts J. Loss of fimbrial adhesion with the addition of Vaccinum [sic] macrocarpon to the growth medium of Pfimbriated Escherichia coli. J Urol. February 1998;159:559-562.
- Zafriri D, Ofek I, Adar R, Pocino M, Sharon N. Inhibitory activity of cranberry juice on adherence of type 1 and type P fimbriated Escherichia coli to eukaryotic cells. Antimicrob Agents Chemother. January 1989;33(1):92-98.
- Suvarna R, Pirmohamed M, Henderson L. Possible interaction between warfarin and cranberry juice. BMJ. 2003;327(7429):1454.
- Commission on Safety of Medicines. Possible interaction between warfarin and cranberry juice. Curr Prob Pharmacovigil. 2003;29:8.
- Commission on Safety of Medicines. Possible interaction between warfarin and cranberry juice. Curr Prob Pharmacovigil. 2004;30:10.
- Grant P. Warfarin and cranberry juice: an interaction? J Heart Valve Dis. 2004;13:25-26. Cited by: Aston JL, Lodolce AE, Shapiro NL. Interaction between warfarin and cranberry juice. Pharmacotherapy. 2006;26(9):1314-1319.
- Rindone JP, Murphy TW. Warfarin-cranberry juice interaction resulting in profound hypoprothrombinemia and bleeding. Am J Ther. 2006:13(3):283-284. Cited by: Aston JL, Lodolce AE, Shapiro NL. Interaction between warfarin and cranberry juice. Pharmacotherapy. 2006;26(9):1314-1319.
- Aston JL, Lodolce AE, Shapiro NL. Interaction between warfarin and cranberry juice. Pharmacotherapy. 2006;26(9):1314-1319.
- Brinker F. Herb Contraindications and Drug Interactions. 3rd ed. Sandy, OR: Eclectic Medical Publications; 2001. Online Updates at: http://www.eclecticherb.com/emp/updatesHCDI.html.
- Greenblatt DJ. Cranberry juice & warfarin: Is there an interaction? Anticoagulation Forum Newsletter 2006;10(1):1, 3. Cited by: Bussey HI. Warfarin - Cranberry Juice Interaction: Expert Finds Data Lacking. Clotcare Online Resource. Available at: http://www.clotcare.com/ clotcare/warfarincranberryjuice.aspx. Accessed September 17, 2007.
- 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. January 2006;79:125–133.
- Karg PJ. All bogged down: Record cranberry crops, soft markets force industry to eye marketing order. Available at: http://www.rurdev.usda. gov/rbs/pub/may01/allbog.htm. Accessed February 23, 2005.
- Kasang L. Health and Wellness with Cranberries. Nutraceuticals Now. Summer 2001. Available at: http://www.nutraceuticalsnow.com/issues/ back/2001summer/cranberries.php. Accessed February 23, 2005.