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Can Cranberry Juice Prevent UTIs?
February 16, 2009
What is a Urinary Tract Infection?
Frequent urination? Check. Burning during urination? Check. Feeling as if you’re unable to hold your urine? Check. Cloudy, foul- smelling urine? Check. Passing a very small amount of urine despite the urgency to use the restroom? Check. These symptoms, along with mild fever, fatigue, and lower abdominal pain, constitute a urinary tract infection. A urinary tract infection, or UTI, is a bacterial infection affecting any part of the urinary tract, which consists of the kidneys, ureters, bladder, and urethra. Bacteria found around the vagina and in the digestive system may enter the urinary tract and cause the infection, but most commonly it is caused by the bacteria found around the rectum, Escherichia coli (E. coli). UTIs can affect both men and women; however, because men have a longer urethra than women, it is more difficult for bacteria to enter a man’s bladder, and therefore UTIs are far less common in men than in women (http://www.hmc.psu.edu/healthinfo/uz/uti.htm). Additionally, it is estimated that 20% of women will develop a UTI in a lifetime. Although UTIs can be easily and quickly treated with antibacterial drugs, those affected are very likely to develop another UTI at some point. Because of this, UTI prevention strategies are especially valuable to women worldwide.
UTI Prevention Strategies
Doctors nationwide can agree on many UTI prevention strategies for women. These include: drinking plenty of water daily, urinating once you feel the need to, wiping from front to back to avoid the spread of anal bacteria to the vagina, taking showers instead of baths, cleansing the genital area before sexual intercourse, avoiding the use of feminine cleansers, and wearing cotton underwear (http://www.hmc.psu.edu/healthinfo/uz/uti.htm). Another prevention strategy suggested is drinking cranberry juice (http://www.newsweek.com/id/107229). Many have tried this strategy without knowledge of whether or not cranberry juice is actually helpful. Through a number of scientific studies, the properties of cranberry juice have been analyzed in order to assess this claim.
Why Cranberries/ Cranberry Juice?
Cranberries (Vaccinium macrocarpon) are fruit native to North America and were used medicinally by Native Americans to treat kidney and bladder infections (Lynch, 2004). Continually, cranberries, specifically cranberry juice, have been used for the prevention of UTIs. In a study regarding this claim, Jepson and Craig (2007) found that the cranberry is 90% water and also consists of three acids—quinic acid, malic acid, and citric acid. It was initially suggested that the prevention of UTIs derived from the excretion if hippuric acid (from the quinic acid) into the urine, acidifying the urine, and having an antibacterial effect. However, several trials of this study disproved that theory; the trials showed that there was little to no difference in levels of hippuric acid in the urine of those that had and had not consumed cranberry juice. It is currently suggested that cranberry juice contains compounds that prevent bacteria from attaching itself to the cells lining the urinary tract, and thus prevent a UTI. Jepson and Craig (2007) identified these compounds as fructose and proanthocyanidins, which are also found in other fruits of the Vaccinium family.
Fructose and Proanthocyanidins in the Prevention of UTIs
Fructose is a simple sugar found in many fruits that the body uses for energy (http://en.wikipedia.org/wiki/Fructose). Proanthocyanidins are tannins, compounds of organic structures called phenols, found naturally in cranberries (http://en.wikipedia.org/wiki/Proanthocyanidin). Jepson and Craig (2007) found that these compounds work by preventing the adhesion of two types of fimbriated E. coli, one that is sensitive to and one that is resistant to mannose, a sugar compound similar in structure to fructose and found naturally in cranberries, to cells lining the urinary tract. (Fimbria is an appendage used by bacteria for binding to host cells.) It has been found that fructose can hinder the adhesion of type 1 fimbriated (mannose- sensitive) E. coli. In a study regarding the Type 1 fimbriae on E. coli and the urinary tract, it was found that type 1 fimbriae promote adherence to mucosal surfaces and inflammatory cells, resulting in an enhanced inflammatory response to the UTI (Connell, Agace, Klemm, Schembri, Marild, and Svanbord, 1996). Proanthocyanidins can hinder the adherence of P- fimbriated (mannose- resistant) E. coli. In another study, it was found that P- fimbriae stimulate adherence to uroepithelial cells, cells that compose tissue that line the surface of the urinary tract, and that E. coli that contain P- fimbriae account for the majority of UTIs (Rice, Peng, Spence, Wang, Goldblum, Corthesy, and Nowicki, 2005). Without adhesion, the bacteria are unable to multiply and therefore, are unable to cause an infection.
Frimbriated E. coli
Prevention vs. Treatment
Studies show that it cranberry juice can indeed help prevent UTIs, especially in women who have had a UTI before. A study conducted by Kontiokari, Sundqvist, Nuutinen, Pokka, Koskela, and Uhari (2001) split up 150 women, all of whom had a UTI caused by E. coli, into three groups: one group receiving a cranberry- lingonberry juice (7.5 g cranberry and 1.7 g lingonberry in 50 mL of water) once a day for six months, one group receiving 100 mL of lactobacillus GG five days a week for one year, and the last group acting a control group. (Lingonberries belong to the same genus as cranberries, Vaccinium, and lactobacillus is a bacterium used in the production of many dairy foods products (http://en.wikipedia.org/wiki/Lactobacillus)). After six months, 16% of women in the cranberry- lingonberry group had another UTI, 39% of women in the lactobacillus group had another UTI, and 36% of women in the control group had another UTI. These results displayed a 20% reduction in absolute risk in the cranberry- lingonberry group compared to the control group. In another study, the dietary factors protecting women from urinary tract infections were investigated (Kontiokari, Laitinen, Jarvi, Pokka, Sundqvist, Uhari, 2003). One hundred and thirty- nine women, all of whom had a diagnosis for a UTI, were matched with 185 women, all of whom did nit have a diagnosis for a UTI. They were surveyed about their dietary habits, and it was found that a frequent consumption of fresh juices, especially berry juices, was associated with a decreased risk of recurrence of a UTI. In the study conducted by Jepson and Craig (2007), a number of studies concerning cranberry products and UTIs, from 1994 to 2005, were reviewed and summarized in order to gather evidence for the role of cranberries and blueberries (blueberries are also in the same genus as cranberries, Vaccinium) in UTI prevention. There were a total of 1011 participants, both men and women, young and old, and the studies tested cranberry juice cocktail, cranberry tablets, and placebo juices. A summary of the studies showed no results for blueberries, but suggested that cranberry products can be effective in preventing UTIs, especially in younger populations. Because it is proven that drinking cranberry juice can prevent a UTI, many assume that cranberry juice can also be used to treat a UTI. However, there is no evidence that cranberry juice can be used as treatment (http://www.newsweek.com/id/107229).
Types of Cranberry Juice and How Much
Studies have shown that most types of cranberry juice, including regular cranberry juice cocktail and sugar- free cranberry juice cocktail, as well as cranberries, are effective in the prevention of a UTI (http://www.sciencedaily.com/releases/2008/07/080721152005.htm). Studies have not been consistent with the type of cranberry juice used, but numerous studies have used cranberry juice with a 30% concentration of cranberries (http://www.newsweek.com/id/107229). It has been suggested that juices with higher concentrations of cranberry will have stronger results http://www.sciencedaily.com/releases/2008/07/080721152005.htm). Also, there have been no studies regarding a specific dose of cranberry juice in order to achieve prevention. However, it has been suggested to drink 8 ounces of pure, unsweetened cranberry juice three times daily (Lynch, 2004).
Because urinary tract infections are so common in women, it is very important that women know how to prevent it. It is suggested that cranberry juice contain compounds that hinder the adhesion of E. coli bacteria to the cells lining the urinary tract, thus preventing a urinary tract infection. Studies have proven this claim, showing a 20% reduction of UTI occurrence, especially women who have previously had a UTI. Along with other methods, such as drinking lots of water daily and urinating when you feel the urge, cranberry juice can be a natural and inexpensive method for UTI prevention. However, antibacterial drugs, rather than cranberry juice, should be used for the treatment of a UTI.
The websites that provided information about cranberry juice and urinary tract infections were news and information sources, whose sole purpose is to inform the public. The websites are in no way affiliated with any manufacturers of cranberry juice or with any cranberry juice products. The research studies that provided information about cranberry juice and urinary tract infections were also news and information sources, sponsored by various medical journals. Therefore, these sources are very trustworthy and should be considered valuable knowledge. Wikipedia was also used for very basic, general information so the information obtained from it may or may not be credible.
(2004). Urinary Tract Infections (UTI). from Penn State Hershey Web site: http://www.hmc.psu.edu/healthinfo/uz/uti.htm
Lynch, D. M. (2004).Cranberry for Prevention of Urinary Tract Infections. American Family Physician. 2175-77.
Jepson, R. G., & Craig, J. C. (2007). A systematic review of the evidence for cranberries and blueberries in UTI prevention. Moleculary Nutrition & Food Journal. 51, 738-45.
Fructose. from Wikipedia Web site: http://en.wikipedia.org/wiki/Fructose
Proanthocyanidin. from Wikipedia Web site: http://en.wikipedia.org/wiki/Proanthocyanidin
Connell, I, Agace, W, Klemm, P, Schembri, M, Marild, S, & Svanborg, C (1996). Type 1 fimbrial expression enhances Escherichia coli virulence for the urinary tract. 9827-32.
Rice, J. C., Peng, T, Spence, J. S., Wang, H, Goldblum, R. M., & Corthesy, B (2005). Pyelonephritic Escherichia coli Expressing P Fimbriae Decrease Immune Response of the Mouse Kidney. 16, 3583-91.
Kontiokari, T, Sundqvist, K, Nuutinen, M, Pokka, T, Koskela, M, & Uhari, M (2001). Randomised trial of cranberry-lingonberry juice and Lactobacillus GG drink for the prevention of urinary tract infections in women. 322, 1571-73.
Lactobacillus. from Wikipedia Web site: http://en.wikipedia.org/wiki/Lactobacillus
Kontiokari,, T, Laitinen, J, Järvi, L, Pokka, T, Sundqvist, K, & Uhari, M (2003). Dietary factors protecting women from urinary tract infection. 77, 600-04.
Springen, K (February 1, 2008). The Cranberry UTI Cure. from Newsweek Web site: http://www.newsweek.com/id/107229
(20008, July 25). How Cranberry Juice Can Prevent Urinary Tract Infections. from Science Daily Web site: http://www.sciencedaily.com/releases/2008/07/080721152005.htm
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