Urinary Tract Infection (UTI) is a common ailment estimated to affect about 60% of women over their lifetime, with a third of them likely to get recurrent infections. Cranberries have been used widely for several decades as a traditional remedy for the prevention and treatment of urinary tract infections (UTIs).
Is the popularity of this traditional remedy justified?
Some scientists have hypothesized that cranberries make the urine more acidic, which makes it inhospitable to bacteria like Escherichia coli (E.coli) which is one of the major causes of urinary tract infections. The main suggestion is that cranberries prevent bacteria (particularly E.coli) from adhering (sticking) to uroepithelial cells that line the wall of the bladder. Without adhesion, E.coli cannot infect the mucosal surface of the urinary tract. Studies have also shown how cranberry materials restrict the movement of P.mirabilis bacteria (commonly found in UTI) and reduce the production of an enzyme by the bacteria that helps the infection to spread [1,2].
However, opinions based on clinical studies on this subject seem to be divided.
Treatment of UTI
Jepson RG and Craig JC, in their 1998 review to assess the effectiveness of cranberries in the treatment of UTIs, conclude that “There is no evidence to suggest that cranberry juice or other cranberry products are effective in treating UTIs” .
Prevention of UTI
Yes, Cranberries Are Useful For Preventing Recurrence of Urinary Tract Infections
In 2001, a research team led by Assistant Professor Kontiokari T and Sundqvist K conducted a study to determine whether recurrences of urinary tract infection can be prevented with cranberry-lingonberry juice. They concluded that “Consumption of 50 ml of cranberry-lingonberry juice concentrate daily reduced recurrences of symptomatic urinary tract infection by about half compared with the control group. Self treatment with cranberry juice may reduce the need for antimicrobials for recurrent urinary tract infection” .
Jepson RG and Craig JC, in their 2008 review to assess the effectiveness of cranberries in the prevention of UTIs in susceptible populations, claimed that “There is some evidence that cranberry juice may decrease the number of symptomatic UTIs over a 12 month period, particularly for women with recurrent UTIs. It’s effectiveness for other groups is less certain” .
No, Cranberries Are Not Useful For Prevention of Recurrent Urinary Tract Infections
A 2011 study conducted by Barbosa-Cesnik and team concluded that “Among otherwise healthy college women with an acute UTI, those drinking 8 oz of 27% cranberry juice twice daily did not experience a decrease in the 6-month incidence of a second UTI, compared with those drinking a placebo” .
Jepson RG and Craig JC, in a 2012 update to their 2008 review, concluded that “Prior to the current update it appeared there was some evidence that cranberry juice may decrease the number of symptomatic UTIs over a 12 month period, particularly for women with recurrent UTIs. The addition of 14 further studies suggests that cranberry juice is less effective than previously indicated. Although some of small studies demonstrated a small benefit for women with recurrent UTIs, there were no statistically significant differences when the results of a much larger study were included. Given the evidence that the benefit for preventing UTI is small, cranberry juice cannot currently be recommended for the prevention of UTIs” .
Cranberries have properties that might be beneficial in preventing and treating UTI. However, thus far, these properties have not shown up conclusively in clinical studies. Could a higher dosage work better (does 50 ml contain sufficient amount of beneficial elements)? Can the nature of intake (whole cranberry fruit, juice, concentrated powder) make a difference? Can the frequency and duration of intake impact the results (how many times a day and for how many weeks or months on continuous basis)? These questions will hopefully be answered by future studies.
Till we get more conclusive evidence to the contrary, it is probably best to assume that we cannot count on cranberry juice to solve our UTI problems – but including cranberries in your daily diet is not going to hurt either.
Hidalgo, Gabriela, Michelle Chan, and Nathalie Tufenkji. “Inhibition of Escherichia coli CFT073 fliC expression and motility by cranberry materials.” Applied and environmental microbiology 77.19 (2011): 6852-6857.
McCall, Jennifer, et al. “Cranberry impairs selected behaviors essential for virulence in Proteus mirabilis HI4320.” Canadian journal of microbiology 59.6 (2013): 430-436.
Jepson, Ruth G., Lara Mihaljevic, and Jonathan C. Craig. “Cranberries for treating urinary tract infections.” The Cochrane Library (1998).
Kontiokari, Tero, et al. “Randomised trial of cranberry-lingonberry juice and Lactobacillus GG drink for the prevention of urinary tract infections in women.” Bmj 322.7302 (2001): 1571.
Jepson, Ruth G., and Jonathan C. Craig. “Cranberries for preventing urinary tract infections.” Cochrane Database Syst Rev 1 (2008).
Barbosa-Cesnik, Cibele, et al. “Cranberry juice fails to prevent recurrent urinary tract infection: results from a randomized placebo-controlled trial.” Clinical infectious diseases 52.1 (2011): 23-30.
Jepson, Ruth G., and Jonathan C. Craig. “Cranberries for preventing urinary tract infections.” Cochrane Database Syst Rev 1 (2012).
Edited By: Vivek Chhetri