Urinary tract infections, or UTIs, are common bacterial infections that in some cases cause distressful symptoms like the frequent urge to urinate, pain during urination and fatigue. Some evidence suggests that cranberry juice prevents UTIs in women, but results from a recent controlled clinical trial suggest otherwise. The conflicting evidence for the efficacy of cranberry products in the treatment of UTIs likely results from not using a standardized cranberry product in clinical trials.
Mechanism
Cranberry juice and supplements contain proanthocyanidins, which prevent the adherence of bacteria to cells of the urinary tract. A study in the "Journal of Urology" found that 15 of 22 subjects given 15 oz. of cranberry juice had a significant decrease in bacterial adherence one to three hours after juice consumption.
UTIs in Women
A review of 10 clinical trials in the January 2008 issue of the "Cochrane Database of Systematic Reviews" concludes that cranberry products significantly reduce the recurrence of UTIs in women with recurrent infections. Results from a clinical trial reported in the January 2011 issue of "Clinical Infectious Diseases" suggest cranberry juice does not significantly decrease the incidence of recurrent UTIs in healthy college women.
UITs in Other Groups
A review in a 2009 issue of the journal "Drugs" notes that there is little evidence that cranberry products are effective in treating UTIs in the elderly, people with neurogenic bladder or children. Neurogenic bladder is a disorder that develops in some people with spinal cord diseases or injuries and causes difficulty in passing urine without the aid of a catheter.
Adverse Effects
A review in the January 2008 issue of "Alternative Medicine Review" notes that 400 pregnant women who were surveyed after taking cranberry products did not report any adverse events. However, the review in "Drugs" reports that in some people cranberry products cause gastrointestinal problems and weight gain, which is likely attributed to the sugar content in the juice. Cranberries do contain a high concentration of oxalic acid. This compound can increase the formation of kidney stones. A study in a 2001 issue of "Urology" reports that healthy volunteers who were administered cranberry supplements for 7 days had increased oxalates in their urine. Further investigation is necessary to determine if cranberry juice increases kidney stone formation. There is one positive and one negative report that cranberry juice affects that activity of the blood-thinner, warfarin.
References
- "Clinical Infectious Diseases"; Cranberry Juice Fails to Prevent Recurrent Urinary Tract Infection: Results from a Randomized Placebo-Controlled Trial; C. Barbosa-Cesnik et al.; January 2011
- PubMed: Cranberries for Preventing Urinary Tract Infections
- "Alternative Medicine Review"; Natural Approaches to Prevention and Treatment of Infections of the Lower Urinary Tract; K.A. Head; September 2008
- PubMed: Cranberry and Urinary Tract Infections
