How Cranberries Help Urinary Tract Infections, New Discoveries
You’ve been told that cranberries help fight urinary tract infections, but exactly how these little fruits work has not been fully understood. Now new discoveries from two studies add important information about cranberries and their impact on urinary tract and other types of infections.
What’s new about cranberries?
For many years, the common explanation about how cranberries help prevent development of urinary tract infections (UTIs) has been that specific phytochemicals called proanthocyanidins (PACs) stopped the bacteria associated with UTIs from attaching themselves to the walls of the urinary tract. But there appears to be more to the story.
Professor Nathalie Tufenkji, of McGill University’s Department of Chemical Engineering, and her colleagues conducted two studies that have enhanced our understanding of the role of cranberries in preventing UTIs and other infections. Here’s what they found:
- Cranberry powder can interfere with the swimming activity of bacteria called Proteus mirabilis, which are often involved in complicated UTIs. Understanding such movement is significant because it helps explain how the infections spread
- Higher concentrations of cranberry powder are better able to reduce the ability of the bacteria to produce an enzyme (urease) that raises the virulence of infections
- Derivatives of cranberry may be helpful in stopping the spread of bacteria associated with implantable medical devices such as catheters, which are commonly involved in causing UTIs
In previous work performed at McGill, the researchers found that cranberry has the ability to interfere with the movement of other bacteria associated with UTIs, such as E. coli, which is the organism implicated in most UTIs, especially in younger women.
Tufenkji noted that their findings are important because they “highlight the role that cranberry consumption might play in the prevention of chronic infections.” In fact, 25 to 50 percent of women who have had an uncomplicated urinary tract infection can expect to experience another infection within one year, while up to 5 percent of women have recurring UTIs.
Previous research has suggested cranberry juice is beneficial for the heart and that it may also stop staph infections. Cranberry juice is sometimes included as part of a detox program because it is high in vitamin C, manganese, and antioxidants.
Conventional treatment of urinary tract infections
Currently, the basic conventional treatment for urinary tract infections is a course of antibiotics, typically nitrofurantoin or trimethoprim-sulfamethoxazole (TMP-SMX). Nitrofurantoin frequently causes upset stomach and interacts with many other medications. TMP-SMX resistance is a growing problem, and it cannot be used by anyone allergic to sulfa drugs. It also can interfere with contraceptives.
Ciprofloxacin or other fluoroquinolones may be prescribed when these choices are ineffective or cannot be tolerated. Fluoroquinolones are associated with significant gastrointestinal side effects, such as diarrhea, stomach pain, nausea, and vomiting.
More than 150 million cases of urinary tract infections are reported around the world each year, the majority of which occur in women. Any research that furthers current knowledge about effective treatments for UTIs, including natural remedies such as cranberries, is sure to be welcomed by millions of people around the world.
Chan M et al. Inhibition of bacterial motility and spreading via release of cranberry derived materials from silicone substrates. Colloids and Surfaces. B Biointerfaces 2013 Oct 1; 110:275-80
McCall J et al. Cranberry impairs selected behaviors essential for virulence in Proteus mirabilis HI4320. Canadian Journal of Microbiology 2013 Jun; 59(6): 430-36
University of Maryland Medical Center