Many people swear by cranberry juice as the natural remedy to fight off urinary tract infections, also known as UTIs. Curious to see if the folklore held up, researchers at the Worcester Polytechnic Institute and University of Massachusetts Dartmouth set out to find out what makes it so good for UTIs.
They broke down the juice into various chemical compounds and exposed a strain of E. coli, the most common cause of UTIs, to these compounds.
E. coli cause UTIs by sticking to epithelial cells that line the urinary tract and multiplying into a biofilm, said Dr. Terri Camesano, professor of chemical engineering at WPI. Biofilms are communities of bacteria that form thin layers on surfaces. Sometimes, biofilm formation is necessary for infection.
Her team used atomic force microscopy to measure E. coli’s adhesive properties in the presence of various cranberry juice compounds. An atomic force microscope measures nano forces on the surfaces of cells or molecules and relays that data to a computer.
When researchers exposed E. coli to compounds called flavonols, the adhesive forces on the surface of the bacteria were significantly weakened, according to the study published in May in the journal Food & Function.
“If bacteria are not able to attach, that makes it hard for them to cause infection,” said Camesano.
The relationship between cranberry juice and urinary tract health is uncertain – some studies find scant evidence that cranberry juice affects infection. Other studies find links between cranberry juice and urinary tract health in the form of either preventing UTI recurrence or changing the ability of E. coli to adhere to other cells.
Camesano said she would continue to work further on cranberry juice research to understand what molecules have anti-adhesive effects in order to make more concentrated dosages to prevent infection. The group’s work was funded by the Cranberry Institute, a trade group that supports the cranberry food production industry.
NOTE: This story was updated to reflect the Cranberry Institute as the source of funding and alternative findings for the role of cranberry juice in urinary tract health.