It’s not the acidity of cranberry juice that prevent urinary track infections and cystitis, it’s natural chemicals in the tarty juice that prevent pathogenic bacteria from adhering to the cells that line the urinary tract. That’s according to research in the Journal of Medicinal Food.
Urinary tract infections (UTIs) cost $2b annually in the US and are a major burden on healthcare systems. They are common in patients with a urinary catheter in place, but some people are also more susceptible to such infections than others, particularly after sexual activity, although the infections are rarely sexually transmitted in nature.
Adhesion of Escherichia coli bacteria (which live in the lower gut) to cells lining the urinary tract is the first step in the development of a UTI. Chemicals found in cranberry products called proanthocyanidins (PACs) prevent this microbe from adhering to these urinary tract epithelial cells by affecting the surface properties of the bacteria.
Paola Pinzón-Arango, Yatao Liu, and Terri Camesano, from Worcester Polytechnic Institute, in Massachusetts, exposed E. coli grown in culture to either light cranberry juice cocktail or cranberry PACs and measured the adhesion forces between the bacteria and a silicon surface using atomic force microscopy. They demonstrated that the longer the bacteria were exposed to either the cranberry juice or the PACS the less able were the bacteria to adhere.
Cranberries, one of only three species of fruits native to North America, have a long history of medicinal food use. Native Americans used the fruit for the treatment of bladder and kidney ailments.