Native Americans were the first to use cranberry as a treatment for bladder and kidney ailments. In addition to traditional usage, cranberry has a long history of scientific research studying its benefits on the urinary tract.

Cranberry supports the health of the urinary tract by inhibiting the adhesion of bacteria to the epithelial lining of the urethra, which is typically how bacteria enter the urinary tract. One of the primary beneficial compounds in cranberries are proanthocyandins (PACs), they help protect against bacteria by collecting in the urine relatively intact and also by binding to pathogenic bacteria from the colon and decreasing their harmfulness (1).

Cranberry supports the health of the urinary tract by inhibiting the adhesion of E. coli to the epithelial cell lining of the urethra. One study found that cranberry extract can reduce the ability of E.coli to adhere to the urinary epithelial cells by roughly 50% (2).

A dose dependent study found that women given 500 mg cranberry extract standardized to 1.5% PACs reduced urinary E. coli adherence by 36%. Women given 1000 mg daily showed even further reduction of E. coli at 65% (3).

Science has established that proanthocyanidins (PACs) in cranberries are important inhibitors of E.coli. A study looked at varying doses of PACs and found that there was a significant dose-dependent reduction in the bacterial adherence to human epithelial cells 24 hours after ingestion compared to placebo. The study participants were given doses of PACs ranging from 0 to 72 mg (4).

A second study had similar findings. Participants who consumed 108 mg of cranberry in capsule form, had a significant decrease in bacterial adherence to human uroepithelial cells 12 hours after consumption when compared with placebo (5).