People once thought the acidity of cranberry juice was what prevented and relieved UTI infections. Additional research shows that proanthocyanidins (PACs), one of the primary antioxidants found in cranberries, are the actual heroes. These PACs pack a punch, by changing the surface properties of E. coli bacteria (one of the main causes of UTI's and inhibit their ability to adhere to cells in the urinary tract).[1],[2],[3]