Cranberry produces a certain class of molecules known as flavonoids, substances that have been investigated for their nutritional benefits and antibacterial activity. Studies have shown that the particular flavonoids produced by the cranberry have a strong antibacterial effect. Cranberry juice has been used for years and recommended by many doctors for patients with recurrent urinary tract infections. Cranberries contain a type of flavonoid that is capable of defeating the bacteria that cause urinary tract infections, and this flavonoid is attached to a sugar that seeks out the cells that line the urinary tract. Cranberry is great for urinary tract infections and kidney stones.