The US-based Worcester Polytechnic Institute (WPI) found that the little hooks which E. coli use to affix themselves to the lining of the urinary tract are susceptible to cranberry juice exposure, and lose their ability to attach effectively with extended exposure. This makes them more likely to be swept away with the passage of urine in the urinary tract. Furthermore their ability to attach was found to be directly related to the concentration of cranberry juice in the urine.
The bottom line: YES! Add cranberry juice to your regular diet but make sure it's the SUGAR FREE kind.