Consumption of cranberry fruits or juice rich in polyphenols is associated with a wide range of potential health benefits. We and others have previously showed that cranberry juice concentrate and its phytochemicals, flavonols, anthocyanins and A-type proanthocyandins, may have potential to be chemopreventive agents. Although a number of cranberry constituents have been implicated in cancer prevention, our understanding about which metabolites are bio-available to reach target sites and thereby elicit cancer chemopreventive properties is still lacking. However, poor plasma bioavailability of cranberry constituents may be overcome by their potential interactions with gut microbiota by providing cancer prevention through induction of compositional and functional modifications of gut microbiota. Well-designed clinical trials evaluating metabolic and gut microbiome changes associated with cranberry consumption would provide useful information about the cancer patient's response to dietary intervention with cranberry constituents.