BACKGROUND: Several epidemiological studies and intervention trials have demonstrated that grapes and blueberries, which are rich in flavanols, can lower the risk of cardiovascular disease. However, the mechanisms of action of these compounds remain unclear due to their low bioavailability. OBJECTIVE: This study aimed to characterize the sensory properties, blood flow velocity, and oxidative stress of a polyphenol rich grape and blueberry extract (PEGB) containing approximately 16% flavanols (11% monomers and 4% dimers). METHOD: A sensory property of PEGB was compared with quercetin at uniform concentration using healthy young subjects. In addition, the reactivity of PEGB with O RESULTS: At a concentration where quercetin was barely tasteful, flavanol in PEGB exhibited a robust astringent taste. Furthermore, under pH conditions mimicking the oral cavity and intestinal tract, PEGB promoted O CONCLUSION: The results demonstrate that PEGB exhibited a pronounced astringent taste, O