Food flavonols: Nutraceuticals with complex health benefits and functionalities

Background: Flavonols are one of the most promising class of bioactive compounds belonging to the broad family of the flavonoids, characterized by a unique set of features in their basic chemical skeleton and several specific substitutions in selected position of the rings A, B and C. This interesting class of phytochemicals includes compounds such as quercetin, kaempferol, myricetin, rhamnetin, morin, fisetin, galagin, azaleatin and their respective glycosyl derivatives. They have been identified in several foods and provide them great health benefits. Scope and approach: This review updates and integrates, in a critical fashion, the current knowledge on flavonols as food sources, chemical features, structure-activity relationships, bioavailability and health benefits (from preclinical and clinical studies), focusing on both in vitro and in vivo reports. Key findings and conclusions: Dietary flavonols are bioavailable molecules in human with impressive health benefits (such as antioxidation, cardioprotection, antibacterial, antiviral and anticancer activity) and the process of metabolization also produces compounds with remarkable bioactivities just like the corresponding precursors. Their inclusion into human diet is highly recommended for their unquestionable health promoting properties, being excellent nutraceuticals as well as ingredients for good functional food.