Abstract
Flavonoids are present in various plant foods such as vegetables, fruits and beverages. Flavonoids are known as powerful antioxidants and have attracted much attention to their potential role in the prevention of various diseases. In plant foods, most flavonoids exist as glycosides and/or acidic forms, and the type of a sugar moiety is a major determinant of the intestinal absorption. In the gastrointestinal tract, dietary flavonoids are mainly absorbed as their aglycone forms by simple diffusion, whereas there are some kind of membrane transporters that may work for cellular influx of certain flavonoids. The predominant circulating molecules after an oral consumption are conjugative metabolites because flavonoids undergo extensive intestinal and hepatic glucuronidation and sulfation. ABC transporters have been shown to serve for the cellular efflux of flavonoid metabolites. This review will summarize the current literatures regarding on the transport mechanism of dietary flavonoids and their conjugative metabolites.
