There were significant differences between chemical characteristics of ribose (Rib)-, glucose (Glc)-, and fructose (Fru)-lysine (Lys) Maillard reaction products (MRPs). Rib was the most reactive sugar and exerted the greatest change in Maillard-reaction (MR), followed by Glc and Fru in the sugar-Lys model. All three sugar-Lys MRPs not only exhibited strong free radical scavenging activity in chemical systems, but also protected intestinal Caco-2 cells from injury caused by oxidants and transition metal ions. Different chemical characteristics of MRPs generated by the three sugars could not be...