Quercetin　is　a　well-studied　natural　product　with　multiple　pharmacological　properties.　In　this　study,　we　demonstrated　that　quercetin　suppressed　protein　digestion　in　the　intestinal　fluid　by　inhibiting　trypsin,　a　key　digestive　enzyme.　However,　we　also　observed　a　previously　unknown　property　of　quercetin:　promoting　the　intestinal　absorption　of　proteins.　In　addition,　the　promoted　protein　absorption　was　mediated　by　internalization　of　digested　oligopeptides　in　the　intestinal　epithelia　rather　than　increasing　the　intestinal　paracellular　permeability.　Notably,　four　other　flavonoids　also　achieved　such　enhanced　intestinal　absorption,　suggesting　that　this　effect　was　associated　with　the　aglycone　flavonol　backbone,　but　not　related　to　their　inhibitory　potencies　against　trypsin.　This　study　demonstrates　that　quercetin　exhibits　dual　effects　on　protein　digestion　and　absorption:　1)　suppressing　protein　digestion　by　inhibiting　trypsin　in　the　intestinal　fluid;　2)　promoting　the　intestinal　absorption　of　oligopeptides　in　the　intestinal　villi　cells.