title: In vitro digestion and lactase treatment influence uptake of quercetin and quercetin glucoside by the Caco-2 cell monolayer.
abstract: BACKGROUND
  Quercetin and quercetin glycosides are widely consumed flavonoids found in many fruits and vegetables. These compounds have a wide range of potential health benefits, and understanding the bioavailability of flavonoids from foods is becoming increasingly important.
  
  
  METHODS
  This study combined an in vitro digestion, a lactase treatment and the Caco-2 cell model to examine quercetin and quercetin glucoside uptake from shallot and apple homogenates.
  
  
  RESULTS
  The in vitro digestion alone significantly decreased quercetin aglycone recovery from the shallot digestate (p < 0.05), but had no significant effect on quercetin-3-glucoside recovery (p > 0.05). Digestion increased the Caco-2 cell uptake of shallot quercetin-4'-glucoside by 2-fold when compared to the non-digested shallot. Despite the loss of quercetin from the digested shallot, the bioavailability of quercetin aglycone to the Caco-2 cells was the same in both the digested and non-digested shallot. Treatment with lactase increased quercetin recovery from the shallot digestate nearly 10-fold and decreased quercetin-4'-glucoside recovery by more than 100-fold (p < 0.05), but had no effect on quercetin recovery from apple digestates. Lactase treatment also increased shallot quercetin bioavailability to the Caco-2 cells approximately 14-fold, and decreased shallot quercetin-4'-glucoside bioavailability 23-fold (p < 0.05). These Caco-2 cells had lactase activity similar to that expressed by a lactose intolerant human.
  
  
  CONCLUSIONS
  The increase in quercetin uptake following treatment with lactase suggests that dietary supplementation with lactase may increase quercetin bioavailability in lactose intolerant humans. Combining the digestion, the lactase treatment and the Caco-2 cell culture model may provide a reliable in vitro model for examining flavonoid glucoside bioavailability from foods.
authors.affiliation: Department of Animal Science, Cornell University, Ithaca, New York 14853-7201, USA. JDB42@cornell.edu
authors.forename: Jeanelle
authors.initials: J
authors.lastname: Boyer
authors.forename: Dan
authors.initials: D
authors.lastname: Brown
authors.forename: Rui Hai
authors.initials: RH
authors.lastname: Liu
mesh_terms: D000818:Animals; D018938:Caco-2 Cells; D002851:Chromatography, High Pressure Liquid; D004063:Digestion; D005638:Fruit / Q000737:chemistry; D005960:Glucosides / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D043322:Lactase / Q000378:metabolism*; D027845:Malus / Q000737:chemistry; D019697:Onions / Q000737:chemistry; D010434:Pepsin A / Q000378:metabolism; D011794:Quercetin / Q000031:analogs & derivatives / Q000378:metabolism*; D027781:Shallots / Q000737:chemistry; D013552:Swine
chemical_list: D005960:Glucosides; C016527:isoquercitrin; D011794:Quercetin; D043322:Lactase; D010434:Pepsin A; C080613:spiraeoside