Concord and Niagara Grape Juice and Their Phenolics Modify Intestinal Glucose Transport in a Coupled in Vitro Digestion/Caco 2 Human Intestinal Model
While the potential of dietary phenolics to mitigate glycemic response has been proposed, the translation of these effects to phenolic rich foods such as 100% grape juice (GJ) remains unclear. Initial in vitro screening of GJ phenolic extracts from American grape varieties (V. labrusca; Niagara and Concord) suggested limited inhibitory capacity for amylase and a glucosidase (6.2% 11.5% inhibition; p 0.05) Separately, all GJ extracts (10 100 uM total phenolics) did reduce intestinal trans epithelial transport of deuterated glucose (d7 glu) and fructose (d7 fru) by Caco 2 monolayers in a dose dependent fashion, with 60 min d7 glu/d7 fru transport reduced 10% 38% by GJ extracts compared to control. To expand on these findings by assessing the ability of 100% GJ to modify starch digestion and glucose transport from a model starch rich meal, 100% Niagara and Concord GJ samples were combined with a starch rich model meal (1:1 and 1:2 wt:wt) and glucose release and transport were assessed in a coupled in vitro digestion/Caco 2 cell model. Digestive release of glucose from the starch model meal was decreased when digested in the presence of GJs (5.9% 15% relative to sugar matched control) Furthermore, transport of d7 glu was reduced 10% 38% by digesta containing bioaccessible phenolics from Concord and Niagara GJ compared to control. These data suggest that phenolics present in 100% GJ may alter absorption of monosaccharides naturally present in 100% GJ and may potentially alter glycemic response if consumed with a starch rich meal.
Nutrients