Abstract
Sucrase‐isomaltase (Si) and maltase‐glucoamylase (Mgam) are mucosal glucosidases required for digestion of starch to glucose. Ablation of maltase‐Mgam reduces in vivo starch digestion.
Aim
Test whether slowly digestible starch diets induce changes in glucosidase activities.
Methods
Rice starch was encapsulated in alginate microspheres to target small intestinal sites of starch digestion. Three groups of eight 8‐wk old mice were given a maize 13C‐starch test feed. Then they were fed rice maltodextrin, 0.5% rice starch microspheres, or 1% rice starch microspheres diets for 7 d, and a second maize 13C‐starch test feed. Blood 13C‐glucose produced from fed maize 13C‐starch was measured by GC‐MS. Activities of sucrase, maltase, and glucoamylase were measured by Dahlqvist assays.
Results
Absorption of glucose from 13C‐starch was suppressed by feeding slowly digestible starch diets (ANOVA 0.000). Correlation was found between jejunal Si and Mgam activities and glucose absorption from 13C‐starch (R2 0.64, 0.67). Jejunal Si and Mgam activities were correlated (R2 0.74).
Conclusions
1. Slowly digestible starch diets down‐regulate jejunal Mgam and Si activities. 2. Negative feedback on Si and Mgam activities regulates subsequent absorption of glucose from starch.
Grant Funding Source: internal funding