New insights suggest isomaltooligosaccharides are slowly digestible carbohydrates, rather than dietary fibers, at constitutive mammalian α-glucosidase levels

Isomaltooligosaccharides (IMOs) have been characterized as dietary fibers that resist digestion in the small intestine; however, previous studies suggested that various alpha-glycosidic linkages in IMOs were hydrolyzed by mammalian alpha-glucosidases. This study investigated the hydrolysis of IMOs by small intestinal alpha-glucosidases from rat and human recombinant sucrase-isomaltase complex compared to commonly used fungal amyloglucosidase (AMG) in vitro. Interestingly, mammalian alpha-glucosidases fully hydrolyzed various IMOs to glucose at a slow rate compared with linear maltooligosaccharides, whereas AMG could not fully hydrolyze IMOs because of its very low hydrolytic activity on alpha-1,6 linkages. This suggests that IMOs have been misjudged as prebiotic ingredients that bypass the small intestine due to the nature of the assay used. Instead, IMOs can be applied in the food industry as slowly digestible materials to regulate the glycemic response and energy delivery in the mammalian digestive system, rather than as dietary fibers.

Automated summary

This study found that mammalian alpha-glucosidases fully hydrolyzed Isomaltooligosaccharides (IMOs) to glucose, although at a slow rate, while AMG could not fully hydrolyze IMOs due to its very low hydrolytic activity on alpha-1,6 linkages.