Hypocholesterolemic and hypoglycemic effects of enzymatically modified carbohydrates from rice in high-fat-fed C57BL/6J mice

Scope: Enzymatically modified rice starch (ERS) synthesized with 4-a-glucanotransferase has a longer structure than rice starch, which could delay digestion, similar to dietary fiber. We investigated the effects of ERS on glucose and lipid metabolism with mice fed a high-fat diet containing ERS (HFD-ERS). Method and results: Four weeks of ERS feeding showed hypoglycemic effects with a significant reduction in fasting glucose (46%), insulin (57%), and leptin (83%) levels; improved glucose tolerance (20% in AUC of oral glucose tolerance test); and increased adiponectin concentrations (127%) compared to the HFD group. Notably, phosphorylation of AMP kinase (AMPK) was markedly induced in the HFD-ERS livers compared to HFD livers. Additionally, ERS significantly reduced total cholesterol concentrations with induction of fecal bile acid excretion (121%, Po0.05) in the HFD-ERS group compared to the HFD group. The mRNA and protein expressions of hepatic LDL receptors were significantly induced. However, cholesterol 7 alpha-hydroxylase (CYP7A1) expression was downregulated possibly due to induction of intestinal farnesoid X receptor (FXR; 12.4-fold, po0.05) and fibroblast growth factor-15 (FGF-15; 12.2-fold, po0.01). Conclusion: Our data suggest that ERS feeding may have hypoglycemic and hypocholesterolemic effects via a mechanism similar to that of dietary fiber.