High-hydroxypropylated tapioca starch improves insulin resistance in genetically diabetic KKAy mice

Effects of Selenium Supplementation on the Diabetic Condition Depend on the Baseline Selenium Status in KKAy Mice

Oxidative stress in obesity leads to insulin resistance in type 2 diabetes. Some selenoproteins possess antioxidant properties, suggesting that selenium (Se) may protect against type 2 diabetes; however, evidence from epidemiological studies is contradictory. We hypothesized that Se status before supplementation (baseline) contributes to the supplementation outcome. This study aimed to clarify the influence of baseline Se status on the effect of Se supplementation on the diabetic condition. Six-week-old KKAy mice were fed a diet without supplemental Se or with 0.1 ppm Se in the form of L-selenomethionine (SeM) for 2 weeks to create low-Se and sufficient-Se baseline statuses, respectively. For the next 4 weeks, low-Se mice were given a SeM (0.5 ppm Se)-supplemented diet, and sufficient-Se mice were given either a SeM (0.5 ppm Se)- or sodium selenite (0.5 ppm Se)-supplemented diet; control groups continued on baseline diets. Serum Se concentrations, glutathione peroxidase (GPx) activities, adiponectin levels, glucose tolerance, and insulin sensitivity were analyzed. All mice became diabetic during the 2-week baseline induction period. At the end of the supplementation period, Se-receiving groups demonstrated significantly higher Se concentrations and GPx activities than their respective controls. Sufficient-Se mice receiving SeM had lower blood glucose levels and better insulin sensitivity than control and sodium selenite-receiving mice, whereas low-Se mice receiving SeM showed no such improvements compared with their controls. Our results suggest that Se supplementation in the form of SeM may help prevent type 2 diabetes aggravation in people taking the 55 μg/day Se recommended dietary allowance.

Hydroxypropylation of high-amylose maize starch changes digestion and fermentation-dependent parameters in rats

It was examined whether the physiological effects of high-amylose maize starch (HAMS) are influenced by hydroxypropylation. Rats were fed one of the following three diets: an AIN-93-based diet with waxy maize starch (WMS) as a starch source, or this diet with 150 g of WMS replaced by either HAMS or hydroxypropylated HAMS (HP-HAMS). The activities of amylase in bile-pancreatic juice and sucrose, maltase and isomaltase of the jejunum and ileum were not affected by diet, but the digestibility of HAMS was decreased by hydroxypropylation. The amounts of SCFA in caecal content and H2 excreted in the breath and flatus for HAMS were decreased by hydroxypropylation. Plasma glucagon-like peptide-1 (GLP-1), glucose and insulin concentrations were not affected by diet. On the basis of PCR-denaturing gradient gel electrophoresis (DGGE) profiles, the similarity in caecal bacteria population of the HP-HAMS group and HAMS group was low, but that of the HP-HAMS and WMS groups was high. The amount of caecal IgA was not affected by hydroxypropylation, but those in the HAMS and HP-HAMS groups were greater than that in the WMS group. Plasma and liver concentrations of TAG and cholesterol for HAMS were not affected by hydroxypropylation. These results show that the small intestinal digestibility and fermentation-dependent parameters such as caecal SCFA and H2 productions and caecal bacterial profile of HAMS were affected by hydroxypropylation, but parameters of glucose metabolism such as GLP-1 and insulin, those of lipid metabolism such as plasma TAG and cholesterol and the amount of caecal IgA were not.