Amino acid composition of soybean protein increased postprandial carbohydrate oxidation in diabetic mice

The effects of an amino acid mixture simulating dietary soybean protein on the postprandial energy metabolism was investigated using type II diabetic mice. KK-A(y) strain mice were fed restrictive isoenergetic and isonitrogenous diets (35% of energy as protein and 5% as fat) based on either casein, soybean protein isolate hydrolysate (SPI-H), SPI-HET (ethanol unsoluble fraction of SPI-H), SPI-AA and casein-AA (amino acid mixtures simulating SPI-H and casein). To measure dietary carbohydrate oxidation, the animals were fed a diet containing (13)C-glucose. Postprandial respiratory quotient and expired (13)CO(2) were higher in the SPI-AA than in the casein-AA group, as the differences were similarly observed in mice fed SPI-H and casein diet. No significant differences were observed in the postprandial respiratory quotient and expired (13)CO(2) between the SPI-H and SPI-HET group. In conclusion, this study on food-restricted mice indicates that the amino acid mixtures simulating SPI-H or casein could affect postprandial energy metabolism in diabetic mice, as observed in those fed SPI-H or casein in the form of peptide or protein.