Co-administration of D-Allulose and Soy Protein Favorably and Additively Alters Lipid Metabolism in Sprague-Dawley Rats

D-Allulose, a C3 epimer of D-fructose, modulates lipid metabolism. Soy protein has been reported to have antidyslipidemic properties. Therefore, we hypothesized that the combination of D-allulose and soy protein would have favorable effects on lipid metabolism. Sprague-Dawley rats were fed 21.7 % casein or 21.7 % soy protein diets with or without 3% D-allulose for 4 weeks under standard (experiment 1) or high-fat conditions (experiment 2). Under the high-fat diet condition, while D-allulose alone increased serum triglyceride levels, co-administration with soy protein suppressed this increase in serum triglyceride levels. Soy protein and D-allulose alone decreased hepatic triglyceride levels under the standard fat diet, and their combination yielded the lowest hepatic triglyceride levels, accompanied by a decrease in hepatic enzyme activities associated with fatty acid synthesis. In conclusion, soy protein and D-allulose co-administration might have additive effects on lipid metabolism, highlighting broader implications for the application of D-allulose in the development of functional foods.