Capsaicin Regulates Glucose Metabolism in Rats Fed with Dietary Fiber by Regulating Microbiota-Short Chain Fatty Acids

Capsaicin and dietary fiber are effective natural food ingredients to control the obesity and metabolic diseases. The aim of the present study was to investigate the improved anti-obesity effects by adding capsaicin to a high-fiber diet. Sprague–Dawley rats were fed with high fiber diet, and different doses of capsaicin. Plasma parameters, gut microbiota, bile acid and short-chain fatty acids were analyzed to detect the improved effects and possible mechanisms. The results showed that the addition of capsaicin further decreased the fasting blood glucose and insulin, and increased beta-muricholic acid, deoxycholic acid, chenodeoxycholic acid, and 3 beta-ursodeoxycholic acid when compared to only high fiber diet. Administration of 0.05 g/kg capsaicin showed the highest of tauro-alpha-muricholic acid sodium salt and tauro-beta-muricholic acid sodium salt and 0.1 g/kg capsaicin resulted in the highest of lithocholic acid, cholic acid and hyodeoxycholic acid. Capsaicin increased the abundance of microorganisms including Akkermansia, Allobaculum et al. and increased the short-chain fatty acids, especially acetic acid and butyric acid. Results from our study indicated that the addition of capsaicin have better effects to reduce the weight, insulin and fasting blood glucose, and the possibly mechanism can be due to the changes in bile acid composition, microbial abundance and shortchain fatty acids.