Structural characteristics of resistant starch-enriched rice during digestion and its effects on gut barrier function in high-fat induced obese mice

Dietary supplementation with indigestible carbohydrates is known to improve the gut environment and prevent obesity and inflammatory diseases by modulating the gut microbiota. In previous work, we established a method for the production of resistant starch (RS)-enriched high-amylose rice (R-HAR) using citric acid. The present study aimed to evaluate changes in structural characteristics during digestion of R-HAR and its effects on the gut health. A three-step in vitro digestion and fermentation model was used, then, RS content, scanning electron microscopy, and branch chain length distribution were analyzed during in vitro digestion. During the digestion of R-HAR, the RS content increased, and the structure was predicted to have a greater impact on the gut microbiota and gut environment. To study the intestinal health effects of R-HAR, its anti-inflammatory and gut barrier integrity activities were assayed in HFD-induced mice. Intake of R-HAR suppressed colonic shortening and inflammatory responses induced by HFD. Furthermore, R-HAR exhibited gut barrier protective activity with an increase in tight junction protein levels. We determined that R-HAR may be a potentially beneficial intestinal environment improver, which may have various implications in the food industry as rice.