Chewing behavior and bolus particle size of rice shape gut microbiota functionality and microbial metabolite signatures

Abstract

The size of food particles and their surface area affect how accessible the substrates are to the gut microbiota. This study aimed to examine how the oral breakdown of rice influences the gut microbiota functionality, considering the oral phase, digestion, and colonic fermentation. Increasing the number of chews per bite produced more and smaller particles and increased total bolus surface area, influencing microbial activity and microbial metabolite production. Higher bile salt hydrolase activity and total short- chain fatty acid (SCFA) levels were found in large particles. Focusing on SCFAs, acetic acid was correlated with larger particle sizes. Propionic acid production was associated with a larger surface area, while butyric acid production was highly correlated to the fiber content. Untargeted lipidomics highlighted that particle size influenced numerous metabolites beyond SCFA. This study showed that food particle size could be an innovative strategy to modulate gut microbiota functionality and microbial metabolite production.