Dietary Fibers as Drivers of Short-Chain Fatty Acids Homeostasis: A Review of Intestinal Production, Systemic Distribution, and Inter-Individual Variation

Gut microbiota-derived short-chain fatty acids (SCFAs) are critical regulators of physiological health, with their production significantly affected by gut microbiota and dietary fiber intake. This review examines SCFAs production heterogeneity along the intestinal longitudinal axes and at different extraintestinal sites, and highlights how interactions between dietary fibers and SCFAs-producing microbes disrupt SCFAs homeostasis in chronic diseases. Additionally, we discuss both consistent and individualized responses of SCFAs-producing microbes to fiber interventions. Notably, intestinal transit and microbiota composition primarily govern longitudinal SCFAs production, with the colon serving as the principal fermentation site. The variability in colonic SCFAs production correlates specific SCFAs-producing microbes and fiber types, affecting systemic SCFAs distribution. While fiber supplementation consistently raises total SCFAs and acetate levels, individual differences in SCFAs-producing microbes lead to significant variation in propionate and butyrate production. Overall, this review advances the understanding of individualized SCFAs production, highlighting the necessity of predicting SCFAs production.