Dietary polysaccharides as direct substrates for SCFA production: mechanisms and precision prebiotic intervention strategies

Conventional prebiotics lack the structural specificity to direct colonic fermentation toward defined outputs. Dietary polysaccharides (DPs) serve as direct fermentation substrates, and their architecture—monosaccharide composition, glycosidic linkages, molecular weight and branching—determines which short-chain fatty acid (SCFA)-producing taxa can access them. This selectivity is governed by carbohydrate-active enzyme (CAZyme) repertoires and cross-feeding networks. We propose a dual-track precision framework: structure-guided matching of DPs to target SCFA producers, and individualized selection informed by baseline microbiota and disease-specific deficits. The proposed dual-track framework is a theoretical model that requires rigorous validation in human clinical trials. This work provides a mechanism-driven theoretical basis for advancing dietary polysaccharides from empirical prebiotics to precision nutrition tools.