Ideal dietary fiber model: Personalized gut microbiota modulation based on structure-function relationships.

Dietary fiber has emerged as a central modulator of gut microbiota composition and host physiology, garnering unprecedented scientific attention. Here, we propose the "Ideal Dietary Fiber Model"-a personalized, structure-guided framework designed to precisely shape gut microbial ecosystems and promote host health. Departing from traditional fiber classifications, this model emphasizes the construction of composite fiber formulations based on detailed structural parameters, including monosaccharide composition, glycosidic linkage types, and degree of polymerization. Particular focus is given to oligosaccharides, whose fine structural features confer high selectivity in modulating microbial communities and the production of key metabolites such as short-chain fatty acids, indoles, and neurotransmitter precursors. This review synthesizes recent advances in fiber-microbiota interactions across metabolic, inflammatory, and neurocognitive diseases, including obesity, type 2 diabetes, Non-Alcoholic Fatty Liver Disease, inflammatory bowel disease, colorectal cancer, depression, anxiety, and Alzheimer's disease. While mechanistic insights continue to expand, current evidence remains largely preclinical, highlighting the gap between experimental findings and clinical translation. We argue that integrating microbiome stratification with fiber structure-function databases will be essential for advancing precision nutrition. The Ideal Dietary Fiber Model offers a conceptual and practical foundation for microbiota-targeted dietary design, but its therapeutic potential requires rigorous clinical validation.