Macromolecular Organization in Lentinula edodes: Integrating Co-Occurring Bioactives for Structure-Function...

Diet-microbe-host interactions are increasingly recognized as properties of complex food matrices rather than the sum of isolated compounds. Lentinula edodes (shiitake) provides a chemically diverse system containing β-(1→3),(1→6)-glucans, heteropolysaccharides, phenolics, terpenoids, eritadenine, ergothioneine, and bioactive peptides. Evidence suggests that biological effects attributed to shiitake are better interpreted within the whole matrix rather than through reductionist, single-compound approaches. Key structural features-including β-glucan branching, molecular-weight distribution, conformational stability, and polysaccharide-phenolic interactions- shape microbial accessibility and downstream host responses. Here, macromolecular organization refers to the architecture and co-occurrence of these components across digestion and microbial transformation. Across experimental systems, shiitake polysaccharides are linked to shifts in gut microbial composition, including enrichment of butyrate-producing and mucin-associated taxa such as Faecalibacterium, Roseburia, Akkermansia, and Bifidobacterium. These changes are often accompanied by altered short-chain fatty acid profiles and related signaling pathways. In parallel, low-molecular-weight compounds, particularly eritadenine and ergothioneine, are associated with lipid metabolism and redox-related processes in preclinical and limited human studies. However, interpretation is constrained by variability in structural characterization, study design, and limited availability of structure-resolved human data. This review integrates evidence across biosynthesis, processing, microbial fermentation, and host responses, emphasizing context-dependent associations rather than causal claims. By positioning shiitake as a model system, it highlights the value of structure-guided frameworks and outlines directions to improve reproducibility and translational relevance in functional food science. These insights extend beyond shiitake and provide a framework for interpreting structure-function relationships in complex food systems.