Gut microbiota and metabolites in lipid metabolism and intramuscular fat deposition: mechanisms and implications for meat quality

Intramuscular fat (IMF) content serves as the key determinants of meat quality. Emerging evidence indicates that gut microbiota and their metabolites significantly influence IMF deposition levels by modulating host lipid metabolism through multiple pathways, positioning microbial regulation as a pivotal target for meat quality improvement. However, existing studies remain fragmented, predominantly focusing on isolated mechanisms or correlations without a systematic view of the regulatory network. This review consolidates the core mechanisms through which microbiota-derived metabolites including short-chain fatty acids, bile acids, branched-chain amino acids, trimethylamine N-oxide, tryptophan derivatives, succinate, polyamines etc., regulate IMF deposition and proposes a targeted intervention framework, the "gut microbiota/metabolites-IMF axis". By integrating these insights, we provide a theoretical foundation and define practical research pathways to assess the potential of microbial-based strategies for improving meat quality in swine production.