Mechanistic pathways linking gut microbial metabolites, microbial structural products, and host-microbe co-metabolites to mitochondrial function.

Gut-derived microbial metabolites modulate host mitochondrial function. To our knowledge, no prior systematic review has synthesized evidence linking these metabolites to direct mitochondrial endpoints across all major metabolite classes. PubMed, Scopus, and Web of Science were systematically searched through March 2026 for studies examining direct mitochondrial endpoints in relation to ten classes of gut-derived metabolites. Gut-derived microbial metabolites exert diverse effects on mitochondrial function, ranging from bioenergetic enhancement to direct toxicity. After contextual evidence was excluded from the certainty assessment, four metabolite-mitochondrial outcome groupings had moderate certainty: butyrate, propionate, indoxyl sulfate, and lipopolysaccharide. Evidence for p-cresyl sulfate, H₂S, and urolithin A was rated low; evidence for the remaining metabolite classes was low or very low. Butyrate generally enhances mitochondrial biogenesis, ATP generation, and electron transport chain activity across multiple experimental models. Indoxyl sulfate generally impaired mitochondrial function, whereas p-cresyl sulfate produced concentration- and model-dependent effects. PGC-1α emerges as a central regulatory node, integrating microbial metabolic signals to control mitochondrial biogenesis and oxidative metabolism. Many microbial metabolites demonstrate concentration-dependent biphasic effects. These findings support a mechanistic microbiome-mitochondrial framework in which diverse gut-derived molecules converge on a limited set of mitochondrial control nodes: electron transport chain activity, reactive oxygen species handling, biogenesis, and mitophagy. The evidence base is predominantly preclinical; these insights should be considered hypothesis-generating.