The human body is now viewed as a complex ecosystem that on a cellular and gene level is mainly prokaryotic. The mammalian liver synthesizes and secretes hydrophilic primary bile acids, some of which enter the colon during the enterohepatic circulation, and are converted into numerous hydrophobic metabolites which are capable of entering the portal circulation, returned to the liver, and in humans, accumulating in the biliary pool. Bile acids are hormones that regulate their own synthesis, transport, in addition to glucose and lipid homeostasis, and energy balance. The gut microbial community through their capacity to produce bile acid metabolites distinct from the liver can be thought of as an "endocrine organ" with potential to alter host physiology, perhaps to their own favor. We propose the term "sterolbiome" to describe the genetic potential of the gut microbiome to produce endocrine molecules from endogenous and exogenous steroids in the mammalian gut. The affinity of secondary bile acid metabolites to host nuclear receptors is described, the potential of secondary bile acids to promote tumors, and the potential of bile acids to serve as therapeutic agents are discussed.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a significant global health issue, affecting over 30% of the population worldwide due to the rising prevalence of metabolic risk factors such as obesity and type 2 diabetes mellitus. This spectrum of liver disease ranges from isolated steatosis to more severe forms such as steatohepatitis, fibrosis, and cirrhosis. Recent studies highlight the role of gut microbiota in MASLD pathogenesis, showing that dysbiosis significantly impacts metabolic health and the progression of liver disease. This review critically evaluates current microbiome-centered therapies in MASLD management, including prebiotics, probiotics, synbiotics, fecal microbiota transplantation, and emerging therapies such as engineered bacteria and bacteriophage therapy. We explore the scientific rationale, clinical evidence, and potential mechanisms by which these interventions influence MASLD. The gut-liver axis is crucial in MASLD, with notable changes in microbiome composition linked to disease progression. For instance, specific microbial profiles and reduced alpha diversity are associated with MASLD severity. Therapeutic strategies targeting the microbiome could modulate disease progression by improving gut permeability, reducing endotoxin-producing bacteria, and altering bile acid metabolism. Although promising, these therapies require further research to fully understand their mechanisms and optimize their efficacy. This review integrates findings from clinical trials and experimental studies, providing a comprehensive overview of microbiome-centered therapies’ potential in managing MASLD. Future research should focus on personalized strategies, utilizing microbiome features, blood metabolites, and customized dietary interventions to enhance the effectiveness of these therapies.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a significant global health issue, affecting over 30% of the population worldwide due to the rising prevalence of metabolic risk factors such as obesity and type 2 diabetes mellitus. This spectrum of liver disease ranges from isolated steatosis to more severe forms such as steatohepatitis, fibrosis, and cirrhosis. Recent studies highlight the role of gut microbiota in MASLD pathogenesis, showing that dysbiosis significantly impacts metabolic health and the progression of liver disease. This review critically evaluates current microbiome-centered therapies in MASLD management, including prebiotics, probiotics, synbiotics, fecal microbiota transplantation, and emerging therapies such as engineered bacteria and bacteriophage therapy. We explore the scientific rationale, clinical evidence, and potential mechanisms by which these interventions influence MASLD. The gut-liver axis is crucial in MASLD, with notable changes in microbiome composition linked to disease progression. For instance, specific microbial profiles and reduced alpha diversity are associated with MASLD severity. Therapeutic strategies targeting the microbiome could modulate disease progression by improving gut permeability, reducing endotoxin-producing bacteria, and altering bile acid metabolism. Although promising, these therapies require further research to fully understand their mechanisms and optimize their efficacy. This review integrates findings from clinical trials and experimental studies, providing a comprehensive overview of microbiome-centered therapies’ potential in managing MASLD. Future research should focus on personalized strategies, utilizing microbiome features, blood metabolites, and customized dietary interventions to enhance the effectiveness of these therapies.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a significant global health issue, affecting over 30% of the population worldwide due to the rising prevalence of metabolic risk factors such as obesity and type 2 diabetes mellitus. This spectrum of liver disease ranges from isolated steatosis to more severe forms such as steatohepatitis, fibrosis, and cirrhosis. Recent studies highlight the role of gut microbiota in MASLD pathogenesis, showing that dysbiosis significantly impacts metabolic health and the progression of liver disease. This review critically evaluates current microbiome-centered therapies in MASLD management, including prebiotics, probiotics, synbiotics, fecal microbiota transplantation, and emerging therapies such as engineered bacteria and bacteriophage therapy. We explore the scientific rationale, clinical evidence, and potential mechanisms by which these interventions influence MASLD. The gut-liver axis is crucial in MASLD, with notable changes in microbiome composition linked to disease progression. For instance, specific microbial profiles and reduced alpha diversity are associated with MASLD severity. Therapeutic strategies targeting the microbiome could modulate disease progression by improving gut permeability, reducing endotoxin-producing bacteria, and altering bile acid metabolism. Although promising, these therapies require further research to fully understand their mechanisms and optimize their efficacy. This review integrates findings from clinical trials and experimental studies, providing a comprehensive overview of microbiome-centered therapies’ potential in managing MASLD. Future research should focus on personalized strategies, utilizing microbiome features, blood metabolites, and customized dietary interventions to enhance the effectiveness of these therapies.