Targeting the human gut microbiome: a comparative review of probiotics, prebiotics, synbiotics, and postbiotics

BACKGROUND: The human gut microbiome plays a central role in regulating host health, serving as a core hub for systemic physiological interactions. Dysregulation of the gut microbiome is implicated in a wide spectrum of local and systemic diseases. Research has evolved from establishing associations to elucidating the mechanistic roles of gut microbes and developing targeted strategies for their modulation, with a growing emphasis on their bidirectional communication with other organ systems. AIM OF REVIEW: This review aims to synthesize current knowledge on the composition and function of the gut microbiome, its functional crosstalk with the host, and its integral role in both health and disease. A major focus is placed on critically evaluating the mechanisms, efficacy, and applications of key microbiome-directed interventions-probiotics, prebiotics, synbiotics, and postbiotics-in maintaining or restoring gut-centric ecological balance. KEY SCIENTIFIC CONCEPTS OF REVIEW: The gut microbiome acts as a dynamic microbial organ essential for digestion, immune maturation, and metabolic homeostasis. Dysbiosis, characterized by a loss of beneficial microbes and an overgrowth of potential pathogens, is a critical factor in the pathogenesis of gastrointestinal disorders, metabolic diseases, and other systemic conditions. The gut microbiome engages in continuous bidirectional communication with distant organs, including the oral cavity, lungs, skin, and urinary tract, via specific axes (e.g., gut-oral, gut-lung, gut-skin), thereby exerting widespread influence on host physiology. Probiotics, prebiotics, synbiotics, and postbiotics represent complementary strategies to counteract dysbiosis and reestablish gut ecological integrity, ranging from introducing live beneficial bacteria to utilizing inactivated microbial cells and their bioactive metabolites. Enhancing the translational potential of these interventions requires deeper mechanistic insights and robust clinical validation.