Human Microbiota and Their Metabolites: Drivers of Host Physiology and Health

The human microbiota constitutes a diverse and dynamic community of microorganisms, including bacteria, fungi, viruses, and archaea, that inhabit various body sites such as the gut, skin, oral cavity, and respiratory tract. These microbial populations establish a symbiotic relationship with the host, playing crucial roles in maintaining physiological homeostasis. The gut microbiota, in particular, is central to metabolic, immunological, and neurological functions. It contributes to nutrient metabolism, synthesis of essential vitamins, regulation of gut barrier integrity, and modulation of immune responses. Moreover, microbial metabolites such as short-chain fatty acids (SCFAs) influence host energy balance, inflammatory signaling, and neurobehavioral processes through the gut–brain axis. Dysregulation of the microbiota, known as dysbiosis, has been linked to a range of disorders, including metabolic syndrome, inflammatory bowel disease, obesity, and neurodegenerative conditions. Understanding the complex interactions between human microbiota and host physiology offers new avenues for therapeutic interventions, such as probiotics, prebiotics, and microbiota-targeted therapies, to restore microbial equilibrium and promote health.