Biochemistry of Human Gut Microbiota: Related Diseases and Dietary Interactions

The human gut microbiota represents a complex and dynamic ecosystem of trillions of microorganisms that play a fundamental role in maintaining physiological homeostasis, regulating metabolism, and modulating the immune system. This narrative review explores the biochemical intricacies of the gut microbiome, focusing on the dominant phyla (Firmicutes, Bacteroidetes, Actinobacteria, Proteobacteria, Verrucomicrobia, Fusobacteria) and their specific contributions to host health. A critical emphasis is placed on the metabolic outputs of these microorganisms, such as short-chain fatty acids (SCFAs) like butyrate, which serve as vital energy sources and anti-inflammatory signaling molecules. Conversely, the review examines how dysbiosis, the disruption of microbial balance, is mechanistically linked to the pathogenesis of diverse conditions, including obesity, diabetes mellitus, inflammatory bowel disease (IBD), and gout. Furthermore, it highlights the profound impact of dietary interventions on microbial architecture, notably, how non-digestible carbohydrates promote beneficial taxa and eubiosis, while high-fat and high-sugar diets drive metabolic endotoxemia and systemic inflammation. By synthesizing current knowledge on microbial biotransformations of proteins and polyphenols, this work underscores the bidirectional relationship between nutrition and the microbiome. Ultimately, understanding these biochemical interactions is essential for developing targeted probiotic, prebiotic, and nutritional strategies to prevent and manage chronic metabolic and inflammatory disorders.