The Human Gut Microbiota: Implications in Gastrointestinal Health and Disease

The human gut microbiota plays a central role in gastrointestinal health, yet its alterations in Latin American populations remain understudied. This study aimed to characterize microbial diversity, taxonomic composition, and short-chain fatty acid (SCFA) profiles in patients with gastrointestinal disorders in Mexico and Ecuador. A total of 430 adults (54% female, mean age 42.5 years, mestizo and indigenous backgrounds) were recruited and divided into five groups: inflammatory bowel disease (n=120), irritable bowel syndrome (n=80), colorectal cancer (n=70), celiac disease (n=60), and healthy controls (n=100). Demographic and clinical data were collected using structured questionnaires and validated instruments, while stool samples were analyzed through 16S rRNA sequencing and SCFA quantification. Results showed that alpha diversity was highest in healthy controls and significantly reduced in inflammatory bowel disease and colorectal cancer, with intermediate values in irritable bowel syndrome and celiac disease. Beta diversity analysis demonstrated distinct clustering between healthy and diseased groups, with greater heterogeneity among Ecuadorian participants. Taxonomic analysis revealed depletion of Faecalibacterium prausnitzii and enrichment of Ruminococcus gnavus, Fusobacterium nucleatum, and Bacteroides fragilis in diseased groups. Functional profiling indicated butyrate depletion as a consistent marker of gastrointestinal disorders, with higher propionate levels observed in Ecuador. These findings reinforce the role of microbial diversity and specific taxa as hallmarks of gastrointestinal health and disease, while highlighting the importance of regional research. The study underscores the potential of microbiota-based biomarkers and therapies to inform clinical practice and public health strategies in Latin America.