Gut Bacteria: A Beneficial Symbiosis or a Hidden Threat? Investigating the Dual Role of Bacteria in Gastrointestinal Diseases.

The intestinal microbiota is a highly dynamic and intricate system that supports digestive function, modulates immune responses, and protects against gut disorders. This review explores the impact of gut microorganisms on gastrointestinal conditions, including irritable bowel syndrome (IBS), Crohn's disease (CD), ulcerative colitis (UC), and colorectal cancer (CRC). Beneficial microbiota such as Lactobacillus, Bifidobacterium, Faecalibacterium, and Akkermansia help reduce inflammation and maintain intestinal homeostasis by producing short-chain fatty acids (SCFAs). These metabolites regulate immune mechanisms and reinforce the gut barrier while also suppressing harmful pathogens. In contrast, pathogenic bacteria including Fusobacterium nucleatum, Escherichia coli, Bacteroides fragilis, and Clostridium difficile contribute to gastrointestinal disorders by producing toxins, increasing mucosal permeability, and stimulating inflammatory responses. Additionally, microbial dysbiosis-alterations in microbiota composition-can lead to chronic inflammation and neoplastic changes in intestinal cells, thereby promoting CRC development. Future studies may further clarify microbiota-pathogen interactions, which may provide a basis for exploratory therapeutic strategies.