The Contribution of Bifidobacterium to Colonic Digestion and Its Implications in Adult Enteral Nutrition: A Scoping Review

The gastrointestinal (GI) tract performs four fundamental physiological functions: motility, secretion, digestion, and absorption. Among these, colonic digestion is uniquely dependent on the resident microbiota, which ferments dietary substrates that escape digestion in the small intestine. This microbially driven process yields short-chain fatty acids (SCFAs) — particularly acetate, propionate, and butyrate — which serve as energy substrates for colonocytes, modulate immune responses, and contribute to intestinal barrier integrity. Bifidobacterium represents one of the most abundant and well-characterized commensal genera in the adult human colon. Its metabolic activities include the fermentation of non-digestible oligosaccharides and dietary fiber, the production of acetate and lactate, and the cross-feeding of metabolites to other beneficial microorganisms such as butyrate-producing bacteria. Beyond metabolic contributions, Bifidobacterium species are implicated in immune modulation, competitive exclusion of pathogens, and maintenance of mucosal barrier function. In adult patients receiving enteral nutrition (EN), disruption of the intestinal microbiota is common. Contributing factors include the underlying clinical condition, antibiotic exposure, altered gut transit, and the composition and route of enteral formula delivery. This dysbiosis has been associated with impaired enteral tolerance, increased intestinal permeability, systemic inflammatory responses, and elevated risk of infectious complications — particularly in critically ill, postoperative, and geriatric populations. Despite a growing body of literature on probiotic supplementation in EN, evidence specifically characterizing the role of Bifidobacterium — from its mechanistic contributions to colonic physiology through to clinical outcomes in adult EN — remains dispersed across diverse study designs and clinical settings. No comprehensive evidence map has been developed that bridges basic GI physiology with applied clinical nutrition in this specific context. This scoping review is therefore designed to systematically map the available evidence on Bifidobacterium's role in colonic digestion and its implications for adult enteral nutrition, identify key themes and research gaps, and provide a structured foundation for future primary research and clinical guidelines.