Journey of dietary fiber along the gastrointestinal tract: role of physical interactions, mucus, and biochemical transformations

Dietary fiber-rich foods have been associated with numerous health benefits, including a reduced risk of cardiovascular and metabolic diseases. Harnessing the potential to deliver positive health outcomes rests on our understanding of the underlying mechanisms that drive these associations. This review addresses data and concepts concerning plant-based food functionality by dissecting the cascade of physical and chemical digestive processes and interactions that underpin these physiological benefits. Functional transformations of dietary fiber along the gastrointestinal tract from the stages of oral processing and gastric emptying to intestinal digestion and colonic fermentation influence its capacity to modulate digestion, transit, and commensal microbiome. This analysis highlights the significance, limitations, and challenges in decoding the complex web of interactions to establish a coherent framework connecting specific fiber components' molecular and macroscale interactions across multiple length scales within the gastrointestinal tract. One critical area that requires closer examination is the interaction between fiber, mucus barrier, and the commensal microbiome when considering food structure design and personalized nutritional strategies for beneficial physiologic effects. Understanding the response of specific fibers, particularly concerning an individual's physiology, will offer the opportunity to exploit these functional characteristics to elicit specific, symptom-targeting effects or use fiber types as adjunctive therapies.