The fate of dietary polysaccharides in the digestive tract

Dietary polysaccharides are widely used as functional foods owing to their diverse bioactivities, which are mainly determined by the degradation, absorption, and utilization process of polysaccharides. The complex structures of polysaccharides support their escape from human digestive enzymes leading to specific digestion patterns. Therefore, understanding the dynamic processes of polysaccharides within the gastrointestinal tract is important to explore the benefit of host health and the scientific applications of polysaccharides. This review overviewed the digestive properties of polysaccharides in the oral, gastric, small intestine, and colonic models. The focus is on the process of polysaccharide interaction with intestinal symbiotic bacteria, including the catabolic properties of polysaccharides with different structures and gut microbes with individualized differences, the involvement of the mono- or oligosaccharide fragments in microbial energy metabolism processes, as well as their enormous prospects for application. Degradation and metabolism of polysaccharides in the body are the basis for their biological activity. Notably, polysaccharides with different structures are selectively degraded by specific intestinal microorganisms, participate in microbial energy metabolism, support the colonization of key microorganisms, and promote electron transfer and cross-feeding in the intestine to maintain intestinal microbial diversity. The study of the metabolic process of polysaccharides provides a scientific theoretical basis for the targeted intervention of intestinal microbes to obtain health benefits in the metabolic process of polysaccharides.