Advances in oral absorption of polysaccharides: Mechanism, affecting factors, and improvement strategies

Polysaccharides have been widely used as biomaterials and drugs after oral administration due to their suitable physicochemical properties, good bioactivities and low toxicities. However, studies on their pharmacokinetics and absorption mechanism after oral administration are significantly restricted by the lack of polysaccharide detection methods. With the advancement of polysaccharide detection technologies such as immunoassays, fluorescent and isotopic labelling, the oral pharmacokinetics of polysaccharides have gradually been revealed. Here, paracellular pathway, transcellular pathways and M cell-mediated transport were analysed as mechanisms for oral absorption. The potential factors affecting the oral absorption of polysaccharides, including their charge, molecular weight, spatial structure and dose, as well as the species and physiological state of organisms, were analysed. Based on the absorption mechanism and influencing factors, we look forward to further investigating possible strategies for improving the oral absorption of polysaccharides.