Effects of Natural Polysaccharides on the Gut Microbiota Related to Human Metabolic Health

Natural polysaccharides (NPs) are sugar chains bound by glycosidic bonds that are composed of at least 10 monosaccharides and have broad biological activity. The human body microbiome is a complex ecosystem that plays a role in host metabolism, immunity, and other important life activities. Numerous studies have demonstrated an obvious relationship between the gut flora and the occurrence of many human diseases. Many studies have reviewed and investigated the effects of polysaccharides on the microbiome, but the underlying mechanisms remain unclear. Most of these studies have focused on the effects of NPs on microbes, as they are important “foods” for the intestinal flora. However, polysaccharides can also affect microbes by improving gut homeostasis. Therefore, the purpose of this review is to introduce recent research that looks at how NPs affect microbiomes by directly acting as fermentation substrates and enhancing gut homeostasis. In addition, this study provides a succinct summary of NP extraction, purification, and structural characteristics, as well as a discussion of their structure‒activity correlations. This study also sheds light on future directions and obstacles in the use of NPs with protective properties, with the aim of providing insights into their potential applications in disease treatment.