Bioactive Polysaccharides Targeting Gut Microbiota to Modulate Host Health: A Gear Effect Theory

Bioactive polysaccharides are macromolecular polymers with broad biological activities. Recent evidence has highlighted their role in modulating host health primarily through interactions with gut microbiota. However, the complex structure of bioactive polysaccharides, the heterogeneous nature of gut microbiota, and the variability in their interactions posed challenges to fully understand these relationships. This review aims to clarify these interactions by examining several key aspects. It begins by reviewing the mechanisms through which different phyla of gut microbiota degrade bioactive polysaccharides, clarifying their direct interactions. Then, how bioactive polysaccharides influence the relationships within gut microbiota was discussed, focusing on commensalism, mutualism, and competition. This review comprehensively examines the health effects of bioactive polysaccharides resulting from targeted modulation of gut microbiota. Importantly, we propose a novel “gear effect” theory to explain how bioactive polysaccharides drive gut microbiota to modulate host health, highlighting the crucial role of primary degraders in this process. Overall, this review provides valuable insights into the relationships among bioactive polysaccharides, gut microbiota, and host health, guiding future research on precision nutrition targeting gut microbiota modulation.