Dietary fiber-based colon-targeted delivery systems for polyphenols

Natural polyphenols have potential therapeutic effects on colon-based diseases and gut microbial dysbiosis. However, the delivery of pure polyphenols to the colon has to overcome chemical instability, degradation, and metabolism in the upper gastrointestinal tract after oral ingestion. Dietary fibers have been exploited as microbiota-triggered release systems to protect polyphenols in the upper gut and specifically deliver them to the colon. This review focuses on the recent development of colon-targeted polyphenol delivery systems using encapsulation technologies based on dietary fibers for both food and pharmaceutical applications. The detailed characteristics and advantages of commonly used dietary fibers and the main mechanisms of encapsulation preparation are discussed. The challenges of targeting the colon and the colonic health benefits of polyphenols are elaborated. In addition, the scope for specific modulation of gut microbiota by the selective combination of polyphenol and dietary fiber is highlighted. The microbial-triggered release mechanisms of dietary fiber-based delivery systems maintain the structural integrity and protect the polyphenols during passage through the harsh environment of the upper gastrointestinal tract to maximize their concentration in the colonic region. In addition, dietary fibers offer several advantages over other materials for polyphenol encapsulation and delivery, including strong dietary fiber-polyphenol binding interactions, high colonic mucoadhesion, and synergistic prebiotic effects from dietary fiber and polyphenol that result in health benefits for the colon and the body.