Exploring the synergistic benefits of insoluble dietary fiber and bound phenolics: Unveiling the role of bound phenolics in enhancing bioactivities of insoluble dietary fiber

Insoluble dietary fiber (IDF) has been widely recognized for its diverse physiological activities, with increased intake being linked to a reduced risk of certain non-communicable diseases. Therefore, a comprehensive analysis of the composition, biological activity, and mechanisms of IDF is crucial for advancing its application in functional foods. There is a growing interest in the role of bound phenolics (BP) associated with IDF in the physiological activities of IDF. This review offers an overview of IDF's physiological activities, explores the interactions between BP and IDF, and discusses how BP enhance IDF's bioactivities. Mechanisms underlying the synergistic effects of IDF and BP are elucidated, and key directions for future research are proposed. IDF demonstrates various physiological activities, including oxidative stress reduction, blood glucose regulation, modulation of gut microbiota composition, and anti-inflammatory effects. The presence of BP, typically associated with IDF through covalent and noncovalent bonds, plays a pivotal role in enhancing the bioactivities of IDF. BP in IDF actively regulate intestinal flora structure and promote IDF metabolism into more short-chain fatty acids (SCFAs), which, alongside BP and metabolites, synergistically exert local or systemic biological activities. Understanding the synergistic effects of IDF and BP provides valuable insights into IDF, contributing to the development of functional dietary fiber foods and dietary interventions aimed at enhancing human health.