Plant-polyphenols based second-generation synbiotics: Emerging concepts, challenges, and opportunities.

There is a growing interest in identifying alternatives to traditional oligosaccharide-based prebiotic agents owing to their undesirable attributes, such as a lack of microbial growth specificity and limited inherent bioactivity. In addition, a novel concept of second-generation synbiotic agents is currently emerging, which argues that prebiotic agents could be best defined on the basis of their physiological effects or functional capacities in the host rather than their specific microbial targets. Plant polyphenols are rapidly emerging as suitable prebiotic and synbiotic candidates that may fulfil these criteria. As we begin to understand the intricate interrelationship between dietary polyphenols and the gut microbiome, a functional synergy can be observed that suggests the appropriateness of the amalgamation of polyphenols and probiotic agents to develop second-generation synbiotic agents. In the present review, we study evidence pertaining to the prebiotic and synbiotic attributes of polyphenols, as well as their relationship with probiotic bacteria, and discuss their efficacy, suitability, and strategies to develop second-generation synbiotic agents. We provide a perspective that polyphenol-based synbiotic agents are fundamentally superior to the traditional carbohydrate-based synbiotic agents and could therefore offer health benefits of both polyphenols and probiotic agents in a synergistic manner.