Aimed at students, researchers, nutritionists, and developers in food technology, this research text addresses the nascent field of metabiotics. Metabiotics are products based on components of cells, metabolites, and signaling molecules released by probiotic strains, engineered to optimize host-specific physiological functions in a way that traditional probiotics cannot. This book examines the history, processes, design, classifications, and functions of metabiotics. It includes an overview of the composition and function of the gut microbiota, and discusses development of target-specific metabiotics. Further coverage includes comparisons to traditional probiotics, as well as probiotic safety and side-effects. Metabiotics: Present State, Challenges and Perspectives provides a complete history and understanding of this new field, the next phase of the probiotic industry.