Book excerpt: Bringing together expert researchers in the fields of microbiome, metabolism, and nutrition research, this book compiles the current state of knowledge from authorities specifically on how diet regulates microbial function with metabolic implications for the human host. Chapters cover the broad concepts of microbial-host interactions under the dietary influences of specific macronutrients, micronutrients, small molecule generation and bile acid circulation, with inclusion of later clinical chapters encompassing topics like bariatric surgery and our current understanding of probiotics, prebiotics, and synbiotics. Covering a timely topic from a functional standpoint, the book fills a gap in the existing literature. While increased attention is placed on descriptive work, it will importantly highlight emerging functional and mechanistic research findings that illustrate the inner workings of the dietary-microbial-host orchestration of metabolic regulation. Providing an exciting summary of the importance of current microbial function, it will also summarize the next major directions in the field of microbiome research.