Nutrients and functional components are essential for the development and maintenance of human and animal health. The analysis of the literature reveals that the quality and quantity of these elements are key parameters which may have a different functional output on host health. In the digestive tract, ingested nutrients are broken down into small peptides, amino acids, etc, which then can be absorbed by intestinal epithelial cells to exert various physiological functions.

Currently, interactions between diet, gut microbiota, and inflammation-related diseases raise much interest. Studies have shown that the gut microbiota is highly associated with dietary perturbations, taking an average of 3.5 days for each diet-responsive bacterial group to reach a new steady-state after a dietary disturbance. However, the impact of dietary components and derivatives on gut microbiota diversity and composition needs further exploring. Additionally, gut microbiota is known to play a crucial role in maintaining immune and metabolic homeostasis and protecting against pathogens. Thus, protein metabolism is presumably governed, at least in part, by the gut microbiota and its signal to a host’s physiological, nutritional, and immunological processes. There is great interest in identifying the effects of dietary protein and its derivatives on the gut microbiota and mechanisms of subsequent metabolic responses.

The goal of this Special Issue is, therefore, to collate state-of-the-art research focused on the effects of different sources, types, and levels of the dietary functional components on the gut microbiota and host metabolism. We are particularly interested in studies that improve our understanding of the molecular and biochemical mechanisms of host metabolism in inflammation-related diseases. We welcome the submission of Reviews, Systematic Reviews, Mini-Reviews, Hypothesis and Theory, Perspectives, Clinical Trials, and Original Research articles that allow narrowing existing gaps in the knowledge. Systematic reviews are particularly encouraged.

Potential topics include but are not limited to the following:

• Comparison of gut microbiota and host metabolic responses, to different nutrients and functional components in animal and clinical models
• Interactions between nutrients and functional components, gut microbiota, and the host metabolism
• Identification and characterization of target microbiota in response to small molecules and their effect on host metabolism
• Identification and characterization of signaling pathways in host tissues that are modulated by the crosstalk between nutrients and functional components, gut microbiome, and inflammation-related diseases