How diet and the microbiome shape health or contribute to disease: A mini-review of current models and clinical studies

The human gut microbiome is a complex ecosystem of commensal microorganisms that help to shape host development and health. Host diet directly influences not only the composition, but also the function of the microbiome. In turn, the microbiome impacts the health of the host through production of metabolites from ingested food. Studies of this host-microbe relationship have recently enhanced our understanding of disease development and pathogenesis, and are now being targeted to combat disease symptoms and promote health. For example, dietary shifts to a high-fat, high-sugar Western diet drives microbiome dysbiosis in several disease models, which correlates with disease severity. Reintroduction of fiber, increased antioxidants, or decreases in fat and sugar intake helps to restore microbial balance to a healthier composition and often improves disease parameters. Analyses of microbiome-produced metabolites emphasize that understanding how diet shifts the function of the microbiome may be of critical importance for therapeutic targeting of the host-microbe relationship to promote health. In this mini-review, we discuss what is known about the three-way relationship between diet, the microbiome, and disease utilizing animal models, as well as the findings from human clinical trials of dietary therapeutics.