Effect of Diet and Dietary Components on the Composition of the Gut Microbiota

Abstract

Diet and dietary components have profound effects on the composition of the gut microbiota and are among the most important contributors to the alteration in bacterial flora. This review examines the effects the "Western", "plant-based", "high-fat", "medical ketogenic", and "Mediterranean" diets have on the composition of the gut microbiota in both mice and human subjects. We show that specific dietary components that are commonly found in the "plant-based" and "Mediterranean" diet play a role in shifting the microbial composition. This review further evaluates the bacterial metabolites that are associated with diet, and their role in systemic inflammation and metabolic endotoxemia. Furthermore, the associations between diet/dietary components and altering bacterial composition, may lead to potential therapeutic targets for type II diabetes, obesity, and inflammatory diseases.

Keywords: chronic disease; diet; gut microbiota.

Figure 1

A traditional “Western diet” that is high in fat, high in processed sugar, and low in fiber results in an increase in Firmicutes, Proteobacteria, Mollicutes, Bacteroides spp., Alistipes spp., and Bilophila spp., Enterobacteriaceae, Escherichia, Klebsiella, and Shigella while decreasing the beneficial bacteria Bacteroidetes, Prevotella, Lactobacillus spp., Roseburia spp., E. Rectale, Bacillus bifidus and Enterococcus resulting in a reduction in SCFA production. It also increases LPS, TMAO, and inflammatory cytokines increasing risk for nutrition-related chronic diseases, obesity, and type II diabetes. Adherence to a plant-based diet that is rich in whole grains, fruits, and vegetables had inverse effects on the bacterial composition. It reduced opportunistic bacteria resulting in a reduction in LPS, TMAO, and inflammatory cytokines. It also increased the production of SCFAs, reducing inflammation and risk for obesity and type II diabetes.