[Roles of enteric microbial composition and metabolism in health and diseases]

A complex microbiota colonizes mucosal layers in different regions of the human gut. In the healthy state, the microbial communities provide nutrients and energy to the host via fermentation of non-digestible dietary components in the large intestine. In contrast, they can play roles in inflammation and infection, including gastrointestinal diseases and metabolic syndrome such as obesity. However, because of the complexity of the microbial community, the functional connections between the enteric microbiota and metabolism are less well understood. Nevertheless, major progress has been made in defining dominant bacterial species, community profiles, and systemic characteristics that produce stable microbiota beneficial to health, and in identifying their roles in enteric metabolism. Through studies in both mice and humans, we are recently in a better position to understand what effect the enteric microbiota has on the metabolism by improving energy yield from food and modulating dietary components. Achieving better knowledge of this information may provide insights into new possibilities that reconstitution of enteric microbiota via diet can provide the maintenance of healthy state and therapeutic/preventive strategies against metabolic syndrome such as obesity. This review focuses on enteric microbial composition and metabolism on healthy and diseased states.