Figure 2.

Roles and modulation of gut microbiota. In addition to helping digestion and synthesizing vitamins and other metabolites, such as short-chain fatty acids (SCFAs), the members of the gut microbiota play an important role in host defense (by producing antimicrobial compounds and competing against pathogens for adhesion sites and nutrients) as well as in the development and training of the immune system. The gut microbiota is influenced by a wide array of factors such as diet, probiotics, and antibiotics.