Our Unindicted Coconspirators: Human Metabolism from a Microbial Perspective

The human gut is populated by a microbiota composed of tens of trillions of organisms and millions of genes that together form a metabolic organ. Intra- and interpersonal differences in the structure and functions of this organ suggest that it could contribute to our normal metabolic variations and also to metabolic disorders. This Commentary discusses experimental approaches for connecting microbial and host metabolism in the context of health and disease.