Abstract: The human gut is a chemical factory, wherein hundreds of microbial species transform our dietary inputs into bioactive molecules that are absorbed into the bloodstream and circulated throughout the body. We have developed a community-scale metabolic model of the gut microbiome, called MICOM (short for MIcrobial COMmunity), which can be leveraged to design personalized dietary, prebiotic, and probiotic interventions aimed at augmenting the production of beneficial metabolites and decreasing the production of detrimental metabolites. Overall, we show how MICOM can be leveraged to understand ecological interactions among microbes and to engineer the metabolic outputs of the gut to improve human health. Video courtesy of Institute of Ecology and Evolution at U Oregon.