The community of microbiota (microorganisms such as bacteria, yeast, fungi, and viruses) in our body (the microbiome) is an important part of human health. It affects immunity, organ system interactions, and the metabolism of nutrients and substances foreign to the body, such as drugs. Kinari Shah, a Research Fellow at DIA, scrutinises how a deeper knowledge of the biology of the microbiome may ultimately help us to use the microbiome effectively in clinical trials in a way that will impact health outcomes overall.