The flow velocity in our digestive system directly determines how well nutrients are absorbed by the intestine and how many bacteria live inside it. This is the result of a new study by researchers from the Max Planck Institute for Dynamics and Self-Organization (MPI-DS) and the Technical University of Munich (TUM). The group of Karen Alim revealed the physics mechanisms of how the intestine can regulate itself to optimize nutrient absorption while limiting unwanted bacterial growth at the same time.