Disease is an act of piracy. When microbes infect us, they steal our resources so they can thrive at our expense. We fight them off with direct attacks, using an army of immune cells and antibodies. But we also have subtler countermeasures: we can, for example, deprive them of the nutrients they need.

Iron is one such nutrient. Many of the most important enzymes only work when they embrace iron atoms, and that’s true for blue whales and bacteria alike. So, when bacteria infect us, they try to scavenge iron from our bodies. We, in turn, try to halt their advances by withholding this nutrient.

Matthew Barber and Nels Elde from the University of Utah School of Medicine have found clear