We engineer the Escherichia coli Ferric Uptake Regulation (FUR) system using a genetic inverter so that they produce siderophores (iron chelators) in response of high concentrations of iron. These engineered bacteria are delivered to the patient's intestine by encapsulating them in an ingestible polymer (capsule) that specifically degrades in the duodenum. Once released into the intestine, the bacteria respond to ambient iron by secreting elevated levels of siderophores, thereby chelating the iron to prevent its absorption by the patient.