Pettenkofer studied under Liebig; it was Pettenkofer’s own work as a research student that led Liebig onto his own important work on meat extracts. In Munich, he was joined by a younger of Liebig’s students, Voit: they founded a biological journal together, and in a long collaboration, effectively founded modern nutritional science (Pettenkofer providing resources and some essential skills, while Voit did the bulk of the work). Koch visited him to discuss his (Koch’s) radical new theory about cholera epidemiology; while Pettenkofer disagreed, he later drunk a broth of cholera bacteria sent by Koch, and survived.