The thought that health is a form of capital goes way back to the 19th century. Max von Pettenkofer compares health and economics and health states with capital in the following quotation:
Just as the effort to obtain greater profits, an not merely fear of losses, is the driving force in economics, so too it must be in hygiene as a doctrine of health. Hygiene (as a subject) must establish and investigate all the influences exerted on the organism by its natural and artificial environment, in order to increase its well-being through this knowledge. Health really is a form of property or capital, which is to be sure usually inherited, but which must also be acquired by its owner and can be increased as well as reduced.
This is quoted from Death in Hamburg by Richard J. Evans, p. 242.
Pettenkofer–a Bavarian innovator– even called the subject of hygiene “health economics” to make the parallel even more explicit.