In the 1930s, it was generally accepted that the body needed sodium to function, but no one had studied what broke down when the sodium in a person’s diet was removed. One researcher researcher and four volunteers decided to find out. It was awful.
The body’s need for salt wasn’t hard to establish. Anyone with a tongue noticed that the sweat and tears which came out of the body tasted the same as the little crystals leftover when sea water evaporated. Later research confirmed that it’s the sodium that makes sodium chloride so necessary to us, but, well into the twentieth century, no one quite knew what would happen when sodium levels dropped. Doctor Robert McCance wasn’t about to let that kind of ignorance persist. He recruited four volunteers and desalinated them — via io9