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.
He started the process by getting the existing salt out of their body. Every day, the volunteers spent some times surrounded by heat lamps and research assistants. The former caused them to sweat, and the latter sponged up their drippings.
To make sure that no new salt entered their body, the volunteers ate vegetables that had been boiled three times over, specially-made bread, and synthetic milk. The food wasn't a pleasure to eat, but soon the volunteers lost all pleasure in eating. They lost their sense of taste. What few strong flavors managed to get through to them were altered enough to be repugnant. Onions tasted like sweet grease. Other foods, and cigarettes, tasted of nothing.
Eventually the volunteers became too exhausted to eat. As their sodium levels continued to drop, they could barely function due to fatigue. Although their vital signs seemed fine, their blood changed, becoming dark and sticky. Now we know that the volunteers were suffering from hyponatremia, a condition caused by consuming too little sodium or too much water. Without salt to regulate the water consumption of their cells, the cells were altering, filling with water and swelling up.
The trial only lasted 10 days, after which the volunteers were given salty food. Within minutes, they could taste food again — something which delighted them even more that the release from fatigue — and recovered fully. Other people with hyponatremia haven't been as lucky. The condition can cause seizures, coma, and death. So maybe you should have salt lick on stand-by. You know, just in case.