Salt: From the Roman Legion to Your Electrolyte Packet

Salt: From the Roman Legion to Your Electrolyte Packet

You've probably heard that Roman soldiers were paid in salt—and that this is where we get the word salary. It's a great story. It's also almost certainly not true.

The Romans had money. We find Roman coins throughout the former empire, including around military forts such as those along Hadrian's Wall, and we have evidence that Roman soldiers were paid in money. What we do have is an ancient linguistic connection between the Latin sal, meaning salt, and salarium, which eventually gives us salary. Somewhere along the way, that became the much better story that a legionary went to the quartermaster and collected his wages at the imperial salt lick.

But the fact that the story sounds believable tells us something important: salt really was extraordinarily valuable.

Long before Rome, humans sought salt just as other animals do. Animals travel to mineral licks, and humans learned to exploit saline springs, coastal deposits, and eventually salt mines. Nobody needed to measure a serum sodium to discover salt. We had two very good reasons to want it: salt tastes good, and salt preserves food.

That second property changed civilization. Meat and fish could be salted and dried. Vegetables could be fermented. Milk could be transformed into cheese, concentrating its nutrition and allowing it to last far longer than fresh milk. Salt helped food survive winter, travel aboard ships, and provision armies. The Egyptians even used natron—a mixture of sodium salts rather than ordinary table salt—to dry and preserve their dead. Hence the mummy. Or occasionally, presumably, the daddy.

Once everyone wanted salt, governments discovered the next obvious thing to do: tax it. Salt became a source of state revenue in ancient China, traveled along trade routes in Rome, was burdened by the French gabelle, and eventually became the focus of Gandhi's famous Salt March against British rule in India.

Then something changed. We got very good at producing salt, and we invented refrigeration. One of the principal reasons humans had consumed large quantities of salt—preserving food—became much less important. Unfortunately, we didn't stop liking the taste. Modern food manufacturers discovered that salt was cheap, improved flavor and texture, and could be added to almost everything.

Today, the problem is rarely finding enough sodium. It's avoiding too much of it.

There was, however, one particularly clever moment when public health