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 took advantage of our universal salt habit. Iodine deficiency once produced enormous numbers of goiters and, more importantly, could impair fetal and childhood brain development. In 1924, iodized salt appeared on grocery shelves in Michigan as part of the American effort to combat endemic iodine deficiency.

The idea was beautifully simple: everybody eats salt, so put iodine in the salt. Salt iodization became an extraordinarily effective way to prevent iodine-deficiency disorders, and it remains recommended by the World Health Organization.

Which makes today's fascination with expensive “mineral” salts particularly amusing. Celtic sea salt, Himalayan pink salt, and other specialty salts contain magnesium, calcium, and other minerals—but in trace amounts. If you like their taste or texture, wonderful. I have fancy salts in my kitchen too. That's cuisine, not cardiology.

If you want magnesium, eat some nuts.

And then buy Morton's.

We have performed a similar trick with hydration. There are people who genuinely need extra sodium: athletes exercising for hours, people working in extreme heat, and people experiencing substantial fluid losses. The development of sports drinks was a reasonable response to athletes losing both water and electrolytes during prolonged exercise.

Somehow, that became the idea that everyone needs mango-flavored electrolytes simply because they own a water bottle.

Most of us don't.

Sodium is essential, but essential doesn't mean unlimited. The WHO currently recommends adults consume less than 2,000 mg of sodium per day—about 5 grams of salt—and notes that average global sodium intake is more than twice that amount. Most dietary sodium isn't necessarily coming from the salt shaker. Processed meats, breads, sauces, prepared foods, restaurant meals, cheese, and other frequently consumed foods can contribute substantial amounts.

That doesn't mean your food needs to be bland. Cook vegetables. Eat legumes. Have fish. Use olive oil, herbs, spices, lemon, and vinegar—and use enough salt to make good food taste good. Just don't confuse seasoning your dinner with adding unnecessary sodium to an already sodium-rich diet.

Salt helped build civilizations. It preserved food, provisioned armies, generated taxes, helped make cheese possible, and eventually became a vehicle for preventing iodine deficiency. We spent thousands of years figuring out how to get enough of it.

Now we've become so good at it that we're paying extra to put more of it in our water.

Listen to this episode of FORK U for the story of salt, and head over to drsimpson.com for the deeper dive into sodium, blood pressure, vascular health, salt sensitivity, gastric cancer, electrolytes, and what the science actually says about how much salt we should be eating.