14 August 2024

Do we still need salt?

The feted mineral’s long and storied history with humans is evolving once more.

Photo by ATU Images

Combatants in the Great Salt Debate divide into two camps with radically different views. One believes that we eat too much salt and should reduce our intake (a lot). The other believes that we eat too much salt and should reduce our intake (a bit). The weapons for each side are research papers that prove their point, and angry scorn for the “flawed” research that doesn’t.

The health journalist Claudia Hammond and her team at the BBC’s World Service recently convened a panel of professors (of cardiology, chemistry and health economics) to bring calm elucidation to this complex subject, plus a food historian (me) for some history.

Do we even need to add salt to our food? Natural and human history give some interesting answers. Palaeolithic people and indigenous populations who lived principally by hunting did not. Fresh meat provides the carnivorous body with all the salts it needs. Wild herbivores, however, find salt licks in nature, and as our Neolithic ancestors began to add more plants to their diet, salt works start to appear in the archaeological record. As coastal gardeners know, few edible plants take up salt, and plant-based diets need a supplement from somewhere. For the same reason that a salt bath helps heal wounds by battling bacteria, it preserves protein – meat, fish and cheese – through the hungry winter, or keeps it edible through a hot summer. Most traditional savoury foods – herring, gravadlax, salt cod, bacon, cheese, olives, pickles, soy and fish sauce – testify to our salt dependence.

Like many humans, natural sugars are prone to turn to alcohol when they break down – which is why we so often salt fruit and vegetables before pickling them. The salt holds off bacteria and yeasts, allowing the sugars to break down and produce lactic acid, a natural preservative. In bread-baking, salt inhibits the yeast’s natural exuberance, allowing the baker to control the rate at which the dough rises and put a little backbone into the gluten, to give strong pockets to be filled with hot air in the oven.

The baker has to get the balance right. Pour some salt on to a lump of live yeast and you will see it slump pitifully, as the moisture from the yeast is taken up by salt. As our professor of cardiology explained, if you have too much salt in the blood vessel, it attracts water and that leads to high blood pressure. But it also, as described by the professor of chemistry, makes salted fish and meat so delicious; in drawing out the water, salt intensifies the taste of the flesh.

Whoever controlled the source of salt in the ancient world controlled food supplies. Romans salted the language as they paid a “salary” to their “soldiers” so they might buy the salt they needed to curb the bitterness in salad, make a piquant salsa or preserve meat in salami (our “sauce” and “sausage” both derive from the Latin for “salted”). Their armies conquered territory by taking over the salt works. The Spanish seized control of the Americas in the same way. Venice grew wealthy controlling the salt trade; French rulers financed their luxury via the much-hated gabelle, or salt tax. The British, depending on salted meat for their navy, did something different. Anxious to protect Cheshire and local producers, they regulated and taxed salt only in the empire. The American Revolution shows how popular this idea was with the 13 colonies. Gandhi walked 240 miles in protest at the legislation that forced Indians to pay tax on their salt. At a beach in Gujarat he raised a fistful of salty mud and declared: “With this, I am shaking the foundations of the British empire.”

For Gandhi, the salt tax was particularly iniquitous because the poor needed salt for their food. However, newer ways of preserving food – canning, vacuum-packing, freezing – means that salt is today largely redundant. The professors all agreed that the majority of our excessive salt intake comes from industrially produced food. Are the food corporations that put it there, then, avaricious empires ruining the welfare of whole populations? That is the salient question.