You can be forgiven for thinking that just looking at salt funny will make your heart explode.
If you regularly eat food with too much salt, in the long run that just might happen. Excess salt raises your blood pressure, and if your blood pressure stays high then you may be in for a host of problems, like heart failure and stroke.
Eating too much salt is also linked to osteoporosis, stomach cancer and kidney disease. There’s even a new study suggesting that excess salt might cause your immune system to turn against you.
But all that comes with excess salt. Here’s the thing: We actually need some salt to survive. People have been harvesting salt from the earth and building salt works to produce salt from salt water for thousands of years. It’s so important that it used be used as a form of currency; the word salary comes from the Latin word sal, which means salt; Roman soldiers were paid a salarium, or “salt money.”
Know your frenemy
Before we dive into what salt does for us, though, we have to understand what it is.
Salt’s a chemical compound made up of two atoms: one of sodium (abbreviated Na on the periodic table) and one of chlorine (abbreviated Cl). Putting the two together gives you salt’s chemical name: sodium chloride, or NaCl.
In our bodies, salt dissolves and breaks into two ions (atoms that have either gained or lost an electron and so which have a tiny negative or positive electrical charge; that’s important, and I’ll come back to that in a second). The sodium becomes an Na+ ion, and the chlorine a Cl-.
Sodium takes on several tasks, most of which have to do with it getting pulled into and pushed out of cells. Together with potassium and calcium, it helps generate the electrical impulses in nerves and tell muscles when to contract. It also plays a major role in helping make sure our bodies have the right amount of water in them — and water is the breeding ground for the chemical reactions that make our cells work.
Note that I said, “the right amount of water.” This is where our kidneys come into play. In addition to filtering waste from our blood, the kidneys keep track of how much sodium we have. Too much, and they trigger thirst and filter some sodium out; too little, and they return some of that sodium to the blood stream.
And if we have too much sodium — say, from eating too much salt — the kidneys keep sending out signals for the body to reain water. Too much water means too much fluid in the bloodstream, which puts pressure on our blood vessels, narrowing them and thinning their walls. As the pressure goes up, the heart has to work harder to move the blood more efficiently, which gradually weakens it and leads to heart failure.
So that’s the sodium story, but….
“Just a minute,” you might say. “You’ve only taked about the sodium so far. But salt is both sodium AND chlorine.” True. So what does the chlorine do? That’s not as clear. It seems to help produce the hydrochloric acid in the stomach (which helps digest our food), and also some of the compounds our white blood cells use to destroy bacteria.
Because it’s negatively charged, Cl- from salt also helps keep Na+ and other positively charged ions (like those of potassium and calcium) balanced. (I say “from salt” because direct exposure to chlorine gas or high levels of dissolved chlorine can be quite dangerous; chlorine gas is a potent poison, and we use chlorine to disinfectant water, after all.)
A swing too far toward low salt?
While I was writing this post, I came across a couple of pieces that push back on the sodium-high blood pressure link and raise concerns about the health effects of not having enough salt (and therefore sodium) in the diet. I suspect that the studies they cite need some shoring up, though I’ve not had a chance to delve into them. And there is so much salt in the Western diet that I also suspect it’s hard for the average person to get to the point where they’re eating so little salt as to start feeling the effects of hyponatremia (like confusion, fatigue, muscle cramps, and so on).
But when it comes down to it, salt (like water) is the stuff of life. And as with all things in life, it’s all about balance.
Would someone pass me the pepper?