To put it bluntly, without salt you would die. I learned this from Professor Steve Simasko. He told me that every single one of the cells in your body needs salt to function. So quick, get me some potato chips!

Or just a potato. Luckily for us, salt is everywhere, not just in the salty, greasy foods that are not very good for us. Even a plain old potato has 10 milligrams of sodium. Okay, you’re right, that’s not much. But when so many of our food have LOTS of salt, we aren’t really in any danger of dying from a lack of it.

It wasn’t always so easy. I’m sure you’ve heard the term SALARY. Nowadays, we like to get paid in money. But the word actually comes from the Latin word "sal," which means SALT. And that’s because a long time ago, salt was so valuable that bosses would pay their employees with it!

Professor Simasko explains that my brain makes me
crave potato chips. Or something like that!

Let’s back up a second: What is salt exactly? You're right when you say that table salt is sodium and chloride, but let’s get even more specific. When you look at salt, you see a hard white crystal, but inside your body that crystal separates into IONS. An ion is an atom that has either a positive or a negative electrical charge. Sodium has a positive charge, and chloride has a negative charge.

Sodium chloride isn’t the only salt out there—there are LOTS of different salts. But this is one of the really important ones. You also need potassium and calcium, which you get from different salts in your diet.

A while back, Professor Simasko helped us understand bioelectricity. Remember, cells use electricity to communicate with each other. And ions are the basis of electricity in the body! Bioelectricity is how nerve cells transmit impulses, how muscle cells contract, how cells grow, and how hormones are secreted.

Professor Simasko explained that to do this work, cells use ions to create electrical potentials and closely related chemical potentials in the form of ION GRADIENTS. An ion gradient is when you have more of a certain ion on one side of the cell membrane than the other. Special proteins in the membrane of cells maintain these ion gradients by pumping certain ions in and others out.

This process takes energy. About 50 percent of your energy is used to create these gradients—that’s right, HALF of it. Cells work hard all day, pumping ions in and out.

But why? Following the law of ENTROPY, these ions want to undo that gradient! Given a chance, they will move in and out of the cell until the concentrations are the same on both sides of the membrane. And this desire creates a force, and the cell can use that force to do work.

Salt has other jobs in your body, too. Take enzymes, for example. Anything your body does, enzymes are involved at some point. You need them to digest your food, to make new blood cells, to fight infections…

But if you don’t have the right ion concentrations in your body fluids, enzymes don’t work right. This is because enzymes are proteins, and proteins won’t fold right if they don’t have the right ions surrounding them. And if proteins don’t fold right, they don’t work.

And how did salt come to be so important to us? Well, think WAY back, to when single-celled organisms first evolved. What was their environment like? Right, it was SALTY. Early cells evolved in the sea. Later on, when animals moved to the land, one of the big obstacles they faced was getting enough salt. This was especially true of animals that moved far away from the sea.

But still, why does salt TASTE so GOOD? Well think about it. Would you eat salt if it tasted BAD? Because salt is SO important, you have a special place in your brain that makes you want to eat it. You go for the potato chips, and animals such as deer and cows go for salt licks.

But if salt is so great, why do we hear so much about LOW SALT diets? Aren’t we supposed to be eating less salt, not more?

Well, according to Professor Simasko, that’s only true for the small percentage of people who have trouble regulating their salt. Normally, your kidneys will get rid of any extra salt, so it’s actually better to have a bit too much than too little.

But if for some reason your kidneys don’t work so well anymore, you will hold onto too much salt. Salt attracts water, so your blood volume will increase. Then you have hypertension, and that’s bad. But again, if your kidneys are healthy you will have no problem dealing with extra salt.