Salt gets a bad rap, and for good reasons. Salt increases blood pressure. High blood pressure leads to stroke and heart attack. So why not do away with the evil stuff altogether?

Salt is actually one of the reasons that the human race survived frozen winters and hot, barren summers. Before the days of refrigeration, we were hunters and gatherers. Or farmed the great wheat and rice fields. Or fished the seven seas. A hunted deer, or slaughtered cow, or a boatload of fish would be a family feast.

But what to with all that extra food when everyone was stuffed and nodding off on the couch while watching the caveman football (or the jousting match, or the gladiatorial games)? The answer, of course, is salt. Salting the meat and fish, like jerky or baccala, was an essential way to prevent all kinds of bacteria, fungi and viruses I can’t even pronounce from putrefying the meat, making it toxic, inedible and stinky.

One hot Friday afternoon in July, we boiled lobster at my house for a family gathering. We all sat around, crunching shells and dipping lobster in melted butter under a scorching sun. I tossed the shells and lobster slime in the garbage, where they fermented and rotted in 90 degree heat until Sunday night, when I put the trash out. Straining over the barrel to squeeze another white bag of garbage down into it the putrid miasma of rotting lobster violated my nose, throat, and sinuses. I gagged.

Salt was valuable to humanity because it stopped things from rotting by preserving them. It was so valuable that it became a sort of currency in the Middle Ages, and cities like Venice, Munich, and Liverpool became rich by making, exporting, and trading salt.

Sometimes, I even prescribe salt. I have a few patients who, rather than having high blood pressure, get profoundly dizzy when they stand up. Standing drains blood into the legs; a reflex senses the lower blood pressure in the brain and tells the body to squeeze blood out of the legs and up into the head. But in some diseases, like Parkinson’s and diabetes, that reflex stops working well and that patient can pass out, hit their head or break a hip. It can be quite debilitating.

A similar but self-limiting phenomenon can happen to healthy young people who develop a condition called POTS, or postural orthostatic tachycardia syndrome. When I tell each of these patients to load up on salt, they look at me like I was a heretic. One lady looked me and shrieked incredulously, “But, you’re a DOCK-TOR!” Of course, I’m not saying that more salt is good for most people, but for any rule, there are exceptions.

There are other conditions when the body needs more salt. Sweating a lot and becoming “dehydrated” really means losing water and salt. The same thing happens with diarrhea and profuse vomiting. Water alone is inadequate; you need salt. Products like Gatorade, Pedialyte, and Liquid IV are all basically just water and salt. Of course it is a bad marketing tool to call it “salt”; better to call it “electrolytes,” which is just a sexy name for salt. (“It’s like, electric and it lights me up!”). Calling it "electrolytes" also lets the companies charge a lot more money. Truth is, your grandma’s chicken soup, a bowl of ramen, and even a slice of bread will give you all the electrolytes you need.

Most of us, of course, eat way too much salt. When my patient tells me that she “never adds salt” and doesn’t understand how her legs could be so swollen, she usually doesn’t realize that the slice of white bread she ate has as much salt as a single serving bag of potato chips. Or that anything in a jar or can or box, even if it’s “low salt” probably has too much salt. “Low salt” and “electrolytes” may be good marketing ploys, and salt itself may have a bad rap, but it’s best to take such things with a grain of, well, salt.