Which isn't to say that salt must always be added, because some food contains its own. But in the absence of salt, food would be relatively bland. Salt doesn't as much change or add flavor as make food taste more like itself. A tomato tastes more vivid. Corn is not only sweeter but more complex. Meat tastes not only richer but juicier.
When all you can taste is salt, on the other hand, something is wrong. Too much salt can obscure the flavor of the food. In the case of ingredients that are, in one way or another, inadequate, salt can help pick up the slack.
Restaurant and processed foods are usually salted to the hilt, but all too often, home-cooked meals end up undersalted. This is not just a rookie move. Experienced cooks are guilty of this. I've been scolded for it myself, in fact, more times than I should admit in public.
As with most primary flavors, like acid, umami, sour or bitter, I'm usually looking to layer my salts in various forms, using the likes of capers, cheese, anchovies, soy or fish sauce, to name a few. These add a wealth of flavors in addition to that salty sodium.
I'm fortunate enough not to have high blood pressure, so my thoughts on salt are all about flavor, taste and culinary success. For those with healthy blood pressure, evidence is mounting that there is no correlation between sodium intake and cardiovascular disease or stroke. This case has been pretty solid since about 2011, and support for it keeps growing. Nonetheless, organizations like the American Heart Association and the American Stroke Association are still pushing for lower salt intake across the entire population.
Meanwhile, some recent studies have presented compelling evidence that other fundamental assumptions about salt are wrong as well. A team of cosmonauts was kept in isolation to simulate long-distance space travel, and their sodium intakes were monitored, as were their urine and blood sodium levels, as reported by the New York Times. To the researchers' surprise, eating more salt made the cosmonauts less thirsty. They also ate more food under a high-salt diet, assuming that more was available. And if more food wasn't available they complained, and lost weight.
It was expected that more dietary salt would compel the cosmonauts to drink more water, in order to dilute the extra salt and stabilize their salt levels. But instead the crew drank less water and without the extra water, their blood sodium levels remained steady.
The researchers, based in the U.S., Germany and Russia, eventually realized that the cosmonauts were diluting the extra sodium by producing their own water by burning fat. The process is identical to what a camel does in the absence of drinking water; its hump is full of fat, which breaks down to water when the animal is dehydrated. The cosmonaut study was followed up by a mouse study that found mice on a high salt diet had to eat 25 percent more to maintain their weight.
While this study didn't investigate whether we eat too much salt, the evidence does continue to grow that people without high blood pressure don't need to watch their salt intake, and can season as they wish.