Salt Sugar Fat (42 page)

The sixty-two participants were asked to keep careful track of everything they ate and drank for the week. To increase the reliability of their record-keeping, the Monell investigators spiked their saltshakers with a tracer that showed up in their urine, a particularly clever move that, through the regular samples they took, allowed the researchers to see precisely how much salt the shakers were contributing. At the end of the week, they gathered up all of the data and crunched the numbers.

There was hardly any sodium in the water they drank, so that was ruled out as a source. Some sodium occurs naturally in foods—such as Swiss chard and spinach—but the participants would have had to gorge themselves on these things for them to make any difference. The naturally occurring sodium in their meals contributed only a bit more than 10 percent of the total sodium they consumed in the week. And as for the much-maligned saltshaker: It delivered just
6 percent
of their sodium intake.

Had they conducted this study a few centuries earlier, the Monell researchers would likely have gotten very different results. The salted fish that Swedes ate in the sixteenth century, for example, pushed their sodium intake way beyond even the levels consumed today, and until the advent of the refrigerator, people throughout the world
relied heavily on salt to preserve their meat and fish. For the people in the Monell study, however, the natural sodium in their food and the salt they were adding themselves came to barely a fifth of the salt being consumed. Where was the rest coming from?

By 1991, when this study was done, cooking from scratch was in steep decline, steadily replaced by processed foods that were preassembled, precooked, and packaged to go. Like everyone else in the country, the study participants were getting the bulk of their meals at the supermarket, where the price of convenience was the salt that these groceries contained. The researchers discovered that more than three-quarters of the salt they consumed in the week came from processed foods. The companies making these products weren’t just adding salt. They were dumping sack after sack of it into their boxed macaroni and cheese, their chicken à la king heat-and-serve meals, their canned spaghetti and meatballs, their salad dressings, tomato sauces, pizzas, and soups. Even items that manufacturers were making expressly for people who wanted to lose weight or manage afflictions like diabetes—the low-fat, low-sugar versions of their brands—were delivering huge doses of salt. From one aisle to the next, there wasn’t much in the grocery store that didn’t have added salt. As much as, if not more than, sugar and fat, the salting of processed food had become a way to increase sales and consumption.

The power of salt in food is smartly summed up by the industry’s largest supplier of salt, Cargill, which says in its sales literature:
“People love salt. Among the basic tastes—sweet, sour, bitter and salty—salt is one of the hardest ones to live without. And it’s no wonder. Salt, or sodium chloride, helps give foods their taste appeal—in everything from bacon, pizza, cheese and French fries to pickles, salad dressings, snack foods and baked goods.”

People don’t just love salt, they crave salty foods. Depending on one’s point of view, the supermarket is either a goldmine—or a minefield—of salt-heavy foods. For perspective on the salt loads delivered by groceries,
consider the number 2,300. This is the maximum amount of sodium, measured in milligrams, that the federal government recommends people eat every day. In 2010, the government
lowered this target for people who are especially vulnerable to the hazards of salt: people fifty-one years or older, blacks of any age, and anyone with diabetes, hypertension, or chronic kidney disease.
These 143 million people—a majority of American adults—were now being urged to keep their sodium intake below 1,500 milligrams a day—less than a teaspoon a day.

With these lower limits in mind, it is easy to see why most of us are getting far more sodium than we should, with teenage boys and men averaging twice as much. The labels on foods in the grocery store tell the story. And going natural is no help when it comes to salt; even health-conscious manufacturers deliver heavy doses. Amy’s Organic Minestrone Soup has 580 milligrams of sodium in a cup. Newman’s Own Organic Pasta Sauce has 650 milligrams in half a cup. In perusing an expansive supermarket in New York City, my personal favorite was a frozen roast
turkey dinner from Hungry Man. Salt made nine separate appearances in the list of ingredients on the side of the box, more than any other item. Helpfully, the list broke the dinner down into all of its parts. Not only did salt appear in the meat component, the gravy, the stuffing, and the potatoes, it was also the leading ingredient in something called “turkey type flavor” and ranked near the top in another mysterious component called “potato flavor.” In all, the sodium in this microwavable dish came to 5,400 milligrams, which is more salt than people should eat over the course of two days. Unless, that is, the people are baby boomers or older, black, or suffering from sodium-sensitive disease. In this case, the Hungry Man dinner would deliver enough salt to meet their quota for half a week.

T
o understand why anyone would want to eat three and a half days’ worth of salt in a single sitting, I turned once more to Monell. This time, however, instead of delving into the bliss points for sugar and fat, I met with its scientists to go over their pioneering work on salt. The lead researcher who performed the shaker study had since moved on to another subject, the mouthfeel of fat, but the center now had one of the foremost authorities on salt. His name is Paul Breslin, and he is a biologist trained in the field of experimental psychology. When he is not conducting research at Monell, he is forty-five miles north in Princeton Junction, New Jersey, where he teaches and runs his own laboratory at Rutgers University. I arranged to meet him there. Breslin’s lab included a typical tasting room, which was divided into stations where test subjects are given a seat and asked to sample food or drink in order to test their likes and dislikes. In a smaller, adjoining space, he was completing the construction of something a little more unusual in food-science circles: Here, in a large metal cabinet that looked like a refrigerator (except the temperature was set to 77 degrees), Breslin was incubating fruit flies, which have proven quite useful in exploring the mysteries of salt. The genes of flies can be manipulated rapidly, allowing scientists to home in on particular traits. Moreover, their tastes are surprisingly similar to those of humans.

“Most of the things we love, they love, and most of the things we hate, they hate,” Breslin said. “We both like fermentation, and they love wine, beer, cheese, vinegar, bread. That’s why they are in our kitchens.” Fruit flies also like modest levels of salt in their food. The manipulation of their genes has helped scientists identify the cellular mechanism by which our own mouths detect salt. More recently, Breslin has been studying the flies not for the mechanics of
how
people taste salt but for clues on
why
we love it so much.

It is, after all, just a dumb, white rock that gets dug out of the ground or drawn from the sea.

Breslin is a food scientist who loves the food he studies and thinks deeply about the food he loves. Like some of his colleagues at Monell, he
is not shy about poking the giants of the food industry. His own pet peeves include the low-calorie lines of ice cream that companies make for people who want to lose weight, which Breslin believes only encourages them to overindulge.
“I think the interest in making a low-fat, low-sugar ice cream, which is almost oxymoronic as far as I’m concerned, is to allow people to eat four gallons a day,” Breslin said. “That’s not what ice cream is designed for.” He eats ice cream for what it is, a treat to be relished in small amounts. Then again, he has a lean build and seems in control of any compulsions to overeat. His latest infatuation—as a scientist and an eater—was the oil pressed from olives. In its finest, most expensive grades, olive oil will provoke a sting or itch at the back of the throat, which Breslin has been studying for its similarities to the irritation caused by ibuprofen, the anti-inflammatory drug; anti-inflammatory compounds, whether in drugs or foods, may prove to be effective in preventing disease. Friends started sending him expensive bottles—not to test, however, but to consume, because he also discovered that he loved olive oil for its taste. Sometimes he sips it straight, without even a hunk of bread, which only gets in the way of the bouquet.

What Breslin loves most, however, is salty food. We drove to a Greek delicatessen near his lab to pick up lunch, and ended up gorging on the stuff. The feta cheese was swimming in salt; the spinach pies were loaded too. “You should try one of these so you know what I’m talking about,” he said, pointing to a bowl of cracked green olives. “They’re my all time favorites.” The grocery clerk handed me one, soaked in a garlicky, deeply salty brine that was, indeed, amazing. I could see the joy in Breslin’s eyes when he got one of the olives to taste. “I used to be someone who is borderline hypertensive, and so I was told to worry about it,” he said. “But my blood pressure has been perfectly normal for a long time now, and so I pay no attention to it. I love salty foods. I don’t know if it’s just because of the psychological reward of eating something that’s truly yummy, or if it’s physiological in terms of salt doing something for me. But my personal perception is that when I eat these foods I actually feel
better
. I don’t mean
feel better in that I feel like I’ve been exercising and feel, like, vigorous. I just feel better, like you would feel if you had a small dish of your favorite ice cream.”

Back in his lab, where we got down to the science behind all that pleasure, it became clear that much about salt’s powers of allure remains a mystery. The very idea of salt inducing feelings of joy seems crazy, given that it is just a mineral, dead and devoid of any sustenance. Sugar and fat, by contrast, come from plants and animals and are loaded with the calories people need to avoid withering away. It makes sense that when scientists slide someone into an MRI scanner and drip a sugary or fatty solution into their mouth, the electrical circuit in their brain lights up and floods them with feelings of pleasure. This stimulus, we know, comes from the part of the brain that rewards us for doing things that keep it alive or perpetuate the human race. Things like eating and sex.

Salt is not entirely worthless, of course. It does contain sodium, whose importance to our well-being should not be overlooked. In 1940,
researchers reported the case of a child who had a condition that diminished his capacity to absorb sodium. He needed massive amounts of salt to survive, and he knew this instinctively. One of the first words he could say was “salt.” At age one, he was licking salt off his crackers. Later, he ate it directly from the saltshaker. His parents and doctors were clueless about his condition, however, and during a prolonged hospital stay, the boy could get only foods that were low in salt, and he died. Even in not so dire a case, a diet lacking sufficient sodium will cause trouble, researchers have found. Rats develop less bone and muscle mass, have smaller brains. Still, most people need only tiny amounts of sodium, which makes it all the more difficult to understand why the vast majority of people are so prone to eating massive amounts of the stuff.

Part of the explanation for this goes back to the tongue map, the diagram that purports to show that we taste sugar only at the tip of the tongue. Likewise, this same map depicts salt as having a very limited zone—the edges of the tongue, and only toward the front, at that. The map, however, is as wrong on salt as it is for sugar. We taste salty foods like we do sweets,
throughout the mouth. “Anyone can demonstrate this for themselves at home,” Breslin told me. “All you have to do is take some lemon juice, honey, cream off your espresso, and a solution of table salt, and stick the tip of your tongue in each of them. You’ll get sour, sweet, bitter, and salty, all on the tip on your tongue, which right there smashes the tongue map.” The taste for salt doesn’t end at the tip of the tongue. People are one big sponge for the salty taste. As there are for sugar, the body has receptors for detecting salt that go all the way through the mouth and down to the gut.

All this hardwiring for the salty taste would seem to imply that the body wants to make sure it gets a lot of salt. If we were not able to taste it so easily, and if salt were not so alluring, who would be bothered to rummage through the kitchen cabinet for those pretzels? People would stick with the sugary and the fatty. This desire for salt seems to have some grounding in evolutionary history. When everything lived in the ocean, animals had no problem getting the sodium they needed to survive. They wallowed in salty water. On land, however, the early climate was hot and dry. The pre-human mouths that crawled out of the sea may have developed the salty taste receptors as a means of ensuring that their owners didn’t forget about salt when they foraged for food.

It’s plausible, certainly. But people today aren’t merely remembering salt; they’re devouring it. Thus, the Hungry Man turkey dinner, with its half-week load of salt. Or the popcorn at Yankee Stadium that was so heavily salted one recent afternoon, I had to miss parts of two innings, the first waiting in line for the popcorn and the second getting drinks for my kids to un-kink their throats. The cravings we get for certain foods are a topic that none of the food companies supporting Monell are eager to raise. But Breslin not only freely discusses food cravings, he doesn’t hesitate to link salty foods to an even more dicey subject: drug abuse.