Salt Sugar Fat: How the Food Giants Hooked Us (42 page)

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.

T
he notion that some foods behave like narcotics goes back at least twenty years in scientific circles.
One of Breslin’s favorite papers was published in
1991, the same year as the saltshaker study. It was written by a professor of psychiatry at the University of Cincinnati named Stephen Woods, who compared eating to taking narcotics. Both, he wrote, pose a considerable challenge to the body’s fundamental goal of staying on an even keel. This balancing trick is known as homeostasis, and eating, like doing drugs, throws things out of whack. “Ultimately whatever you eat ends up in your blood, and our body wants the blood levels of everything—from carbon dioxide to oxygen to salt and potassium and lipids and glucose—to be constant,” Breslin said. “Probably our bodies would be happiest if we could never eat and just somehow magically be able to have some intravenous drip or something that would maintain those things constantly. When you eat, you’re pushing all kinds of stuff into your blood, which goes against the concept of homeostasis, so your body basically responds to that by saying, ‘Holy smokes, what are you doing to me? I have to deal with this now.’ You have to get yourself back to some constant homeostatic level. Insulin is one of the things you release to push sugar out of the blood and into the cells. This is exactly what happens when you take drugs. When you inject heroin into your body, your body says, ‘Holy cow, what have you done to me?’ It has to try and metabolize these things, and there’s all kinds of coping mechanisms for that.”

The blood gets especially besieged when processed food is ingested, flooding the system with its heavy loads of salt, sugar, and fat. But where the links between eating and drugs get really interesting is in the brain. There, narcotics and food—especially food that is high in salt, sugar, and fat—act much alike. Once ingested, they race along the same pathways, using the same neurological circuitry to reach the brain’s pleasure zones, those areas that reward us with enjoyable feelings for doing the right thing by our bodies. Or, as the case may be, for doing what the brain has been led to believe is the right thing.

One of the most intriguing accounts of salt’s effect on the brain appeared in a 2008 paper by researchers at the University of Iowa entitled, “Salt Craving: The Psychobiology of Pathogenic Sodium Intake.” In lay terms, this translates to the craving people get for salt at levels so high it
causes disease. The authors reviewed all the brain scanning and other scientific investigations that had been done on salt to date, and they concluded that salt could be lumped with other things in life that become problematic when overdone. Salt, the authors concluded, was similar in this way to “sex, voluntary exercise, fats, carbohydrates and chocolate, in its possessing addictive qualities.”

For obvious reasons, the word
addiction
is a particularly touchy subject among food manufacturers. They prefer saying a product is crave-able, likable, snack-able, or almost anything other than saying it is addictive. For them, the term
addiction
conjures images of strung-out junkies who hold up 7-Elevens at gunpoint for the money they need for another fix. Addiction also raises barbed legal issues that industry is loath to engage. In reality, processed food is so inexpensive and easy to procure that no one need rob a convenience store for a fix—never mind the fact that the convenience store itself, in this case, is the dealer of the fix.

In 2006 a law firm whose clients included both tobacco and food manufacturers produced a remarkable treatise on the legal fights the processed food industry might face if people tried to hold them accountable for the obesity epidemic. The authors conclude that the food industry overall is in good shape legally, that the strategy used in suing tobacco manufacturers wouldn’t work nearly as well on food manufacturers. But a large section of the report is devoted to the subject of addiction, and the authors labor to identify a strategy that companies could use to persuade a jury that food isn’t addictive. In the end, they don’t deny there are parallels between overeating and drug abuse. They argue, instead, that the word
addiction
traditionally has had defining qualities, such as the severely painful symptoms of withdrawal, that are not readily applicable to the desire for food. “Labeling the perceived overconsumption of chocolate, for example, as ‘chocolate addiction,’ even if this practice is associated with high levels of comfort (emotional) eating and somewhat unstable eating patterns, risks trivializing serious addictions,” they write.

Paul Breslin frames the question of addiction a little differently. When people abuse drugs long enough, he noted, the motivation to take more
drugs becomes less a matter of wanting the benefit of the drug—the high—and more a matter of wanting to avoid the awful feeling generated by the craving itself. Similarly, when people start feeling hungry, they are not seeking the primary benefit of food, the calories needed to keep them alive. Rather, they are responding to the body’s signal that it does not ever want to be put in the position of
needing
to eat. Most people in America never feel true hunger pain, the gut-wrenching result of being starved for nutrition. Consider how often people say they feel hungry during a single day, Breslin said.
“With few exceptions, we can go a day without food or water with no problems whatsoever. The body has enough calories. But people who fast for a day feel awful. Your body comes to expect that we will feed it, and it has all these mechanisms in place so if you don’t do it, then you start to feel awful. Ultimately you end up feeding yourself in order to feel okay.”