by Hope Jahren
These signals, rooted in evolutionary biology, have given rise to a paradox of malnourishment amid a global abundance of food. In many countries, including England and the United States, poor diet now rivals smoking as the greatest public health risk. Malnutrition does not necessarily mean lack of food, but rather lack of proper nutrients. You can eat five meals a day and qualify as malnourished. (Case in point: Morgan Spurlock’s near-lethal experiment in Supersize Me.) When it comes to certain nutrients, in fact, an estimated 80 to 90 percent of obese individuals are malnourished. (The same percentage holds for nonobese individuals.) Globally, more than 600 million adults and 42 million children under the age of five are obese. Alongside the rise in weight, we’ve seen a corresponding increase in diabetes, heart disease, and a host of other diet-related problems. In the United States, more than a quarter of the population suffers from some form of metabolic syndrome or illness. Nutrition in many ways is the great public health battle of our times.
It’s more than just the descent of man, of course. Modern society often perceives health and flavor as mutually opposed. In England, I met Jozef Youssef, an energetic 34-year-old chef who splits time between research collaborations with psychologists and running Kitchen Theory, a London pop-up restaurant where he tests various scientific findings on small groups of diners—including ways to make “healthy” and “tasty” seem complementary rather than antagonistic. Youssef cited the example of a green smoothie. “We see it and we think, it’s good for you but it’s probably not enjoyable,” he said. “Why is that?” (This also works the opposite way lately, as people have been questioning exactly how healthy the overpriced green smoothies are at Whole Foods.) A study published this year in the Journal of the Association for Consumer Research found that people tend to feel less full and eat more after consuming a food they perceive as “healthy,” even if it’s identical to one that is marked as unhealthy. For example, they will feel hungrier after a “healthy” cookie—and go on to eat more overall.
In this way evolution and socialization are locked in unending conflict, nature and nurture conspiring to produce ever-increasing consumption of less-than-ideal foods. And indeed, past efforts to replace the salt-sugar-fat trifecta with healthier equivalents haven’t been successful. Think margarine instead of butter, saccharin replacing sugar, artificial polymers (macromolecules synthetically created in a lab) replacing the fat content of milk or ice cream. It’s your low-fat frozen yogurt, diet soda, the 100-calorie snack pack. The results, from a flavor perspective as well as a dietary one, have been underwhelming. Instead of curbing obesity and metabolic disorders, these innovations seem to have resulted in the opposite. This may, of course, be correlation rather than causation, but still—and perhaps worse—some of the substitute substances haven’t proven to be as healthful as first suggested. Companies scrambled to scrub margarine from their recipes after research showed that it was actually more harmful than the butter it replaced, while recent work from people like Dana Small, a neuropsychologist and physiologist at Yale, highlights the metabolically disruptive effects of artificial sweeteners, even ones derived from natural substances, like Splenda.
What’s more, many (most? all?) low-fat and low-sugar products don’t taste good, aren’t eaten as often as their sinful counterparts, and end up a bust both nutritionally to the customer and financially to the producer. And the consumption of the real thing keeps rising. Sugar was first introduced to the Western palate via New Guinea about 10,000 years ago. By 1800, Americans were consuming an average of seven pounds of the powder a year. Today our consumption tops over 100 pounds. (By way of comparison, we eat about 50 pounds of beef.) Though we are drinking less soda than before—2012 production was 23 percent lower than a decade prior—people are still taking in 30 gallons of regular soda per person each year, according to New York University professor and public health advocate Marion Nestle. And things like diet soda seem to have a reverse psychological effect: new research suggests that tricking your brain into thinking it has consumed calories when it hasn’t can, over time, have a host of negative metabolic consequences, as the connection between the energy signal of sweetness and its actual energy content decouples. And so you consume more, and even worse, you want to keep consuming more (the dreaded sweet tooth).
Why should neurogastronomy be different? Why would it succeed where basic physiological nutrition has failed? Part of the answer stems from the insight research has given into how exactly our bodies derive energy and flavor signals from food via the brain. It’s not about calories—that is, eliminating calories in the manner of artificial sweeteners likely won’t work. Instead it’s a far more complex process of taste perception. It’s a growing understanding that psychology plays a more central role in the experience of eating than previously thought, a realization that we need to be fooling the brain, not the body.
In 1936, H. C. Moir, an analytic chemist from Scotland who had worked at a baked-goods factory, presented what may be the earliest findings that show just how much our brain affects taste. He had people eat incongruously colored jellies—green-colored orange, red-colored lemon, and the like. He then had them taste chocolate-colored sponge cakes, one of which was imbued with cocoa and the other with vanilla. Only one person was able to correctly identify each taste in the two tests—and over half got more than 50 percent of the answers wrong. Some of the answers given for the orange candy: almond, strawberry, blackcurrant, and pineapple. For lemon: cherry, raspberry, strawberry, damson. Some tasters thought the chocolate biscuit was vanilla, and the vanilla chocolate, while others volunteered coffee, orange, or even unflavored.
“The majority of those who came below 50 percent went to great pains to assure me that they were considered by their wives or mothers, or other intimates, to be unduly fastidious about their food, and were invariably able to spot milk turning well in advance of any other member of the household,” Moir wrote. “Consequently, it was obvious that the method of testing was at fault, and not the palate being tested. Further, many brought in a plea of individual idiosyncrasy in that they did not like table jellies etc., but comparatively few made this plea before the test.”
When it comes to the caloric content of food, our brains aren’t easily fooled. You can, it turns out, engineer all the low-fat polymers and artificial sweeteners you want, but they will likely not make us eat fewer calories or gain less weight: our brain is too smart for that. In one study, de Araujo genetically engineered a group of mice so that they would no longer taste sweetness. The receptors that signal “sweet” to the brain simply didn’t function. He found that though they started off indifferent to sugar, the mice soon learned that when they were hungry, it was better to consume a solution with sugar rather than one that was all water. They had no way to distinguish the two from a sensory perspective—tastewise, to them, they were identical—but somehow their brains learned where the energy source lay. Soon the rodents were consuming just as much sugar as nonmodified animals. The effect was completely absent with artificial sweeteners. In another study, de Araujo followed up with a group of regular mice. This time the mice were offered two sweet solutions, one with sugar and one with artificial sweetener. The solution with the sweetener tasted sweeter—and so one would think would be the more attractive of the two. And indeed, for the first day the mice consistently drank the sweeter water. But then something happened: they began to ignore the artificial sweetener and instead focused exclusively on the real sugar solution. “Somehow the brain knows when something is purely sweet and good-tasting versus when that good taste comes along with energy,” de Araujo said. In other words, we have two separate systems that signal the value of food. It’s not just about taste; it’s about how taste is incorporated into our brain’s reward system. And artificial substitutes—ways of lowering calories while keeping their sensory qualities—simply do not work. The brain isn’t fooled. It knows real calories from the taste of calories.
Research like de Araujo’s doesn’t just show us wha
t won’t work: it suggests what might work instead. The deeper understanding of sensory integrations gives an alternative approach to making nutritional changes to the diet: alter rather than substitute. Use real sugar, real energy, real fats and salts and the whole gamut of flavor, but do so in lower quantities, in a way that makes the result taste good and sends actual energy signals to the brain, creating an experience that is both psychologically and physically satisfying.
On my wander through the boroughgroves at the Fat Duck, my dish wasn’t just a plate of food. It came with an abundance of theatrical effects, all of which served specific functions. My hearing was engaged—the crackle of the ground and rustle of leaves. My vision—not just the beauty of the plate but the forest mist, the mini-terrarium, the variegated effects of the lighting. (“Unique to each table,” Blumenthal pointed out. Each diner’s lighting is calibrated depending on where she finds herself on her journey at any given point.) My smell—both when I first inhale the earthiness (via orthonasal smell, or what we typically think of as smell) and after I put the first bite of the powdered-mushroom log into my mouth and exhale (by way of retronasal smell, or, as Shepherd explained, “the smell that comes internally, from behind, from our mouths into our nasal cavities”). My touch—the texture of the smooth mushroom, contrasting with the roughness of the faux bark, the crispness of the greens, the creaminess of the truffle butter. Even something I don’t usually think of as a sense—my memory—combined to put me in mind of memories of family walks through the woods. The idea is that due to the multisensory pleasure of the experience, not only will I enjoy the dish more, but I will feel more satiated after having eaten less. “When you first see it you think this guy’s taking the piss,” said Francis McGlone, head of the Somatosensory and Affective Neuroscience group at Liverpool John Moores University and until recently head of the food neuroscience research group at Unilever. “There’s nothing on the plate but these small portions. But you won’t leave the restaurant hungry. Because there’s so much complexity, in terms of textures, colors, tastes; it’s almost symphonic. You reach satiety faster.”
Fast food is so addictive because salt, sugar, and fat never appear together in nature. Try to imagine a naturally occurring food that is fatty, has high amounts of sugar, and is salty to boot and you’ll come up short. And so, strongly reinforcing neural pathways that were only ever meant to fire in isolation, to tell us that a food is worth eating, now activate all at once, creating an enticing, addictive cascade that is greater than the sum of its parts. In a sense Blumenthal’s approach is doing the same thing—only using complex psychological flavor rather than purely physiological taste reinforcement.
One basic approach to this focuses on actual changes to the composition of food—ways of cooking different substances that make them taste sweeter, saltier, or spicier than they actually are. A favorite of Blumenthal’s, which he has used successfully in the Fat Duck for more than a decade, is a method called encapsulation, in which he presents a flavor in a way that makes it seem far larger than it is. “If you think of a cup of coffee made with one ground bean, that would be really insipid,” Blumenthal suggested. But if you crunch a bean in your mouth, you suddenly have a much stronger coffee flavor, even if the cup itself is quite weak. A single whole bean can deliver a greater flavor punch than multiple beans that have been ground and brewed. The same thing happens with a spice, like coriander. Add a few seeds to a dish rather than grinding them, and suddenly the flavor becomes much more intense, even though the overall quantity of coriander goes down. “Every so often your mouth crunches one and there is an explosion of flavor that makes it much more interesting,” Blumenthal said.
With an encapsulation approach—a few strong bursts rather than dispersed flavor—Blumenthal has successfully reduced the salt content of multiple dishes in his restaurants. The final taste experience is just as salty overall, even though the amount of sodium has been reduced. It’s a method that one could see playing out in mass-produced items, including your beloved Doritos, fast-food fries, snack bars, cereals, even packaged meals that rely on large doses of sodium to deliver post-frozen taste. “You have fewer, larger grains of salt, and suddenly you can deliver the same flavor, but with less,” Blumenthal told me.
Barry Green, formerly at the Monell Chemical Senses Center in Philadelphia and now at Yale, accomplishes something similar through heat. A psychophysicist—someone who studies how physical sensations get interpreted by the brain—Green has worked on the way the thermal sensitivity of the mouth—that is, our perception of hot and cold—can affect a food’s flavor. Temperature, and specifically temperature change, can influence how sweet we think something is. Fifteen years ago, while Green was working at Monell, a University of Michigan study found that some of the taste fibers (specialized nerve cells) in the chorda tympani nerve, one of the three cranial nerves responsible for sending taste sensations to the brain, were sensitive to temperature. The nerves responded to warm liquids much as they did to sweetness—even when there was no sugar present.
In a later study Green called this phenomenon “thermal taste”: temperature that evokes a flavor. We have fibers that get excited when we warm them up, which might make a food or liquid taste sweeter than its sugar content warrants. One way to think about it is to picture yourself licking an ice cream cone. The initial cold taste isn’t nearly as sweet as the flavor of the warmed ice cream once it’s back in your mouth. That finding has immediate implications for a multitude of foods. One easy way to get a sweet kick: take sodas, juices, fruit, and whatever else out of the refrigerator.
One of Blumenthal’s signature dishes at the Fat Duck is a rabbit “tea”—actually a velouté of rabbit—that is both hot and cold. A specially engineered gel keeps the two sides separate until poured. The result is disorienting: your tongue is hot and cold at the same time. The flavor is intense, the pleasure surprising—and the relatively lower levels of seasoning needed to deliver a flavorful experience perhaps most surprising of all.
While it’s difficult to imagine the packaged-food equivalent of dual-temperature tea, the same effect, Green pointed out, can be attained by warming something that is cold or by cooling the tongue itself so that the same food tastes relatively warmer. Two things happen physiologically when the sensation of either warming or cooling hits the tongue. In the first case sweetness increases, while in the second the perception of saltiness becomes more intense. In 2010, Campbell’s Soup had something of a PR disaster when it announced that it had lowered the sodium content of its soups. Customers protested that the reformulated versions didn’t taste as good, and sales fell. Yet imagine the exact same reformulation but with the introduction of, say, a chilled soup like gazpacho. The cooling would create an enhanced salty flavor, and the soup might replace less healthful alternatives. Knowing some of the thermal principles involved in flavor perception may enable Campbell’s to create tweaks not just there but to its hot soups, in ways that reduce sugar and salt but enhance flavor.
Another, potentially broader area of experimentation comes from olfaction. Our brains form associations between smells and tastes that in turn affect both how much we like a certain food and our bodies’ anticipated response to it (how our brain prepares the rest of the system for the calories it thinks it’s going to consume). Those associations can then be used to trigger the reward system even when the perceived reward is smaller than the actual one. Take vanilla. Vanilla isn’t actually sweet. It’s quite bitter. But in the Western world we have come to associate it with sweet foods, and so to us it signals sweetness. When we smell it, our sweet receptors go on high alert—and the food we eat tastes sweeter than it otherwise would.
I have to imagine that some of the pungency and sheer fungal intensity of my mushroom dish comes from the olfactory tricks that punctuated it. The fog that spread over the table wasn’t just visual: it spread the scent of the moss. Throughout the meal, I could tell without looking when another table had gotten to this particular point in th
e dinner. The scent heralded its arrival better than anything else could. The mushroom powder on the plate further reinforced and carried the scent, so that by the time I took a bite, all my taste buds were primed for the resulting flavor. A few weeks later Blumenthal told me he still wasn’t completely happy with the dish. “We’re still working on creating the perfect smell of the woods,” he said.
Part of my pleasure from the mushroom dish doubtless derived from the childhood associations I carry with its taste—mushroom-picking with my grandfather, cooking up big skillets of freshly gathered mushrooms and onions in the early fall with the whole family. (We’re Russians, after all.) But to someone for whom that affinity is absent, or even reversed, the techniques could have detracted from rather than enhanced the experience, by concentrating the flavor so intensely. Likewise, to a non-Western palate, even something that seems as straightforward as Blumenthal’s proposed vanilla addition might backfire. Some Japanese pickled foods contain an almondlike aroma, for example, while sweet almond desserts are mostly absent. The implication here is that taste-smell associations—and the resulting preferences in food—can be changed from experience. Yes, some taste is innate, but the way we perceive it psychologically is a learned process, one that starts in the womb. In one study newborns whose mothers had eaten food with anise during pregnancy enjoyed its scent more than those with mothers who had not. Children of mothers who drank milk flavored with carrots while pregnant were more likely to eat carrots. Adults, unlike children, are far better positioned to make mindful food choices. The fact that associations between basic tastes and nonbasic smells develop so early could become a powerful way to subtly change preferences along more nutritious lines.
In the 1970s, UCLA psychologist Eric Holman discovered that certain sweetened substances could make rodents prefer certain foods by virtue of their presence. For instance, by adding a saccharin to either a banana- or an almond-flavored solution, he was able to make rats prefer the taste of bananas or almonds, respectively, a process known as “flavor nutrient conditioning.” In recent years that work has been picked up with humans. Maltodextrin, a glucose polymer, is imperceptible to most of us. It doesn’t taste sweet. In fact, it doesn’t taste like anything. For it to activate the sweet receptors in the brain, the body must first break it down into glucose. If we mix it into another food, we don’t realize there’s a sugar present, but we still develop a preference for that flavor. In one study, people who tasted foods with maltodextrin mixed in would reliably choose the flavor that had been associated with the polymer in subsequent tests. They had been trained to prefer one food over another by a sort of sensory trickery. Imagine dusting a child’s broccoli florets with maltodextrin and transforming a disliked vegetable into a favorite. Ethically questionable, yes. But also potentially quite effective at nudging children toward healthier choices at a sensitive period in life when many such choices are first formed. The end result would be a society that makes better, more nutritious choices without seeing them as a necessary evil or sensory tradeoff. Broccoli would be a preferred taste, a food you choose because you’ve learned to enjoy it and find it inherently rewarding. When you went to reach for a snack, a broccoli crisp would be just as, if not more, enticing as a potato chip. “If we can find out how to do that on a large scale,” de Araujo told me, “we could completely change diet.”
