The Science That Could Make You Crave Broccoli More Than Chocolate

In a room filled with bean-bag chairs and crayon drawings at Philadelphia’s Monell Chemical Sciences Center, Nuala Bobowski doles out two shots of sugar water. One has the average concentration preferred by adults, the other a concentration preferred by kids. There’s a twinkle in her eye as she waits for me to taste them and guess which is which. One is so sweet that it makes me sputter and gasp. That’s the one most 5- to 15-year-olds like. It has more sugar than a can of soda.

I shouldn’t be surprised. Kids love pushing aside their bitter veggies at dinnertime and reaching for desserts instead. It’s a preference that’s biologically ingrained. In some ancient corner of the human brain, bitterness triggers warning signs of potentially poisonous plants, while sweet taste is a signal for energy and calories, says Bobowski, now an assistant professor of exercise and nutrition science at St. Catherine University in St. Paul, Minnesota. “Thousands of years ago, liking for sweet taste would have conferred an advantage for survival.”

Today, however, these biological preferences get us into trouble by encouraging diets linked to increasing rates of obesity and disease. One might think that a trick like genetically modifying bitter vegetables to taste sweeter could solve the problem, but that would only increase cravings for sweet food, the way artificial sweeteners in sodas do. Still, there may be a solution. A new field wants to change how people perceive the flavor of food itself. By rewiring our brains into thinking that broccoli tastes more delicious and chocolate cake less so, this approach, known as neurogastronomy, may have found the secret to nudging people into eating more healthily. It may even help patients who’ve lost their sense of taste or smell enjoy their food again.

Neurogastronomy takes a multidisciplinary approach to food, blending the expertise of scientists, chefs, clinicians, and agriculture professionals. The field is led, in part, by the University of Kentucky neuropsychologist Dong Han and the acclaimed Montreal chef Fred Morin. Together, they launched the International Society of Neurogastronomy and held its inaugural meeting in 2015 to encourage pioneering research between the scientific and culinary worlds. Now, the fledgling society has attracted funding from the National Institutes of Health.

“[Neurogastronomy] brings together people from very different fields that are typically victims of being in our own silos and limiting our thinking to in-the-box thinking,” says Han “We’re attempting to really challenge each other and apply our science and our craft to address global questions in health.”

The basic premise of neurogastronomy is that food flavors are created in the brain, as a product of information from all our senses. The Yale neuroscientist Gordon Shepherd coined the term neurogastronomy in 2006 when he first realized how important odors were in generating particular flavors. Odors are what give a steak its distinct smoky flavor, and make it different from the char-grilled flavor of chicken, he explains. If you bite a juicy ribeye, some of its molecules bind to taste receptors on the tongue—giving the basic sensations of sweet, salty, sour, bitter, or umami—while other, more volatile odor molecules waft up the back of your mouth into your nose. This retronasal smell signal merges with taste signals in the brain’s orbitofrontal cortex to give a more complex sense of flavor.

Most people are unaware of this blending of signals, Shepherd says—until they get a cold or sinus infection and everything seems to have the same bland flavor.

Chefs have been intrigued by flavor creation for years. Many have dabbled in molecular gastronomy, a close cousin of neurogastronomy that approaches flavor from a purely chemical perspective, trying to understand how different ingredients and cooking reactions change the way food molecules interact. Neurogastronomy looks at flavor from a different angle: It considers how those molecules are interpreted in the brain and how they influence brain regions that control emotion, memories, food preferences, cravings, and appetite.

For the Atlanta-based pastry chef Taria Camrino, that means consciously mixing and layering ingredients in ways that will help trigger certain emotions in people when they eat. “The taste has to rest on their palate a particular way, and the smell has to layer over the food and it has to remind someone of an experience,” she says. Different ingredients’ textures and temperatures, the color of the plate they’re presented on, and the ambience they’re presented in have all been found to influence how people perceive food flavors.

For clinicians, a better understanding of smell has led to new ways of improving the quality of life for patients with Alzheimer’s disease, Parkinson’s, epilepsy, and traumatic brain injury, as well as for those undergoing cancer treatment. It’s a common complaint that these patients experience degraded senses of smell or taste, but “a lot of the times smell and taste is not carefully looked at or assessed [in treatment],” says Han. Others have lost their sense of smell because of congenital anosmia or childhood head trauma. In America, more than 13 million people suffer from some form of olfactory dysfunction, according to a National Health and Nutrition Examination Survey (NHANES).

In December, researchers and culinary professionals including Han and Camerino teamed up at the neurogastronomy symposium in Lexington, gathering inside the University of Kentucky campus kitchens, to create meals for people with smell or taste loss. They personalized dishes based on details about how chemotherapy may have affected patients’ ability to produce saliva or swallow, for example. And they used culinary insights about textures and other factors, like pungency, that may still be able to trigger some sensations to help patients regain the desire to eat.

In the lab, too, neurogastronomy is helping scientists focus their research on ways of helping patients. “So much of research is on animal models, trying to understand mechanisms, that it’s easy to get lost in the details and not think about the overall impact and directions that one ought to work in,” says Tim McClintock, a scientist who specializes in olfaction at the University of Kentucky. He’s developed a new test for identifying individual receptors and nerve cells in the nose that respond to specific odors. Ironically, it only works in mice, but McClintock believes it could lay the groundwork for a map of human olfaction, making it a lot easier to manipulate a person’s sense of smell and, therefore, flavor.

Mastering flavor is no easy task. There are more than 400 smell receptors in the human nose. Each can respond to multiple different odor molecules, and each type of odorant can also activate multiple receptors. Taste receptors are fairly complex, too. For one, researchers have found taste receptors in the lungs, intestines, and pancreas, which they suspect encode information about metabolism. And recently, researchers have proposed that humans have receptors for tastes other than the five basic ones; fat and calcium are among the leading candidates.

But as neurogastronomists discover more about the complexities of flavor and how it affects people’s brains and behavior, they’re learning how to improve diets on personal, cellular, and even genetic levels. The good news is that inborn taste inclinations are not immutable. Indeed, researchers have demonstrated that not only does a childhood preference for high salt and sugar decrease with age, as Bobowski showed me with her two sugar-water shots)—it can also decrease in adults through repeated exposure to less salty food. And according to a 2015 French study, individuals can be retrained to like less fatty foods too.

Sweet and bitter preferences are harder to shift, says Bobowski. But given more research and implementation beyond the test kitchens, neurogastronomy may finally provide a nutritional intervention that works.