Brain food for thought

The science of neurogastronomy digs deep into our brains to alter our perception of flavour and the way we enjoy food

Most people think taste buds in the mouth are the reason eating and drinking are a pleasurable (or sometimes repugnant) experience. However, these tiny bundles of nerves are responsible for only part of the show. Taste buds provide just a single-note experience of what we consume.
When a person eats something, the information from smell, taste, hearing, sight and touch all merge in the orbitofrontal cortex, the central processing centre for the five senses. These bits of information incorporate to form the brain's perception of flavour. A useful exercise is the "nose-pinch test," says Dr. Gordon Shepherd, a professor of Neuroscience at the Yale School of Medicine. Try pinching your nose shut and then putting a fruit-flavored candy in your mouth. Chances are, you'll experience only its sugary sweetness, not its bright, distinguishing flavour (such as orange, cherry or strawberry). "But when you un-pinch the nose, immediately the full flavour that was built into the candy comes flooding into the brain," says Shepherd. In other words, the brain creates flavours.
"Food has the elements on which the brain works to create what we sense and call flavour, and that attracts us to the food," Shepherd, who has studied the olfactory system since the 1960s, says. That's an adaptation that keeps us alive: Homo sapiens eat because food tastes good. "I began to realise that humans maybe specially adapted for the flavour of the food they eat," he adds.
Shepherd's decades of work have led the way for a growing field of neuroscience research called "neurogastronomy" (a term he coined for a paper in Nature), which seeks to understand how all five senses are involved in flavour perception - and what it means when that ability degrades.
Dan Han, chief of University of Kentucky's neuropsychology services, says a patient once came to see him because he was suffering from taste and smell loss. The man had already consulted a dozen physicians, and none could explain why his cheeseburgers taste like aluminum foil and orange soda like a weird mixture of fizz and gasoline. Six years before, the man had sustained mild brain trauma from a car accident that damaged the smell section - the olfactory bulb - in his brain.
Han first got turned on to the power of taste perception in 2012, when he travelled to Montreal for a conference. When Han, a foodie, asked around for dinner recommendations, everyone suggested Joe Beef, a high-end gastropub, which was among Anthony Bourdain's recommendations, and one of Pellegrino's 2015 top 100 restaurants in the world. Han and his fellow neuroscientists were unable to sit down to dinner until 10 pm, due to a mix-up with reservations. By then, the kitchen was beginning to wind down, and co-owner and co-chef Fred Morin was making his rounds in the dining room. Morin, it turned out, is fascinated by neuroscience. Before the group knew it, the chef was seated at the table, and talking about the brain. He'd recently bought a copy of Shepherd's book Neurogastronomy: How the Brain Creates Flavor and Why It Matters, after a recommendation from his physician.
Morin and Han realised there could be an opportunity to collaborate. Both wondered what would happen if you put the world's best neuroscientists and culinary experts together. Could that benefit people suffering in silence at the dinner table? It was a novel idea, says Morin. The two made a deal: If Han could get the clinicians and scientists interested, Morin would bring the chefs. Two years later, Han, Morin and others in culinary arts, food science, agriculture and medicine formed the International Society of Neurogastronomy. Based on the pioneering work of Shepherd, the group's stated mission is to "advance Neurogastronomy as a craft, science, and health profession, to enhance quality of human life, and to generate and disseminate knowledge of brain-behaviour relationships in the context of gastronomy."
Morin has also developed a sort of prescription for tailoring meals to suit the taste- and smell-challenged. At the symposium, Morin and other chefs demonstrated: he took a bland potato soup, an archetype of the slop served to a convalescing patient in a hospital, then fancied it up with some greenery and chicken skins seasoned with barbecue spices. He has a clear vision of what works best to help those with taste and smell loss keep their appetite. For example, the emphasis should be on preparing foods with a pleasing texture. He serves a soft meat with plenty of connective tissue and collagen, such as slow-braised lamb shoulder. He also avoids ingredients that contain chemicals responsible for distinct sensations such as cool, hot, tingly and pungency. Mint, jalapeño pepper and carbonation, to name a few examples, create what's known as chemosensory irritation, the detection of chemical irritants in the nose, mouth and skin . This sensory system acts independently from smell and taste and is carried by the trigeminal nerve, which transmits sensations from the face to the brain. In a person with taste and smell loss, something like wasabi-spiked soy sauce or fresh chilies doesn't properly integrate with the olfactory and gustatory system and only causes irritation.
Charles Spence, a professor of experimental psychology at Oxford University, is investigating how plate colour can influence whether a person eats only one bite or finishes a meal. For example, he says research shows people rate ice cream as 10 per cent sweeter and 15 per cent more flavourful when it's served on a white plate rather than a black plate. In the real world, the impact of plate and utensil colour on appetite is generally ignored, with potentially disastrous results. For instance, red is possibly the worst for encouraging food consumption. A 2013 study published in the medical journal Appetite found that when people were served on red plates and cups, they cut calorie consumption by 40 per cent - even when the researchers topped the plate with chocolate. The researchers hypothesise that red plates may lead people to eat less because the colour is universally associated with stop signs and danger.
Spence is also conducting research with Sant Joan de Déu, a children's hospital in Barcelona, Spain. Children undergoing chemotherapy and radiation often refuse to eat because food, to them, has a metallic taste.
Those in the emerging field of neurogastronomy feel a kinship to pioneering sexologists William Masters and Virginia Johnson. In the 1950s and '60s, the pair forever changed our understanding of human sexuality at a time when patients were embarrassed to discuss it even with their doctors. "Masters and Johnson said, 'No, this is the science of life,'" says Han. "Next thing you know, 40 or 50 years later, not only is it a legitimate science - it's a trillion-dollar industry."
The medical world is slowly coming around to the fact that a patient's ability to enjoy food is not just a triviality-and it's likely that there's money to be made in neurogastronomy. Han and his colleague Tim McClintock, a professor of physiology at the University of Kentucky, are collaborating on research that could result in pharmaceutical drugs to reverse taste and smell loss. But his research could also point to a way to alter flavour for people with normal smell and taste functions. Take, for instance, the durian fruit, commonly eaten in Southeast Asia. It's known for a stench so unbearable that it's banned on Singapore's mass transit system. But durian also happens to be superbly nutritious. McClintock says his research may one day lead to the development of blockers for certain receptors involved in detecting these malodours, making durian more palatable. The possibilities are endless: the future of food could one day include broccoli that tastes like chocolate.
- IBT Media

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