Kicking It Up a Notch: How Some Spices Trick the Brain

(Editor’s note: This article from a past issue of Brain World magazineIf you enjoy this article, consider a print or digital subscription!)


When the chili pepper was first exported from Mexico about 500 years ago, it was an overnight success. Fiery-hot peppers were quickly adopted all over Asia, West Africa, and elsewhere around the world. Rather than avoiding a food that burns, people wanted more.

“It’s odd that something that tasted ‘bad’ would be so readily adopted,” says Paul Rozin, a professor of psychology at the University of Pennsylvania who has been studying spicy foods for decades. Through conditioning, people have grown to like other foods they once disliked. Coffee is bitter, but it has a pleasant aroma and stimulating effects. It’s also addictive. Jalapenos, habaneros, and other chilies, however, are not addictive — they merely burn.

Spicy foods fascinate because they have “impact,” according to Rozin. Even a touch of spice can add novelty and excitement to a meal. Ask anyone who has tasted the scorching heat of wasabi. Yet what causes the curious sensations triggered by certain spices? Is there any benefit to eating food that burns?

DECEIVING THE BRAIN

The five basic tastes — sweet, salty, bitter, savory, and sour — ensure our survival. Receptors on the taste buds send messages to the brain along nerve fibers to create the sensation of taste. Yet, the taste buds alone do not produce “taste.” The tongue also has receptors for temperature (and pain and pressure). Certain chemicals trigger receptors for other senses, mimicking temperature or touch, for instance, and contributing to what we experience as taste.

One food that deceives the mind is the Szechuan peppercorn. The tiny pods are often added to Mapo tofu and other dishes. The Szechuan peppercorn causes a peculiar tingling sensation that numbs the lips and mouth. It has an electrifying taste that often surprises and even unsettles people who try it for the first time.

The numbing spiciness of the Szechuan peppercorn is due to a compound called “sanshool” that is also found in the Japanese sansho. Sanshool confuses the senses by simultaneously acting on different types of nerve endings, activating receptors that are sensitive to cold and touch. Some people compare the buzzing sensation to touching a nine-volt battery. The unique appeal of sanshool could be its mimicry of touch.

Neuroscientists have tested whether people experience the buzzing effects in the same way when they eat Szechuan peppercorns. The study, titled “Food Vibrations: Asian Spice Sets Tips Trembling,” was published in the journal Proceedings of the Royal Society. Researchers asked 28 participants to compare the tingling sensation caused by sanshool to vibrations produced by a mechanical device placed on their fingertips. After sanshool extract was applied to their lips, they selected the frequency of mechanical vibrations that matched the buzzing sensation, which was about 50 megahertz — the same frequency belonging to a certain type of nerve that transmits the sensation of touch. They concluded that the chemical compounds in Szechuan peppercorns act on touch fibers, sharing the same pathway as physical touch.

“This is the first time that we’ve been able to show how chemicals activate touch fibers, inducing a measurable frequency,” said the lead author of the study, Dr. Nobuhiro Hagura. The study was too small to draw any conclusions. Yet, it adds to research on how the brain processes sensory information. Scientists hope such findings could help improve our understanding of neurological conditions like chronic pain.

CAN EATING SPICY FOODS MAKE YOU HAPPY?

Another compound that has intrigued scientists is “capsaicin,” the molecule that gives Tabasco sauce its kick. Capsaicin is found in hot peppers and a variety of other foods. Capsaicin is a flavorless, odorless chemical that causes pain and irritation. It also induces a burning sensation if you rub it on your skin or get it into your eyes.

Peppers are not really addictive, although some people speak of them as if they were. Scientists are still uncertain why an aversion to a food that causes a burning or stinging sensation is converted into a preference. One hypothesis is that eating capsaicin triggers the release of neurotransmitters to compensate for the pain. When you bite into a chili pepper, the capsaicin binds to a receptor on the nerve cells in your mouth called TRPV1, which is also activated by hot temperatures. Capsaicin tricks your nervous system into thinking that you have actually touched something hot. Nerve fibers running from the tongue send signals alarming your brain that there is a fire in your mouth.

When your brain gets the message that your mouth is on fire, it responds by releasing neurochemicals, such as endorphins, to block the heat. Endorphins are the brain’s “feel-good” chemicals that alleviate pain. Some scientists believe the endorphin rush actually exceeds the amount needed to counteract the irritation. As such, the good effects outweigh the bad. The endorphin rush causes a pleasant feeling in the body that leads to a sense of euphoria and a natural high. Spices could thus increase the levels of neurochemicals that boost your sense of well-being and make you happier.

In addition, if you eat spicy dishes regularly, your tolerance will increase. As the nerves become desensitized, the heat receptors stop responding as strongly. The nerves on the tongue are able to tolerate more pain. This well-researched phenomenon is known as the capsaicin desensitization.

Hot peppers have long been used as a folk remedy, owing to their pain-alleviating ability. More recently, capsaicin has been rediscovered by modern medicine as a potent pain reliever. Capsaicin creams and ointments are available to treat mild joint or muscle pain, including backaches, sprains, strains, arthritis, cramps, and bruises. A high-dose capsaicin patch was approved several years ago for neuropathic pain. Yet, the results in humans are mixed.

A LONGER, HEALTHIER LIFE

Having a passion for peppers is harmless, as there are virtually no negative health effects. But do spices have a positive effect on health?

A recently published study in British Medical Journal claims they do. The authors tracked the diets of more than 485,000 Chinese adults and found that people who ate more spicy foods tended to live longer, healthier lives.

The study followed healthy volunteers aged 30 to 79, for an average of seven years. Findings demonstrated that men and women were likely to live longer if they ate spicy foods. People who ate hot foods once or twice a week had a 10 percent lower risk of mortality. The positive effects were even stronger among those who consumed spices more often. Participants who ate fiery fare six to seven times a week had a 14 percent lower risk. Enjoying spicy foods three to five times a week also decreased the chance of having ischemic heart disease, respiratory ailments, and even cancer. While the authors can only speculate about a cause, they note that capsaicin may be a factor. They point out that previous studies have demonstrated its anti-inflammatory effects.


“Chilies are eaten by billions of people and loved,” says Rozin. “It’s not just the burn,” he says. “The burn goes with the flavor.” The jury is still out on why people are drawn to spicy heat. Yet, if you get more pleasure out of food, then it may be worth spicing up your diet.

(Editor’s note: This article from a past issue of Brain World magazineIf you enjoy this article, consider a print or digital subscription!)

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