Szechuan Peppercorn Tingles Mouth Like Vibrator

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The tingle diners feel while eating foods containing Szechuan peppercorn is equivalent to being lightly tapped on the lips 50 times per second, a new study finds.

Szechuan peppercorn is unique among all other ingredients in producing the sensation. The study, published in the latest issue of Proceedings of the Royal Society B, reveals how information sent to the brain via chemicals can equal information going to the brain via actual touch.

In the future, the discovery could lead to breakthroughs for paralyzed individuals, people with certain chronic pain conditions and gourmets seeking the ultimate "mouth explosion" of taste and flavor.

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There are some foods out there that seem as though they'll burn a hole through your tongue. What's spicy food got that causes such a reaction? And why does it make you sweat?

"We knew from studies in animals that the active ingredient in Szechuan pepper selectively activates the 'light touch' (nerve) fibers," lead author Nobuhiro Hagura told Discovery News. "This made us interested in whether this unusual way of activating light touch fibers actually produces a conscious sensation of touch."

Hagura, a researcher at University College London's Institute of Cognitive Neuroscience, and colleagues Harry Barber and Patrick Haggard analyzed how 28 participants reacted when Szechuan pepper, ethanol (alcohol), water, and then a vibrator -- similar to an electronic massager or sex toy -- was applied to their lower lips. The subjects wore noise-canceling headphones, so they could not hear the buzz of the vibrator.

A few of the participants thought they felt a tingle when alcohol and water were applied, but nearly all believed that the Szechuan peppercorn-produced tingle was equivalent to that of the vibrator. Further investigation concluded that the pepper tingle equaled 50 light taps per second.

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Szechuan peppercorn goes into the food record book of ingredients that send information to the brain that is comparable to actual touch. Menthol is another such ingredient, producing a cooling sensation akin to touching ice or something else that is cold. Natural oils found in cloves and oregano can impart warming and numbing sensations. Mustard oil can induce pain, as can too much chile.

That familiar chile burn, however, likely benefited early humans.

Danise Coon, a senior research specialist at New Mexico State University's Chile Pepper Institute, told Discovery News that chiles were probably first cultivated for medicinal purposes.

"Even today," Coon said. "Capsaicin (from chiles) is added to arthritis creams. It produces a heat/pain response in the brain that can be even bigger than the individual's arthritis or muscle soreness."