Szechuan Pepper Taps Nerve Fibers 50 Time Per Second: Study

A recent research conducted by the University College London found that the Asian spice Szechuan pepper gives a tingly, lip-rattling sensation and chemically stimulates the light-touch fibers present on the tongue and the lips, which send around 50 light taps to the brain per second.

"This is the first time that we've been able to show how chemicals activate touch fibers, inducing a measurable frequency," Dr. Nobuhiro Hagura, lead author of the study, UCL Institute of Cognitive Neuroscience, said in a press release.

"We know that natural products like chilli, mustard oil and menthol can activate the thermal and pain fibers in the skin, but we wanted to find out why Szechuan pepper specifically works on the light-touch fibers, producing a conscious sensation of touch and that distinctive tingling feeling," Dr. Hagura added.

An experiment was conducted on 12 volunteers. They were given Szechuan pepper to eat and asked to match the frequency of the tingling sensation they were experiencing by adjusting a vibrating stimulus, at either lower or higher, on their fingertips.    

The researchers found that an active ingredient in the spice triggered specific RA1 fibers present on the tongue and lips. These fibers are responsible for sending out the light taps on the skin to the nerve fibers present in the brain.

 "What we found was that a unique active ingredient in the pepper, called sanshool, activates these fibers, sending a highly specific signal to the brain. Szechuan peppers and physical touch sensations share this same pathway to the brain," said Dr. Hagura. "We hope that laboratory studies of the tingling sensations caused by sanshool could help to clarify the brain processes underlying these sensations, and how they are related to pain in some cases."

The UCL researchers also aim at examining the causes why people like eating Szechuan pepper and how can the taste of food be improved with touch sensation.