A new study has revealed that the carbon dioxide in fizzy beverages sets off the same pain sensors in the nasal cavity as mustard and horseradish.
"Carbonation evokes two distinct sensations. It makes things sour and it also makes them burn. We have all felt that noxious tingling sensation when soda goes down your throat too fast," said Emily Liman, an associate professor of neurobiology in the USC College of Letters, Arts and Sciences at the University of Southern California.
The burning sensation is caused by nerves that respond to pain, skin pressure and temperature in the nose and mouth.
"The cells that responded to CO2 were the same cells that detect mustard," Liman said.
These cells express a gene known as TRPA1 and serve as general pain sensors. The gene, however, provides only one aspect of carbonation's sensory experience. Another study had shown earlier that carbonation trips cells in the tongue that convey sourness.
The study is published online in the Journal of Neuroscience.