I do not often chew gum, but when I do, I chew something minty. When the bill comes at the end of a meal, I cannot help but take a mint. And of course, when I brush my teeth, my toothpaste is minty. Perhaps I should be wondering why so much mint, but instead I wonder, why does it taste so cool?
Normally, we detect coldness through our sensory neurons. These neurons have a protein called TRPM8, which stands for “Transient Receptor Potential Cation Channel Subfamily M member 8”. TRPM8 is an ion channel, changing shape to allow calcium ions into the nerve cell when the environment is below about 26C. The brain interprets a signal from TRPM8 as coldness.
The active chemical in mint is a terpene alcohol called menthol or peppermint camphor, or 2-isopropyl-5-methylcyclohexanol, but let’s stick with menthol for now. Traditionally, it is extracted from the leaves of plants like peppermint (Mentha piperita), in which it may act as a natural insecticide. It can kill mosquito larvae and repel the adults. Demand for menthol has led to the development of synthetic versions, involving scientists like Ryoji Noyori, the 2001 Nobel Laureate Chemistry, though so far, the synthetic versions tend to be less minty.
Menthol does not make your mouth colder, but it makes your brain think that it is, like a chemical version of fake news. When menthol binds to TRPM8, the ion channel reacts as though it were cold. This effect lingers for some time, making your breathe or water taste cold. Not only that, but some studies indicate that athletes perform better with exposure to menthol. How cool is that? If you have any freshly minted comments on menthol, please add them below.