The science that explains why mint gives a cooling sensation in the mouth
Mint doesn't lower the temperature of the mouth, but menthol activates the receptors that detect cold, and the sensation is real.
Mint is one of the most refreshing herbs, and its coolness is due to menthol, a compound that binds to TRPM8 receptors. These receptors detect temperature changes and are activated by cold, but menthol activates them even without a drop in temperature. It's, in a way, the cooling version of chili peppers.
Menthol doesn't affect body temperature, but it interacts directly with the nervous system, which is why the sensation is so real. This is why it's used in products like chewing gum and toothpaste, and in candies simply called "mints." Its soothing properties also explain its presence in cough drops.
Its fresh flavor helps to counteract bitterness, such as that of chocolate or alcohol. That's why it appears in cocktails like the mojito, where it's best to muddle it to release its aroma.
Muscle balms and menthol shampoos use the same mechanism to create a cooling sensation on the skin. This cooling effect may have some placebo effect, but it helps to distract from pain or discomfort.
