So why does it feel cooler when you chew a mint or eat mint?
The inside of your mouth (and your skin generally) is covered with sensory receptors – various little structures that detect and respond to something from the environment, and send a nerve signal back to the brain when activated; that’s how your brain knows anything about the outside world. They detect light on your retina, vibrations in the inner ear, pressure against your skin, tastes/smells in your tongue and nose, and also temperature.
But they’re not all entirely single-function; the same sensory receptors that detect cold can also be activated by menthol. They’re named TRPM8, but “also known as the cold and menthol receptor”. Your brain doesn’t know which of the two is activating the receptor – just that it’s getting the “cold” and/or menthol signal, which is interpreted as a cold feeling.
While menthol is present those receptors are just generally easier to activate, so everything seems colder than it usually would.
Similar effect with chilli peppers, where a receptor can be activated by capsaicin that is usually responsible for sensing heat and pain.
Well explained answer from noggin-scratcher. Futher in the thread someone asks:
What happen, when you eat mint and peppers at the same time ?
Here is another answer from noggin-scratcher.
Well this guy says its a bad idea.
My best guess: they target different receptors so they can’t cancel each other out. It’s not like combining hot fudge with ice cream where the temperature can physically balance out to a medium amount of heat.
So your brain just gets a confusing mess of signals from both receptors, to the combined effect of “A LOT OF TEMPERATURE THINGS ARE HAPPENING RIGHT NOW” and interprets that as being either hot enough or cold enough that all the receptors are going off.
Maybe sort of similar to how if you can set up an expectation for something hot, a blindfolded person will yelp at the touch of an ice cube as if they’ve been burned. Extremes of temperature getting a bit crossed over with each other.
This is a pretty interesting topic. In short, when you eat mint, the brain receptors gets the cold signal which gives you the cold feeling.