Monday June 25, 2018 Q&A

Mint freshens your breath because menthol:


1 releases pheromones

2 lowers the temperature in your mouth

3 binds with the cold receptors in your mouth

Answer: 3, menthol binds with the receptors that detect cold.

Natural mint and mint-flavored products like chewing gum and toothpaste are known for the fresh feeling they leave in your mouth. The sensation they produce is real. It is caused by the reaction of a chemical component we are all familiar with: menthol.

You've probably heard of capsaicin, the hottest component in a chili pepper. It's what creates the burning sensation in your mouth as it binds with the receptors that normally detect heat. Menthol reacts in a similar way, except that it binds with the receptors that detect cold. It doesn't actually lower the temperature in your mouth, but instead tricks the nerve cells into thinking that the mouth is fresher than it really is. Those cells then send that information on to the brain.

But menthol can do more than just refresh us. Studies have shown that it also has analgesic properties, which is why it is found in creams, gels and patches aimed at relieving various aches and pains, in everything from your muscles to your head. In fact, menthol is present in such a vast range of products – including after-shave creams, decongestants and mouthwash – that you probably use it every day without even realizing.

Unsurprisingly, there is nowhere near enough natural menthol available to meet demand, which is estimated to be around 35,000 tons per year. So synthetic menthol has been produced in increasing quantities since 1973.

Menthol comes in the form of optical isomers. One of the optical isomers is produced naturally, and it is this one that creates the refreshing effect. The other isomer, which is produced synthetically in the lab, does not have the same cooling power. The tiny difference between the two isomers no doubt prevents the synthetic variety from activating our cold receptors.

From the book “Pourquoi l'asperge donne-t-elle une odeur au pipi?” PPUR.