Asked by: Smera Ahuja, Winchester
Spicy compounds are produced by plants to deter animals from eating them. They have evolved to be as irritating as possible to the mucous membranes of mammals. In fact, the capsaicin in chilli doesn’t actually cause tissue damage, but it triggers the nerve receptors that normally detect heat, and your nose is fooled into producing extra mucus to protect your sinuses.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
