Why can some people load up on the hot stuff but not others? There are people who can bite into bird's eye chilli (Thai chilli padi) or jalapenos (red hot Mexican chilli peppers) without batting an eyelid.

For many people, however, raw chillies make their eyes and noses run and start a fire in their mouths.

Have the chilli eaters destroyed the sensory receptors in their mouths and throats?

No, said Dr Harry T. Lawless, a professor of food science at Cornell University and an expert in the taste, smell and sensory evaluation of food. Answering this question put to him by a reader in The New York Times, he said that 'people who eat a lot of the stuff tend to develop a tolerance that we call desensitisation'.

'There is nothing harmful in the capsaicin molecule, the active ingredient of hot peppers. Capsaicin is kind of a harmless drug and, like any drug, we develop a tolerance to it.'

One theory, he said, is that a neurotransmitter gets depleted so that people respond less vigorously to capsaicin the more they are exposed to it.

The capsaicin molecule has both stimulating and anaesthetic properties, he added. In 1952, The Dublin Medical Press recommended it as a temporary cure for toothache and pharmacologists, particularly in Hungary, have studied this anaesthetic property in related molecules.

'The antidote to the mouth burning and the eyes watering is to eat more, either right away or later,' DrLawless said. Chronic desensitisation seems to be a matter of long-term dietary change, he said, but there is also the short-term numbing effect.

His favourite antidote is frozen yogurt. 'Indian mothers give ghee or clarified butter to children who eat too much curry,' he said.

This article was first published in Mind Your Body, The Straits Times.