Why Are Chillis Hot?
RMIT University Professor Peter McIntyre explains why chillies are hot.
Why chillies are hot with Professor Peter McIntyre
[Professor Peter McIntyre, sitting in a laboratory]
Spicy foods can cause pleasure and pain. So, for instance, chilli peppers can liven up a really bland meal and make it much more interesting. But they can also cause some reactions in your body.
They can make you perspire, even when the temperature's not really hot outside. And they can make your mouth feel like it's on fire, it hurts so much that you feel like you're burning.
Chillies hurt because they contain a substance called capsaicin, which binds to a receptor that's found on some pain sensing nerve cells. That receptor is called TRPV1 and it's an ion channel. When capsaicin binds to it, it opens and allows a small current to pass across the nerve cell membrane and causes the nerve to fire.
That impulse will travel all the way along the nerve, up to the spinal cord and then on up to the brain where we'll perceive it as pain. And normally when we sense pain like that, we'll try and remove ourselves from whatever is causing the painful stimulus.
We keep eating chilli probably because it activates a reward pathway in the brain that rewards us for that sensation that we're having. But it may also be that it makes us feel cooler and changes the way our bodies respond to temperature a little bit.
Understanding how these ion channels work is an important process in trying to find new painkilling drugs because they seem to be in pain pathways and we don't really understand how they work. They're not just there to respond to spicy foods. If we could understand how they're normally opened, then we might be able to block that process when it occurs in an inappropriate way and, thereby, make new painkilling drugs.
Professor Peter McIntyre is the Deputy Director of the Health Innovations Research Institute at RMIT University.
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