Can chillies cause health harms?

Chris Smith asked chemist Philip Broadwith and biologist Tom Ireland...

Philip - As far as I can understand it, capsaicin and other hot compounds - like allicin that's in the sulphur compounds in hot things like wasabi and mustard - all activate exactly the same receptor in your body as it responds to temperature. That's something called TRPV1. I'm not going to go into the long name, but it's the same receptor. So the same thing in your body that is responding to changes in temperature is also responding to this chemical stimulus. And after that, everything physiological is exactly the same. The degree of activities, how painful is it? With chillies, there's different ways of experiencing chilli. If you just cook with a chilli fruit, you're going to get a certain amount of chilli depending on how hot the chilli is. They're measured on a thing called the scoville scale, which originally was how much do I have to dilute this stuff in a sugar solution until I can't detect the heat anymore. But now it's directly correlated to an actual physical amount of capsaicin, and chilies range from zero, which is your kind of bell peppers, up to a few million, which is California reapers and ghost peppers or whatever, probably best not to eat them. You can get chemical burns from eating these chilies. They can physically harm you. But if you take the membrane of the chilli and extract the capsaicin out of it and get pure capsaicin that has a scoville rating of 16 million, which is a lot and eating that definitely will cause you problems.

Chris - A friend of mine used to work on the pain system in the body and he used to use pure capsaicin in the lab and he said he went for a wee one day and it must have had some on his fingers. He said it was the best lesson in washing your hands before you go to the lavatory that you're ever going to get. And then people have said to me, as a virologist, they say you can always tell the person who works on herpes in the lab because they always wash their hands before they go for a wee. What do we know about the physiological effects of chillies in the body? Does it do harm? Is it good for you, Tom, anything you can tell us?

Tom - Yeah, so as Phil said, this is essentially setting your alarms off that there's dangerous heat or abrasive damage to your tissues when there isn't. So you get all the physiological responses that's trying to flush this stuff away. So you get your mouth filled with saliva. This is if you're eating it of course and your nose and your eyes start to stream and you can get similar effects at the other end of your digestive system as well. So in a sense your body's responding as if there's some kind of dangerous heat in your mouth, but because there isn't actually any burn damage or abrasion to your flesh, you don't get the inflammatory response that you would get if you were actually seriously burnt. But what happens when you have these really extreme chilies where they've been bred to have these scoville units in the millions is actually the pain is so intense that you start getting these really horrible symptoms that can feel almost like you are experiencing some terrible damage. I've seen a video of my friend at a chilli pepper festival, which started off quite funny, but he soon starts to feel really unwell and overwhelmed with pain and he's unable to breathe and the ambulances are called and it's really unpleasant. But again that's just caused by the pain itself. It's not actually any burning going onto his mouth.