Spiciness explained

Like many spice junkies, Dr. Marco Tizzano once believed he could develop a tolerance to the burning, painful sensations generated by eating chilies. But as a chef and researcher in chemosensory sensations, he now knows better. Dr. Tizzano explains how capsaicin creates a chemical cascade inside your body, and why emotions might make chili lovers think they can handle the heat.

TRANSCRIPT

Like many spice junkies, Dr. Marco Tizzano once believed he could develop a tolerance to the burning, painful sensations generated by eating chilis.

But as a chef and researcher in chemosensory sensations, he now knows better.

Dr. Tizzano explains how the compound capsaicin creates a chemical cascade inside your body and why emotions might make chili lovers think they can handle the heat.

A lot of people enjoy, you know, stuff that is painful.

So I was one of these persons that say, 'Oh, I eat always chili pepper.

I can eat more and more and get accustomed to that and get to the next step and get into always hotter chili.'

In reality, it's not so simple.

Most of the time you're just, 'Ah, it's hot.'

And then you take another one and say, 'It will be less.'

And it's even more.

It's not the more you eat, the less you perceive that.

Marco Tizzano is an investigator at the Monell Chemical Senses Center, whose interest in the science of spicy didn't begin in a lab.

Nights and weekends, I was working as a chef, and I was fascinated by the idea of the other type of perception, of sensory perception -- how that works.

And that is how I started my adventure in science.

While Dr. Tizzano can cook many delicious dishes, his research has little to do with taste and smell.

Instead, his focus is on chemosthesis.

Chemosthesis is practically the science, the study, the perception of the pain transmitted by the trigeminal nerve.

Which branches out from a central ganglion in your head down throughout your nose, mouth, and eyes.

And so all these processes will just transmit the sensation from this periphery part to the central ganglion and give you a sensation of pain or cold or warmed, depending what you are using as stimuli.

In the case of chili peppers, that stimuli is a molecule known as capsaicin, which causes a burning sensation, amongst other maladies.

How does one molecule achieve such a lasting effect?

Capsaicin is a molecule that will bind specifically to a class of receptors that are called TRPV.

And they are in the mouth, the nose, the eyes.

So imagine capsaicin like a key and the receptor to be one like a door.

When the capsaicin will bind to the door, we open the receptor.

And the receptor will allow ion to run through it.

This change of potential will be transmitted through the nerve, to the central nervous system, to the brain, and that is where you get the pain sensation of the heat.

But then locally, there is this release of a neurotransmitter that is called Substance P and CGRP.

And those are the ones that will cause you the swelling, the pain, and the other sensations.

But then there is also fibers in the nose.

You will active there a local inflammation.

And that is why you have a runny nose or sneezing, because the same nerve is also stimulating the eyes.

Then you will have your watering eyes.

And because the whole reaction is meant to protect you from what your body has deemed unhealthy, there are few methods to stop the process.

You can't drink water because...

The sensation will come back again because capsaicin is still stuck on the receptor.

Another way is to drink something that contains fat, like milk, or something that contains alcohol, like beer, because the alcohol and fat in the milk will actually move that from the receptor.

So what if you expose the system over and over again?

Can you actually desensitize it?

There is all this study that they must train that very short presentation of a capsaicin molecule in a very short time frames will cause you to desensitize the receptor.

The perception that we'd be stronger and stronger and stronger until you stop because you cannot bare that anymore.

The pain does diminish eventually.

But that's not because you've gained a tolerance to the chemical.

What happens is that the receptor will not desensitize but it will internalize inside the membrane of the fibers because you want to protect the nerve from getting damaged.

If the pain does seem to go away in the long term, you might actually be damaging your nerves.

If there is somebody more sensitive to that, maybe it makes that system... And also, sometimes you cannot come back from that.

And you will lose that system.

And if all of this doesn't convince you that you can't just build tolerance to spicy food, just remember -- it's all in your head anyway.

There is several study that demonstrate that if you eat hot pepper or if you're a person that don't eat hot pepper and you provide them different concentration of chili pepper, both of them will describe, with no statistical difference, that this chili pepper were unbearable or mild or very bland, and that is because the people that eat hot peppers -- they perceive that as a pain, but they enjoy it.

They eat that and say, 'Oh, I can do that.'

But it's just because you want to do that.

But it's very painful anyway.