Why Hot Peppers Set Your Mouth on Fire
Clip: Season 47 Episode 17 | 4m 2sVideo has Closed Captions
The chemical that makes chili peppers so hot evolved to keep animals from eating the plants.
How does a chili pepper make your mouth feel like its on fire? When you eat peppers, capsaicin molecules fit into the heat pain receptors of your mouth, sending a false signal to your brain that's identical to the one it would receive if you ate something literally burning hot.
National Corporate funding for NOVA is provided by Carlisle Companies. Major funding for NOVA is provided by the NOVA Science Trust, the Corporation for Public Broadcasting, and PBS viewers.
Support provided by:
Why Hot Peppers Set Your Mouth on Fire
Clip: Season 47 Episode 17 | 4m 2sVideo has Closed Captions
How does a chili pepper make your mouth feel like its on fire? When you eat peppers, capsaicin molecules fit into the heat pain receptors of your mouth, sending a false signal to your brain that's identical to the one it would receive if you ate something literally burning hot.
How to Watch NOVA
NOVA is available to stream on pbs.org and the free PBS App, available on iPhone, Apple TV, Android TV, Android smartphones, Amazon Fire TV, Amazon Fire Tablet, Roku, Samsung Smart TV, and Vizio.
Buy Now
NOVA Labs
NOVA Labs is a free digital platform that engages teens and lifelong learners in games and interactives that foster authentic scientific exploration. Participants take part in real-world investigations by visualizing, analyzing, and playing with the same data that scientists use.Providing Support for PBS.org
Learn Moreabout PBS online sponsorship- [David] Here at the Berks Pepper Jam in Bethel, Pennsylvania.
- Smell that.
- [David] An annual festival of food, entertainment, and contests, all centered on chili peppers.
- Woo!
- [MC] We begin our contest with the long hots.
(bell ringing) Let's turn up the heat!
Eat!
- And we're off.
Zesty, with just a hint of poison.
- [MC] Round two.
We're gonna start with the red Fresno Pepper.
Eat, eat, eat, eat, eat, eat, eat, eat!
- There's gotta be some easier way to learn about molecules.
(bell ringing) - [MC] All right, all right, are we ready?
Eat!
- That was not designed for human consumption.
- [MC] Round number four, habanero peppers.
- Parts of my body I didn't know I had are on fire.
- [MC] 10 more seconds, you got this.
- I can't.
- [MC] Don't go.
Don't do it!
Oh!
(bell ringing) The orange Copenhagen pepper.
Eat!
- What am I doing?
- [MC] Eat, eat, eat, eat, eat, eat, eat, eat!
- Oh man, oh my God.
(David coughing) - [MC] Don't do it!
- I want it!
(train whistle blowing) Cheers.
- [MC] Oh!
- So I'm the first to fall.
How does a pepper's capsaicin convince my mouth it's on fire?
Not recommended.
I think I'll find the answer here at Penn State University's Department of Food Science.
- We all study food.
So you have psychologists and microbiologists and engineers.
- [David] I'm here to see John Hayes.
He knows a thing or two about the active ingredients in these.
- So when you went and tasted them, what did you experience?
- Oh man, my gut twisted, my tongue burned, my flesh burned, I cried, I got red, my nose ran.
It's like putting your tongue on the stove and leaving it there.
- That was an aversive response.
This plant has evolved a chemical called capsaicin.
And the reason it makes that is to keep animals from eating the chili pepper.
(David laughing) - Oh man.
The chili festival people never got that message.
And we're just a really stupid species.
- Exactly.
We're one of the only species that learns to like that sensation.
- [David] Ultimately, pepper plants are playing a pretty good trick on humans as well.
Capsaicin really is a key ingredient.
It has a long spindly tail attached to a ring.
- That ring end fits into a specific receptor that's expressed all over your body.
- Not just our tongue.
- Not just your tongue.
- Oh man.
- This receptor, this lock, is actually heat pain sensor.
- [David] Normally, the receptor, called TRPV1, activates when it in contact with something over 106 degrees.
(buzzer sounding) The result is a pain message to the brain.
Ouch!
Something's hot!
- It's a warning signal to tell your body danger.
- [David] And here's the tricky part.
When you eat peppers, those capsaicin keys fit into the heat pain receptors in your mouth, altering their sensitivity.
- And so what the capsaicin does is it fits into this molecular thermometer and it lowers the temperature at which it activates it.
- Like a changed thermostat, they now activate at body temperature, sending a false signal that's identical to the one your brain would receive if you ate something literally burning hot.
It lowers the temperature at which we feel burning pain.
- Yes.
- But it's not actually burning us?
- Correct.
- It's not, I'm not gonna see scar tissue.
- No.
- No matter how hot it is, it's all a fake out.
- Absolutely.
Video has Closed Captions
In the atomic world, everything is in motion, vibrating because of thermal energy. (4m 49s)
Beyond the Elements: Reactions Preview
Video has Closed Captions
Discover the fascinating chemistry that makes our world and everything in it—including us. (30s)
How Killer Snail Venom Plays a Key Role in Drug Development
Video has Closed Captions
What’s in this snail’s paralyzing venom? (6m 8s)
What Gives Hot Peppers Their Heat?
Video has Closed Captions
"Beyond the Elements" host David Pogue explores the science of hot peppers—viscerally. (8m 22s)
Providing Support for PBS.org
Learn Moreabout PBS online sponsorship
National Corporate funding for NOVA is provided by Carlisle Companies. Major funding for NOVA is provided by the NOVA Science Trust, the Corporation for Public Broadcasting, and PBS viewers.