[♩INTRO].

If you’ve ever had wasabi…. Well, actually, you probably haven’t eaten real wasabi.

That’s because it’s super rare outside of Japan. That green stuff that comes with your sushi is just a blend of horseradish and mustard dyed to look like wasabi. But if you’ve ever thought you had wasabi, or are just a fan of plain ole horseradish in general, you’re familiar with that special burning sensation that fills your nose.

Well, that’s thanks to a chemical that’s abundant in those foods one that triggers your body’s defenses to toxins. Wasabi and horseradish are both cabbage-type plants related to things like broccoli, kale, Brussels sprouts, and mustard. And they’ve been selectively bred for at least a thousand years to have nice, big rhizomes, a type of underground stem, because those are ground or shredded to add that special kick to your meal.

The nose burn largely comes from a compound called allyl isothiocyanate. It’s also found to a lesser extent in mustard and radishes. It easily becomes airborne, so when you eat wasabi or horseradish, a bunch of it floats up into your nose, right to where you have all these special detectors for it.

These detectors are called receptors, and they’re molecules on the surface of nerve cells that allow them to respond to things. Each type of receptor responds to different groups of molecules. The one for allyl isothiocyanate is called TRPA1.

And it detects more than wasabi and horseradish. It also alerts your body to the presence of tear gas, cigarette smoke, and car exhaust. Basically, a bunch of possible airborne irritants.

When triggered, receptors tells their nerve cells to message the brain, which results in that itching or burning sensation. And there are simply more of these receptors in your nose than in your mouth, which is why you really feel the burn there. Enough of the offensive substance leads to coughing, crying, basically anything to try and get it out of you.

TRPA1 is related to other pain-causing receptors, like TRPV1 the one responsible for the burn of hot chilis. But it’s kind of weird because it responds to a lot of things. In addition to wasabi and airborne irritants, it can also be set off by chemicals produced by your own cells, so it’s sometimes to blame for pain, itching, or burning associated with inflammation or immunological diseases.

And it even seems to be involved in sensing dangerously cold things. It has so many triggers that scientists are still trying to figure out all the ways it can go off, and how the body uses it. But in the meantime, some are harnessing its powers for good.

A group of researchers is hoping to develop a special fire alarm for the hard of hearing. Instead of making a loud sound, it would spray a mist made of allyl isothiocyanate. It’s basically a wasabi alarm!

Because it’s probably better to have the feeling of fire in your nose than have an actual fire at your feet. Thanks to Jan Bartnik for asking about horseradish! And thanks to all of our patrons who voted on this question in our poll.

We really can’t say it enough: without our patrons, we couldn’t do what we do. If you have some burning questions like this that you’d like us to consider, you can learn more about joining our community of patrons at Patreon.com/SciShow. [♩OUTRO].