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Ever taken a bite of something, like broccoli or kale, and thought: “Whoa that’s bitter!”?
Ever taken a bite of something, like broccoli or kale, and thought: “Whoa that’s bitter!”?

Multiply that feeling many, many times over and you’ve got denatonium,
Multiply that feeling many, many times over and you’ve got denatonium,

the most bitter compound we know of.
the most bitter compound we know of.

And it was discovered totally by accident.
And it was discovered totally by accident.

Back in 1958, researchers at a Scottish pharmaceutical company were experimenting with the anesthetic lidocaine.
Back in 1958, researchers at a Scottish pharmaceutical company were experimenting with the anesthetic lidocaine.

You may have heard of it,
You may have heard of it,

it’s often in those gels that you can use to help cool the pain of a sunburn.
it’s often in those gels that you can use to help cool the pain of a sunburn.

And it’s frequently used by doctors and dentists because a quick injection of the stuff
And it’s frequently used by doctors and dentists because a quick injection of the stuff

makes a small area of the body wonderfully numb.
makes a small area of the body wonderfully numb.

That’s because it stops up the channels in neurons that allow sodium ions to flow in and out.
That’s because it stops up the channels in neurons that allow sodium ions to flow in and out.

When these sodium channels can’t open and close properly,
When these sodium channels can’t open and close properly,

the neurons aren’t able to send pain signals to your brain.
the neurons aren’t able to send pain signals to your brain.

And that’s great, because no one needs to feel what’s going on
And that’s great, because no one needs to feel what’s going on

when their wisdom teeth are being removed.
when their wisdom teeth are being removed.

Since lidocaine is incredibly useful,
Since lidocaine is incredibly useful,

the drug researchers were trying to see if they could find something similar that worked even better.
the drug researchers were trying to see if they could find something similar that worked even better.

But when they added a benzyl group to it, they ended up with something different,
But when they added a benzyl group to it, they ended up with something different,

a compound that we call denatonium.
a compound that we call denatonium.

It isn’t a better numbing agent,
It isn’t a better numbing agent,

but it does bind a different family of proteins better than lidocaine does: taste receptors.
but it does bind a different family of proteins better than lidocaine does: taste receptors.

Specifically, it binds to bitter taste receptors in the Taste 2 Receptor or TAS2R family.
Specifically, it binds to bitter taste receptors in the Taste 2 Receptor or TAS2R family.

Humans have more than forty different TAS2Rs, several of which bind to denatonium.
Humans have more than forty different TAS2Rs, several of which bind to denatonium.

But that doesn’t completely explain its bitterness.
But that doesn’t completely explain its bitterness.

Scientists think it might retain some of it’s lidocaine-like ability
Scientists think it might retain some of it’s lidocaine-like ability

and block ion channels to create its super bitter taste.
and block ion channels to create its super bitter taste.

But they’re not sure.
But they’re not sure.

What they are sure of, though, is that it’s really, really, really bitter.
What they are sure of, though, is that it’s really, really, really bitter.

Denatonium, in its marketed form “Bitrex,”
Denatonium, in its marketed form “Bitrex,”

has held the Guinness World Record for bitterest substance for half a century.
has held the Guinness World Record for bitterest substance for half a century.

And that’s because humans can taste it in solutions at really, really low concentrations,
And that’s because humans can taste it in solutions at really, really low concentrations,

just a few parts per million.
just a few parts per million.

A sugar cube-sized amount of it can make an entire Olympic-sized swimming pool taste gross.
A sugar cube-sized amount of it can make an entire Olympic-sized swimming pool taste gross.

And yet, you probably have it in your home without even knowing it.
And yet, you probably have it in your home without even knowing it.

It’s odorless and colorless, so it doesn’t affect how products look or smell.
It’s odorless and colorless, so it doesn’t affect how products look or smell.

And outside of being bitter, it’s considered unreactive,
And outside of being bitter, it’s considered unreactive,

so it’s basically non-toxic and isn’t destroyed by water or most other chemicals.
so it’s basically non-toxic and isn’t destroyed by water or most other chemicals.

All of which makes it the ideal stuff to put in or on things you don’t want people to swallow.
All of which makes it the ideal stuff to put in or on things you don’t want people to swallow.

You might have heard about the big fuss in 2017
You might have heard about the big fuss in 2017

when Nintendo released their new Switch game cartridges, for example,
when Nintendo released their new Switch game cartridges, for example,

because they’d laced them with denatonium and apparently everyone noticed.
because they’d laced them with denatonium and apparently everyone noticed.

My question: Why were adults licking nintendo games in the first place?
My question: Why were adults licking nintendo games in the first place?

You can also find denatonium in special nail polishes designed to help stop people from biting their nails.
You can also find denatonium in special nail polishes designed to help stop people from biting their nails.

And it’s added to everything from liquid dish detergent to industrial alcohol and antifreeze
And it’s added to everything from liquid dish detergent to industrial alcohol and antifreeze

to keep people especially children, safe.
to keep people especially children, safe.

It’s even used in rat poison,
It’s even used in rat poison,

turns out that rat tongues are about 30,000 times less sensitive to denatonium than we are,
turns out that rat tongues are about 30,000 times less sensitive to denatonium than we are,

so it doesn’t scare them off.
so it doesn’t scare them off.

And its effects aren’t restricted to your tongue.
And its effects aren’t restricted to your tongue.

You have similar taste receptors in your gut,
You have similar taste receptors in your gut,

and scientists have found that directly injecting denatonium solutions into stomachs can slow the digestion process,
and scientists have found that directly injecting denatonium solutions into stomachs can slow the digestion process,

increase feelings of fullness, and even help lower blood sugar levels.
increase feelings of fullness, and even help lower blood sugar levels.

So they’re investigating whether denatonium, or something like it, can help treat overeating or diabetes.
So they’re investigating whether denatonium, or something like it, can help treat overeating or diabetes.

And taste receptors are also present on the smooth muscles of your airways.
And taste receptors are also present on the smooth muscles of your airways.

So, inhaling denatonium can lead to bronchodilation,
So, inhaling denatonium can lead to bronchodilation,

the expansion of your airways that leads to increased airflow.
the expansion of your airways that leads to increased airflow.

And ultimately, that means further research on denatonium could help people breathe easier.
And ultimately, that means further research on denatonium could help people breathe easier.

Turns out there are a lot of great ways to use super bitter compounds.
Turns out there are a lot of great ways to use super bitter compounds.

Who would have thought something so revolting could do so much good?
Who would have thought something so revolting could do so much good?

Thanks for watching this episode of SciShow!
Thanks for watching this episode of SciShow!

And thanks as always to our patrons on Patreon.
And thanks as always to our patrons on Patreon.

Without your support, we wouldn’t be able to make tasty nuggets of science wisdom like this video.
Without your support, we wouldn’t be able to make tasty nuggets of science wisdom like this video.

If you’d like to learn more about how you can help support us while sweetening your
If you’d like to learn more about how you can help support us while sweetening your

SciShow experience, you can head over to Patreon.com/SciShow to lean more about joining our community of patrons.
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