How would you react
if I told you your food contains…
calcium disodium
ethylenediamine triacetate?
Would you ask where you could sign a petition to ban it?
I mean, hopefully not,
because you’re watching a show
where we love science things with big names.
But sometimes people get nervous a
bout food having more t
han a certain number of syllables.
Which is why I’m here to say
that ethylenediamine triacetate -
or EDTA for short -
is a molecular superhero.
It’s protecting your food from spoilage –
and it does this by…
kinda cheating at chemistry.
[intro]
Now, EDTA has a ton of uses,
but one of its most common uses
is as a food preservative
due to its unique chemistry.
It’s also administered
as an iron supplement,
as a treatment for lead
and mercury poisoning,
and even in cosmetics.
EDTA has been on the scene
since 1935,
when it was synthesized
by Austrian chemist Ferdinand Münz.
He was looking for a way
to create sour flavors in food,
to make up for a shortage
of a different sour additive,
citric acid.
Now, this is pre-World War II Germany,
and Münz was Jewish.
And he was interned in a concentration camp.
However, he survived
and continued working in chemistry
after the war.
The use of EDTA would persist,
with scientists in Germany and abroad discovering
new ways to synthesize it.
Along the way,
people figured out that EDTA
didn’t just give food a sour flavor.
It also helped trap stray metals,
reducing the potential for heavy metal poisoning.
To understand how EDTA does this,
we first have to talk about coordination compounds.
These compounds are made up of big organic,
or carbon-containing,
molecules that have one or more metal ions
at their centers.
In chemistry, speaking very broadly,
nonmetals tend to form covalent bonds
with each other and ionic bonds with metals.
In ionic bonding, there is a transfer of electrons
from one atom to another.
In covalent bonding,
two atoms share electrons with each other.
In the simplest version,
each atom contributes one electron
to form a bond.
But coordination compounds
go well beyond this simple system
by forming covalent bonds
between organic compounds and metal ions.
In this case,
the organic compound donates both electrons
to the metal in a coordination bond.
You can think of it like having a friend
that wants to start a business.
If you give your friend money, they take it from you,
and you’re never involved in whatever happens after that,
that’s an ionic bond.
If you and your friend go into business together
and you each put in some amount of money,
that’s a covalent bond.
And if you put in all the money,
but you and your friend
still run the business together
as equal partners,
well, that’s something like a coordination bond.
It’s a way to game the simplest rules of chemistry
and let organic,
non-metallic compounds
form bonds with metals.
A lot of important biological molecules work this way,
which is why animals and plants
need trace amounts of iron and other metals
to survive and be healthy.
Like For example, hemoglobin,
which uses an iron atom
to transport oxygen in your blood.
But there’s a reason
why we get iron from our food
instead of just gnawing on iron bars.
We need small amounts of metal in our blood to survive,
but too much can be harmful.
Excess metals can be dangerous,
or reactive, or both.
Compounds that form coordination complexes
with those metals keep them
from going anywhere else and causing trouble.
So, enter our hero,
EDTA.It has six electron pairs
that can form coordination bonds,
not to mention,
a whole bunch of single bonds
that are capable of twisting and deforming.
That means EDTA can wrap around any ion like a cage,
trapping it and keeping it from harming you.
Well, any ion capable of forming up
to six coordination bonds,
but that’s getting a little in the weeds.
The term for this is chelation,
which comes from the Greek word for claw.
Chelating agents like EDTA
can scavenge dangerous metals,
like lead, and lock them up
until they can be harmlessly eliminated
from your body.
In fact, EDTA is so good at this
that it’s administered medically
to treat lead poisoning.
But these agents don’t just keep metals from poisoning you.
Remember when we mentioned
that a lot of biological molecules need metals
to actually work?
Well a lot of the chemicals
that make food lose their color and flavor over time
are enzymes that require metals to function.
EDTA disrupts the function of those enzymes
by confiscating their metals,
letting food stay fresh for longer.
What’s more,
we aren’t the only ones
that need trace amounts of metals to function.
Bacteria do too –
which is why chelators like EDTA
can act as anti-bacterial agents
by stealing the metals away from those bacteria
before their populations can take off
and cause spoilage.
But because EDTA
is just so good at stealing metals,
we actually have to nerf it a bit.
Otherwise it might steal all the metals
out of our bodies, too.
That’s why we add the calcium and sodium to EDTA,
blocking some of its binding capability
so that it doesn’t slurp up everything
in its path.
Now, in case this sounds too glowing,
we do want to include some of the risks
associated with EDTA.
Because no, this video was not sponsored
by the people who make EDTA.
There’s some evidence that EDTA
can contribute to intestinal inflammation in mice.
This hasn’t been observed in humans,
but it’s good to look out for.
And in medical use,
EDTA is often prescribed in amounts
that could lead to kidney problems.
Now octors generally agree that
when you have severe lead poisoning,
some kidney side effects
are the least of your worries,
so this risk is considered acceptable.
Overall, it’s generally agreed
that EDTA is safe when consumed
in the recommended amount.
And remember:
The dose makes the poison.
Even water’s dangerous
in really high amounts.
So embrace the big long
unpronounceable names.
Because Everything’s less scary
when you understand how it works.
And it’s always good
when people are excited,
not scared, about science.
So tell your friends: that big ol’ acronym
on the ingredients list is helping you out –
and bending the rules of chemistry
along the way.
Thanks for watching this episode of SciShow,
and thanks to all the patrons on Patreon
who made it possible.
You guys rule. We’ll see ya next time.
[ OUTRO ]