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 ]