The difference between essential and non-essential amino acids

HostWe hear so much about protein in our food, whether it's in a steak or a bowl of beans, but we don't always talk about what's actually inside that protein. It turns out that protein is just a big word for a bunch of smaller building blocks that our bodies need to work right.

HostWhen people start digging into the details, they often hear about these two groups called essential and non-essential amino acids. It sounds like one group matters and the other doesn't, so what's the real split there?

GuestThe names are actually a bit of a trick. It makes it sound like you can just ignore the non-essential ones, but your body needs all twenty of them to keep you alive and moving. Think of them like the letters of the alphabet. If you want to write a sentence, like building a muscle or fixing a cut, you need the right letters to spell the words. If you're missing even one letter, the whole process just stops.

GuestThe real difference is all about who does the work. Your body is like a very smart factory. For about eleven of those twenty letters, the factory has the blueprints and the tools to make them from scratch. Those are the non-essential ones. They're not optional for your health, but it's not essential that you find them in your food because your body can just build them on its own whenever it needs more.

HostSo if the body is such a great factory, why does it stop at eleven? It seems like a bit of a flaw to be so reliant on what we find to eat for the other nine.

GuestIt does feel like a risk, right? But it's actually a way to save energy. Making these things from scratch is a long, hard process for your cells. Over a very long time, our ancestors were eating enough plants and meat that already had those nine specific amino acids. Our bodies basically decided to stop doing the hard work. We outsourced the job to the food chain.

GuestBy not making those nine essential amino acids ourselves, we save a lot of internal power that we can use for other things, like keeping our hearts beating or thinking. The catch is that we're now on the hook for them. We have to eat them every day because our bodies aren't very good at storing extras for a rainy day.

HostI have heard people talk about a wooden barrel when they explain this. How does a barrel help us understand a burger or a salad?

GuestIt's a great way to see the problem. Imagine a barrel made of wooden slats of different heights. Each slat represents one of those nine essential amino acids we have to eat. Now, if you want to fill that barrel with water, which represents your body building new tissue, the water can only go as high as the shortest slat.

GuestYou could've a ton of eight of those amino acids, but if you're low on the ninth one, the water leaks out at that low point. You can't use the extra of one to make up for the lack of another. Your body needs the full set at the same time to get the job done. This is why we talk about protein quality. Some foods have all nine in the right amounts, while others might be a bit short on one or two.

HostThis makes it sound like we should all be worried about every single bite of food. Does this mean people who don't eat meat are constantly dealing with a leaky barrel?

GuestNot at all, but it does mean you have to be a bit smarter about how you mix things. Most meat and dairy are what we call complete proteins, meaning they have all nine essential slats at a good height. Most plants might be short on one or two. For example, grains like rice are often low in one specific amino acid, but beans have plenty of that one.

GuestBeans might be low in a different one that rice has in spades. When you eat them together, like a classic bowl of rice and beans, the slats pull even. You end up with a complete set. You don't even have to eat them in the exact same mouthful, as long as you get a good variety over the course of the day.

HostYou mentioned earlier that there are twenty of these in total, with eleven we make ourselves. Are those eleven always easy for the body to handle?

GuestUsually, yes, but there's a weird third group we should mention. We call them conditional amino acids. Most of the time, they stay in the non-essential camp because our internal factory is humming along just fine. But if you get really sick, or if your body is under an incredible amount of stress from an injury, the factory can’t keep up with the demand.

GuestIn those moments, your body basically sends out an emergency signal saying it can no longer make enough on its own. Suddenly, a non-essential amino acid becomes essential. You have to start getting it from your diet or through a supplement to help your body heal. It shows that the line between these groups isn't as thick as we think.

HostIt's interesting that our needs change based on what's happening to us. It makes me wonder if there's a limit. I mean, could we ever find a person who can make all twenty, or is the nine-piece gap pretty much hard-wired into being human?

GuestIt seems pretty hard-wired. We have been living this way for so long that we have actually lost the genetic blueprints to make those nine. We would need a total rewrite of our biology to change that. Right now, the big area of study is whether the exact balance of those nine should change as we get older or if we're training for a marathon.

GuestWe're finding that the perfect height for those barrel slats might be different for a sixty-year-old than it's for a twenty-year-old. We're still trying to pin down exactly how much of each specific one is best for different stages of life.

HostThe protein bricks on your dinner plate aren't just there to be burned for energy, they're the actual physical parts your body uses to rebuild itself. Seeing that half the kit has to be shipped in from the outside changes how a simple bowl of rice and beans looks on the table.