If you’ve seen the term ‘BCAAs’—which stands for branched chain amino acids—online or on a supplement label, you may have wondered what they are and why your body needs them. Turns out they’re pretty darn important, especially if you exercise.
Let’s Talk About Amino Acids
Time for a quick biology lesson: All proteins in our bodies, like muscle tissue and skin, are made up of molecules called amino acids. There are 20 types of amino acids, nine of which we can’t produce on our own. These are called ‘essential amino acids.’ Of these nine essential amino acids, three have slightly different molecular structures and are called ‘branched chain amino acids,’ explains Michael Roberts, Ph.D., director of the Molecular and Applied Sciences Lab at Auburn University. The three BCAAs are valine, leucine, and isoleucine.
Got it? Good. Let’s move on…
How Do We Get The ‘Essentials’?
Since our bodies can’t make essential amino acids, including BCAAs, we have to get them from food, says Roberts. Luckily, we’ve got plenty of options.
Plant sources of branched chain amino acids include many types of legumes, whole grains, and nuts, like chick peas, corn, and almonds. Animal sources include eggs, meat, and milk proteins, according to the Huntington College of Health Sciences. Yep, that’s why “BCAAs” is printed all over your tub of whey protein. Dairy and meat are particularly rich sources of BCAAs, says Roberts.
So say you drink a glass of milk. Your stomach and small intestine break down that milk’s protein into individual amino acids and send them into your blood stream.. From there, many BCAAs go to skeletal muscle cells. “Our muscles are made up of hundreds of thousands of amino acids,” Roberts says. Yeah, they’re that important.
BCAAs, Muscle, And Exercise
Maintaining muscle mass is important because our bodies use the protein stored there to support vital tissues and organs that also need protein (like our skin, heart, and liver), help maintain our metabolism, and provide the strength we need for daily activities, explains a paper published in the American Journal of Clinical Nutrition. That’s where BCAAs come in. “We’re constantly breaking down muscle for various reasons, and BCAAs play a crucial role in rebuilding it,” says Roberts.
Our muscles are made up of hundreds of thousands of amino acids.
While everyone needs BCAAs, they’re especially important for those who exercise—so runners, weight lifters, and general fitness lovers, listen up. “When you exercise, you break down extra muscle protein for energy,” says Roberts. “You can’t resynthesize protein, rebuild that muscle, and recover from a workout without amino acids.” If you train hard day after a long day but fall short on eating protein, you’ll lose muscle mass over time, Roberts says. Hence why every trainer and their mother seem obsessed with post-workout fuel: No BCAAs, no gains. That after-sweat snack might be a glass of chocolate milk or a protein shake, but you can also supplement with a BCAA supplement. “The benefit of a supplement is that it doesn’t have to be broken down in your stomach and small intestine, and hits your bloodstream (and your muscles) quickly,” says Roberts.
Leucine, one of the three branched chain amino acids, seems to have a particularly strong impact on muscle synthesis. Though all of the branched chain amino acids are needed to rebuild muscle, leucine signals cells to take up those other amino acids, says the Huntington College of Health Sciences. That’s why you’ll often see BCAA supplements that contain a larger amount of leucine than they do amino acids like valine. Whey protein is also high in leucine, Roberts says.
Though muscle synthesis is BCAAs’ most important function, they can also become a source of energy when you work out. “We can turn carbs, fat, and amino acids into cellular fuel, called ATP,” says Roberts. Though the energy we convert from branched chain amino acids only makes up about 5 percent of the total energy we convert while exercising, it makes a difference if you’re an endurance athlete or lifting weights at a high volume, he adds.
When you exercise, you break down extra muscle protein for energy.
BCAAs might even help you stay focused throughout your workouts. Researchers call it the ‘central fatigue hypothesis:’ When BCAAs are present in your blood stream in high numbers, they prevent the conversion of tryptophan into serotonin. Since serotonin is associated with sleep and rest, lower levels may help you push through a workout with more ease, explains a review published in The Journal of Nutrition. It’s important to note, though, that while scientifically sound in theory, this hypothesis hasn’t been fleshed out in research, says Roberts.
Feed Your Muscles
Branched chain amino acids are pretty magical, right? To make sure you’re fueling your muscles to maintain an active lifestyle or make gains in the gym, focus on following your workouts with a high-protein meal, says Roberts. He recommends a post-meal snack or meal that includes an intact protein source like milk, whey protein, or a BCAA supplement. To keep the levels of BCAAs in your blood as stable as possible, try to consume protein every three hours or so, he says.