There are some topics in the health and fitness industry that inspire passionate debates. One of these is whether or not to drink a BCAA supplement. Plenty of gym bros and recreational lifters alike drink them while they work out to give them energy, or while they’re doing their intermittent fasting so they don’t “go catabolic."
Those opposed will tell you that if you just eat regular complete proteins, you’ll be fine and shouldn’t waste your money.
Both sides will back their arguments up with legitimate research. So... who’s right?
Well, let’s dive in a little bit and explain why "it depends" is actually the best answer.
First of all, a quick primer on BCAA’s or Branched Chain Amino Acids:
They are the individual links that make up the chains we call proteins. There are 20 amino acids: nine of which are considered essential, meaning our bodies do not synthesize them; six of which are considered “conditionally essential,” meaning we sometimes need to supplement under times of intense physical stress; and five of which are considered non-essential, meaning we can synthesize them and don’t need to ingest them.
In terms of building muscle, three amino acids in particular play the largest role: Leucine, Isoleucine, and Valine. Leucine especially has been found to provide the most potent stimulus for muscles to begin growing. In the research, this is known as “Muscle Protein Synthesis.” Isoleucine, meanwhile, is responsible for increasing glucose uptake into cells. So, when most people talk about taking BCAA’s - they’re specifically talking about these three. Many supplements only contain those three amino acids, and we’ll see in a minute why that’s a problem.
Amino acids play a huge role in the body, including energy metabolism, muscle repair, and the synthesis of hormones and neurotransmitters. It’s a good thing then that amino acids can be found in many whole foods you’re probably already consuming. The recommended dietary allowance for leucine, isoleucine, and valine combined is 42-72 mg/kg of body weight – or roughly 3-6 grams for a 170lb person. Check out the table below to see how much of the three muscle-building BCAA’s are found in some common foods:
There are some studies that demonstrate a benefit to taking supplemental BCAA’s, including reduced muscle soreness, faster recovery of strength and increased muscle building over placebo.
A study done by Stoppani, et al. (2009) showed that participants who consumed 14g of BCAA’s per day over eight weeks gained twice as much lean mass and strength and lost twice as much body fat as the other groups in the study. Other researchers were quick to point out that the study was funded by Scivation, the company that produces and sells Xtend, a BCAA supplement. They also noted some errors in the statistical analysis of the study, leading some to question the validity of the results.
Another study published in 2017 by Waldron, et al., found that ingesting 0.087g/kg of BCAA’s, “increased the rate of recovery in isometric strength (5%), CMJ height (3%), and perceived muscle soreness compared with placebo after a single hypertrophy-based training session among diet-controlled, resistance-trained athletes.” Unfortunately, in that study, the sample size was only 16 athletes and the testing was done after just a single bout of exercise. The problem is studies can show an effect of a supplement after a single bout of exercise, but studies done over the course of weeks may not show any "real” benefit in terms of increased muscle mass or strength.
Theoretically, it makes sense that BCAA’s could have a beneficial impact. One of the benefits touted by supplement makers is the ability for BCAA’s to decrease fatigue by inhibiting the uptake of other amino acids like Tryptophan and Tyrosine. Inhibiting these could decrease fatigue by decreasing concentrations of Serotonin in the brain, a neurotransmitter that can stimulate parts of your brain to help you sleep or make you feel happy. However, low serotonin is also associated with anxiety, depression, sleep problems, and carbohydrate cravings. BCAA’s can also lower the production of catecholamines, which can actually impair exercise performance.
Similarly, studies have shown that BCAA’s can decrease cortisol levels when taken during a workout. Initially, that sounds like a great idea. Less cortisol means less muscle breakdown, which could in theory mean more muscle building. The problem is that we actually want cortisol levels to spike during a workout, because it will signal the body to break down fat and utilize it for energy. And we actually want some level of inflammation during and after the workout so we can give the muscle the stimulus it needs to get bigger and stronger.
One unique property of supplemental BCAA’s is that because they’re already broken down, they’re not metabolized in the liver. They go directly from the bloodstream to the tissues, where they can exert their effects. However, many supplemental BCAA’s are incomplete. They only contain certain amino acids. This is a problem because studies have shown that the full complement of amino acids is required to induce muscle building, and when you only give some of the amino acids, the body may actually start breaking down muscle to synthesize the other ones it needs (Wolf, et al., 2017).
Now, there are certain instances where you could make the case that supplemental BCAA’s do make sense. Vegans, for example, might have a hard time getting enough of certain essential amino acids. Leucine, especially, is one that vegans may have trouble hitting the recommended daily minimum dosage. That said, it is absolutely possible to get enough BCAA’s on a vegan diet. There are several plant-based foods that are considered “complete proteins," including buckwheat, quinoa, and soy. The trouble is eating them in sufficient quantities to hit the threshold needed for muscle protein synthesis.
Another group that may benefit is people that generally have a low-protein diet. These folks may notice some muscle-building benefits of supplemental BCAA’s, assuming they get all of the essential amino acids with the BCAA’s. A low protein diet is considered anything less than 1-1.5g/kg of body weight, or about 77-115g of protein for a 170lb person.
There’s also one more situation where drinking supplemental BCAA’s may have a beneficial impact – and that’s if you believe they do. The placebo effect is a real thing. So, if you take them and believe that they will make a difference for you, then they may in fact have a benefit.
Outside of those instances, however, the research is relatively clear: BCAA’s alone will not help you increase your strength or muscle mass. A systematic review published in 2017 concluded the following,
“An extensive search of the literature has revealed no studies in human subjects in which the response of muscle protein synthesis to orally-ingested BCAAs alone was quantified, and only two studies in which the effect of intravenously infused BCAAs alone was assessed.... We conclude that the claim that consumption of dietary BCAAs stimulates muscle protein synthesis or produces an anabolic response in human subjects is unwarranted.”
Examine.com reviewed 143 studies on the subject and concluded the following:
“For people with low dietary protein intake, BCAA supplementation can promote muscle protein synthesis and increase muscle growth over time. Supplementation can also be used to prevent fatigue in novice athletes. BCAAs are important to ingest on a daily basis, but many protein sources, such as meat and eggs, already provide BCAAs. Supplementation is unnecessary for people with a sufficiently high protein intake (1-1.5g per kg of bodyweight a day or more).”
While the ultimate decision is up to the individual, my personal recommendation would be to save your money and get all of the amino acids from whole food sources like meat, eggs, fish, or dairy. For more resources on BCAA’s check out some of the following articles:
Stay tuned in the coming weeks as we take a look at some other hotly debated topics in the health and fitness world.
And remember: Use your powers for good!