What Are BCAA Supplements—And Are They Effective For Building Muscle? (2024)

Amino acids are organic compounds that serve as building blocks for protein synthesis, which is important for building and maintaining muscle. There are a few foods that contain all of the essential amino acids your body needs, including beef, fish, chicken, poultry, dairy, eggs and soy.

There are three branch chain amino acids (BCAAs)—leucine, isoleucine and valine—that are especially critical for skeletal muscle function.

Leucine plays a significant role in muscle protein synthesis while isoleucine promotes a healthy protein metabolism. Isoleucine is critical to the maintenance of whole-body function on a physiological level, including growth, protein metabolism and immunity. Lastly, valine can help stimulate muscle growth and tissue repair.

In supplement form, manufacturers suggest BCAAs have positive effects on athletic performance and even weight loss, which is why BCAA supplements tend to be popular amongst the fitness community and athletes.

In a nutshell, BCAA supplements claim to help strengthen endurance during workouts, minimize muscle fatigue and support healthy weight control. Recent 2019 research suggests the positive effects of BCAAs on muscular health are possibly due to their ability to stimulate muscle protein synthesis after strenuous movement activity. Still, the same research explains BCAA supplementation alone—absent of the consumption of other essential amino acids—is not enough to sustain maximum protein synthesis, suggesting a proper diet of high quality protein may be even more important to muscular health than supplementing with BCAAs alone^[1]Santos CS, Nascimento FEL. Isolated branched-chain amino acid intake and muscle protein synthesis in humans: a biochemical review. Einstein (Sao Paulo). 2019;17(3):eRB4898. .

While a 2021 meta-analysis of studies on male participants in Nutrients did find an association between BCAA supplementation and decreased muscle soreness, every study used had less than 50 participants^[2]Khemtong C, Kuo CH, Chen CY, Jaime SJ, Condello G. Does Branched-Chain Amino Acids (BCAAs) Supplementation Attenuate Muscle Damage Markers and Soreness after Resistance Exercise in Trained Males? A Meta-Analysis of Randomized Controlled Trials. Nutrients. 2021;13(6):1880. . The efficacy of BCCAs and muscle soreness requires more research, especially when it comes to a more complex participant pool and the fact that this data point is always self-reported and can vary, which can make it difficult to assess.

Research around weight loss and BCAA supplementation follows the same pattern; there are some positive findings, but the subject warrants much larger studies. According to a smaller 2021 study in Nutrients, when paired with a moderate protein hypocaloric diet (i.e a high protein diet), BCAA supplementation led to a higher chance of achieving weight loss for those already living with obesity^[3]Ooi DSQ, Ling JQR, Ong FY, et al. Branched Chain Amino Acid Supplementation to a Hypocaloric Diet Does Not Affect Resting Metabolic Rate but Increases Postprandial Fat Oxidation Response in Overweight and Obese Adults after Weight Loss Intervention. Nutrients. 2021;13(12):4245. .

While there are many BCAA supplements on the market, the lack of large, high-quality studies on their benefits means that you should talk with your registered dietitian nutritionist (RDN) before starting yourself on a BCAA regime to make sure it’s the right supplement for you—and will actually help you with your specific goals.

“When choosing the right BCAA supplement, I highly suggest you look for a 2:1:1 ratio of leucine, isoleucine and valine,” says Jesse Feder, a registered dietitian nutritionist and personal fitness trainer in Miami.

Feder further explains that “this ratio is well-researched compared to the other ratios on the market.” The Recommended Dietary Allowance (RDA) of BCAAs is contingent on this ratio: 45 milligrams per kilogram of leucine per day, 22.5 milligrams per kilogram of isoleucine per day and 22.5 milligrams per kilogram of valine per day. However, it’s important to note that this RDA is for sedentary individuals; active individuals need more.

“You will also see ratios that go all the way up to 10:1:1, but there is limited research on [the efficacy of] this amount,” continues Feder.

Always check recommended intake instructions for your supplements of choice, which you can find on the product’s Supplement Facts panel. If a product doesn’t include this information, that’s a major red flag.

While research suggests peak BCAA levels occur approximately 30 minutes after ingestion and falter after 180 minutes, this is only based on a small study of healthy male students^[4]Tsunekawa K, Matsumoto R, Ushiki K, et al. Significance of serum branched-chain amino acid to tyrosine ratio measurement in athletes with high skeletal muscle mass. BMC Sports Sci Med Rehabil. 2021;13(1):1. . Based on the findings from this small sample group, it could be ideal to supplement BCAAs shortly before the start of a workout session—but different BCAA brands may also have different directions around ingestion time.

“You may see supplements that are [formulated for intake] before, during or after your workout,” says Feder. Timing of intake is typically included in the “suggested use” section of a product’s packaging—but be mindful of the fact that these suggestions aren’t regulated and are often a results of marketing.

There are no reported adverse effects of taking BCAAs short or long term, according to research. However, “excessive consumption may lead to nausea, diarrhea or tummy upsets for those with sensitive stomachs,” according to Feder. Additionally, high intake of any kind of amino acid can also elevate ammonia production levels in the urine and blood, which at high levels can cause liver or kidney damage

Like most supplements, it’s best to stick with the dosage recommendation on the supplement itself, or a registered dietitian nutritionist.

While it may be tempting to believe a supplement is all you need to increase lean muscle mass, like many subjects in fitness, the long way is usually a better way. Eating a nutritious diet that includes optimal amounts of lean protein for an active lifestyle can also lead to muscle building, especially when combined with resistance training, according to the American College of Sports Medicine (ACSM). Because natural forms of complete protein, such as meat, eggs, fish, cheese and certain protein powders, contain all essential amino acids (including BCAAs), focusing on getting an adequate amount of complete protein every day will help you with your fitness goals.

The ACSM also points out that pre-exercise protein supplementation (whether through a protein shake or food), may also aid in post-workout recovery (i.e soreness).

If you’re an athlete or simply looking to up your gym and muscle game, talk to a registered dietitian nutritionist or a certified personal trainer about the optimal amount of daily protein for you and your goals.