The answer so far
Amino acids are building blocks of protein. BCAAs are only three of the nine essential amino acids your body must get from food.
BCAAs are three essential amino acids found in protein foods and sold separately as supplements. They participate in muscle protein building, but evidence that BCAA supplements improve muscle growth, performance or recovery is limited and inconsistent. A short-term change in muscle chemistry does not prove a long-term benefit.1
On this page
What are BCAAs?
The name means branched-chain amino acids: leucine, isoleucine and valine. They are called essential because the body cannot make enough of them and must obtain them from the diet. Foods that provide protein can supply these amino acids. Leucine also participates in signalling processes that help regulate muscle protein production; signalling is only one part of building tissue. See what is in a protein drink.31
BCAAs versus complete protein
Building muscle protein requires all the essential amino acids, not only the three BCAAs. A complete protein supplies all nine in adequate proportions; a varied diet can also provide them across foods. An isolated BCAA product and a protein shake are therefore different products. Whether either is useful depends on the whole diet and the person’s circumstances; a BCAA label does not establish that adding it will improve results. For the broader evidence, read do protein powders build muscle?.31
What did a muscle study actually show?
In a 2017 crossover experiment, ten young resistance-trained men received a BCAA drink after exercise on one occasion and a placebo on another. The measured rate of producing muscle proteins over the following four hours was 22% higher with BCAAs. The participants had eaten a protein-containing breakfast earlier. This is an acute laboratory measurement in a small group, not evidence of 22% more muscle growth or strength over months. The experiment did not directly compare BCAAs with a complete protein drink. GlaxoSmithKline Healthcare supported the study through a research grant.2
Do supplements improve training or recovery?
The US National Institutes of Health says studies have not consistently shown that BCAAs improve performance, build muscle mass or aid recovery. A promising short-term mechanism does not settle those practical outcomes. Studies differ in participants, diet, training and products; evidence in one setting cannot establish benefits for everyone.1
Choosing and using products
Check whether a label describes BCAAs alone, a complete protein or a mixture with other ingredients such as caffeine. Products vary in composition, serving size and quality. Supplements can add expense and may duplicate nutrients already present in the diet. If you have a medical condition or take medicines, ask a qualified clinician or pharmacist about your circumstances. Compare protein bars and protein products before assuming one format is better. NIH describes limited short-term BCAA studies in which no safety concerns were reported. That does not establish the safety of long-term use, higher amounts or every combination product.14
Further reading
Trusted external resources selected to help explain this page. They open in a new tab.
- BCAAs and performance: evidence summary ↗US government evidence summary covering performance and safety; includes a section on BCAAs.
- The 2017 BCAA experiment ↗Ten resistance-trained young men; four-hour muscle protein synthesis rather than long-term growth.
Sources, kept close.
Selected supporting sources; this is not a complete literature review.
- Dietary Supplements for Exercise and Athletic Performance: Health Professional Fact SheetNIH Office of Dietary Supplements · US official evidence summary
- Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis following Resistance Exercise in HumansFrontiers in Physiology / PubMed · Primary research — small acute crossover experiment, 2017
- Protein in dietMedlinePlus · U.S. National Library of Medicine consumer reference
- Questions and Answers on Dietary SupplementsU.S. Food and Drug Administration · Regulator consumer guidance