Branched-Chain Amino Acids

Last Updated: November 14 2022

Branched-chain amino acids (BCAAs) are three essential amino acids that are frequently supplemented because of their role in muscle growth and development. These amino acids are naturally found in dietary protein sources. Studies show that supplementation of BCAAs alone does not increase muscle growth, as all essential amino acids must be present for muscle protein synthesis to occur.

Branched-Chain Amino Acids is most often used for

What are branched-chain amino acids?

BCAAs refer to three essential amino acids: leucine, isoleucine, and valine. They are distinct from other essential amino acids as they possess a branched side chain and play a large role in the regulation of muscle mass. They are present in high amounts in muscle tissue in comparison to other essential amino acids.[121] BCAAs cannot be synthesized in the body, so they are important to ingest daily. Daily protein sources, such as eggs and meat, typically provide an adequate amount.[122]

What are branched-chain amino acids’ main benefits?

The main benefit of BCAAs are their ability to enhance muscle growth and alleviate muscle fatigue. Studies found that supplementing with BCAAs alone does not provide an optimal muscle protein synthesis response, as all essential amino acids are required for muscle protein synthesis.[123][124] There seems to be a role for BCAA supplementation in increasing muscle protein synthesis if they are taken along with a meal that has an adequate amount of essential amino acids.[124] However, there is no evidence that BCAA supplementation enhances muscle strength or hypertrophy when adequate protein requirements are met.[122] BCAA supplementation for fatigue may be beneficial, based on a meta-analysis of BCAA effects on markers of muscle damage. The results found that BCAA supplementation reduced muscle damage and muscle soreness after exercise, but may not speed up the recovery of muscle performance.[125]

What are branched-chain amino acids’ main drawbacks?

There is a growing interest in understanding the correlation between the amount of BCAAs present within the body and insulin resistance. In insulin resistant states, such as in people with obesity, there appear to be higher circulating levels of BCAAs.[126] However, serum BCAAs seem to be more of a biomarker of insulin resistance, and their potentially causative role is not well understood and requires further research.

How do branched-chain amino acids work?

Amino acids are the building blocks of proteins, and adequate amounts of all essential amino acids are required for adequate protein synthesis. BCAAs alone do not promote muscle protein synthesis.[123]

What else is Branched-Chain Amino Acids known as?
Note that Branched-Chain Amino Acids is also known as:
  • BCAAs
  • BCAA
Branched-Chain Amino Acids should not be confused with:
Dosage information

The three BCAAs are leucine, isoleucine, and valine. They’re considered the most anabolic of the nine essential amino acids and have therefore been marketed as a sports supplement. However, it's possible that only leucine is especially anabolic, and that leucine taken alone is actually more anabolic than leucine taken with isoleucine and valine, due to competition for both absorption in the gut and entry into muscle tissue.

The standard leucine dosage is 2–10 grams. The standard dosage for isoleucine is 48–72 milligrams per kilogram of bodyweight, assuming a non-obese person. Further research is needed to determine valine’s optimal dosage and the reason for supplementation.

A combination dose is 20 grams of combined BCAAs, with a balanced ratio of leucine and isoleucine.

Supplementation with BCAAs is not necessary if enough BCAAs are provided through the diet.

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