Supplements containing BCAAs, or branched-chain amino acids, are popular with bodybuilders and athletes for boosting muscle growth and performance. Limited research suggests that BCAAs may also have some other health benefits.

BCAAs are essential amino acids. The three BCAAs are leucine, isoleucine, and valine.

The body uses amino acids to make proteins, which are the building blocks of every cell, tissue, and organ. Amino acids and proteins also play a crucial role in metabolism.

There are 20 amino acids, of which nine are essential. The body cannot make essential amino acids, so a person needs to get them from their diet.

In this article, we discuss some potential health benefits of BCAAs. We also describe sources of these amino acids and possible risks.

Exercise performance

Taking BCAA supplements may help reduce exercise fatigue and improve endurance.

In a 2013 studyTrusted Source involving 26 college-age males, researchers randomly assigned participants to groups. One group took a BCAA supplement and the other a placebo. The team then asked the participants to cycle to exhaustion.

The researchers found that during the cycling, blood levels of serotonin were lower in the participants who took BCAA. Serotonin is an important brain chemical that also plays a role in exercise fatigue.

BCAA supplementation also improved energy metabolism and lowered levels of substances that indicate muscle damage, such as creatine kinase and lactate dehydrogenase.

The researchers concluded that BCAA can improve exercise performance.

Lean muscle mass

According to the authors of a study from 2009Trusted Source, BCAA supplementation can also help improve lean mass and decrease the percentage of body fat.

The study involved 36 strength-trained males who had practiced resistance training for at least 2 years.

The participants underwent an 8-week resistance-training program, and the researchers randomly assigned them to groups. Each received either:

• 14 grams (g) of BCAAs
• 28 g of whey protein
• 28 g of carbohydrates from a sports drink

The researchers found that the participants who took BCAAs had a more significant decrease in body fat and a greater increase in lean mass, compared with the other groups.

Muscle mass during illness

BCAAs, particularly leucine, may help maintain muscle mass in people with chronic conditions.

According to a 2012 reviewTrusted Source, a variety of illnesses can affect protein synthesis, which can lead to a loss of body protein and skeletal muscle mass.

The authors found evidence that a high-protein diet that provides additional leucine can help maintain muscle mass in people with chronic diseases such as cancer.

Muscle damage

A 2017 systematic reviewTrusted Source found some evidence that BCAA supplementation can help reduce the muscle damage that occurs during high-intensity exercise. However, the authors caution that the evidence base was limited to one small study and that confirming these findings will require more research.

Results of a small study from 2013Trusted Source show that adult male participants who took a BCAA supplement during exercise had lower blood levels of substances that indicate muscle damage than those who took a placebo.

The researchers concluded that BCAA supplementation may reduce muscle damage after endurance exercises.

Tardive Dyskinesia

Those who take certain drugs may have a condition called tardive dyskinesia that causes uncontrolled movements. Some antipsychotic drugs and some anti-nausea drugs can cause this condition. Some evidence indicates that supplements of BCAAs can reduce symptoms.

Health Risks

Branched-chain amino acid supplements are considered safe when taken in proper doses for short periods of time. As far as researchers have observed, BCAAs cause very few adverse effects. BCAAs may interact with medications, including thyroid hormones, drugs for Parkinson’s, and medicines for diabetes. 

High Blood Pressure

One study has found that high concentrations of BCAAs are associated with an increased risk of high blood pressure in middle-aged men and women. This study had some limitations, so the topic needs further study.

Before Surgery

Research indicates that limiting amino acids before surgery could reduce the risk of complications. In particular, the risk of stroke and heart attack may be lessened.  

Amounts and Dosage

A typical BCAA dosage for muscle enhancement is up to 20 grams a day taken in divided doses. This amount appears to be safe. If you are taking BCAAs for a purpose other than muscle growth, your doctor will specify the dosage.

The Take-Home Message

BCAAs are beneficial for athletes, individuals engaged in high volume or prolonged exercise, those on restrictive diets who many not get enough from whole food sources, or for anyone otherwise at risk of lean tissue breakdown. Research has shown supplemental BCAA intake to be safe for healthy adults in doses of 4-20 g per day, with prolonged intake one week or more showing greater benefits than acute (short term) intake. Aim for 2-3g leucine between meals, before, during or after workouts to maximize muscle protein synthesis. Smaller amounts of BCAAs taken repeatedly over the course of a long training bout are likely beneficial for delaying the onset of fatigue and preventing muscle tissue breakdown.