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.
Taking BCAA supplements may help reduce exercise fatigue and improve endurance.
In a 2013 study 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.
According to the authors of a study from 2009, 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.
BCAAs, particularly leucine, may help maintain muscle mass in people with chronic conditions.
According to a 2012 review, 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.
A 2017 systematic review 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 2013 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.
A 2015 study investigated the effects of combined BCAA and arginine supplementation on intermittent sprint performance over 2 consecutive days. Arginine is another type of amino acid.
The study involved 7 females and 15 males who had competed at a national or international level in handball. The participants played simulated handball games over 2 consecutive days.
The researchers found that intermittent sprint performance on the second day was significantly better in the athletes who had taken the supplement, compared with those who had taken the placebo.
The authors concluded that their results could have "significant practical applications" for athletes who have to compete on consecutive days.
BCAA supplementation may benefit people with liver disease.
Over 2 years, Model for End-Stage Liver Disease (MELD) test scores improved significantly among participants who consumed BCAAs, compared with those who did not.
Doctors calculate MELD scores by measuring levels of certain substances in the blood, such as creatinine and bilirubin. They use the resulting score to help determine how close a person is to having liver failure.
The authors concluded that long-term BCAA supplementation has beneficial effects in people with advanced liver cirrhosis and that understanding these effects will require further research.
Another study from 2017 also found that BCCA supplementation improved low muscle strength among people with liver cirrhosis. The researchers assessed muscle strength by testing each participant's hand grip.
BCAAs are essential amino acids, which means that the body cannot make them. However, a wide variety of foods contain BCAAs, and most people can get enough by eating a protein-rich diet.
BCAAs are present in:
- meat, poultry, and fish
- dairy products, such as milk and cheese
- nuts and seeds
- soy products, such as tofu and tempeh
- legumes, including beans, peas, and lentils
Also, many health and fitness stores sell BCAA supplements, and a person can purchase them online.
There is no officially recommended BCAA dosage. Depending on the desired benefit, studies have used different dosages of these supplements.
Before taking a BCAA supplement, read the label and follow the manufacturer's recommendations carefully.
BCAA supplements are generally safe if a person follows the manufacturer's instructions and does not exceed the maximum stated dosage.
However, anyone who experiences serious side effects should stop taking the supplement and consult their doctor.
Some research suggests that there may be a link between BCAAs and certain diseases, including:
- Diabetes. Research indicates that increased BCAA levels may be markers of type 2 diabetes. However, it is not clear whether they are involved in developing insulin resistance.
- Liver problems. According to a 2016 study, there is an association between high levels of BCAAs and nonalcoholic liver disease and liver injury.
- Cancer. Some research has suggested a link between BCAA metabolism and cancer. According to a 2018 review, BCAAs are "essential nutrients for cancer growth," and tumors use them as a source of energy.
- Heart disease. Another 2018 review suggests that high levels of BCAAs may be a marker for heart diseases.
BCAAs are essential amino acids. The body cannot make them, so a person needs to get BCAAs from their diet or as supplements.
Research suggests that taking BCAA supplements may improve muscle mass and performance and may reduce muscle damage from exercise. BCAAs may also benefit people with liver disease.