Protein supplements including whey protein and branched-chain amino acids (BCAAs) can support muscle growth, enhance muscle synthesis, reduce muscle soreness, improve muscle recovery after resistance training and exercise. BCAA is a popular supplement of choice among athletes and sports enthusiasts to recover quickly after strenuous physical activity.
This article describes BCAA’s benefits, dosage, food sources, and risk.
What are BCAAs?
There are 20 different types of amino acids that make up all the proteins in the human body.
Out of 20 amino acids, 9 are considered essential amino acids (EAAs) because our bodies cannot make them in sufficient quantities.
BCAAs are among the essential amino acids. There are 3 BCAAs:
Almost 50% of the essential amino acids in food are BCAA proteins. Approximately, 35% of essential amino acids in muscles are BCAAs (1).
Since BCAAs are essential amino acids, they cannot be produced in the body. They must be acquired from dietary sources.
For protein synthesis and muscle mass development, enough amount of protein containing essential and non-essential amino acids is required (2).
Leucine is the principal essential amino acid required for protein synthesis.
Leucine and its metabolite beta-hydroxy-beta-methyl butyrate (HMB) in combination with other amino acids can decrease protein degradation and enhance protein synthesis (3).
READ: More on how leucine induces lean muscle development
Isoleucine is an essential amino acid important for several functions. It plays an important role in modulating growth, fatty acid metabolism, and the immune system (4).
Isoleucine is also important for glucose regulation and may have glucose-lowering effects (5).
Valine, the third member of BCAAs is also required for protein synthesis. So far, no human study has shown that valine alone can promote protein synthesis, but an appropriate amount of valine in the diet is required for protein synthesis.
What do BCAAs do?
In exercise and physical training, they are of particular interest because they can promote faster recovery, reduce soreness, central fatigue, muscle damage, and improve lean muscle mass development.
Unlike other essential amino acids that are metabolized in the liver, BCAAs are metabolized in skeletal muscles (6,7).
This may explain why they are crucial for muscle synthesis and maintenance of muscle mass compared to other essential amino acids.
Most of the research on BCAA has been done for their importance in exercise physiology.
The more important benefits are described below
BCAA help in muscle mass increase
Protein synthesis is the most important benefit of BCAA.
BCAAs participate in the mTOR signaling pathway required to enhance protein synthesis after resistance training (8).
In humans, BCAAs intake causes anabolic protein synthesis when combined with resistance training (9).
Among BCAAs, leucine is the only amino acid known to promote protein synthesis (10).
BCAAs use alone, however, cannot lead to increased protein synthesis (11).
Therefore, an adequate amount of other essential and nonessential amino acids are required to promote muscle mass increase with resistance training.
Do BCAAs help you lose weight?
BCAA intake can be helpful for weight loss and obesity.
A multi-ethnic mixed population study showed an inverse relationship between BCAA and Obesity. High BCAA intake was associated with a low prevalence of obesity and vice versa (12).
A randomized control trial shows that a combination of BCAA (6 g per day) and vitamin B6 (40 mg per day) improved the waist to hip ratio in overweight women although, this combination did not reduce body weight (13).
Increased plasma BCAAs are observed in obese and diabetics, which is most likely due to BCAA metabolism dysfunction (14,15).
Decreased in muscle damage
Exercise-induced muscle damage (EIMD) results in loss of skeletal muscle functions and increase soreness (16).
For athletes and sports enthusiasts, EIMD is a natural consequence of resistance training. BCAA as a dietary supplement can help with reducing EIMD. Several studies show a positive effect of BCAA in reducing muscle soreness.
Research shows that protein supplements containing a high percentage of BCAA resulted in reduced muscle damage (17,18).
In individuals who had exposure to regular exercise, intake of BCAA reduced the damaging effects to some degree (19).
A randomized, double-blind control study showed that the use of BCAA 10 g twice daily had a positive impact in reducing muscle damage after high-intensity muscle-damaging exercise (20).
BCAA consumption resulted in lower serum levels of creatine kinase (CK) and lactate dehydrogenase (LDH) after resistance training (21).
Increase plasma CK and LDH level is an indication of tissue damage.
BCAAs can reduce muscle soreness
Performing unfamiliar exercises most often result in muscle soreness.
Delayed-onset muscle soreness (DOMS) is one of the consequences of performing an eccentric or unfamiliar form of exercise. The symptoms include reduced force capacities, stiffness, swelling, and dysfunction of adjacent joints (22).
BCAA can reduce the soreness of muscle when taken before exercise. A study found that the use of 5 g BCAA in green tea before strenuous exercise significantly reduced muscle soreness even up to 5 days (23).
A meta-analysis concluded that BCAA intake reduces DOMS compared to no BCAA use. Furthermore, the use of BCAA supplements after exercise was effective in reducing soreness compared to no BCAA use (24).
BCAAs for central fatigue and recovery
Another consequence of resistance training and physical exercise is central fatigue. Central fatigue starts at the central nervous system level.
Prolonged exercise causes neural changes affecting physical performance and reducing the nervous system’s ability to activate muscles (25).
Exercise increases serotonin levels in the brain, causing central fatigue. Serotonin production is dependent on amino acid tryptophan. BCAA lowers tryptophan transport to the brain, which reduces serotonin levels, eventually lowering central fatigue and improving physical performance (26).
How much BCAA is needed per day?
Currently, there is no recommended BCAA intake per day. The reason is that there is heterogeneity in the BCAA amount used in different studies.
A high intake of BCAAs may not be beneficial and may not give an advantage in muscle development.
Even a small amount of BCAAs is sufficient to increase protein synthesis. A study used 3 g of BCAA per day and found increased protein synthesis (27).
Many studies have used more than 5 g per day to see the metabolic effect of BCAAs.
A BCAA ratio of 2:1:1 (leucine:isoleucine: valine), similar to naturally occurring animal BCAAs, was used in several studies. This ratio is considered safe (28).
Food sources of BCAA
BCAAs are an integral part of proteins, therefore almost all protein sources contain BCAAs.
The food source of BCAAs are both animals and plants however, BCAAs are readily available from animal sources (29,30).
- Nuts and seeds
BCAA supplements are very popular among athletes and bodybuilders. A good quality BCAA supplement can be beneficial in improving muscle mass. The majority of the supplements contain a serving of 5 g with a BCAA ratio of 2:1:1 (leucine: isoleucine: valine). Please read the label and instructions carefully before use.
Can BCAAs be harmful?
BCAAs are considered safe to consume. Currently, there is no reported case of BCAA toxicity in sports and exercise.
But high amounts of BCAA intake can be toxic, especially BCAA metabolites (31).
Obese and diabetes patients should take BCAA with precaution or avoid them because they already have high serum BCAAs levels, which increase insulin resistance (32).
Patients with Maple syrup urine disease (MSUD) should avoid BCAAs because
BCAAs intake can cause DNA damage. MSUD patients cannot metabolize BCAAs, which leads to toxic accumulation of BCAA and their metabolites (33).
Frequently asked questions (FAQ)
Does BCAA cause hair loss?
At present, no scientific study shows hair loss as the potential harm of BCAA. Research has suggested that nutritional deficiency in essential amino acids can increase the risk of hair loss and alopecia. For example, leucine and isoleucine deficiency is observed among people with different hair loss conditions (34).
Does BCAA help lose belly fat?
Yes, BCAA may reduce body fat, which will eventually help lose belly fat. One study showed that the use of BCAA and vitamin B6 combination can decrease the waist to hip ratio in overweight women.
Do BCAAs reduce serotonin?
Yes, BCAAs can reduce serotonin. An amino acid, tryptophan, is required for serotonin production. BCAAs use tryptophan which reduces its availability for serotonin and thus, serotonin levels are reduced.
When should I take BCAAs?
Currently, there is no hard and fast rule of BCAAs intake time. But many studies on BCAA were conducted in which participants consumed BCAAs around physical exercise. Therefore, taking BCAAs before, during, or after a strenuous physical exercise can be beneficial
Does BCAA affect sleep?
BCAAs may improve sleep. Research shows that people with insomnia have dysfunctional BCAA metabolism during the night. In animals, BCAA supplement reduces the effects of insomnia (35).
Therefore, current research points toward a positive role of BCAA for sleep.
Can BCAA cause depression?
The high doses of BCAAs are detrimental to health and may have depression as a side effect, but low to moderate amounts can be beneficial.
Animal research shows that leucine has an antidepressant function by reducing inflammation (36).
Lower BCAA levels are observed in people suffering from major depression compared to non-sufferers (37).
Population research shows that BCAA consumption is inversely associated with the possibility of getting depressed (38).
Current data suggest that low to moderate intake of BCAA may decrease depression symptoms
Does BCAA increase testosterone?
Current Research On The Effects Of BCAA On Testosterone Increase Is Limited. But Research In Animals Shows That Resistance Training And BCAA Improve Sperm Function And Increase Testosterone Levels (39).
Can I mix BCAA and creatine?
BCAA and creatine can be mixed for consumption during or after physical exercise. BCAA and creatine mix are safe to consume because several research studies were done using whey protein and creatine with no adverse effects in participants (40).
when to take BCAA?
BCAA can be taken before, during, or after the workout. Currently, there is no set rule on when to take BCAA.