However, excessive BCAA usage can have negative side effects, such as reducing performance and increasing the risk for type 2 diabetes. Read on for further detail on the correct dosage and what else BCAA supplements can do for you [4, 5].
What are BCAAs?
BCAAs are the largest collection of amino acids in the body, accounting for up to 35% of muscle proteins .
BCAA formulas have been on the market since 1996, mainly for treating liver diseases such as cirrhosis and hypoalbuminemia .
BCAAs Health Benefits
1) Improves Exercise Performance
Exercise leads to amino acid usage. BCAAs become rapidly depleted after exercise, showcasing the possible beneficial effects of BCAA supplementation .
In a double-blind randomized controlled trial of 218 marathon runners, BCAA supplementation improved mental performance .
The running times of slower athletes improved, but there were no improvements in faster runners .
In another trial of 36 males, BCAA supplementation increased their muscle strength more compared to other supplements, like whey protein and carbohydrate supplements .
This effect could be caused by increases in cortisol as seen in a study of 10 volunteers. Cortisol controls the fight-or-flight response, which can flood muscles with glucose, providing brief but great amounts of energy .
However, a study of 12 athletes found no increases in handgrip strength following BCAA supplementation .
Moreover, excessive BCAA supplementation can decrease exercise performance. A rat study showed that a 3.57% BCAA-supplemented diet increased swimming time until exhaustion by 37%. However, a higher (4.76%) BCAA-supplemented diet decreased swimming times by 43% compared to the controls .
Reduces Fatigue and Increase Endurance
Similarly, BCAA supplementation can increase endurance. In a trial of 10 endurance runners, the runners given BCAA supplements ran better times for two consecutive days in a row in both 5,000 and 10,000 m races .
Oxygen consumption (VO2) is a measure of LT and the study showed that overall VO2 measures increased by 13% and max VO2 increased by 4.2% .
Furthermore, excessive BCAA supplementation leads to increased ammonia production, promoting fatigue .
May Improve Fat Loss
In a trial of 7 volunteers, BCAA supplementation increased fat loss which is associated with improvements in aerobic exercise .
Increases Lean Mass
In a study of 36 body-builders, BCAA supplements increased lean mass by an average of 4 kg, which was more than other bodybuilding supplements like carbohydrate supplements and whey protein .
May Reduce Soreness
In a trial of 12 healthy female volunteers, BCAA supplements decreased delayed-onset muscle soreness (DOMS) by 80%. Soreness reduces exercise performance in subsequent days .
However, in a trial of 21 older volunteers, BCAA supplementation did not improve muscle soreness .
May Reduce Muscle Damage
Supplementing with BCAAs decreases protein degradation in the muscles .
May Increase Short-Term Memory Performance After Exercise
A trial of 12 volunteers showed that after exercise, athletes without BCAA supplementation had reduced short-term memory. Memory performance in BCAA supplemented volunteers did not decrease .
May Decrease Reaction Times
In a trial of 10 soccer players, those given BCAA supplements showed a decrease of up to 10% in reaction time compared to the controls .
May Reduce Perceived Exertion
In a trial of 7 cyclists, BCAA supplementation reduced the exertion that was perceived by the athletes by up to 7%. However, even if their exertion was lower, their exercise performance did not change .
Reduces Perceived Pain
BCAA supplementation decreased blood CO2 levels by 9%, which normally increases with exercise .
It also increased average oxygen intake (by 19%) and minute ventilation (by 22%), which measures the volume of gas inhaled by the lungs per minute .
Finally, BCAA supplementation increases ventilatory response, which allows the body to process and receive oxygen at higher rates .
Does Not Affect Heart Rate
Although some BCAA users mention it as a typical concern before starting supplementation, scientific evidence shows that BCAAs don’t affect heart rate by themselves.
In a study of 12 men taking BCAA and carbohydrate supplements, the supplements did not increase heart rate .
The increased heart rate seen by some users may be due to other components in the supplements such as caffeine.
2) May Improve Liver Health
In one trial, BCAA supplementation not only increased nutritional status but also improved sleep and decreased fatigue in liver cirrhosis patients .
Furthermore, in a trial of 16 controls, 20 chronic hepatitis patients, and 100 cirrhosis patients, BCAA supplementation greatly increased albumin in the blood, which leads to declines in both liver diseases .
Liver survival rate without any detrimental event was around 63.6% with BCAA supplementation .
3) Can Help the Kidneys
BCAA supplementation also improved appetite and nutrition in dialysis patients .
4) May Prevent Heart Failure
In rat studies, BCAA supplementation improved outcomes after induced heart failure and cardiac cachexia (severe weight loss), improving functions such as :
- Decreased heart rate
- Increased heart function
- Increased survival time
- Decreased weight loss
- Increased mitochondrial function
In humans, BCAA breakdown deficiencies are linked to increased heart disease risk .
5) May Increase Energy
During states of increased amino acid levels, the amino acids will compete with glucose to provide energy, thereby becoming a secondary source of energy. In one study, people with high levels of amino acids required 36% less glucose .
Isoleucine and valine can also be converted to glucose for energy .
One gram of BCAA is around 4 calories .
6) May Improve Insulin Resistance and Diabetes
Insulin resistance increases blood sugar levels. In a trial of 27 patients suffering from either insulin resistance or hepatitis C, BCAA supplements improved muscle insulin resistance in 10 of the patients (but remained unchanged in the rest) .
Moreover, BCAA levels can be used to predict insulin resistance. In a weight-loss study of 500 participants, insulin resistance was correlated with increased BCAA levels .
Insulin resistance is the most common cause of type 2 diabetes. In a long-term study of 2,422 subjects, after 12 years, 201 patients with insulin resistance developed type 2 diabetes and had higher levels of BCAAs .
Also, urine leucine levels were significantly higher in 55 type 2 diabetes patients .
BCAA supplementation itself increases the risk of type 2 diabetes. In a 15 year study of 155 middle-aged women, increasing BCAA intake by up to 20% increased the risks of type 2 diabetes by 7% .
7) May Improve Sleep
Some patients with kidney problems develop sleep disorders such as sleep apnea, which can reduce sleep quality and time .
In a study of 7 patients, taking BCAA supplements at night increased rapid eye movement (REM) sleep and decreased end-tidal CO2 levels, which are important for dreaming and respiratory function during sleep .
Limitations of BCAA Supplementation
BCAA mechanisms and amino acid ratios for treating muscle damage and soreness are still unknown .
Also, BCAA supplementation may interfere with the absorption of other amino acids. The blood-brain barrier uses similar mechanisms for amino acid absorption. Extra BCAA supplementation can lead to decreased absorption of tryptophan, tyrosine, and glutamine [43, 44].
BCAAs can be supplemented as:
The powder or lemonade forms tend to taste worse but are the most popular. This is because you have to take a lot of capsules or tablets to get the recommended amount and they take longer to digest.
Also, foods high in protein content such as chicken, turkey, beef, pork, milk, and cheese will be high in BCAA content .
There is still not enough data for correct dosing of BCAA. However, one study found that 0.087g/kg at a 2:1:1 ratio (leucine:isoleucine:valine) improved performance factors such as strength and decreased soreness .
Leucine, one of the BCAAs, is safe for use up to a dose of 35 grams/day in adult males .
It is recommended to take BCAA supplements before and after exercise to reduce muscle damage .
It is important to remember excessive dosing can have the opposite effect and worsen performance. In one rat study, excessive BCAA supplements increased fatigue .
Although there is clinical data on toxic doses on rat studies, human data is not available .
Synergies with Other Supplements
In a trial of 10 endurance runners, combining BCAA supplements with arginine and citrulline supplements improved run time. While BCAA supplementation can increase ammonia levels, arginine and citrulline both decrease them, thus having a protective effect .
Side Effects & Precautions
1) Can Lead to Hyperammonemia
BCAA supplementation increases ammonia levels in the blood (hyperammonemia), which can lead to a variety of different brain disorders such as Reye syndrome and deficiencies of urea cycle enzymes .
Furthermore, hyperammonemia leads to increased fatigue .
2) May Lead to Amyotrophic Lateral Sclerosis (ALS)
ALS is one of the most common neuromuscular diseases, especially in athletes. This is caused by increased BCAA levels, leading to increased excitation of certain neurons .
These neurons become hyperexcited to toxic levels, causing ALS .
3) Decreases Absorption of other Amino Acids
BCAA with morphine, a pain medication, increases the effectiveness and duration of the pain relief .
People with various diseases should not take BCAA supplements.
Patients with McArdle’s disease uptake and degrade BCAA at much higher rates. When they took BCAA supplements, their heart rates spiked and exercise performance decreased .
Maple Syrup Urine Disease is caused by deficiencies in the molecule responsible for BCAA breakdown (branched-chain α-keto acid dehydrogenase). These individuals will have unusually high levels of BCAA, and supplementation could worsen their symptoms .
Should Be Warily Taken by Diabetics
Although not fully validated, BCAA supplementation has been shown to conserve blood glucose and glycogen levels. Diabetics should be wary of taking BCAA supplements, especially during exercise when glucose levels should decrease since BCAA supplements help to conserve glucose levels .
In a study of 73 obese and 77 lean patients, BCAA levels were significantly higher in obese patients. BCAA supplementation can lead to activation of certain pathways such as mTOR, S6K1, and IRS1, which can lead to insulin resistance .
Krüppel-like Factor 15 (KLF15) is a key regulator of the heart’s BCAA catabolic pathway. Defective KLF15 increases levels of branched-chain α-keto acids (BCKA), which are known to promote heart defects and failure .
BCAA supplement users say that their workouts have improved heavily. One user states that the BCAA supplements have helped even during their “cutting” phase.
Other reviews mention that it is hard to go wrong with BCAA supplements no matter the brand.
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