BCAAs
Branched-Chain Amino Acids
The three essential amino acids (leucine, isoleucine, valine) that support muscle protein synthesis and reduce exercise fatigue.
Branched-Chain Amino Acids (BCAAs) consist of three essential amino acids: leucine, isoleucine, and valine. They're unique because they're metabolized directly in muscle tissue rather than the liver. While whole protein sources (and EAAs) are generally more effective, BCAAs remain popular for fasted training, endurance exercise, and situations where full protein isn't practical. Leucine is the primary driver of muscle protein synthesis.
Mechanisms of Action
mTOR Activation
Leucine triggers muscle protein synthesis
Central Fatigue Reduction
Competes with tryptophan to reduce brain serotonin during exercise
Energy Substrate
Can be oxidized directly by muscles during exercise
Recommended Dose
5-10g per serving
Loading: Not applicable; can be taken before, during, or after training
Optimal Timing
- Before fasted training
- During long endurance sessions
- Between meals
Can be taken without food
Best Form
Powder (2:1:1 ratio)
Alternatives: Capsules, Flavored powder
Look for 2:1:1 or higher leucine ratios. Flavored versions mask the bitter taste. Fermented BCAAs may be higher quality.
Duration
Minimum: 2 weeks
Optimal: 8 weeks
Cycling: Not required
Note: Most beneficial for fasted training. If eating protein around workouts, BCAAs offer minimal additional benefit. Common ratio is 2:1:1 (leucine:isoleucine:valine).
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Reduced Muscle Soreness
Less DOMS (delayed onset muscle soreness)
Sustained Mental Focus
Reduced perceived exertion during long workouts
Muscle Preservation
May help preserve muscle during fasted training or caloric deficit
Bitter Taste
Unflavored BCAAs have a strong bitter taste
Generally safe; get most amino acids from food
Most beneficial for fasted or endurance training
Who Should NOT Take This
- Maple syrup urine disease
- ALS (may accelerate progression - avoid)
Drug Interactions
May reduce levodopa absorption
May affect blood sugar; monitor levels
Possible Side Effects
Tip: Take with water; avoid on completely empty stomach
Tip: Use moderate doses; cycle if using long-term
Warnings
- EAAs (Essential Amino Acids) provide more complete benefits
- If eating adequate protein, benefits are minimal
- Avoid if you have ALS
Top studies from 40+ peer-reviewed papers
van Dijk AM et al. • European journal of clinical investigation (2023)
“Prophylactic BCAA supplementation appears safe and might improve survival in cirrhotic patients.”
Key Findings:
- According to meta-analyses, long-term (at least 6 months) BCAA supplementation in cirrhotic patients significantly improved event-free survival (p = .008; RR .61 95% CI .42-.88) and tended to improve overall survival (p = .05; RR .58 95% CI .34-1.00).
- Prophylactic BCAA supplementation appears safe and might improve survival in cirrhotic patients.
- Further research warranted to confirm findings
Soares-Weiser K et al. • The Cochrane database of systematic reviews (2018)
“This review has found that the use of valbenazine or extract of Ginkgo biloba may be effective in relieving the symptoms of tardive dyskinesia.”
Key Findings:
- Studies were primarily of short (three to six6 weeks) duration with small samples size (10 to 157 participants), and most (61%) were published more than 20 years ago.
- Two studies found moderate-quality evidence of a benefit of the intervention compared with placebo: valbenazine (RR 0.63, 95% CI 0.46 to 0.86, 1 RCT, n = 92) and extract of Ginkgo biloba (RR 0.88, 95% CI 0.81 to 0.96, 1 RCT, n = 157), respectively.
- This review has found that the use of valbenazine or extract of Ginkgo biloba may be effective in relieving the symptoms of tardive dyskinesia.
- However, since only one RCT has investigated each one of these compounds, we are awaiting results from ongoing trials to confirm these results.
Gluud LL et al. • The Cochrane database of systematic reviews (2017)
“In this updated review, we included five additional trials.”
Key Findings:
- In a random-effects meta-analysis of mortality, we found no difference between BCAA and controls (risk ratio (RR) 0.88, 95% confidence interval (CI) 0.69 to 1.11; 760 participants; 15 trials; moderate quality of evidence).
- BCAA had a beneficial effect on hepatic encephalopathy (RR 0.73, 95% CI 0.61 to 0.88; 827 participants; 16 trials; high quality of evidence).
- We found no small-study effects and confirmed the beneficial effect of BCAA in a sensitivity analysis that only included trials with a low risk of bias (RR 0.71, 95% CI 0.52 to 0.96).
- In sensitivity analyses that excluded trials with a lactulose or neomycin control, BCAA had a beneficial effect on hepatic encephalopathy (RR 0.76, 95% CI 0.63 to 0.92).
Cai S et al. • Journal of the American Heart Association (2024)
“The increased levels of 3 BCAAs positively correlated with an increased risk of hypertension.”
Key Findings:
- As suggested by the meta-analysis results, elevated BCAA levels were associated with a higher risk of hypertension (isoleucine: summary odds ratio, 1.26 [95% CI, 1.08-1.47]; leucine: summary odds ratio, 1.28 [95% CI, 1.07-1.52]; valine: summary odds ratio, 1.32 [95% CI, 1.12-1.57]).
- The increased levels of 3 BCAAs positively correlated with an increased risk of hypertension.
- Particularly, elevated isoleucine level is a causal risk factor for essential hypertension.
- Increased levels of leucine and valine also tend to increase the risk of essential hypertension, but further verification is still warranted.
Cochet C et al. • Nutrients (2023)
“PROSPERO CRD42022332288.”
Key Findings:
- Mitochondrial function was significantly improved by the administration of BCAA alone (1 RCT) or in association with vitamin D (1 RCT).
- BCAA alone (2 RCTs) or PUFA (1 RCT) were not effective in improving muscle health.
- In conclusion, BCAA in association with vitamin D may be useful in the treatment of sarcopenia and boost mitochondrial bioenergetic and redox activity.
- PROSPERO CRD42022332288.
Study Type Distribution
Goals This Supplement Supports
Related Goals
This information is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare provider before starting any supplement.