Ingredient Repository · Ingredient

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Ingredient

Branched-Chain Amino Acids (BCAAs)

Essential amino acids (Leucine, Isoleucine, Valine) that stimulate muscle protein synthesis and reduce exercise fatigue.

What it is

Branched-Chain Amino Acids (BCAAs) are three essential amino acids—L-Leucine, L-Isoleucine, and L-Valine—featuring a non-linear aliphatic side chain. Combined in the ideal physiological ratio of 2:1:1, BCAAs cannot be synthesized by the human body and must be acquired through diet. L-Leucine serves as the primary molecular trigger for the mechanistic target of rapamycin (mTORC1) signaling pathway, directly stimulating muscle protein synthesis, attenuating muscle breakdown during exercise, and speeding post-workout recovery.

Also known as: BCAAs, L-Leucine, L-Isoleucine, L-Valine, Branched Chain Amino Acids

What it does

  • Triggers mTORC1 signaling to stimulate skeletal muscle protein synthesis.
  • Reduces exercise-induced delayed onset muscle soreness (DOMS) and breakdown.
  • Blunts central nervous system fatigue during prolonged physical exertion.

Amplified by probiotics

Free BCAAs are absorbed in the small intestine via sodium-dependent L-type amino acid transporters (LAT1/SLC7A5). Probiotic lactobacilli and bifidobacteria enhance LAT1 expression and intestinal microvilli mucosal architecture through short-chain fatty acid (SCFA) production and reduced luminal inflammation. Furthermore, active lactic acid bacteria express peptidases and metabolic enzymes that convert residual luminal amino acids efficiently, avoiding toxic proteolytic putrefaction in the large intestine (such as ammonia and p-cresol formation). Probiotic colonization also lowers gut mucosal inflammation, facilitating rapid BCAA uptake into systemic circulation for muscle protein accretion and exercise recovery.

Typical dose

5–10 g/day (2:1:1 Leucine:Isoleucine:Valine ratio)

The evidence

Evidence: strong

The International Society of Sports Nutrition (ISSN) position stand confirms that BCAAs, particularly L-leucine, effectively stimulate muscle protein synthesis and attenuate post-exercise muscle soreness (Kerksick et al. 2018, J Int Soc Sports Nutr). Systematic reviews verify reductions in muscle damage markers (creatine kinase) and accelerated physical recovery (Fedewa et al. 2019, Int J Sport Nutr Exerc Metab).

  1. Kerksick CM, et al. ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr. 2018;15(1):38. PubMed ↗
  2. Fedewa MV, et al. Effect of branched-chain amino acid supplementation on exercise-induced muscle damage: A systematic review and meta-analysis. Int J Sport Nutr Exerc Metab. 2019;29(6):658-666. PubMed ↗

Safety & who should check first

Excellently tolerated at doses up to 20 g/day. Avoid in patients with amyotrophic lateral sclerosis (ALS) or branched-chain ketoaciduria (maple syrup urine disease).