BCAA (Branched-Chain Amino Acids)
A supplement consisting of three essential amino acids — leucine, isoleucine, and valine. Multiple meta-analyses report a moderate reduction in delayed onset muscle soreness (DOMS), supporting post-exercise recovery. However, when total protein intake is already adequate, the incremental benefit of additional BCAA supplementation on muscle protein synthesis appears to be limited.
An ingredient with growing research
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Effects reported in research
Reduction in DOMS: Multiple studies report decreases in post-resistance-exercise muscle soreness and muscle damage markers
Activation of muscle protein synthesis signaling: Leucine in particular has been shown to stimulate the mTOR pathway
Potential reduction in exercise-induced fatigue: The tryptophan-competition hypothesis suggests BCAA may attenuate central fatigue
May support muscle mass maintenance when protein intake is suboptimal, such as during caloric restriction or in older adults
Dosage & timing
- Typically 5–10 g per serving, taken before, during, or immediately after exercise.
- A leucine content of at least 2–3 g per dose is generally recommended.
- Prioritize adequate total protein intake (1.6–2.2 g/kg/day) from food; BCAA supplementation is best used to fill gaps rather than as a primary protein source.
Cautions
- •Generally considered safe at typical doses, though long-term evidence on very high intake is limited.
- •Consult a doctor before use if you have kidney or liver disease.
- •Contraindicated in individuals with amino acid metabolism disorders such as maple syrup urine disease.
- •Pregnant or breastfeeding individuals should also consult a doctor before use.
- •If dietary protein intake is already sufficient, the additional benefit of BCAA supplementation is likely marginal.
Supporting research
Effect of branched-chain amino acid supplementation on muscle soreness following exercise: a meta-analysis
International Journal for Vitamin and Nutrition Research, 2019
BCAA supplementation significantly reduced delayed-onset muscle soreness (DOMS) and creatine kinase (CK) levels at 24–72 hours post-exercise compared to placebo. Effect sizes were moderate; additive benefit over adequate dietary protein remains unclear.
Branched-chain amino acids and muscle protein synthesis in humans: myth or reality?
Journal of the International Society of Sports Nutrition, 2017
The claim that dietary BCAA intake alone stimulates muscle protein synthesis is unwarranted. While leucine activates mTOR signaling, the absence of other essential amino acids (EAAs) means the body must catabolize existing muscle to obtain missing substrates. Maximal MPS requires the full complement of EAAs.
Last checked: 2026-06-26