2.5/5
Weak
evidence
Body composition evidence brief
Leucine
Leucine is important for muscle protein synthesis, but free leucine is usually redundant when total high-quality protein or EAA intake is sufficient.
Headline Finding
Leucine-trigger reviews support its role in MPS; free leucine adds little when complete protein is sufficient.
Dose Context
Most practical value is correcting a low-leucine meal or low-protein diet, not stacking extra capsules on top of adequate protein.
Important Caveat
Most relevant when meals are low in essential amino acids, protein is impractical, or older/clinical anabolic resistance is the target context.
Source Drawer
Linked Research
- Systematic review Young active adults systematic review
- Systematic review Leucine trigger systematic review
- Full text Leucine trigger full text
- Position stand ISSN EAA position stand
- Meta-analysis Protein dose-response meta-analysis
How To Read This Rating
The score reflects evidence that the supplement does its stated job. Some jobs are direct, such as strength, endurance, or recovery; others are indirect, such as sleep, mood, appetite, or health support. A real effect can still receive a cautious practical rating when dose, safety, product quality, or audience fit remain uncertain.
Spot An Evidence Issue?
Send the disputed claim, source link, and why it changes the practical verdict. Corrections that materially affect the claim, dose, caveat, or rating are prioritized.
Report a source or rating issue