What it is
L-Leucine is a branched-chain essential amino acid and the dominant nutrient signal for mTORC1 — the master switch for muscle protein synthesis.
Supplement · Amino Acid & mTOR Activator
L-Leucine
Pure leucine
2.5–5 g · vegan · gluten-free · 30 caps
muscle-wastingsarcopeniaprotein-deficiency muscleliverpancreas
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How it works
A plasma leucine spike above ~120 µmol/L triggers mTORC1, initiating ribosomal translation in muscle. Other amino acids contribute material but leucine alone fires the signal.
Who should take it
Lifters training fasted or eating sub-leucine meals (plant-based), midlife adults preserving muscle, and dieters in caloric deficit who need to anabolic-prime small protein doses.
Avoid / careful
Maple syrup urine disease. Don’t overdose chronically — leucine alone without the other essentials is incomplete.
When to take it
Morning
Noon
Evening
Night
How to take it
With food
Empty stomach
Before food
Flexible — works in any of the above.
FAQs
Frequently asked
Can L-Leucine be taken on its own?
While L-Leucine is a potent signal for muscle protein synthesis, it should ideally be consumed as part of a complete protein source or with other essential amino acids to provide the necessary building blocks.
When is the best time to take L-Leucine?
L-Leucine is most effective when taken before or during fasted training, or with meals that are low in protein, to maximize its anabolic signaling effect.
What is the significance of the leucine spike?
A rapid spike in blood leucine concentration above ~120 µmol/L is the critical trigger for activating the mTORC1 pathway, which is essential for initiating muscle growth and repair.
Research summary
A plain-English read of the literature behind this supplement. Not a clinical recommendation.
A large body of muscle-protein-synthesis trials (Phillips, Wilkinson) confirms the leucine threshold. Long-term hypertrophy benefits depend on total protein and training.
From the blog
Editorial notes
SacredBod's longer take on L-Leucine — context the structured blocks above don't capture.
L-Leucine is a amino acid & mtor activator supplement. L-Leucine is a branched-chain essential amino acid and the dominant nutrient signal for mTORC1 — the master switch for muscle protein synthesis.
How it works
A plasma leucine spike above ~120 µmol/L triggers mTORC1, initiating ribosomal translation in muscle. Other amino acids contribute material but leucine alone fires the signal.
Who it’s for
Lifters training fasted or eating sub-leucine meals (plant-based), midlife adults preserving muscle, and dieters in caloric deficit who need to anabolic-prime small protein doses.
Dosage & timing
- Typical dose: 2.5–5 g
- Best time: morning
- With food: flexible
- Expected onset: Acute MPS within 60 min; chronic effects depend on training.
India context
Availability on Amazon India is currently limited or import-only for this form. International brands (iHerb, NOW Foods, Doctor’s Best) ship to India with variable customs handling. Local Ayurvedic equivalents may offer overlapping benefits.
Safety
Maple syrup urine disease. Don’t overdose chronically — leucine alone without the other essentials is incomplete.
Added to your stack.