L-Leucine
L‑Leucine
Snapshot
L‑Leucine is a branched‑chain amino acid (BCAA) essential for stimulating muscle protein synthesis, supporting muscle recovery, and regulating blood sugar during exercise.
What is L‑Leucine?
L‑Leucine is one of three BCAAs (alongside isoleucine and valine) that the body cannot synthesize and must obtain from dietary sources. It plays a pivotal role in activating the mTOR pathway, which governs muscle protein synthesis.
Where It Comes From
Dietary L‑leucine is found in protein‑rich foods such as meat, poultry, fish, eggs, dairy, soy products, legumes, and nuts. In supplements, it is provided as the free L‑isomer, often in combination with other BCAAs.
Key Nutrients & Compounds
Supplemental L‑leucine delivers the pure L‑isomer. It is frequently combined with isoleucine and valine in a 2:1:1 ratio to optimize synergistic effects on muscle growth and energy metabolism.
Health Benefits
L‑Leucine directly stimulates muscle protein synthesis via mTOR activation, aiding muscle repair and growth. It helps regulate blood sugar by promoting insulin release and enhances recovery by reducing exercise‑induced muscle breakdown.
Recommended Dosage
Typical supplemental doses range from 2 to 5 grams of L‑leucine per serving, within a total BCAA intake of 5–10 g per day, taken around workouts to maximize anabolic response.
How to Use It
Mix L‑leucine powder or BCAA blends into water or sports drinks and consume before, during, or after exercise. Capsules can be taken with water at similar times for convenience.
Who Should Use It?
Athletes, bodybuilders, and active individuals seeking to enhance muscle recovery, growth, and performance benefit most. It may also aid older adults in preserving lean mass during aging.
Possible Interactions or Cautions
High isolated leucine intake can disrupt the balance of other BCAAs. Individuals with branched‑chain ketoaciduria should avoid BCAA supplements. Those with kidney disease should consult a healthcare provider before use.
Final Thoughts
L‑Leucine is the key BCAA for triggering muscle protein synthesis and supporting recovery. When used in appropriate ratios around exercise, it is a powerful tool for muscle health and performance enhancement.
Scientific Studies
Norton, L. E., & Layman, D. K. (2006). Leucine regulates translation initiation of protein synthesis in skeletal muscle after exercise. Journal of Nutrition, 136(2), 533S–537S.
https://doi.org/10.1093/jn/136.2.533S
Koopman, R., et al. (2005). Co‑ingestion of leucine with protein enhances postprandial muscle protein accretion in elderly men. American Journal of Clinical Nutrition, 82(1), 106–113.
https://doi.org/10.1093/ajcn/82.1.106
Churchward‑Venne, T. A., et al. (2012). Leucine‑enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis. Journal of Nutrition, 142(4), 742–748.
https://doi.org/10.3945/jn.111.157230