Leucine
The primary BCAA for triggering muscle protein synthesis.
Also known as: L-Leucine
Overview
Leucine is one of the three branched-chain amino acids (BCAAs) and is widely regarded as the most important for muscle growth. It acts as a powerful signaling molecule that activates the mTOR pathway, which is the primary mechanism for initiating muscle protein synthesis. Supplementing with leucine, or ensuring adequate intake from protein sources, is critical for maximizing muscle anabolism.
Key Benefits
Potent Activator of Muscle Growth
Leucine directly stimulates the mTOR signaling pathway, which is the master regulator of muscle protein synthesis.
Prevents Muscle Catabolism
It can help spare muscle tissue during periods of intense exercise or caloric restriction by reducing the rate of protein breakdown.
Enhances Post-Workout Recovery
By kick-starting the muscle repair process, leucine can help reduce recovery time and muscle soreness.
Dosage & How to Take
To maximize protein synthesis, it's recommended to consume at least 2.5 grams of leucine per meal. This is known as the 'leucine threshold'.
| Purpose | Dose | Notes |
|---|---|---|
| Activate Protein Synthesis | 2.5-5g | Add to a meal or shake that is low in leucine. |
| Post-Workout | 5g | Take with post-workout protein and carbs to maximize the anabolic response. |
Best Time to Take
Best taken with meals (especially those lower in protein) or as part of a post-workout recovery shake.
With or Without Food
Should be taken with other amino acids/protein and carbohydrates for best results.
Forms & Bioavailability
| Form | Absorption | Best For | Notes |
|---|---|---|---|
| Powder | High | Adding to shakes and meals | Allows for precise dosing. |
| Capsules | High | Convenience | Easy to take with meals. |
Side Effects & Safety
Common
- None at typical doses.
Rare
- Extremely high doses may cause an imbalance in other amino acids and increase ammonia levels.
Contraindications
- Individuals with Maple Syrup Urine Disease (MSUD) should not supplement with leucine.
Interactions
Vitamin B6 is required for amino acid metabolism, including leucine.
Scientific Research
Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis
Supplementing with leucine during and after exercise enhances muscle protein synthesis.
Food Sources
Products With Leucine
15 products in our database contain this ingredient
Frequently Asked Questions
Medical Disclaimer
This content is for educational and informational purposes only and is not intended as medical advice. Always consult with a qualified healthcare professional before starting any supplement regimen, especially if you have pre-existing health conditions or are taking medications. The statements on this page have not been evaluated by the Food and Drug Administration.