Leucine
Performance
Also known as: L-Leucine, BCAA component
A
Grade A💊 2.5-5g to boost a meal🎯 2 primary uses🔗 2 synergies⚠️ Review warnings
Levels upFitness+50 pts
Overview
Primary amino acid triggering muscle protein synthesis. Can boost lower-protein meals.
Primary Uses
Muscle protein synthesis triggerProtein quality enhancement
Frequently Asked About Leucine
How much Leucine should I take?
The typical effective range is 2.5-5g to boost a meal. Individual needs vary based on age, body weight, diet, and goals — start at the lower end and adjust based on response. Always consult a healthcare provider before starting a new supplement.
When is the best time to take Leucine?
With lower-protein meals. Consistency matters more than perfect timing — pick a daily anchor (e.g. with breakfast or before bed) and stick with it.
Should I take Leucine with food?
With protein-containing meals.
Does Leucine interact with medications?
Yes — known interactions include None significant. If you take any prescription medication, talk to your doctor or pharmacist before starting Leucine.
What does Leucine pair well with?
Leucine stacks well with Plant proteins and Lower protein meals — these combinations either improve absorption or work synergistically toward common goals.
Who should not take Leucine?
Leucine should be avoided or used with caution by people with MSUD. Pregnant or breastfeeding women should consult a healthcare provider before use.
What are the side effects of Leucine?
Most people tolerate Leucine well. The most commonly reported side effects are Bitter taste and GI upset. Side effects are usually dose-dependent — lowering the dose often resolves them.
Dosage
Typical range
2.5-5g to boost a meal
Timing
With lower-protein meals
With food
With protein-containing meals
Duration
As needed
Special Populations
Elderly, low-protein meals, plant-based eaters
Research & Studies
Search the literature now
We haven’t curated landmark studies for Leucineyet — one-click into the primary literature here. PubMed (RCTs) is usually the highest-signal starting point.
Mechanism of Action
- • Primary mTOR activator
- • Threshold amount triggers MPS (~2.5-3g)
- • Most anabolic amino acid
Evidence Quality
Evidence Grade A
Well-established as MPS trigger
Safety & Contraindications
Serious Warnings
- • None
Contraindications
- • MSUD
Common Side Effects
- • Bitter taste
- • GI upset
Pregnancy & Breastfeeding
Consult healthcare provider
Liver & Kidney Notes
Normal amino acid considerations
Interactions
💊 Medications
- • None significant
🧪 Supplements
- • Protein (enhances)
🍽️ Food & Alcohol
- • With meals
Stacking & Synergies
Pairs Well With
Plant proteinsLower protein meals
Avoid Combining With
Unnecessary with high-leucine protein sources
Best Goal Synergies
Enhancing protein quality
Buying Guide
What to Look For
- • Pure L-Leucine
Standardization Markers
L-Leucine form
Adulteration risk
Low
Practical Notes
- • 2.5-3g is threshold for MPS
- • Very bitter taste
Tags
amino acidmusclemTORtrigger
Top Products with Leucine
Highest-scored catalog products containing Leucine, ranked by our scoring engine.
Browse all Leucine products →
More in Performance
Other ingredients in the Performance category.
Agmatine Sulfate
Arginine metabolite with nitric oxide and pain-modulating effects. Enhances pumps.
Arachidonic Acid (ARA)
Omega-6 fatty acid that amplifies exercise-induced muscle signaling. Increases training response but also inflammation.
BCAAs
A branched-chain amino acid blend in a 2:1:1 leucine-to-isoleucine-to-valine ratio, formulated in instantized (micronized) form for improved solubility. BCAAs support muscle protein synthesis and may reduce exercise-induced fatigue, though whole protein sources provide comparable benefits at lower cost.
Beetroot / Nitrates
Dietary nitrates converted to nitric oxide for improved endurance and blood flow. Can enhance exercise efficiency.
Beta-Alanine
Increases muscle carnosine for buffering acid during high-intensity exercise. Delays fatigue in 1-4 minute efforts.
Beta-Hydroxybutyrate (BHB)
Exogenous ketone body that can elevate blood ketone levels. Used for energy, cognitive function, and supporting ketogenic diets.
Last reviewed: June 2026 by the Formulate Research Team. Sources cited above; methodology and scoring criteria published here.
Cite this page
Formulate Research Team. (2026, June). Leucine — Evidence-Based Supplement Guide. Formulate Supplement Encyclopedia. https://app.formulate-health.app/learning/supplements/leucine
Educational content based on published research and our scoring methodology. Not medical advice — consult a qualified healthcare provider before starting, stopping, or changing supplements, especially if you take medications, are pregnant, or have a medical condition.