✓ No active regulatory warningsFDA MedWatch, EMA EudraVigilance, WHO VigiBase, WADA Prohibited List · 2026-05-29
Updated: 2026-05-29 · v2.0 · Prof. G. Pkhakadze, MD, MPH, PhDCiteEditorial
📰Read the full L-Leucine evidence review on GMJ News →Complete clinical article, references and updates on news.gmj.ge. This page is the structured safety summary.
1
Safe
L-Leucine
L-Leucine
Generally SafeStrongAmino Acids
RDA
Typical 2–5 g
Target
N/A
Upper limit
No UL
Products
5
Dosage by population group — reference
🔗 Best with: Whey Protein, Creatine, Vitamin D✅ USP Verified, NSF Certified for Sport, Informed Sport
⚠ 25 g whey = 2.75 g leucine — trigger already met [1]
⚠ Elderly need 3–4 g/meal due to anabolic resistance [2]
⚠ Whey > leucine > BCAAs (hierarchy of evidence) [1]
⚠ Levodopa interaction (LNAA competition) [1]
ℹ️ Not obtained from food. Not applicable as a daily target — obtained as part of dietary protein rather than tracked individually.
🔬 Lab interpreter
ℹ️ No validated blood test. There is no established laboratory test to assess status or guide dosing for this ingredient. Clinical response and symptoms are the practical guide.
⚕ For professionals — confirm ranges against your local laboratory.
Clinical verdict
Leucine is THE mTORC1 trigger for MPS (~2.5 g/meal). Whey already provides this. Isolated leucine: useful for elderly (anabolic resistance, 3–4 g/meal) or low-protein meals. Unnecessary if eating adequate protein. Whey > leucine > BCAAs [1] [2].
1 How much do I need?
👤 Adults: Specific dosage data under clinical review
👴 Elderly: Specific dosage data under clinical review
🤰 Pregnancy: See guidance
Essential AA. Food-safe [1].
👦 Pediatric: See guidance
Essential nutrient [1].
🏃 Athletes: Standard dose
⚖️ Obesity: Standard dose
Fat-soluble compounds may require dose adjustment in obesity.
🩺 Renal: Consult specialist
Dose adjustment may be needed in renal impairment.
🌱 Vegan: Standard dose

How to take

🍽 Timing: With meals (to trigger MPS) [1].
💊 With food: Add to low-protein meals [2].
🚫 Avoid: Levodopa patients (LNAA competition) [1].
2 Which form?
FormBioavailabilityVeganCost
['L-Leucine powder', 'common', 'Pure amino acid. Add to low-protein meals [1].']StandardCheck label
['Leucine-enriched protein', '', 'Some elderly nutrition products add extra leucine [2].']StandardCheck label
3 Common questions
Do I need leucine if I eat enough protein? ▼
No — 25 g whey already provides 2.75 g leucine. Isolated leucine is useful when protein quantity is limited (elderly, hospital meals) but unnecessary with adequate protein [1] [2].
Is leucine better than BCAAs? ▼
Leucine IS the key BCAA. BCAAs (leucine + isoleucine + valine) add unnecessary amino acids — and BCAAs alone may paradoxically reduce MPS by depleting other EAAs. Whey protein > leucine alone > BCAAs [1].
4 Clinical evidence

Strong

mTORC1 activation by leucine: established molecular biology [1]. Leucine trigger ~2.5 g: confirmed in MPS studies [1]. Elderly anabolic resistance: higher leucine threshold (3–4 g) [2]. HIGH

Moderate

Elderly sarcopenia: leucine-enriched meals improved MPS vs isocaloric, isonitrogenous meals [2]. Hospital nutrition: leucine supplementation in low-protein hospital meals may preserve muscle [2]. MODERATE

Insufficient

Muscle building beyond adequate protein in young athletes [1]. Weight loss [1]. Cognitive function [1]. LOW
5 Safety, toxicity & adverse events

Absolute contraindications

✕ Maple syrup urine disease

Relative

⚠ Advanced liver or kidney disease — nitrogen load
⚠ Can lower blood glucose (insulin secretion) — monitor in diabetes
⚠ Isolated high-dose leucine may lower other BCAAs — balance is preferable

🚩 Red flags

● Levodopa patient — LNAA competition [1]
● Patient buying leucine while eating adequate protein — unnecessary [1]
6 Interactions

Drug interactions

Levodopa Moderate
Mechanism: LNAA transporter competition. [1]
Effect: Reduced levodopa brain penetration. [1]
Action: Avoid high-dose leucine with levodopa [1].

Supplement synergies

Whey protein (provides leucine + all EAAs) · 25–40 g whey
More effective than isolated leucine [1].
7 Regulatory
United States: GRAS. Supplement [1].
8 US supplement products
5
on-market products containing L-Leucine (NIH DSLD)

Brands carrying L-Leucine (1)

Click a brand to see its L-Leucine products.
Or browse all 5 products in one list →
9 Frequently paired with
L-Methionine 4 sharedL-Lysine 4 sharedL-Tryptophan 4 shared
L-Leucine vs Whey ProteinL-Leucine vs Creatine
10 Cite this page
Vancouver: Pkhakadze G. L-Leucine — safety profile [Internet]. Tbilisi: PHIG; 2026 [cited 2026 Jul 15]. Available from: https://supplement.ge/ingredients/l-leucine/
APA 7th: Pkhakadze, G. (2026). L-Leucine — Safety profile. Public Health Institute of Georgia. https://supplement.ge/ingredients/l-leucine/
📋 Editorial information
Author: Prof. G. Pkhakadze, MD, MPH, PhD
Affiliation: David Tvildiani Medical University (DTMU)
First published: January 2026
Last reviewed: 2026-05-29
Next review: January 2027
References: 2 cited sources
COI: SupplementIndex receives no funding from supplement manufacturers. All content independently authored by PHIG.
Process: Systematic literature review
📄 License & reuse
Published under Creative Commons Attribution 4.0 International (CC BY 4.0). You may share and adapt for any purpose with attribution.
Pkhakadze G. "L-Leucine — Safety Profile." SupplementIndex, PHIG, 2026. https://supplement.ge/ingredients/l-leucine/ CC BY 4.0.
GP
Prof. G. Pkhakadze, MD, MPH, PhD
Professor of Public Health · Head of Department, DTMU
Editor-in-Chief, Georgian Medical Journal (ISSN 3088-4322)
Chair, Public Health Institute of Georgia · UEMS Public Health Section
Educational and public health purposes. CC BY 4.0. Consult your healthcare provider before starting any supplement. Corrections: info@accreditation.ge. Publisher: PHIG