Leucine is an essential branched-chain amino acid (BCAA) that must come from food or supplements. It plays a key role in signaling muscle protein synthesis.

How does leucine support muscle growth?

Leucine helps activate the mTOR pathway, which is involved in initiating muscle protein synthesis. This can support muscle repair and growth when paired with adequate protein and training.

What is a typical leucine dose?

Common supplemental amounts are about 2–5 g per serving. Individual needs vary based on diet, body size, and training goals.

When should you take leucine?

It’s often taken around workouts or with meals to support muscle protein synthesis. Many people use it alongside a complete protein source.

Leucine is generally well tolerated at typical supplemental doses for healthy adults. People with medical conditions or those taking medications should consult a clinician before use.

313 wetenschappelijk onderbouwde voedingsstoffen

3251 bronnen geraadpleegd

Informatie ingedeeld naar bewijs

Verken op doel of categorie

Voedingsstof vinden

Populaire keuzes

Eicosapentaenoic acid (EPA)Vitamin D3 Docosahexaenoic acid (DHA)Zinc (Bisglycinate)

313 voedingsstoffen totaal

Vitamin B

Vitamin B1 (Thiamine)

Vitamin B2 (Riboflavin)

Vitamin B3 (Niacin)

Vitamin B5 (Pantothenic Acid)

Vitamin B6 (Pyridoxine)

Vitamin B7 (Biotin)

Vitamin B9 (Folic Acid)

Vitamin B12 (Methylcobalamin)

Vitamin B12 (Cobalamin)

Vitamin A & Carotenoids

Vitamin C

Vitamin D

Vitamin E

Vitamin K

Vitaminoids

Trimethylglycine (Betaine)

NMN (Nicotinamide Mononucleotide)

Pyrroloquinoline Quinone (PQQ)

D-Chiro-Inositol

Coenzym Q10 (Ubiquinone)

Betaine HCL

Nicotinamide Riboside

Vitamin B8 (Myo-Inositol)

Choline

Citicoline (CDP-Choline)

Coenzyme Q10 (Ubiquinol)

Calcium

Calcium Alpha-Ketoglutarate

Magnesium

Magnesium Bisglycinate

Magnesium L-Threonate

Trace Minerals

Copper (Bisglycinate)

Chromium Picolinate

Manganese (Bisglycinate)

Zinc

Pentadecanoic Acid (C15:0)

Phosphatidylserine

R-Alpha Lipoic Acid

Black Cumin Oil

Extra Virgin Olive Oil

Ceratiq wheat oil extract

Phospholipids

Algae Oil

Fish Oil

Conjugated Linoleic Acid

Gamma-Aminobutyric Acid

Alpha-Linolenic Acid

Gamma-Linolenic Acid

Omega-3

Docosapentaenoic acid (DPA)

Eicosapentaenoic acid (EPA)

Docosahexaenoic acid (DHA)

AminoMar

Acetyl-L-Carnitine

PABA (para-aminobenzoic acid)

Essential Amino Acids

Conditionally Essential Amino Acids

L-Theanine

Non-Essential Amino Acids

Beta-Alanine

L-Cysteine Hydrochloride

Amino Acid Derivative

Taurine

Creatine (Hydrochloride)

L-Arginine Alpha-Ketoglutarate

Creatine (Monohydrate)

Akkermansia muciniphila

Lactobacillus Reuteri

Probiotics

Bifidobacterium longum BB536

Prebiotics

Stinging Nettle Extract

Pomegranate Polyphenols

Red Beet Extract

Pine Extract (Pycnogenol)

Oligomeric Proanthocyanidins (OPC)

Ashwagandha Root Extract

Methylsulfonylmethane (MSM)

Citrus Sinensis Extract

Horsetail Stem Extract

Flax Seed Extract

Sulforaphane Glucosinolate

Garlic Extract

Black Pepper

Apricot Kernel Extract

Lovage

Spiny Rest Harrow Root Extract

Juniper Berry Extract

Bearberry Leaf Extract

White Kidney Bean Extract

Lady’s Mantle Extract

Bitter Orange Extract

St. John’s Wort Extract

Japanese Knotweed Extract

Hydroxytyrosol/tyrosol

Olive extract

Sesame seed lignan extract

Broccoli Sprout Extract

Cranberry Extract

Flavon Glycosides

Gentian Root Extract

Griffonia simplicifolia Extract

Ajuga Turkestanica Extract

Amaranthus Leaf Extract

Banaba Extract

Boswellia Extract

Capsaicin

Cayenne Pepper Extract

Celery Extract

Ceylon Cinnamon Extract

Chamomile Extract

Charantin

Chinese Goldthread Root Extract

Citrus Aurantium Extract

Cocoa Extract

Cyanotis Arachnoidea Extract

Fadogia Agrestis Extract

Garcinia Cambogia Extract

Goldenrod Extract

Green Tea Extract

Guarana Extract

Horse Chestnut Extract

Grapefruit Seed Extract

Grape Vine Leaf Extract

Green Tea Polyphenols

Epigallocatechin Gallate (EGCG)

Adaptogens

Cordyceps sinensis extract

Ginsenoside

Lion's Mane (Hericium erinaceus)

Ginseng Extract

Cat's Claw (Uncaria tomentosa)

Arjuna (Terminalia arjuna)

Tribulus Terrestris Extract

Rhodiola rosea

Panax Ginseng Extract

Mushrooms

Reishi Extract

Astragalus Polysaccharides

Hyaluronic Acid

Glucosamine Sulfate

Chondroitin Sulfate

Glucosamine Sulphate 2KCL

Leucine

Moderate study situation·7/10

A higher score indicates better study conditions, but not necessarily effectiveness.

Leucine is an essential amino acid crucial for muscle protein synthesis, recovery, and metabolic regulation.

Exercise Recovery Muscle Repair Essential Nutrient Exercise Performance Muscle Gain Glucose Metabolism Weight Management

dose range

2–5 g

Single or split around workouts/meals

Consumption

Take with a meal or as part of a protein/BCAA supplement. Athletes may use up to 10 g under supervision.

Not fat-soluble.

Best time

Commonly taken pre- or post-workout. Can be taken with the first meal for anabolic support.

Description

Leucine is one of three branched-chain amino acids (BCAAs) that must be obtained through diet or supplementation. It plays a unique role in activating the key pathways of muscle protein synthesis and may support muscle recovery, performance, and metabolic function.

benefits

Main effects with level of evidence

Moderate

Note on evidence

Leucine has strong evidence for muscle protein synthesis and moderate support for improved recovery and limited but growing evidence for metabolic regulation.

Stimulates muscle protein synthesis

Strong

Leucine is a primary trigger for activating the mTOR pathway, leading to increased muscle protein synthesis and promoting muscle repair and growth.

Particularly relevant for: Athletes · Older Adults · Active Individuals

S1 · American Journal of Clinical Nutrition – Leucine increases muscle protein synthesis S5 · Examine.com – Leucine

Supports muscle recovery after exercise

Moderate

Supplementation can reduce exercise-induced muscle soreness and improve strength recovery.

Particularly relevant for: Athletes · Active Individuals

S2 · Journal of the International Society of Sports Nutrition – Effects of leucine-enriched supplements post-exercise S5 · Examine.com – Leucine

May aid metabolic health and weight management

Limited

Leucine may help regulate blood sugar, support insulin sensitivity, and favorably impact body composition, though this evidence is preliminary.

Particularly relevant for: Individuals Managing Weight · People with Insulin Resistance

S3 · Nutrients – Leucine supplementation and metabolic health S5 · Examine.com – Leucine

Safety & Information

Important safety information & known risks

For educational purposes only • not medical advice

Leucine is generally safe at recommended doses for healthy individuals but poses risks in specific populations.

warning notices

Adverse effects may include gastrointestinal discomfort at high intakes.
Toxicity risk exists for those with maple syrup urine disease or advanced kidney disease.
Chronic excess leucine can cause amino acid imbalance.
Avoid leucine supplementation if you have maple syrup urine disease.
Do not use leucine supplements in cases of severe kidney impairment unless under clinical supervision.
Monitor for hypoglycemia when combining leucine with diabetes medications.

Known interactions with medications

May enhance effects of anti-diabetic drugs.

Contraindications / special precautions

Maple syrup urine disease
Advanced renal impairment

interactions

Important interactions between active ingredient ↔ supplement / medication / food

Leucine interacts with certain medications, notably for diabetes, and may impact branched-chain amino acid balance.

Leucine may enhance effects of anti-diabetic drugs.

drug · Diabetes medications

MonitorModerate

Why

Leucine can improve insulin sensitivity and lower blood glucose, potentially increasing hypoglycemia risk when combined with diabetes medications.

recommendation

Monitor blood glucose closely when using leucine alongside diabetes drugs.

S3 · Nutrients – Leucine supplementation and metabolic health S4 · NIH ODS – Branched Chain Amino Acids Fact Sheet

Leucine may be unsafe in severe kidney impairment.

lifestyle · Chronic Kidney Disease

AvoidStrong

Why

Impaired clearance in chronic kidney disease can worsen metabolic disturbances and lead to toxicity.

recommendation

Do not supplement leucine with advanced kidney disease unless advised by a specialist.

S4 · NIH ODS – Branched Chain Amino Acids Fact Sheet S6 · EFSA Journal – BCAA Safety evaluation

mechanisms of action

Brief explanations of how it works

mTOR pathway activation

Leucine uniquely stimulates the mTOR signaling pathway, which increases muscle protein synthesis and anabolic processes.

S1 · American Journal of Clinical Nutrition – Leucine increases muscle protein synthesis S5 · Examine.com – Leucine

Modulation of glucose metabolism

Leucine has been shown to increase insulin secretion and improve glucose uptake in animal and early human studies, which may support metabolic health.

S3 · Nutrients – Leucine supplementation and metabolic health S5 · Examine.com – Leucine

Sources & References

Primary literature and reviews on which these statements are based

6 sources

American Journal of Clinical Nutrition – Leucine increases muscle protein synthesis

Key study on leucine’s effect on muscle protein synthesis.

Journal of the International Society of Sports Nutrition – Effects of leucine-enriched supplements post-exercise

Muscle recovery benefits of leucine.

Nutrients – Leucine supplementation and metabolic health

Overview of metabolic effects and glycemic control.

NIH ODS – Branched Chain Amino Acids Fact Sheet

General safety and dietary information.