Leucine
The branched-chain amino acid that triggers muscle growth.
What is Leucine?
Leucine is an essential branched-chain amino acid and the most potent dietary trigger of muscle protein synthesis — it activates the mTOR pathway that tells muscle to build and repair. It is the amino acid athletes and researchers watch most closely for muscle maintenance and recovery.
Health benefits of Leucine
- The key signal that switches on muscle protein synthesis
- Supports muscle growth, repair and recovery from exercise
- Helps preserve lean muscle during weight loss and aging
- Plays a role in blood-sugar regulation
Top food sources of Leucine
See full rankingWhey and dairy, meat, fish, eggs, soy, and to a lesser degree legumes and seeds. Values shown per 100 g.
Soy protein isolate, PROTEIN TECHNOLOGIES INTERNATIONAL, SUPRO
7,200 mg
Egg, white, dried, powder, glucose reduced
7,172 mg
Soy protein isolate, PROTEIN TECHNOLOGIES INTERNATIONAL, ProPlus
7,100 mg
Egg, white, dried
6,838 mg
Soy protein isolate
6,783 mg
Soy protein isolate, potassium type
6,783 mg
Soy protein isolate, potassium type, crude protein basis
6,783 mg
Egg, white, dried, flakes, glucose reduced
6,695 mg
Seal, bearded (Oogruk), meat, dried (Alaska Native)
6,386 mg
Whale, beluga, meat, dried (Alaska Native)
5,778 mg
Fish, cod, Atlantic, dried and salted
5,106 mg
Seaweed, spirulina, dried
4,947 mg
How much Leucine do you need?
There is no FDA Daily Value for individual amino acids. The WHO estimate is around 39 mg per kg of body weight per day — the highest BCAA requirement — readily supplied by a protein-rich diet.
Leucine deficiency
Outright deficiency is rare. Inadequate leucine, often with low total protein, can blunt muscle building and accelerate muscle loss with age.
Nutrition data per 100 g from the USDA & FooDB databases. Daily Values follow the FDA 2016+ labeling standard for a 2,000-calorie diet. This guide is for general information and is not medical advice.
Frequently asked questions
What does Leucine do?
Leucine is an essential branched-chain amino acid and the most potent dietary trigger of muscle protein synthesis — it activates the mTOR pathway that tells muscle to build and repair. It is the amino acid athletes and researchers watch most closely for muscle maintenance and recovery.
How much Leucine do I need per day?
There is no FDA Daily Value for individual amino acids. The WHO estimate is around 39 mg per kg of body weight per day — the highest BCAA requirement — readily supplied by a protein-rich diet.
Which foods are highest in Leucine?
Per 100 g, some of the richest sources are Soy protein isolate, PROTEIN TECHNOLOGIES INTERNATIONAL, SUPRO, Egg, white, dried, powder, glucose reduced, Soy protein isolate, PROTEIN TECHNOLOGIES INTERNATIONAL, ProPlus, Egg, white, dried, Soy protein isolate.
What happens if I don't get enough Leucine?
Outright deficiency is rare. Inadequate leucine, often with low total protein, can blunt muscle building and accelerate muscle loss with age.