Leucine is an amino acid which was discovered in its impure form in cheese back in 1819, and just a year later - in its crystalline form from muscles and wool. This amino acid got its name from the Greek word leukos, which means "white", since at that time the purification of the substance in question from natural to a white, crystalline state was considered to be noteworthy. Only in the end of the 19th century the structure of Leucine was established by laboratory synthesis. This amino acid is also recognized as one of the three branched-chain amino acids.

Chemical Structure of L-Leucine

Structure of Leucine

Identifiers and properties of Leucine

IUPAC Name: (2S)-2-Amino-4-methylpentanoic acid
Symbol: Three-letter code - Leu. One-letter code - L
Molecular Weight (Molar Mass): 131.17292 g/mol
Molecular Formula (Structural Formula): C6H13NO2
Canonical SMILES: CC(C)CC(C(=O)O)N
Isomeric SMILES: CC(C)C[C@@H](C(=O)O)N
CAS Number: 61-90-5
MDL Number: MFCD00002617
Melting point: 293 °C
Solubility in water: 22.4 g/1 L (20 °C); pKa - 2,36; pKb - 9,60
Rf value in n-butanol/acetic acid/water = 12:3:5 - 0.73
2D Molfile: Get the molfile
3D PDB file: Get the PDB file
Other names: L-2-Amino-4-methylpentanoic acid; alpha-Aminoisocaproic acid; L-alpha-Aminoisocaproic acid; alpha-Amino-gamma-methylvaleric acid; (S)-2-Amino-4-methylvaleric acid; 4-Methyl-norvaline

What are the functions of the Leucine?

Leucine is considered a vital amino acid for the protein synthesis and various metabolic functions - in other words, it is an essential amino acid, which helps in regulating the blood-sugar levels, promotes the growth and the recovery of muscle and bone tissues, as well as the production of the growth hormone. This amino acid is also known for preventing the breakdown of muscle proteins caused by injury or stress. In addition, Leucine may be beneficial for people suffering from phenylketonuria.

Benefits of Leucine

Leucine is turned out to be a great tool not just for muscle building, but for the weight loss as well. Those people who have taken different muscle builders and fat burners, and are apparently searching for something else to give them a finer edge, taking a Leucine supplement might be a good idea.

Studies have revealed that this amino acid acts in a unique way: unlike other amino acids, it aids in burning fat without burning a muscle by sparing the muscle proteins and leaving them to assist in building and in increasing the muscle gain and mass. In other words, it is a great supplement for all those gym rats or dieters who have to workout regularly in attempt to build up muscles while keeping the fat off the body. Researches confirmed that people staying on the protein-rich diet, which includes enough of Leucine, lose more body fat while retaining a more lean muscle mass.

Food sources

You should remember that Leucine is an essential amino acid, so your body cannot produce it naturally but only can obtain it from food like beef, chicken, soya protein, soya beans, fish, cottage cheese, eggs, baked beans, liver, whole wheat, brown rice, almonds, brazil nuts, cashew nuts, pumpkin seeds, lima beans, chick peas (garbanzos), lentils, corn. People on a no-protein diet or strict vegans most likely would not obtain much of Leucine coursing through their blood stream. Here are some food sources that contain leucine along with approximate amounts per serving.

Meat and Poultry. Chicken Breast: A 3-ounce (85-gram) serving of roasted chicken breast provides approximately 2.4 grams of leucine. Beef: A 3-ounce (85-gram) serving of cooked beef contains around 2.5 grams of leucine.

Fish. Tuna: A 3-ounce (85-gram) serving of cooked tuna provides about 2.4 grams of leucine. Salmon: Similar to tuna, salmon contains around 2.3 grams of leucine per 3-ounce (85-gram) serving.

Dairy Products. Milk: One cup of milk contains about 1 gram of leucine. Cheese: Different types of cheese provide varying amounts of leucine, typically ranging from 0.5 to 1.5 grams per ounce.

Eggs. One large egg provides approximately 0.7 grams of leucine.

Legumes. Soybeans: A 1-cup serving of cooked soybeans contains around 2.2 grams of leucine. Lentils: A 1-cup serving of cooked lentils provides about 0.8 grams of leucine.

Nuts and Seeds. Almonds: A 1-ounce (28-gram) serving of almonds contains approximately 0.6 grams of leucine. Sunflower Seeds: Sunflower seeds provide around 0.8 grams of leucine per 1-ounce (28-gram) serving.

Whole Grains. Quinoa: A 1-cup serving of cooked quinoa provides about 0.8 grams of leucine. Brown Rice: A 1-cup serving of cooked brown rice contains approximately 0.4 grams of leucine.

Seafood. Shrimp: A 3-ounce (85-gram) serving of cooked shrimp provides around 1.7 grams of leucine. Crab: Crab is another seafood source with approximately 1.7 grams of leucine per 3-ounce (85-gram) serving.

Cabbage Family Vegetables. Spinach: A 1-cup serving of cooked spinach contains about 0.3 grams of leucine.

These values are approximate and can vary based on factors such as cooking methods, specific varieties of food, and preparation techniques. If you have specific health concerns or conditions that may require additional leucine, it's advisable to consult with a healthcare professional or a registered dietitian for personalized advice.