Leucine ( Leu or L)


    • Leucine is a branched-chain amino acid with the chemical formula HO2CCH(NH2)CH2CH(CH3)2.
    • Leucine is classified as a hydrophobic amino acid due to its aliphatic isobutyl side chain.
    • It is encoded by six codons (UUA, UUG, CUU, CUC, CUA, and CUG) and is a major component of the subunits in ferritin, astacin, and other 'buffer' proteins.
    • Leucine is an essential amino acid, meaning that the human body cannot synthesize it, and it, therefore, must be ingested.
    • It is important for hemoglobin formation.
    • Flavoring ingredient; dietary supplement, nutrient

Health Effects:

    • Anti encephalopathic
    • Essential


    • Indicated to assist in the prevention of the breakdown of muscle proteins that sometimes occur after trauma or severe stress.

Dietary Sources:

    • Leucine is more highly concentrated in foods than other amino acids. A cup of milk contains 800 mg of leucine and only 500 mg of isoleucine and valine. A cup of wheat germ has about 1.6 g of leucine and 1 g of isoleucine and valine. The ratio evens out in eggs and cheese. One egg and an ounce of most cheeses each contain about 400 mg of leucine and 400 mg of valine and isoleucine. The ratio of leucine to other BCAA is greatest in pork, where leucine is 7 to 8 g and the other BCAA together are only 3 to 4 g.

Branched-chain amino acids (BCAAs)

  • Includes- 3 essential amino acids: leucine, isoleucine, and valine whose carbon structure is marked by a branch point.
  • Despite their structural similarities, the branched amino acids have different metabolic routes, with valine going solely to carbohydrates, leucine solely to fats and isoleucine to both. The different metabolism accounts for different requirements for these essential amino acids in humans: 12 mg/kg, 14 mg/kg and 16 mg/kg of valine, leucine, and isoleucine respectively.
  • The BCAA are not without side effects. Leucine alone, for example, exacerbates pellagra and can cause psychosis in pellagra patients by increasing excretion of niacin in the urine. Leucine may lower brain serotonin and dopamine. A dose of 3 g of isoleucine added to the niacin regime has cleared leucine-aggravated psychosis in schizophrenic patients. Isoleucine may have potential as an antipsychotic treatment.