What is Isoleucine

Chemical Name: (2S,3S)-2-amino-3-methylpentanoic acid

Molecular Weight: 131.2

Structrual Formula:

Nitrogen Content: 10.68%

Isoleucine (14)

  • Isoleucine is an essential amino acid, which essential amino acid means it cannot be manufactured by body, and need to be supplied in the diet
  • L-Isoleucine is a neutral, genetically coded amino acid. It is essential in human nutrition
  • Isoleucine is one of three branched-chain amino acids (the others are valine and leucine)
  • Isoleucine is need for hemoglobin formation, stabilizes regulates blood sugar level energy levels and blood-clot formation

Isoleucine and energy poduction

  • Used in the body to produce certain biochemical compounds that helps in engery production
  • During aerobic exercise , isoleucine may provide up to 10% of the total energy produce during long-during activity
  • Important fuel sources for skeletal muscle during periods of metabolic stress (229)
  • Under such conditions, isoleucine may promote protein synthesis , suppress protein catabolism and serve as substrates for gluconogenesis (70)
  • It is mainly catablized in skeletal muscle , stimulating the production of ,amoung other substances ,L-alanine and L-glutamine

Isoleucine and muscle (139, 227)

  • Prevent muscle from breaking down during exercise
  • It can enhance energy , increase endurance
  • Aid in the healing and repair of muscle tissue
  • Prevent muscle at high altitudes and may prolong physical endurance under extreme heat

Isoleucine and Tardive Dyskinesia (TD)

  • Tardive means late; Dyskinesia means abnormal movement (130)
  • This is a side effect caused by long term use of so-called antipsyshotic medications used to treat schizophreniand related psychiatric disorder (130)
  • People with TD suffer from repetitive and uncontrolled movement that can interfere greatly with their quality of life
  • Symptoms of TD : involuntary movements E.g. lip smacking
  • Supplementing with isoleucine could reduce excess phenylalanine in people with this disorder (130)
  • Isolecuine can decrease the availability of L-Phenylalaine in the brain

Isoleucine and Muscle Glucose uptake, glucose oxidation and hepatic gluconeogenesis (195)

Isoleucine and Food

Isoleucine can be found in Cottage cheese, Peanuts, dry whole lentils, sesame seeds, fish, meat and poultry.

Recommended Daily Allowance of Isoleucine

Age group
Infant 3-6 months
child 10-12 years
Amount (mg/kg) of body weight

Adverse effect if taken more than enough of Isoleucine (6)

  • Vomiting
  • Tiredness
  • Upset stomach
  • Redness of face

Precautions (13)

  • Pregnant women and nursing mothers should be avoided
  • Isoleucine can reduce the effectiveness of anti-Parkinson’s drugs, E.g. levodopa


  • 13) Balch, J., MD., Balch, P., CNC., Prescription for Nutritional Healing, 1997.
  • 14) Di Pasquale, Mario, Amino Acids and Proteins for the Athlete, The Anabolic Edge, 1997.
  • 229) Essen P., Heys SD, et al, “The Separate and Combined Effect of Leucine and Insulin on Muscle Free Amino Acids,” Clin. Physiol, 1994.
  • 70) Cynober, Luc, (editor) Amino Acid Metabolism and Therapy in Health and Nutritional Disease, 1995.
  • 227) Bloomstrand, E. , Newsholme,EA, Effect of Branched-chain Amino Supplementation on the Exercise Induced Change in Aromatic Amino Acid Concentration in Human Muscle”, Acta. Physiol. Scand., 1992.
  • 130) Stary O. Tardive dyskinesia from a neurological point of view. Act Nerv Super (Praha). 1981 Dec;23(4):300-1.
  • 139) Borsheim, Elisabet, et al. Branched-Chain Amino Acids activate key enzymes in protein synthesis after physical exercise. American Society for Nutrition J. Nutr. 136:269S-273S
  • 157) Tyson, Don, Amino Acids: Metabolism and Analysis, Interpretation Guide, 1989.
  • 228) Colgan, Michael, MD, Optimum Sports Nutrition, Your Competitive Edge, 1993.
  • 195) Doi Masako, et al. Hypoglycemic Effect of Isoleucine involves increased muscle glucose uptake and whole body glucose oxidation and decreased hepatic gluconeogenesis. Am J Physil Endocrinol Metab 292: E1683-E1693