Isoleucine (Essential amino acids)
Isoleucine is an amino acid that is used in the biosynthesis of proteins. It is one of the three branched chain amino acids alongside both leucine and valine. Relative to the other two BCAAs, isoleucine is intermediate for its ability to induce muscle protein synthesis (stronger than valine, but much weaker than leucine) but is able to significantly increase glucose uptake and the usage of glucose during exercise.
Isoleucine and the other branched two chain amino acids (BCAA) are essential amino acids whose carbon structure is marked by a branch point. These three amino acids (isoleucine, leucine, and valine) are critical to human life and are particularly involved in stress, energy and muscle metabolism. They are referred to as essential amino acid in humans, because the body cannot synthesize them, and thus must be ingested in the diet.
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.
Necessary for hemoglobin formation and regulating blood sugar and energy levels.
Isoleucine has diverse physiological functions, such as assisting wound healing, detoxification of nitrogenous wastes, stimulating immune function, and promoting secretion of several hormones. Necessary for hemoglobin formation and regulating blood sugar and energy levels, isoleucine is concentrated in muscle tissues in humans.
One of the major functions of isoleucine in the body is proteinogenesis, which means isoleucine is a building block for the proteins your body cells make. You can't make the structural and functional proteins your body depends on including the protein that makes up muscle, the antibodies used by your immune system, and a variety of hormones without isoleucine.
Isoleucine is widely recognized as an amino acid able to increase endurance and to help heal muscle tissue. It is particularly recommended to professional athletes and body builders, since the primary function of Isoleucine in the body, is to boost up the energy levels and to assist the body in recovering from strenuous physical activity.
Isoleucine also participates in hemoglobin synthesis, as well as in the regulation of blood sugar. It is also known to promote tissue repair after injury or surgery, and there is substantial evidence reported in the literature that the branched-chain amino acid family, of which isoleucine is part of (the other being leucine and valine), has an anabolic effect on muscle protein synthesis.
Wheat germ is a good source of isoleucine. A cup is about 1g of isoleucine,
L-isoleucine is an essential branched-chain aliphatic amino acid found in many proteins. It is an isomer of leucine.
Even though this amino acid is not produced in animals, it is stored in high quantities. Foods that have high amounts of isoleucine include eggs, soy protein, seaweed, most seeds and nuts, turkey, chicken, lamb, cheese, and fish.
A cup of milk contains about 500mg of isoleucine, a cup of wheat germ has about 1g of isoleucine, one egg and an ounce of most cheese contains about 400mg of isoleucine, and about 3 to 4g of isoleucine in a portion of pork.
Deficiency can be brought about due to poor eating habits or diet. Isoleucine deficiency is marked by muscle tremors.
Generally speaking, isoleucine and the other branched chain amino acids, are decreased in patients with liver disease, such as hepatitis, hepatic coma, cirrhosis, extrahepatic biliary atresia or portacaval shunt. Aromatic amino acids (AAA) on the other hand; tyrosine, tryptophan and phenylalanine, as well as methionine-are increased in these conditions.
Deficiency can also be brought about due to poor eating habits or diet. Isoleucine deficiency is marked by muscle tremors. These are unintentional, rhythmic movements involving to-and-fro movements (oscillations) of the muscles.
Biotin (vitamin B7) is an absolute requirement for the full catabolism of isoleucine (as well as leucine).
Biotin, sometimes referred to as vitamin B7 or vitamin H, is an absolute requirement for the full catabolism of isoleucine (as well as leucine). Without adequate biotin, the human body will be unable to fully break down isoleucine and leucine molecules.
Inability to break down isoleucine, along with other amino acids, is associated with the disease called Maple Syrup Urine Disease, which results in discoloration and a sweet smell in the patient's urine, which is where the name comes from. However, in severe cases, MSUD can lead to damage to the brain cells and ultimately death.
The Food and Nutrition Board (FNB) of the U.S. Institute of Medicine set Recommended Dietary Allowances (RDAs) for essential amino acids in 2002. For isoleucine, for adults 19 years and older, 19 mg/kg body weight/day.
Practically speaking, isoleucine is only likely to be a necessary supplement when wanting to increase glucose uptake; it is outperformed by leucine for inducing muscle protein synthesis and outperformed by HMB (Hydroxy β-Methyl butyrate) for reducing muscle protein breakdown, yet outperforms both of those agents and valine in increasing glucose uptake into skeletal muscle.