The essential amino acid isoleucine is just as important for people who are not exposed to physical stress as it is for those who have to perform at the highest levels as competitive and endurance athletes. Isoleucine is found in every amino acid and therefore has an influence on many bodily functions. A deficiency or excess leads to serious health disorders and, in extreme cases, even death.
What is isoleucine?
Isoleucine is a branched chain essential amino acid that belongs to the group of BCAAs (Branched Chain Amino Acids). Typical of these proteins is that they have a characteristic branching in their structural chain. As an essential amino acid, isoleucine cannot be produced by the body itself, but must be supplied through food or as a dietary supplement. Isoleucine can react alkaline or acidic. It is found in varying amounts in many other amino acids and is not converted in the liver, but is transported directly to the muscles. Since it promotes the build-up of muscle tissue in athletes and highly stressed people, it is also called a “stress amino acid”. The organism breaks it down via fatty acid metabolism. In small amounts, it is also excreted in the urine.
Function, effects, and tasks
Isoleucine, along with the other two BCAAs valine and leucine, builds muscle tissue by promoting the synthesis and storage of proteins in muscles. It also regenerates and maintains muscle tissue. It provides energy in the form of glucose during heavy physical exertion. The essential amino acid regulates hormone balance and blood sugar levels by stimulating insulin secretion in the pancreas. It also provides the growth hormone somatotropin in sufficient quantities. As the branched-chain protein strengthens the immune system, it also promotes wound healing. In the case of severe physical stress, operations and illnesses, it reduces the breakdown of muscle tissue together with leucine and valine. Competitive athletes and sick people should therefore consume additional isoleucine, valine and leucine. The same applies to people who follow a reduction diet. In certain forms of schizophrenia, phenylketonuria and cirrhosis of the liver, isoleucine improves the clinical picture.
Formation, occurrence, properties, and optimal values
Since the body cannot produce isoleucine itself, it should be supplied with food or as a dietary supplement. In addition, it is useful to take it daily in sufficient quantities, since increased stress, diseases and a lot of physical activity lead to the depletion of the amino acid in the body. The optimal amount of isoleucine is 1.4 g per day. The daily minimum is 0.7 grams. During intense physical exertion, the requirement increases to 5 to 10 g daily. In order to always supply the body with a sufficient amount of isoleucine, a balanced healthy diet with legumes, nuts and chickpeas is recommended. Salmon, beef and veal also contain a lot of isoleucine. Wheat germ (1.32 g per 100 g) has the highest content, followed by peanuts (1.23 g) and tuna (1.21 g/100 g). Accidental isoleucine overdose is immediately converted to amino acids and storage fat by a healthy body. However, patients with liver and kidney diseases should consult their treating physician beforehand.
Diseases and disorders
A deficiency of isoleucine can lead to muscle weakness and listlessness. If the transport of the amino acid through the cell membrane is disturbed, Hartrup’s syndrome develops: the cells located in the gastrointestinal tract and kidneys can no longer absorb the vital amino acid. Hartrup’s syndrome manifests itself in symptoms such as lupus-like eczema (pellagra), increased photosensitivity of the skin, too strong or too weak skin pigmentation, seizure-like diarrhea, tremors, spasms, double vision, headaches, depressive moods, delusions, anxiety, etc. A high concentration of proteins can be detected in the patients’ urine. The metabolic disorder is inherited in an autosomal recessive manner and occurs with a probability of 1 to 9 per 100,000. Patients of all ages are affected. The recommended therapy is daily administration of 40 – 200 mg nicotinamide and adherence to a high-protein diet. Neurological-psychiatric symptoms are treated by the appropriate specialists.Excess isoleucine can lead to the occurrence of hyperaminoaciduria, a metabolic disorder in which there is increased excretion of amino acids in the urine. In patients with liver damage or phenylketonuria, blood isoleucine levels are increased up to 10-fold. Maple syrup disease is a very rare metabolic disorder also known as valine-leucine isoleucinuria or leucinosis. Patients with this disease have a genetic enzyme defect. The enzyme alpha-keto acid dehydrogenase is no longer able to break down the amino acid in the blood. Isoleucine, leucine and valine are excreted in the urine, which smells like maple syrup because of their decomposition products. The autosomal recessive disorder has a 1 in 100,000 chance of occurring and presents in newborns with respiratory disturbances, vomiting, unconsciousness, epileptic seizures, and if not treated in time, leads to the death of the child. In patients with maple syrup disease, excessive levels of isoleucine, valine, leucine, keto and hydroxy acids are detectable in all organs and body fluids (acidosis of the organism). For initial care, the infant is given glucose and complex sugars in an infusion solution. He is also not given a high-protein diet for two days. In extreme cases, blood washing may be indicated. To prevent further metabolic derailment, the patient must maintain a low-protein diet for life.
