Leucine

Leucine is one of the essential amino acids. It forms an important part of numerous proteins.

What is Leucine?

Leucine (Leu) is one of a total of 21 proteinogenic essential amino acids. It is also called L-leucine or leukine. Leucine is found in some foods and is considered important for muscles.

L-leucine is an aliphatic amino acid and has the chemical name alpha-aminoisocaproic acid. One of the characteristic features of the amino acid is a branched hydrocarbon chain. Since humans are incapable of synthesizing leucine, the amino acid must be regularly ingested through food. The breakdown of leucine from the body takes place through fat metabolism. In some cases, it is also eliminated through urine and sweat.

Together with the amino acids valine and isoleucine, leucine is a component of the Branched Chain Amino Acids (BCAA). Of these three amino acids, leucine has been researched best to date.

Function, effect & tasks

The amino acid leucine is important for protein synthesis in the human body. This means that it plays a role in building protein in the liver and muscles. A sufficient supply of leucine is also required in order to maintain a certain muscle mass in the body. In addition, the amino acid protects the liver from damage caused by alcohol and has a stimulating effect on fat burning.

Leucine is also important for the body as a source of energy. The energy reserves provided by the amino acid counteract an extensive breakdown of glucose. In this way, the muscles and the brain are able to receive enough glucose if necessary. The leucine also stimulates the secretion of insulin, which takes place in the pancreas. This regulates the blood sugar level in the body. In addition, the muscle tissue accelerates the absorption of the amino acid, which in turn promotes the development of muscles. At the same time, the release of the stress hormone cortisol is reduced.

Leucine also has a positive effect on the growth of children and adolescents because it promotes the release of the important hormone somatotropin, which in turn has a positive effect on organ development. In adults, the somatotropin regulates the proportion of fat and muscle. It supports the provision of free fatty acids. L-leucine also serves as the basic building block for glutamic acid, which means that it is involved in several vital metabolic processes.

Leucine is an important component of numerous proteins. Its hydrophobic nature is important for the development of the secondary structure. The amino acid is also found in body fluids such as saliva, liquor, plasma and milk.

Education, occurrence, properties & optimal values

The human body cannot produce leucine on its own. It must therefore be consumed through food. Another option is to take special dietary supplements that help build muscles. Leucine is found in large quantities in cow's milk, beef, chicken eggs, salmon, rice, walnuts, and whole wheat and corn flour. Other foods that contain leucine are peas, tuna and olives.

The daily requirement for the amino acid L-leucine is around 1.2 grams. Depending on which method is used, the daily requirement is on average 15 milligrams per kilo of body weight. In principle, the required amount can be covered by a balanced diet. However, if a person is exposed to strong athletic loads on the muscles because they do endurance or strength sports, they need additional amounts, which can be supplied with the help of a dietary supplement.

Diseases & Disorders

In some cases there may be a deficiency of L-leucine. This is usually caused by insufficient intake of foods containing leucine.

But a vitamin B6 deficiency is not infrequently the reason for a leucine deficiency. The deficiency symptoms are noticeable through constant fatigue. In addition, the affected people usually feel exhausted.

In addition to an undersupply, an overdose of the amino acid is possible. As a result, there is a risk that protein formation will be disrupted. In addition, an efficient build-up of muscles is counteracted. As a result, those affected suffer from complaints such as nausea, diarrhea and abdominal pain.

Hyperaminoaciduria often increases the isoleucine level in the blood ten-fold. Furthermore, breakdown substances such as isovaleric acid are found in the blood plasma. If the transport or absorption of leucine is impaired, this often leads to Hartnup's syndrome, which is associated with serious symptoms. Those affected suffer from eczema, diarrhea, depression, headaches, paresis and aminoaciduria.

If L-leucine breakdown disorders occur due to a deficiency in the enzyme alpha-keto acid decarboxylase, this can lead to maple syrup disease, a metabolic disease, in babies. Symptoms such as vomiting, seizures, a sweet-spicy odor of the urine, lethargy and poor drinking occur as early as the first week of life of the affected child. Even a coma is possible. Without appropriate therapy, the newborn is at risk of death from ketoacidosis.

But leucine also has positive effects on certain diseases. The healing process of muscle tissue diseases, joint diseases and liver problems is promoted by the amino acid. Together with glycine and other proteinogenic amino acids, leucine is also used in medical infusion solutions.

Anyone who also takes L-leucine via dietary supplements should ensure better absorption within the intestine by allowing the body to get enough fluid. In this way, a higher availability in the cells of the muscles is guaranteed.