Blood & Laboratory Values

Aspartic Acid – Function & Diseases

Aspartic acid

Aspartic acid is a nonessential amino acid that is adequately supplied in the diet. It is part of most proteins . In addition to glutamate , aspartic acid functions as a neurotransmitter .

What is aspartic acid?

Aspartic acid is a non-essential amino acid that is present in sufficient quantities in all protein-containing foods. It contains two acidic groups, making it an acidic amino acid.

Their biosynthesis in the body takes place very simply from oxalic acid by transamination. It occurs in two optically active forms, with D-aspartic acid being of no biological importance. Only L-aspartic acid is a proteinogenic amino acid. Whenever aspartic acid is mentioned in the following, the L-form is always meant. In biochemistry, it is often also referred to as L-aspartate because it is usually present in the body in a deprotonated form. Aspartate serves as an amino group donor in the urea cycle. Aspartic acid is also produced industrially by adding ammonia to the double bond of fumaric acid.

It is of great importance as a starting material for the production of the sweetener aspartame. Aspartame is a dipeptide made from the amino acids aspartic acid and phenylalanine . It is also used for parenteral nutrition in infusion solutions or as a salt former. Their technical use as polyaspartic acid esters in modern paint systems is also of interest.

Function, effect & tasks

The most important function of aspartic acid is its participation in the construction of proteins. It is one of the 20 proteinogenic amino acids. In addition to glutamate, L-aspartate functions as a neurotransmitter in more than half of all synapses in the central nervous system of vertebrates. 

The exact mode of action of aspartic acid has not yet been researched in detail. Among other things, it is said to be active in the climbing fibers of the cerebellum and in the mossy fibers of the Ammonhorn formation. Overall, however, it is said to have a weaker effect than glutamate. Aspartic acid works by stimulating the NMDA receptors. It is also a starting material for the formation of nucleobases. It is available for the synthesis of pyrimidine bases. In the urea cycle, aspartic acid is converted to argininosuccinate by the enzyme argininosuccinate synthetase. Argininosuccinate is a metabolite of the urea cycle.

It is a non-proteinogenic amino acid which is broken down by the enzyme argininosuccinate lyase into the proteinogenic amino acid arginine and fumarate. As part of the urea cycle, L-arginine releases ammonia. The ammonia released by L-arginine is converted into urea, which is excreted through the kidneys. Fumarate converts back to oxaloacetate (oxalic acid). The oxalic acid is transaminated back to aspartic acid using an alpha amino acid. Glutamic acid is usually available for this purpose, which is then converted into ketoglutarate.

Formation, Occurrence, Properties & Optimal Values

Aspartic acid is widely used. Malnutrition leading to aspartic acid deficiency is hard to imagine. L-aspartate is present in all protein foods. Particularly high concentrations are found in the vegetable asparagus.

The asparagus, with its Latin name Asparagus officinalis, is the eponym for the amino acids asparagine and aspartic acid. Very high levels of L-aspartate are also found in legume seedlings, soy protein, dried egg white, cod, peanut flour, dried spirulina, tofu and also sunflower seed flour. However, supplementation with food is not necessary.

Aspartic acid is one of the amino acids that can be sufficiently synthesized in metabolism as well. Even if no L-aspartate were supplied with food, there would be no deficiency because it is one of the most simply structured and easily synthesized amino acids.

Diseases & Disorders

The main health effect of aspartic acid is to convert ammonia to urea via the urea cycle and remove it from the body. The additional intake of L-aspartate is said to help improve ammonia detoxification. 

It was allegedly found in studies that aspartate shows positive effects in states of exhaustion, tiredness and low physical resilience. However, the research results are not so clear that the effect can be finally assessed. However, indications were found that a low concentration of aspartic acid in the organism is associated with stressful situations and states of exhaustion. Together with lysine , aspartic acid can also be used to eliminate heavy metals by forming complexes with heavy metals.

There are contradictory statements about possible negative side effects when taking too high doses of l-aspartate. According to some sources, there are no side effects, while other reports speak of severe nerve damage. Effects on nerve function are suspected because aspartic acid acts as a neurotransmitter alongside glutamate. However, it has not been possible to make any clear statements on this so far. The sweetener aspartame has caused a lot of discussion. Aspartame is a dipeptide of phenylalanine and aspartic acid. Studies have been conducted that have yielded controversial results.

After consuming food and drinks sweetened with aspartame, isolated cases of migraines , other headaches , mood disorders, depressive moods and many more have been described. However, a connection with the sweetener could not be proven and in some cases even ruled out. However, there is a clear contraindication to aspartame for people with phenylketonuria . In phenylketonuria, the amino acid phenylalanine leads to severe metabolic disorders .

With this disease, a special low-phenylalanine diet must also be adhered to. The frequency of this condition is approximately 1 in 8000. Therefore, aspartame is labeled as containing phenylalanine. However, this contraindication has nothing to do with the aspartic acid contained in aspartame. All in all, it can be said that there are quite contradictory statements about aspartic acid with regard to health effects, which do not allow a conclusive assessment.

Lisa Newlon
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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.