Could depression be caused by an amino acid deficiency?

According to a study by researchers from the University of Eastern Finland (UEF), individuals with major depressive disorder (MDD) have reduced arginine levels.

Arginine is an amino acid that the body needs to produce nitric oxide. Nitric oxide is an immune defense and nervous system mediator. Additionally, nitric oxide is necessary for vascular regulation.

The global arginine bioavailability ratio (GABR) is used to determine the body’s arginine levels and it was previously used to measure the body’s ability to produce nitric oxide. Decreased arginine bioavailability is also a recognized independent risk factor for heart diseases.

The study, which was published in Journal of Affective Disorders, revealed that individuals who are diagnosed with MDD have reduced arginine bioavailability. (Related: 10 Nutritional Deficiencies That Cause Depression and Mood Disorders)

Toni Ali-Sisto, a doctoral student and lead author of the study, said that there is a possibility that depression-induced inflammatory responses can cause reduced arginine levels. This decrease may also cause the insufficient production of nitric oxide, which is crucial for the needs of the nervous system and circulation. She added that they have yet to determine the reason for reduced arginine bioavailability in individuals with depression.

The study, which was carried out by the UEF and the Kuopio University Hospital, observed 99 adults who had major depressive disorder and 253 non-depressed controls. The concentrations of three amino acids (arginine, citrulline, and ornithine) were examined from their fasting glucose samples. The results of the examination were then used to compute their GABRs.

The researchers also measured the participants’ symmetric and asymmetric dimethylarginine concentrations, which are both important in the production of nitric oxide.

The results of the depressed and the non-depressed controls were then compared. The scientists also looked into the possibility that these concentrations varied among individuals with depression during a follow-up of eight months, and whether remission of depression can influence the concentrations.

Ali-Sisto noted that while the study determined that individuals with depression have reduced arginine bioavailability, this does not necessarily mean that taking an arginine supplement will effectively prevent depression. She added that further study is required to corroborate this theory.

Based on the study findings, people with depression had weaker arginine bioavailability than the non-depressed controls. The study did not find notable variations in the symmetric and asymmetric dimethylarginine concentrations. Additionally, the use of anti-depressants or anti-psychotics did not influence the concentrations.

Ali-Sisto stated that arginine bioavailability was marginally higher in individuals who had recovered from depression than in those who remained depressed. She concluded that comprehensive information and a longer follow-up period is needed to determine arginine’s role in depression recovery.

Fast facts on amino acids

  • About 20 percent of the human body is composed of protein. Protein is an essential factor for at least all biological processes, and amino acids are the building blocks of protein.
  • The bulk of our cells, muscles, and tissue is composed of amino acids.
  • Amino acids are responsible for various bodily functions, like giving cells their structure.
  • Amino acids are also important in the transport and the storage of nutrients.
  • Additionally, amino acids affect the function of the arteries, glands, organs, and tendons.
  • Amino acids help heal wounds and repair tissue, such as in the bones, muscles, and skin and hair, along with the removal of all kinds of waste deposits produced in processes involving metabolism.

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