The Clinical Significance of Organic Acids Testing to Mental Health – How Fungal, Bacterial, Mitochondrial, and Other Test Markers Influence the Brain

Kurt Woeller, D.O.

Organic acids testing is diagnostic tool that every healthcare practitioner should know about.  Whether you are a family practitioner, psychiatrist, a nutritionist, or other type of practitioner, the information provided by organic acids testing can help identify underlying causes of a variety of chronic illnesses, including the symptoms of autism, neuropsychiatric disorders like depression and anxiety, and neurodegenerative disorders like Alzheimer’s disease.  Below is a review of some of the most clinically significant markers measured with organic acids testing to mental health and the health of the brain in general. 

Many of the case studies reviewed in presentations about organic acids testing involve patients with autism.  While autism may not typically be considered a mental health disorder, it is a neurodevelopmental disorder and many autistic individuals suffer with mental symptoms such as anxiety and depression, along with associated behavioral problems.  Many patients with autism also have mitochondrial dysfunction and chronic infections (like Candida and clostridia), which are measured with organic acids testing. (1)

Mitochondria are linked to every organ system in the body, including the brain, and there markers for mitochondrial function in organic acids testing. Without adequate mitochondrial function, neurons cannot function appropriately to produce neurochemicals such as dopamine and serotonin.  Mitochondria are damaged by various endogenous toxins produced by Candida (a fungus) such as tartaric acid and citramalic acid. Also, certain clostridia bacteria produce propionic acid which damages mitochondria. Candida and clostridia are both measured with organic acids testing.  Mitochondria are also damaged by oxalate, which is produced by Candida and some molds, and is also measured with organic acids testing. Certain molds like Aspergillus produce mycotoxins which directly damage mitochondria. Organic acids testing specifically measures candida toxins, bacteria toxins, and mold toxins, along with mitochondria markers. (2, 3)

Clostridia bacteria can produce various compounds like HPHPA, 4-Hydroxyphenylacetic acid and 4-Cresol (all measured with organic acids testing), and are known to inhibit dopamine metabolism. These chemicals inhibit Dopamine-Beta Hydroxylase which causes neuronal dopamine levels to rise. This has been associated with paranoia and schizophrenia. Also, the breakdown products of dopamine are neurotoxic and cause brain receptor damage.  Chronic infections and the compounds produced from them such as bacteria lipopolysaccharides (LPS), along with elevated cortisol (seen in hypothalamic-pituitary-adrenal dysfunction), viral infections, and beta-amyloid and niacin deficiency (seen in schizophrenia) can trigger tryptophan metabolism problems. Tryptophan is the amino acid precursor to serotonin. In the presence of these chronic stressors, tryptophan conversion to serotonin is reduced. This can lead to depression and anxiety. Elevated tryptophan metabolites can lead to increased quinolinic acid (QA).  (4)

Quinolinic acid is neurotoxic and measured with organic acids testing. It is an NDMA receptor agonist, which is linked to various mental health disorders (anxiety, depression, suicidal ideation) and chronic neurodegenerative diseases (Alzheimer’s, Huntington’s). Quinolinic acid can also block acetylcholine production (linked to memory) and gamma-amino-butyric acid (which can trigger anxiety and panic). (5)

The aforementioned markers in organic acids testing are some of the most clinically significant to mental health and brain function, though there are many other examples.  This information is critical for mental health professionals to help deepen their knowledge about sophisticated testing and advanced solutions for patient intervention. 


  1. Shaw, W., et. al. Increased Urinary Excretion of Analogs of Krebs Cycle Metabolites and Arabinose in Two Brothers with Autistic Features. Clin Chem 41:1094-1104, 1995.
  2. Shaw, W., et. al. Assessment of antifungal drug therapy in autism by measurement of suspected microbial metabolites in urine with GC/MS. Clinical Practice of Alternative Medicine: 15-26.
  3. Persico AM, et. al. Urinary p-cresol in autism spectrum disorders, Neurotoxicol Teratol. 2013 Mar-Apr;36:82-90, 2012 Sep 10.
  4. Heyes MP, et. al. A mechanism of quinolinic acid formation by brain in inflammatory neurological disease. Attenuation of synthesis from L-tryptophan by 6-chlorotryptophan and 4-chloro-3-hydroxyanthranilate. Brain. 1993 Dec;116 (pt 6):1425-50.
  5. Ganiyu Oboh, et. al. Anticholinesterase and Antioxidative Properties of Aqueous Extract of Cola acuminata Seed In Vitro. Int J Alzheimers Dis. 2014; 2014: 498629.