- Hinz M . Relative nutritional deficiencies associated with centrally acting monoamines. Int J Gen Med. 2012;5:413-30
Whenever low or inadequate levels of monoamine neurotransmitters exist, a relative nutritional deficiency is present.
- Fernstrom, J. D. Wurtman, R. J. Brain Serotonin Content: Physiological Regulation by Plasma Neutral Amino Acids. Science (80-. ). 178, 414–416 (1971).
- Matthias Michal et al. Tryptophan catabolites and depression in the general population: results from the Gutenberg Health Study. BMC Psychiatry. 2023 Jan 11;23(1):27.
- Leif Breum et al. Twenty-four-hour plasma tryptophan concentrations and ratios are below normal in obese subjects and are not normalized by substantial weight reduction. Am J Clin Nutr. 2003 May;77(5):1112-8.
The plasma ratio of the concentration of tryptophan to the sum of the concentrations of the other LNAAs (tyrosine + phenylalanine + leucine + isoleucine + valine) (the plasma tryptophan ratio), which summarizes this competitive relation, has been proven to be a useful and reliable predictor of brain tryptophan uptake and central serotonin synthesis.
- John D Fernstrom et al.Tyrosine, phenylalanine, and catecholamine synthesis and function in the brain. J Nutr. 2007 Jun;137(6 Suppl 1):1539S-1547S
- Altamura C. Plasma concentrations of excitatory amino acids, serine, glycine, taurine and histidine in major depression. Eur Neuropsychopharmacol. 1995;5 Suppl:71-5.
- Mitani H. Correlation between plasma levels of glutamate, alanine and serine with severity of depression. Prog Neuropsychopharmacol Biol Psychiatry. 2006 Aug 30;30(6):1155-8.
- Ali-Sisto, T. et al. Global arginine bioavailability ratio is decreased in patients with major depressive disorder. J. Affect. Disord. 229, 145–151 (2018).
- Jun-Xi Pan et al. Diagnosis of major depressive disorder based on changes in multiple plasma neurotransmitters: a targeted metabolomics study. Transl Psychiatry. 2018 Jul 10;8(1):130.
Furthermore, this panel distinguished Major depressive disorder (MDD) subjects from bipolar disorder subjects with high accuracy. This study is the first to globally evaluate multiple neurotransmitters in MDD plasma. The altered plasma neurotransmitter metabolite profile has potential differential diagnostic value for MDD.
- Andreas Baranyi et al. Nitric Oxide-Related Biological Pathways in Patients with Major Depression PLoS. One. 2015 Nov 18;10(11):e0143397.
- Pardridge, W. M. Blood-brain barrier carrier-mediated transport and brain metabolism of amino acids. Neurochem. Res. 23, 635–644 (1998).
- Pandharipande P. et al. Plasma Tryptophan and Tyrosine levels are Independent Risk Factors for Transitioning to Delirium in Critically Ill Mechanically Ventilated Patients: a pilot investigation. Intensive Care Med. 35, 1886–1892 (2009).
- Mauria, M. C. et al. Plasma and Platelet Amino Acid Concentrations in Patients Affected by Major Depression. Neuropsychobiology 37, 124–129 (1998).
- Hestad K, Alexander J, Rootwelt H, Aaseth JO. The Role of Tryptophan Dysmetabolism and Quinolinic Acid in Depressive and Neurodegenerative Diseases.Biomolecules. 2022 Jul 18;12(7):998..
- Delle Chiaie R. Efficacy and tolerability of oral and intramuscular S-adenosyl-L- methionine 1,4-butanedisulfonate (SAMe) in the treatment of major depression: comparison with imipramine in 2 multicenter studies. Am J Clin Nutr. 2002;76(5):1172S-1176S.
The antidepressive efficacy of 1600 mg SAMe/d orally and 400 mg SAMe/d intramuscularly is comparable with that of 150 mgimipramine/d orally, but SAMe is significantly better tolerated.