Neurotransmitters are chemical messengers that help to relay impulses through your brain and nervous system. They are released into the microscopic gaps, called synapses, between adjacent neurons, thus propagating an impulse from one nerve to the next. Dopamine and serotonin, two important neurotransmitters in your body, are produced by the enzymatic conversion of amino acids. The enzymes that catalyze these conversions require the assistance of other nutrients, including vitamins and minerals.
Serotonin is produced in your brain and gastrointestinal tract from the enzymatic conversion of the amino acid L-tryptophan. In this two-step process, L-tryptophan is converted to 5-hydroxy-L-tryptophan, or 5-HTP, by an enzyme called tryptophan hydroxylase, or TPH. TPH requires tetrahydrobiopterin, a nitrogen-containing cofactor, to perform this initial step. In the second step, another enzyme called amino acid decarboxylase, or AADC, converts 5-HTP to serotonin. According to a 1995 “Journal of Neural Transmission” study, the activity of AADC is enhanced by pyridoxal-5-phosphate, an activated form of vitamin B-6.
Dopamine is derived from the amino acid L-tyrosine in a two-stage process that mirrors the synthesis of serotonin. In the first step, tyrosine hydroxylase converts L-tyrosine to L-dopa, once again using tetrahydrobiopterin as a cofactor. L-dopa is then converted to dopamine by AADC, using pyridoxal-5-phosphate as a cofactor. A May 2009 review in “Molecular Genetics and Metabolism” reported that a genetic disorder called AADC deficiency, in which amino acid decarboxylase is only partially functional, can be ameliorated by treatment with pyridoxal-5-phosphate.
Both tyrosine hydroxylase and tryptophan hydroxylase contain iron. As this integral metallic element alternates between two electronic states, it helps to regulate the activity of the hydroxylase enzymes, according to a February 2006 review in “Biochemistry.” Magnesium and zinc help to potentiate the activities of serotonin and dopamine but are not intimately involved in neurotransmitter synthesis.
Adequate protein intake usually ensures a sufficient supply of amino acid precursors for neurotransmitter synthesis. Dr. Elson Haas, author of “Staying Healthy with Nutrition,” recommends a daily intake of 0.8 grams of protein per kilogram of lean body weight, or about 0.4 grams per pound. Recommended dietary allowances for vitamin B-6 range from 0.1 milligram for infants to 2 milligrams for lactating females. Daily iron needs vary from 0.27 milligram for infants to 27 milligrams for pregnant women. Magnesium requirements range from 30 milligrams for infants to 420 milligrams for adult males, and zinc requirements vary from 2 milligrams for infants to 14 milligrams for pregnant women.
- “Journal of Neural Transmission”; Pyridoxine Effect on Synthesis Rate of Serotonin in the Monkey Brain Measured with Positron Emission Tomography; P. Hartviq, et al.; 1995
- “Molecular Genetics and Metabolism”; A New Perspective on the Treatment of Aromatic L-Amino Acid Decarboxylase Deficiency; G.F. Allen
- “Biochemistry”; Reduction and Oxidation of the Active Site Iron in Tyrosine Hydroxylase: Kinetics and Specificity; P.A. Frantom, et al.; February 2006
- “Pharmacological Reports”; Antidepressant Activity of Zinc and Magnesium in View of the Current Hypotheses of Antidepressant Action; B. Szewczyk, et al.; 2008