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OBJECTIVE: Extracellular dopamine concentrations were estimated through measurement of [(11)C]raclopride binding with positron emission tomography after dietary manipulation of the dopamine precursors tyrosine and phenylalanine. METHOD: Healthy male subjects were scanned on two occasions: once after receiving a balanced amino acid drink and once after receiving a drink mixture from which tyrosine and phenylalanine were omitted. RESULTS: Dietary tyrosine and phenylalanine depletion increased [(11)C]raclopride binding in the striatum by a mean of 6%. The change in [(11)C]raclopride binding correlated significantly with the fall in the ratio of tyrosine and phenylalanine to large neutral amino acids. CONCLUSIONS: This is the first demonstration of an effect of a dietary manipulation on brain dopamine release in humans. This result provides support for the further investigation of the role of dietary manipulations in the treatment of neuropsychiatric disorders.

Original publication




Journal article


Am J Psychiatry

Publication Date





1887 - 1889


Adult, Beverages, Brain, Carbon Radioisotopes, Corpus Striatum, Dopamine, Humans, Male, Middle Aged, Phenylalanine, Raclopride, Reference Values, Tomography, Emission-Computed, Tyrosine