Reduction of brain dopamine concentration with dietary tyrosine plus phenylalanine depletion: an [11C]raclopride PET study

Am J Psychiatry. 2003 Oct;160(10):1887-9. doi: 10.1176/appi.ajp.160.10.1887.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Beverages
  • Brain / diagnostic imaging
  • Brain / metabolism*
  • Carbon Radioisotopes
  • Corpus Striatum / metabolism
  • Dopamine / metabolism*
  • Humans
  • Male
  • Middle Aged
  • Phenylalanine / administration & dosage*
  • Raclopride* / metabolism
  • Reference Values
  • Tomography, Emission-Computed*
  • Tyrosine / administration & dosage*


  • Carbon Radioisotopes
  • Tyrosine
  • Raclopride
  • Phenylalanine
  • Dopamine