The effects of dietary neurotransmitter precursors on human behavior.

H. R. Lieberman*, S. Corkin, B. J. Spring, R. J. Wurtman, J. H. Growdon

*Corresponding author for this work

Research output: Contribution to journalArticle

53 Scopus citations


The neurotransmitter precursors tryptophan and tyrosine are present in a variety of foods. In order to document possible effects of tryptophan and tyrosine on human behavior, single oral doses of these substances and matched placebos were administered to 20 men in a double-blind, crossover study. Various tests of mood state and performance were then administered. Tryptophan increased subjective fatigue and decreased self-ratings of vigor and alertness, but did not impair performance on any of the tests. Tyrosine produced no effects in our young population compared with placebo, but did decrease reaction time relative to tryptophan. It may be concluded that tryptophan has significant sedative-like properties, but unlike other sedatives may not impair performance.

Original languageEnglish (US)
Pages (from-to)366-370
Number of pages5
JournalAmerican Journal of Clinical Nutrition
Issue number2
Publication statusPublished - Aug 1 1985


ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

Cite this

Lieberman, H. R., Corkin, S., Spring, B. J., Wurtman, R. J., & Growdon, J. H. (1985). The effects of dietary neurotransmitter precursors on human behavior. American Journal of Clinical Nutrition, 42(2), 366-370.