Dose-dependent effects of oral tyrosine administration on plasma tyrosine levels and cognition in aging

Ondine van de Rest*, Mirjam Bloemendaal, Rianne De Heus, Esther Aarts

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

8 Citations (Scopus)

Abstract

The effects of tyrosine on plasma response and cognition in aging are unknown. We assessed the dose-dependent response to tyrosine administration in older adults in both plasma tyrosine concentrations and working memory performance. In this double blind randomized cross-over trial 17 older adults (aged 60–75 years) received a single administration of 100, 150, or 200 mg/kg body weight of tyrosine. For comparison, 17 young adults (aged 18–35 years) received a dose of 150 mg/kg body weight of tyrosine. Tyrosine plasma concentrations were determined before and 90, 120, 150, 180, 210, and 240 min after tyrosine intake. Working memory was assessed using the N-back task at 90 min after tyrosine administration. Older adults showed a dose-dependent increase in plasma tyrosine concentrations (p < 0.001), and the plasma response was higher than for young adults with the same dose (p < 0.001). Load-dependent working memory performance decreased with higher doses of tyrosine (p = 0.048), especially in older adults with greater dose-dependent plasma tyrosine responses (p = 0.035). Our results show an age-related increase in plasma tyrosine response, which was associated with a dose-dependent decline in cognitive functioning in older adults.
Original languageEnglish
Article number1279
JournalNutrients
Volume9
Issue number12
DOIs
Publication statusPublished - 1 Dec 2017

Keywords

  • Aging
  • Catecholamines
  • Dopamine
  • Dose-response
  • Plasma amino acids
  • Tyrosine
  • Working memory

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