Effects of dietary phenylalanine and tyrosine on circulating thyroid hormone levels and growth in the chick

R. G. Elkin, W. R. Featherston, J. C. Rogler

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Studies were conducted to investigate the effects of a phenylalanine-tyrosine deficiency on serum thyroid hormone concentrations and growth in chicks from 0 to 14 days of age. Birds fed diets severely deficient in aromatic amino acids (AAA), lysine or valine were found in most trials to have reduced serum concentrations of either 3,5,3'-triiodothyronine (T3) or 3,5,3',5'-tetraiodothyronine (T4). Approximately one-half of the samples assayed did not show detectable levels of 3,3',5'-triiodothyronine (reverse T3). The reduction in serum thyroid hormone levels was not observed until chick growth was markedly affected and was not specific for AAA deficiency. Phenylalanine alone could not efficiently supply tyrosine when dietary AAA were suboptimal as evidenced by significantly greater weight gains in chicks fed 50:50 or 55:45 (mole:mole) mixtures of phenylalanine and tyrosine as compared with birds fed the same total amount (moles) of AAA supplied solely by phenylalanine. However, at or above requirement levels, phenylalanine could completely meet the chick's demand for tyrosine. Serum tyrosine concentrations generally reflected the dietary levels of AAA.

Original languageEnglish (US)
Pages (from-to)130-138
Number of pages9
JournalJournal of Nutrition
Volume110
Issue number1
DOIs
StatePublished - 1980

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

Fingerprint Dive into the research topics of 'Effects of dietary phenylalanine and tyrosine on circulating thyroid hormone levels and growth in the chick'. Together they form a unique fingerprint.

Cite this