Oral N-acetyl-L-cysteine is a safe and effective precursor of cysteine

R. N. Dilger, D. H. Baker

Research output: Contribution to journalArticle

Abstract

Relative bioavailability and toxicity of N-acetyl-L-Cys (NAC) were evaluated in 9-d chick growth assays. The bioavailability of NAC relative to Cys was determined by feeding young chicks a highly purified crystalline AA diet singly deficient in Cys. Bioavailability estimates were obtained using standard slope-ratio methodology. N-Acetyl-L-cysteine was shown to be as effective as Cys in supporting chick growth, and was assigned a relative bioavailability value of 100%. To assess toxicity, a nutritionally adequate corn-soybean meal diet was supplemented with graded concentrations of NAC (isomolar to 10, 20, 30, or 40 g/kg of Cys, as-fed). When NAC supplied 10 or 20 g/kg of Cys, chick growth performance was unaffected, but NAC supplying 30 or 40 g/kg of Cys reduced (P < 0.05) BW gain by 13 and 34%, respectively, relative to the unsupplemented control diet. Only plasma-free NAC was substantially increased (P < 0.05) because of excess dietary NAC; plasma-free Cys was unaltered. We concluded that dietary NAC is efficacious in supplying Cys in support of chick growth, and only large excesses of NAC are growth depressing. Hence, the human clinical benefits of oral NAC likely result from its ability to deliver Cys safely and effectively to the portal circulation.

Original languageEnglish (US)
Pages (from-to)1712-1718
Number of pages7
JournalJournal of animal science
Volume85
Issue number7
DOIs
StatePublished - Jul 1 2007

Keywords

  • Bioavailability
  • Chick
  • Cysteine
  • N-acetyl-L-cysteine
  • Toxicity

ASJC Scopus subject areas

  • Food Science
  • Animal Science and Zoology
  • Genetics

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