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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2006-835v1 85/7/1712    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Dilger, R. N. Articles by Baker, D. H. Search for Related Content PubMed PubMed Citation Articles by Dilger, R. N. Articles by Baker, D. H.

Oral N-acetyl-L-cysteine is a safe and effective precursor of cysteine¹

Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana 61801

² Corresponding author: dhbaker{at}uiuc.edu

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. Bio-availability 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.

Key Words: N-acetyl-L-cysteine • bioavailability • chick • cysteine • toxicity

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				R. N. Dilger and D. H. Baker DL-Methionine Is as Efficacious as L-Methionine, but Modest L-Cystine Excesses Are Anorexigenic in Sulfur Amino Acid-Deficient Purified and Practical-Type Diets Fed to Chicks Poult. Sci., November 1, 2007; 86(11): 2367 - 2374. [Abstract] [Full Text] [PDF]