Dietary sulfur amino acid effects on fasting plasma cysteine/cystine redox potential in humans

• Type of Material: Article
• Authors: Dean P Jones, Emory University; Youngja Park, Emory University; Nana Gletsu-Miller, Emory University; Yongliang Liang, Emory University; Tianwei Yu, Emory University; Carolyn Jonas Accardi, Emory University; Thomas R Ziegler, Emory University
• Language: English
• Date: 2011-02-27
• Publisher: Elsevier: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2011 Elsevier Inc. All rights reserved.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.nut.2010.01.014
• Title of Journal or Parent Work: Nutrition
• ISSN: 0899-9007
• Volume: 27
• Issue: 2
• Start Page: 199
• End Page: 205
• Grant/Funding Information: This research was supported by NIH grants ES012929 and ES011195 (DPJ), DK55850 and K24 RR023356 (TRZ) and the Emory General Clinical Research Center grant M01 RR00039/UL1 RR025008.
• Keywords: Oxidative stress; amino acid balance; cardiovascular disease; methionine
• Research Categories: Health Sciences, General; Biology, Physiology

Abstract

Objective: Oxidation of plasma cysteine/cystine (Cys/CySS) redox potential (EhCySS) has been associated with risk factors for cardiovascular disease in humans. Cys and CySS are derived from dietary sulfur amino acids (SAA), but the specific effects of SAA depletion and repletion on Cys/CySS redox indices are unknown. The present study examined the effect of dietary SAA intake level on free Cys, free CySS and EhCySS in human plasma under fasting conditions. Research Methods and Procedures: Healthy individuals aged 18–36 y (n=13) were equilibrated to foods providing the RDA for SAA and then fed chemically defined diets without SAA (0 mg·kg−1·d−1; n=13) followed by SAA at levels approximating the mean (56 mg·kg−1·d−1; n=8) or 99th percentile (117 mg·kg−1·d−1; n=5) intake levels of Americans. Fasting plasma samples were collected daily during 4-d study periods and analyzed for free Cys, free CySS and the EhCySS. Results: The SAA-free diet significantly (p<0.05) decreased plasma free Cys concentrations and oxidized EhCySS values after 4 days of SAA depletion. With SAA repletion at 56 mg·kg−1·d− 1, plasma free Cys increased significantly and values for EhCySS became more reducing. Administration of a diet providing a higher dose of SAA (117 mg·kg−1·d−1) resulted in a significantly higher level of free Cys and a more reducing EhCySS. Conclusions: These results show that free Cys and Cys/CySS redox potential (EhCySS) in fasting plasma are affected by dietary SAA intake level in humans. Significant changes occur slowly over 4 days with insufficient SAA intake, but rapidly (after 1 day) with repletion.