Relation between stable isotope ratios in human red blood cells and hair: Implications for using the nitrogen isotope ratio of hair as a biomarker of eicosapentaenoic acid and docosahexaenoic acid

Sarah H. Nash, Alan R. Kristal, Bert B. Boyer, Irena B. King, Jordan S. Metzgar, Diane M. O'Brien

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

Background: The nitrogen isotope ratio (expressed as δ15N) of red blood cells (RBCs) is highly correlated with the RBC long-chain ω-3 (n-3) fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in Yup'ik Eskimos. Because δ15N can also be measured in hair samples, it could provide a noninvasive, retrospective biomarker for EPA and DHA intakes. Objectives: We investigated the agreement between δ15N in hair and RBCs and then evaluated the relations between hair δ15N and RBC EPA and DHA. We also assessed the agreement in carbon isotope ratios (δ13C) between hair and RBCs, because δ13C has been proposed as a dietary biomarker in other populations. Design: We assessed relations between hair and RBC δ15N and δ13C in a community-based sample of 144 Yup'ik Eskimos and examined the correlations between δ15N and RBC EPA and DHA in a subset of these participants (n = 44). Results: We showed a 1:1 relation with good agreement between hair and RBC δ15N (r = 0.91) and δ13C (r = 0.87). Hair isotope ratios were greater than RBC ratios by 1.5‰ for δ15N and by 2.3‰ for δ13C. There were strong correlations between hair δ15N and RBC EPA and DHA (r = 0.83 and 0.84, respectively). Conclusions: These results support the use of hair δ15N values as a biomarker of EPA and DHA intakes. Because hair collection is noninvasive and the samples require no special processing, studies of EPA and DHA intakes in large populations could use biomarkers rather than self-reports to assess these fatty acids.

Original languageEnglish (US)
Pages (from-to)1642-1647
Number of pages6
JournalAmerican Journal of Clinical Nutrition
Volume90
Issue number6
DOIs
StatePublished - Dec 1 2009

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

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