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13C tracer recovery in human stools after digestion of a fat-rich meal labelled with [1,1,1-13C3]tripalmitin and [1,1,1-13C3]triolein

Authors

  • Laure Gabert,

    1. Lyon University, CRNH-RA and Center for European Nutrition, Safety and Health, Pierre-Bénite, France
    2. Hospices Civils de Lyon, Pierre-Bénite, France
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  • Cécile Vors,

    1. Lyon University, CRNH-RA and Center for European Nutrition, Safety and Health, Pierre-Bénite, France
    2. Lyon University, INSERM U1060, INRA U1235, CarMeN Laboratory, Oullins, France
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  • Corinne Louche-Pélissier,

    1. Lyon University, CRNH-RA and Center for European Nutrition, Safety and Health, Pierre-Bénite, France
    2. Hospices Civils de Lyon, Pierre-Bénite, France
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  • Valérie Sauvinet,

    1. Lyon University, CRNH-RA and Center for European Nutrition, Safety and Health, Pierre-Bénite, France
    2. Lyon University, INSERM U1060, INRA U1235, CarMeN Laboratory, Oullins, France
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  • Stéphanie Lambert-Porcheron,

    1. Lyon University, CRNH-RA and Center for European Nutrition, Safety and Health, Pierre-Bénite, France
    2. Hospices Civils de Lyon, Pierre-Bénite, France
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  • Jocelyne Drai,

    1. Lyon University, CRNH-RA and Center for European Nutrition, Safety and Health, Pierre-Bénite, France
    2. Hospices Civils de Lyon, Pierre-Bénite, France
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  • Martine Laville,

    1. Lyon University, CRNH-RA and Center for European Nutrition, Safety and Health, Pierre-Bénite, France
    2. Lyon University, INSERM U1060, INRA U1235, CarMeN Laboratory, Oullins, France
    3. Hospices Civils de Lyon, Pierre-Bénite, France
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  • Michel Désage,

    Corresponding author
    • Lyon University, CRNH-RA and Center for European Nutrition, Safety and Health, Pierre-Bénite, France
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  • Marie-Caroline Michalski

    1. Lyon University, CRNH-RA and Center for European Nutrition, Safety and Health, Pierre-Bénite, France
    2. Lyon University, INSERM U1060, INRA U1235, CarMeN Laboratory, Oullins, France
    3. Lyon University, INSA-Lyon, CarMeN Laboratory, INSERM U1060, Villeurbanne, France
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  • Presented at the 6th Congress of the French Society of Stable Isotopes (Société Française des Isotopes Stables, SFIS) held 26–29 October 2010 in Toulouse, France.

M. Désage, Centre de Recherche en Nutrition Humaine Rhône-Alpes (CRNH-RA), Centre Hospitalier Lyon Sud, Centre de Biologie et Anatomie Pathologie du Sud (CBAPS), Bât. 3D, 165 chemin du Grand Revoyet, F-69310 Pierre-Bénite, France.

E-mail: michel.desage@chu-lyon.fr

Abstract

Lipid metabolism studies focus mainly on oxidation and storage but rarely on faecal elimination, which is needed to assess total lipid distribution during the postprandial period. The purpose of the present work was to set up and validate the analysis of lipid tracers in stools, with an aim of later using this methodology in studies of postprandial lipid tracer metabolism. Eight subjects received a mixture of [1,1,1-13C3]tripalmitin and [1,1,1-13C3]triolein with a fat-rich meal. The nature and amounts of 13C lipids excreted in stools during 3 days post-dose were determined by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) analysis of fatty acid methyl esters (FAMEs) from total fatty acid (TFA), free fatty acid (FFA) and triacylglycerol (TAG) fractions. The results were expressed as the Cumulative Tracer Recovery of the administered dose (CTR%). The quantities and labelling of FAMEs were higher in FFA than in TAG, indicating that label loss was not due to a lack of digestive lipase activity. The labelling was higher for C16:0 than for C18:1. The CTRs were 7.03 ± 0.77% and 6.87 ± 0.91%, respectively, in TFA and FFA for [1-13C] C16:0, while they were 0.60 ± 0.15% and 0.51 ± 0.11% for [1-13C] C18:1 (mean ± sem). By studying the kinetics of lipid excretion from subjects, two groups emerged. The first one showed rapid excretion in stool #1, whereas the second showed slower excretion in stools #2–#3. A significant difference was found in the FFA in stool #1 for C16:0 (p < 0.01) and C18:1 (p < 0.05). Individual excretion kinetics showed marked variability. Nevertheless, the CTR over the 3-day study period was substantial and homogenous for all subjects. These results confirm that the assessment of faecal elimination is of great importance when establishing total lipid distribution during the postprandial period and validate the analysis of cumulative tracer loss during 72 h post-tracer ingestion. Copyright © 2011 John Wiley & Sons, Ltd.

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