Geographical patterns of human diet derived from stable-isotope analysis of fingernails

Authors

  • Gabriela B. Nardoto,

    Corresponding author
    1. Laboratório de Ecologia Isotópica, Centro de Energia Nuclear na Agricultura—Universidade de São Paulo, 13416-000 Piracicaba, São Paulo, Brazil
    • Avenida Centenário 303, 13146-000 Piracicaba, São Paulo, Brazil
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  • Steven Silva,

    1. Stable Isotope and Tritium Laboratories, US Geological Survey, Menlo Park, California 94025
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  • Carol Kendall,

    1. Stable Isotope and Tritium Laboratories, US Geological Survey, Menlo Park, California 94025
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  • James R. Ehleringer,

    1. Stable Isotope Ratio Facility for Environmental Research, Department of Biology, University of Utah, Salt Lake City, Utah 84112
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  • Lesley A. Chesson,

    1. Stable Isotope Ratio Facility for Environmental Research, Department of Biology, University of Utah, Salt Lake City, Utah 84112
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  • Epaminondas S.B. Ferraz,

    1. Laboratório de Ecologia Isotópica, Centro de Energia Nuclear na Agricultura—Universidade de São Paulo, 13416-000 Piracicaba, São Paulo, Brazil
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  • Marcelo Z. Moreira,

    1. Laboratório de Ecologia Isotópica, Centro de Energia Nuclear na Agricultura—Universidade de São Paulo, 13416-000 Piracicaba, São Paulo, Brazil
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  • Jean P.H.B. Ometto,

    1. Laboratório de Ecologia Isotópica, Centro de Energia Nuclear na Agricultura—Universidade de São Paulo, 13416-000 Piracicaba, São Paulo, Brazil
    2. Stable Isotope Ratio Facility for Environmental Research, Department of Biology, University of Utah, Salt Lake City, Utah 84112
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  • Luiz A. Martinelli

    1. Laboratório de Ecologia Isotópica, Centro de Energia Nuclear na Agricultura—Universidade de São Paulo, 13416-000 Piracicaba, São Paulo, Brazil
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Abstract

Carbon and nitrogen isotope ratios of human fingernails were measured in 490 individuals in the western US and 273 individuals in southeastern Brazil living in urban areas, and 53 individuals living in a moderately isolated area in the central Amazon region of Brazil and consuming mostly locally grown foods. In addition, we measured the carbon and nitrogen isotope ratios of common food items to assess the extent to which these isotopic signatures remain distinct for people eating both omnivorous and vegetarian diets and living in different parts of the world, and the extent to which dietary information can be interpreted from these analyses. Fingernail δ13C values (mean ± standard deviation) were −15.4 ± 1.0 and −18.8 ± 0.8‰ and δ15N values were 10.4 ± 0.7 and 9.4 ± 0.6‰ for southeastern Brazil and western US populations, respectively. Despite opportunities for a “global supermarket” effect to swamp out carbon and nitrogen isotope ratios in these two urbanized regions of the world, differences in the fingernail isotope ratios between southeastern Brazil and western US populations persisted, and appeared to be more associated with regional agricultural and animal production practices. Omnivores and vegetarians from Brazil and the US were isotopically distinct, both within and between regions. In a comparison of fingernails of individuals from an urban city and isolated communities in the Amazonian region, the urban region was similar to southeastern Brazil, whereas individuals from isolated nonurban communities showed distinctive isotopic values consistent with their diets and with the isotopic values of local foods. Although there is a tendency for a “global supermarket” diet, carbon and nitrogen isotopes of human fingernails hold dietary information directly related to both food sources and dietary practices in a region. Am J Phys Anthropol, 2006. © 2006 Wiley-Liss, Inc.

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