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Dietary heterogeneity among Western industrialized countries reflected in the stable isotope ratios of human hair.

Valenzuela LO, Chesson LA, Bowen GJ, Cerling TE, Ehleringer JR - PLoS ONE (2012)

Bottom Line: Although the globalization of food production is often assumed to result in a homogenization of consumption patterns with a convergence towards a Western style diet, the resources used to make global food products may still be locally produced (glocalization).European hair samples had significantly lower δ(13)C values (-22.7 to -18.3‰), and significantly higher δ(15)N (7.8 to 10.3‰) and δ(34)S (4.8 to 8.3‰) values than samples from the USA (δ(13)C: -21.9 to -15.0‰, δ(15)N: 6.7 to 9.9‰, δ(34)S: -1.2 to 9.9‰).Within Europe, we detected differences in hair δ(13)C and δ(34)S values among countries and covariation of isotope ratios with latitude and longitude.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Utah, Salt Lake City, Utah, United States of America. valenzuela@biology.utah.edu

ABSTRACT
Although the globalization of food production is often assumed to result in a homogenization of consumption patterns with a convergence towards a Western style diet, the resources used to make global food products may still be locally produced (glocalization). Stable isotope ratios of human hair can quantify the extent to which residents of industrialized nations have converged on a standardized diet or whether there is persistent heterogeneity and glocalization among countries as a result of different dietary patterns and the use of local food products. Here we report isotopic differences among carbon, nitrogen and sulfur isotope ratios of human hair collected in thirteen Western European countries and in the USA. European hair samples had significantly lower δ(13)C values (-22.7 to -18.3‰), and significantly higher δ(15)N (7.8 to 10.3‰) and δ(34)S (4.8 to 8.3‰) values than samples from the USA (δ(13)C: -21.9 to -15.0‰, δ(15)N: 6.7 to 9.9‰, δ(34)S: -1.2 to 9.9‰). Within Europe, we detected differences in hair δ(13)C and δ(34)S values among countries and covariation of isotope ratios with latitude and longitude. This geographic structuring of isotopic data suggests heterogeneity in the food resources used by citizens of industrialized nations and supports the presence of different dietary patterns within Western Europe despite globalization trends. Here we showed the potential of stable isotope analysis as a population-wide tool for dietary screening, particularly as a complement of dietary surveys, that can provide additional information on assimilated macronutrients and independent verification of data obtained by those self-reporting instruments.

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Distribution of sample locations in Western Europe.Countries where samples were collected are highlighted in grey; black circles represent cities where sampled were obtained. For the names of the cities see Table S1. For the distribution of sample locations in the USA see [33].
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pone-0034234-g001: Distribution of sample locations in Western Europe.Countries where samples were collected are highlighted in grey; black circles represent cities where sampled were obtained. For the names of the cities see Table S1. For the distribution of sample locations in the USA see [33].

Mentions: Human scalp hair was collected as trash from the floors of barbershops and donated by anonymous volunteers in thirteen Western European (WE) countries (Figure 1; Table S1). Although we use the term ‘Western Europe’ to group all thirteen countries sampled in our study, we recognize that some (e.g., Greece, Italy and Malta) are not always classified as Western Europe but rather as Southern Europe. For the United States of America (USA) we used the same dataset of hair samples described by Valenzuela et al. [33], with the addition of 28 new samples. These 28 new samples did not represent new collection sites and thus the sampling locations are the same as those presented in Figure 1 in Valenzuela et al. [33]. All hair samples were placed in paper envelopes at the time of collection. No information was recorded regarding the age, gender, diet, and health or travel history of the donors. We assumed that the hair samples represented individuals local to the collection site. Prior to analysis, hair samples consisting of 20–40 strands of hair were washed twice in a 2∶1 chloroform:methanol mixture at room temperature to remove lipids and other surface contaminants. In the case of dyed hair, the washes were repeated until the solvent mixture was clear and no additional color was leached from the hair. The volume of solvent mixture used in each wash was sufficient to completely submerge all hair strands. The solvent mixture was gently agitated during the washes. After the washes were completed the samples were placed in paper filters and left to dry inside a fume hood. Once the samples were dried they were ground to a fine powder using a ball mill (Retsch; Haan, Germany) and placed in capped 1-dram glass vials for storage until analysis. For δ13C and δ15N analysis, 500 µg (±10%) of ground material was loaded into tin capsules (3.5×5 mm, Costech Analytical; Valencia, CA, USA); for δ34S analysis, 900 µg (±10%) was loaded into tin capsules.


Dietary heterogeneity among Western industrialized countries reflected in the stable isotope ratios of human hair.

Valenzuela LO, Chesson LA, Bowen GJ, Cerling TE, Ehleringer JR - PLoS ONE (2012)

Distribution of sample locations in Western Europe.Countries where samples were collected are highlighted in grey; black circles represent cities where sampled were obtained. For the names of the cities see Table S1. For the distribution of sample locations in the USA see [33].
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3316624&req=5

pone-0034234-g001: Distribution of sample locations in Western Europe.Countries where samples were collected are highlighted in grey; black circles represent cities where sampled were obtained. For the names of the cities see Table S1. For the distribution of sample locations in the USA see [33].
Mentions: Human scalp hair was collected as trash from the floors of barbershops and donated by anonymous volunteers in thirteen Western European (WE) countries (Figure 1; Table S1). Although we use the term ‘Western Europe’ to group all thirteen countries sampled in our study, we recognize that some (e.g., Greece, Italy and Malta) are not always classified as Western Europe but rather as Southern Europe. For the United States of America (USA) we used the same dataset of hair samples described by Valenzuela et al. [33], with the addition of 28 new samples. These 28 new samples did not represent new collection sites and thus the sampling locations are the same as those presented in Figure 1 in Valenzuela et al. [33]. All hair samples were placed in paper envelopes at the time of collection. No information was recorded regarding the age, gender, diet, and health or travel history of the donors. We assumed that the hair samples represented individuals local to the collection site. Prior to analysis, hair samples consisting of 20–40 strands of hair were washed twice in a 2∶1 chloroform:methanol mixture at room temperature to remove lipids and other surface contaminants. In the case of dyed hair, the washes were repeated until the solvent mixture was clear and no additional color was leached from the hair. The volume of solvent mixture used in each wash was sufficient to completely submerge all hair strands. The solvent mixture was gently agitated during the washes. After the washes were completed the samples were placed in paper filters and left to dry inside a fume hood. Once the samples were dried they were ground to a fine powder using a ball mill (Retsch; Haan, Germany) and placed in capped 1-dram glass vials for storage until analysis. For δ13C and δ15N analysis, 500 µg (±10%) of ground material was loaded into tin capsules (3.5×5 mm, Costech Analytical; Valencia, CA, USA); for δ34S analysis, 900 µg (±10%) was loaded into tin capsules.

Bottom Line: Although the globalization of food production is often assumed to result in a homogenization of consumption patterns with a convergence towards a Western style diet, the resources used to make global food products may still be locally produced (glocalization).European hair samples had significantly lower δ(13)C values (-22.7 to -18.3‰), and significantly higher δ(15)N (7.8 to 10.3‰) and δ(34)S (4.8 to 8.3‰) values than samples from the USA (δ(13)C: -21.9 to -15.0‰, δ(15)N: 6.7 to 9.9‰, δ(34)S: -1.2 to 9.9‰).Within Europe, we detected differences in hair δ(13)C and δ(34)S values among countries and covariation of isotope ratios with latitude and longitude.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Utah, Salt Lake City, Utah, United States of America. valenzuela@biology.utah.edu

ABSTRACT
Although the globalization of food production is often assumed to result in a homogenization of consumption patterns with a convergence towards a Western style diet, the resources used to make global food products may still be locally produced (glocalization). Stable isotope ratios of human hair can quantify the extent to which residents of industrialized nations have converged on a standardized diet or whether there is persistent heterogeneity and glocalization among countries as a result of different dietary patterns and the use of local food products. Here we report isotopic differences among carbon, nitrogen and sulfur isotope ratios of human hair collected in thirteen Western European countries and in the USA. European hair samples had significantly lower δ(13)C values (-22.7 to -18.3‰), and significantly higher δ(15)N (7.8 to 10.3‰) and δ(34)S (4.8 to 8.3‰) values than samples from the USA (δ(13)C: -21.9 to -15.0‰, δ(15)N: 6.7 to 9.9‰, δ(34)S: -1.2 to 9.9‰). Within Europe, we detected differences in hair δ(13)C and δ(34)S values among countries and covariation of isotope ratios with latitude and longitude. This geographic structuring of isotopic data suggests heterogeneity in the food resources used by citizens of industrialized nations and supports the presence of different dietary patterns within Western Europe despite globalization trends. Here we showed the potential of stable isotope analysis as a population-wide tool for dietary screening, particularly as a complement of dietary surveys, that can provide additional information on assimilated macronutrients and independent verification of data obtained by those self-reporting instruments.

Show MeSH