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Stable nitrogen and carbon isotope ratios indicate traditional and market food intake in an indigenous circumpolar population.

ABSTRACT: The transition of a society from traditional to market-based diets (termed the nutrition transition) has been associated with profound changes in culture and health. We are developing biomarkers to track the nutrition transition in the Yup'ik Eskimo population of Southwest Alaska based on naturally occurring variations in the relative abundances of carbon and nitrogen stable isotopes (?(15)N and ?(13)C values). Here, we provide three pieces of evidence toward the validation of these biomarkers. First, we analyzed the ?(15)N and ?(13)C values of a comprehensive sample of Yup'ik foods. We found that ?(15)N values were elevated in fish and marine mammals and that ?(13)C values were elevated in market foods containing corn or sugar cane carbon. Second, we evaluated the associations between RBC ?(15)N and ?(13)C values and self-reported measures of traditional and market food intake (n = 230). RBC ?(15)N values were correlated with intake of fish and marine mammals (r = 0.52; P < 0.0001). RBC ?(13)C values were correlated with intake of market foods made from corn and sugar cane (r = 0.46; P < 0.0001) and total market food intake (r = 0.46; P < 0.0001). Finally, we assessed whether stable isotope ratios captured population-level patterns of traditional and market intake (n = 1003). Isotopic biomarkers of traditional and market intake were associated with age, community location, sex, and cultural identity. Self-report methods showed variations by age and cultural identity only. Thus, stable isotopes show potential as biomarkers for monitoring dietary change in indigenous circumpolar populations.

SUBMITTER: Nash SH

PROVIDER: S-EPMC3237231 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Stable nitrogen and carbon isotope ratios indicate traditional and market food intake in an indigenous circumpolar population.

Nash Sarah H SH Bersamin Andrea A Kristal Alan R AR Hopkins Scarlett E SE Church Rebecca S RS Pasker Renee L RL Luick Bret R BR Mohatt Gerald V GV Boyer Bert B BB O'Brien Diane M DM

The Journal of nutrition 20111207 1

The transition of a society from traditional to market-based diets (termed the nutrition transition) has been associated with profound changes in culture and health. We are developing biomarkers to track the nutrition transition in the Yup'ik Eskimo population of Southwest Alaska based on naturally occurring variations in the relative abundances of carbon and nitrogen stable isotopes (δ(15)N and δ(13)C values). Here, we provide three pieces of evidence toward the validation of these biomarkers. ...[more]

PMID: 22157543

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Project description:BackgroundNatural abundance stable isotope ratios are candidate biomarkers of dietary intake that have not been evaluated in a controlled feeding study in a US population.ObjectivesOur goals were to evaluate dietary associations with serum carbon (CIR), nitrogen (NIR), and sulfur (SIR) isotope ratios in postmenopausal women, and to evaluate whether statistical models of dietary intake that include multiple isotopes and participant characteristics meet criteria for biomarker evaluation.MethodsPostmenopausal women from the Women's Health Initiative (n = 153) were provided a 2-wk controlled diet that approximated each individual's habitual food intake. Dietary intakes of animal protein, fish/seafood, red meat, poultry, egg, dairy, total sugars, added sugars, sugar-sweetened beverages (SSBs), and corn products were characterized during the feeding period with the use of the Nutrition Data System for Research (NDS-R). The CIR, NIR, and SIR were measured in sera collected from fasting women at the beginning and the end of the feeding period. Linear models based on stable isotope ratios and participant characteristics predicted dietary intake. The criterion used for biomarker evaluation was R2 ≥ 0.36, based on the study's power to detect true associations with R2 ≥ 0.50.ResultsThe NIR was associated with fish/seafood intake and met the criterion for biomarker evaluation (R2 = 0.40). The CIR was moderately associated with intakes of red meat and eggs, but not to the criterion for biomarker evaluation, and was not associated with intake of sugars (total, added, or SSB). A model of animal protein intake based on the NIR, CIR, and participant characteristics met the criterion for biomarker evaluation (R2 = 0.40). Otherwise, multiple isotopes did not improve models of intake, and improvements from including participant characteristics were modest.ConclusionSerum stable isotope ratios can, with participant characteristics, meet biomarker criteria as measures of fish/seafood and animal protein intake in a sample of postmenopausal women. This trial was registered at clinicaltrials.gov as NCT00000611.

Project description:Knowledge about the primary factor controlling stable isotope ratios of particulate nitrogen (?15NPN) and total dissolved nitrogen (?15NTDN) in a subtropical reservoir can improve the understanding of regional and global nitrogen cycles. Taking Lianhe Reservoir as a representative subtropical reservoir, we studied the spatial and temporal distributions of ?15NPN and?15NTDN and their relationships with the surrounding physicochemical factors and phytoplankton. The results showed that variations in ?15NPN and ?15NTDN followed seasonal thermal cycles. The values of ?15NTDN were inversely proportional to those of ?15NPN. PCA showed that phytoplankton cell density and pH were the primary drivers of the variation of ?15NPN (45.2%). The primary factors influencing ?15NTDN were Chl a and phytoplankton cell density, which both indicated phytoplankton biomass. We also determined that the dominant species was Microcystis densa during the thermal stratification period and Staurodesmus aristiferus during the mixing period. Laboratory experiments showed that ?15NPN values in both M. densa (from 19.5 to 14.6‰) and S. aristiferus (from 19.4 to 16.0 ‰) media decreased significantly as the algal cells grew. Furthermore, the ?15NTDN values increased from 4.9 to 7.9‰ and from 4.7 to 6.9‰ in M. densa and S. aristiferus media, respectively, when the ?15NPN values decreased. These experimental results were consistent with field investigation results and indicated that variations in ?15NPN and ?15NTDN were mainly controlled by phytoplankton cell density, especially the cell density of the dominant species, in both the thermal stratification and mixing periods. The results also suggested that cell density, not phytoplankton species, was the key factor regulating the distribution of nitrogen stable isotopes. These results together indicated that phytoplankton cell density is the primary factor in the regulation of nitrogen stable isotope composition and that its influence is greater than that of other physical and chemical factors. This study provided detailed information supporting the primary role of phytoplankton in the nitrogen geochemical cycle and improved the understanding of biochemical processes in natural subtropical reservoirs.

Project description:BackgroundAn objective measure of added sugar (AS) and sugar-sweetened beverage (SSB) intake is needed. The δ(13)C value of finger-stick blood is a novel validated biomarker of AS/SSB intake; however, nonsweetener corn products and animal protein also carry a δ(13)C value similar to AS sources, which may affect blood δ(13)C values. The δ(15)N value of blood has been proposed as a "correction factor" for animal protein intake.ObjectivesThe objectives were to 1) identify foods associated with δ(13)C and δ(15)N blood values, 2) determine the contribution of nonsweetener corn to the diet relative to AS intake, and 3) determine if the dual-isotope model (δ(13)C and δ(15)N) is a better predictor of AS/SSB intake than δ(13)C alone.MethodsA cross-sectional sample of southwest Virginian adults (n = 257; aged 42 ± 15 y; 74% overweight/obese) underwent dietary intake assessments and provided finger-stick blood samples, which were analyzed for δ(13)C and δ(15)N values by using natural abundance stable isotope mass spectrometry. Statistical analyses included ANOVAs, paired-samples t tests, and multiple linear regressions.ResultsThe mean ± SD daily AS intake was 88 ± 59 g and nonsweetener corn intake was 13 ± 13 g. The mean δ(13)C value was -19.1 ± 0.9‰, which was significantly correlated with AS and SSB intakes (r = 0.32 and 0.39, respectively; P ≤ 0.01). The δ(13)C value and nonsweetener corn intake and the δ(15)N value and animal protein intake were not correlated. AS intake was significantly greater than nonsweetener corn intake (mean difference = 76.2 ± 57.2 g; P ≤ 0.001). The δ(13)C value was predictive of AS/SSB intake (β range: 0.28-0.35; P ≤ 0.01); however, δ(15)N was not predictive and minimal increases in R(2) values were observed when the δ(15)N value was added to the model.ConclusionsThe data do not provide evidence that the dual-isotope method is superior for predicting AS/SSB intakes within a southwest Virginian population. Our results support the potential of the δ(13)C value of finger-stick blood to serve as an objective measure of AS/SSB intake. This trial was registered at clinicaltrials.gov as NCT02193009.

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Stable nitrogen and carbon isotope ratios indicate traditional and market food intake in an indigenous circumpolar population.

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Stable nitrogen and carbon isotope ratios indicate traditional and market food intake in an indigenous circumpolar population.

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