13Carbon and 15nitrogen isotopes in autopsy liver tissue samples from Greenlandic Inuit and Danes: consumption of marine versus terrestrial food
2010
Milman, N. | Laursen, J. | Mulvad, G. | Pedersen, H.S. | Pedersen, A.N. | Saaby, H.
Background/Objectives: The content of 13C and 15N isotopes is higher in marine than in terrestrial food. 13C and 15N in human tissue therefore reflects the relative proportions of marine and terrestrial food consumed by the individual. The objective of this study was to measure 13C and 15N in liver tissue from Greenlandic Inuit and Danes. Subjects/Methods: Normal liver tissue was obtained at autopsy in 1992–1994 from 60 Inuit with a median age of 61 years (range 25–83) and in 1986 from 15 ethnic Danes with a median age of 84 years (range 66–93). By sieving, liver tissue was separated in a ‘cellular fraction’ and a ‘connective tissue fraction’. 13C and 15N in dry liver tissue was measured on a mass spectrometer. δ13C indicates the 13C content relative to the IAEA-CH-6 reference standard. δ15N indicates 15N content relative to the atmospheric nitrogen reference standard. Results: Inuit: median δ13C was −21.2‰ in cellular and −20.0‰ in connective tissue fractions (P=0.001). Median δ15N was 10.6‰ in both cellular and connective tissue fractions. Body mass index was negatively correlated with δ13C in the connective tissue fraction (rs=−0.42, P=0.057). Danes: median δ13C was −27.0‰ in cellular and −24.3‰ in connective tissue fractions (P=0.11). Median δ15N was 9.5‰ in cellular and 8.9‰ in connective tissue fractions (P=0.5). Inuit had higher δ13C than Danes in both cellular and connective tissue fractions (P<0.001) as well as higher δ15N in the cellular fraction (P=0.01). Conclusions: Inuit showed considerable variation in the ratio between marine and terrestrial food consumption, reflecting a vanishing hunter culture where elderly Inuit still adhere to the traditional hunters food with a high content of marine food, whereas the younger urbanized Inuit population consume food with a lower content of marine food and a higher content of terrestrial food. Danes consumed food of almost exclusively terrestrial origin. The present 13C and 15N analyses are in accordance with the dietary patterns obtained by dietary surveys.
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