13Carbon and 15Nitrogen isotopes in autopsy liver tissue samples from Greenlandic Inuit and Danes: consumption of marine versus terrestrial food

Abstract

Abstract Background: 13C and 15N isotopes in human tissue reflects the relative proportions of marine and terrestrial food consumed by the individual. Objective: To measure 13C and 15N in liver tissue from Greenlandic Inuit and Danes Methods: Liver tissue was obtained at autopsy in 1992-1994 from 60 Inuit (median age 61 y) and in 1986 from 15 Danes (median age 84 y). 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 13C content relative to IAEA-CH-6 Reference Standard. δ15N indicates 15N content relative to 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. Body mass index was negatively correlated with δ13C in connective tissue (rs=-0.42, p=0.057). Danes: Median δ13C was -27.0‰ in cellular and -24.3‰ in connective tissue (p=0.11). Median δ15N was 9.5‰ in cellular and 8.9‰ in connective tissue (p=0.5). Inuit had higher δ13C than Danes in both cellular and connective tissue (p<0.001) as well as higher δ15N in cellular tissue (p=0.01). Conclusions: Inuit displayed considerable variation in the ratio between marine/terrestrial food consumption, because elderly Inuit still adhere to the traditional hunters food of marine origin, whereas younger urbanized Inuit consume more terrestrial Western fare. Danes consumed food of almost exclusively terrestrial origin. Key words: 13Carbon; Denmark; Greenland; Inuit; liver; 15Nitrogen;