Objectives We assessed the use of stable isotopes of carbon and nitrogen as biomarkers for traditional versus store‐bought food among the Inuit. Furthermore, we compared the isotope patterns among sociocultural population groups. METHODS As a part of a country‐wide health survey in Greenland during 2005–2010, we analyzed the isotope composition of toenails from 1025 adult Inuit and meat of common species hunted for food. Information on diet and sociocultural variables was collected by interviews. RESULTS Weighted by sex and place of residence to the total population of Inuit in Greenland, the average δ13C value in toenails was −20.2‰ and the δ15N value was 12.0‰ which are higher than in a general Danish omnivorous population. Both isotopes were significantly associated with other biomarkers of marine food and with results of a Food Frequency Questionnaire (FFQ). The percentage of marine food in the diet was estimated at 21% from the mean δ13C value, 25% from the mean δ15N value, and 23% from the FFQ. CONCLUSION Nail samples for analysis of stable isotopes of carbon and nitrogen were convenient to collect during a large population health survey among the Inuit. Isotope enrichment levels showed statistically significant associations with other biomarkers for consumption of marine food and with results of an FFQ and were used to estimate the percentage of marine food in the diet. Isotope levels were significantly associated with a novel score of sociocultural transition.