Assessment of consumption of marine food in Greenland by a food frequency questionnaire and biomarkers

OBJECTIVES: We studied the association and agreement between questionnaire data and biomarkers of marine food among Greenland Inuit.

DESIGN: Cross sectional study.

METHODS: The study population comprised 2,224 Inuit, age 18+ (43% men); data collected 2005-2008 in Greenland. Using a food frequency questionnaire (FFQ), we calculated consumption of seal, whale, and fish (g/day) and as meals/month, intake of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), total N3, and mercury. We measured erythrocyte membrane fatty acids (FA) and whole blood mercury (Hg). Associations were assessed by Pearson correlation and agreement between the 2 methods was assessed by Bland-Altman plots depicting mean difference between the methods. Using multiple linear regressions, the associations were studied between whole blood mercury, erythrocyte FA and frequency or gram per day of seal, whale, and fish.

RESULTS: Partial correlations ranged from r=0.16, p<0.0001 (DHA) to r=0.56, p<0.0001 (mercury). The best fitted lines were found for mercury and DHA. Mean difference was negative for mercury but positive for all the FA biomarkers. In a multiple logistic regression analysis, the best association was found between whole blood mercury and seal consumption, both as frequency in meals and actual intake gram per day: β=1.07 µg (95% CI: 1.06; 1.08) and β=1.04 µg (95% CI: 1.03; 1.04), respectively.

CONCLUSION: Mercury showed the best correlation and agreement between calculated and measured values. Calculated actual intake in gram per day and frequency of meals showed similar associations with whole blood mercury and erythrocyte membrane FAs.