Mercury diminishes the cardiovascular protective effect of omega-3 polyunsaturated fatty acids in the modern diet of Inuit in Canada

Abstract

BackgroundInuit in Canada have low reported incidence of myocardial infarction (MI) because of their traditional rich n-3 fatty acids marine diet. They are experiencing rapid nutrition transition and ischemic heart disease is now becoming a health concern. ObjectivesOur goal was to describe the modern Inuit diet, the eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and methyl mercury (MeHg) intake and estimate their contributions to the risk of MI. We also estimated the effect of promoting the consumption of more traditional food on Inuit's MI risk. MethodsWe estimated the effect of Inuit diet on MI risk with modelling. Model formulas and assumptions were extracted from various epidemiology studies and literatures. International Polar Year Inuit Health Survey (IHS) was a comprehensive health and nutrition survey conducted in 2007–8 with 2072 participants (aged 18–79) in Canada. Traditional food intake, blood biomarkers values from the IHS served as the baseline parameters of model input. ResultsInuit traditional diet contained both high level of EPA, DHA and MeHg and their combined net effect was estimated to reduce the relative risk of MI by 1% for men and 2% for women. Arctic char meat provided the largest amount of EPA and DHA. Ringed seal liver was the main source for MeHg. Increase intake of selected fish, like salmon, herring and Arctic char by 75g per day can reduce the relative risk of MI (RR 0.70, 0.78 and 0.90 respectively). ConclusionsIn the Inuit diet, the beneficial effect on MI of EPA and DHA is diminished by the adverse effect of MeHg. Promoting the increase consumption of fish species with high EPA+DHA and low MeHg may help to prevent MI among Inuit.