Abstract
BackgroundCo‐exposure to environmental contaminants present in fish could mitigate the beneficial effects of fish consumption and possibly explain the lack of association observed for mortality in some geographical regions.ObjectiveTo assess the independent associations of dietary exposure to polychlorinated biphenyls (PCBs) and long‐chain omega‐3 fish fatty acids intake with cardiovascular and cancer mortality.MethodsWe used the prospective population‐based Swedish Mammography Cohort and the Cohort of Swedish Men comprising 32 952 women and 36 545 men, free from cancer, cardiovascular disease and diabetes at baseline in 1998. Validated estimates of dietary PCBs and long‐chain omega‐3 fish fatty acids [i.e. eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] intake were obtained via a food frequency questionnaire at baseline. Information on death was ascertained through register linkage.ResultsDuring a mean follow‐up of 15.5 years, we ascertained 16 776 deaths. We observed for cardiovascular mortality, comparing extreme quintiles in multivariable models mutually adjusted for PCBs and EPA‐DHA, dose‐dependent associations for dietary PCB exposure, hazard ratio (HR) 1.31 (CI 95%: 1.08 to 1.57; P‐trend 0.005) and for dietary EPA‐DHA intake, HR 0.79 (CI 95%: 0.66 to 0.95; P‐trend 0.041). For cancer mortality, no clear associations were discerned.ConclusionThe beneficial effect of fish consumption on the cardiovascular system seems compromised by co‐exposure to PCBs – one likely explanation for the inconsistent associations observed between fish consumption and mortality.
Highlights
Epidemiological studies elucidating the beneficial effects of fish consumption in relation to mortality have not revealed a clear picture
We observed for cardiovascular mortality, comparing extreme quintiles in multivariable models mutually adjusted for polychlorinated biphenyls (PCBs) and eicosapentaenoic acid (EPA)-docosahexaenoic acid (DHA), dose-dependent associations for dietary PCB exposure, hazard ratio (HR) 1.31 (CI 95%: 1.08 to 1.57; P-trend 0.005) and for dietary EPA-DHA intake, HR 0.79 (CI 95%: 0.66 to 0.95; P-trend 0.041)
The beneficial effect of fish consumption on the cardiovascular system seems compromised by co-exposure to PCBs – one likely explanation for the inconsistent associations observed between fish consumption and mortality
Summary
Epidemiological studies elucidating the beneficial effects of fish consumption in relation to mortality have not revealed a clear picture. While Asian studies generally reported inverse associations [1, 2], some Western studies found no association [3, 4] or even a higher risk of mortality associated with high fish consumption [5,6,7]. In the analysis by region, while Asian studies revealed a linear inverse association, Western studies advocated a nearly U-shaped association, with a nadir at fish consumption of ~20 g dayÀ1 for both total and cardiovascular (CVD) mortality [8]. This summarized evidence agrees with our previous results indicating a U-shaped association between a 2019 The Authors. Co-exposure to environmental contaminants present in fish could mitigate the beneficial effects of fish consumption and possibly explain the lack of association observed for mortality in some geographical regions
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