Relationship between fish intake, n-3 fatty acids, mercury and risk markers of CHD (National Health and Nutrition Examination Survey 1999-2002)

Background: Fish consumption has been shown to be inversely associated with CHID, which may be due to n-3 fatty acids. The n-3 fatty acids, EPA and DHA, are naturally found only in marine sources. Dietary intakes of methylmercury from certain fish have been hypothesized to increase the risk of CHD. Objective: To investigate the relationship between 30d fish frequency consumption (assessed by FFQ), total blood Hg concentrations and risk markers of CHD in women aged 16-49 years participating in the National Health and Nutrition Examination Survey 1999-2002. Design: Multiple linear regression analyses were used to test 0) the relationships between 30d fish frequency consumption and five CHD risk markers, i.e. HDL. cholesterol (HDL-C), LDL cholesterol, total cholesterol, TAG and C-reactive protein (CRP); and (ii) if total blood Hg attenuated any associations between fish consumption and CHD risk markers in non-pregnant, non-diabetic females aged 16-49 years. Results: Total 30d fish frequency consumption was negatively associated with CRP (b= -0.10, 95% CI -0.19, -0.02, P=0.015) and positively associated with HDL-C (b= 1.40, 95% CI 0.31, 2.50, P = 0.014). Adjustment for other risk factors did not significantly attenuate the associations. Despite the collinearity between fish and Hg, there is a protective association between fish intake and CHD risk factors. Conclusions: The levels of DHA + EPA and other nutrients in fish may be adequate to offset the hypothesized risks of heart disease related to ingesting Hg from fish.