Evaluation of Conventional and Novel Dietary Strategies to Promote Intake of Omega-3 Highly Unsaturated Fatty Acids
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Intakes of the highly unsaturated fatty acids (HUFA, ≥20 Carbons, ≥3 double bonds) eicosapentaenoic acid (20:5n-3; EPA) and docosahexaenoic acid (22:6n-3, DHA) greater than 0.25 g/d are currently recommended for health benefits. Targets for omega-3 blood biomarkers have also been proposed based on associations with protection against coronary heart disease mortality. The relationship between diet intakes and blood biomarkers is not well defined, particularly differences between men and women. North American intakes and blood biomarkers of EPA and DHA are typically below recommendations and targets. To address this disparity, adherence to dietary advice strategies to increase EPA + DHA intake was investigated over one year. Adherence was sustained up to 12 weeks and long-term adherence was well characterized by the % of DHA in erythrocytes. For women, n-3 HUFA blood biomarkers increased following nutraceutical or combined strategy dietary advice but not seafood or functional food advice. To assist in the assessment of EPA + DHA intakes, food sources of EPA and DHA in Canada were incorporated into a semi-quantitative, nutrient-specific food frequency questionnaire (FFQ) and validated. The FFQ is an adequate tool for estimating habitual EPA and DHA intake and ranking Canadian adults by their intakes. The blood biomarker response to recommended intakes of 0.25, 0.5 and 1 g/d EPA + DHA was also characterized in adult men and women. Blood n-3 HUFA biomarkers increased in a dose-dependent manner and aligned with blood targets associated with primary cardiac arrest risk reduction. Sex differences in the DHA:EPA ratio in blood observed with low intakes at baseline disappeared following 0.25 g/d EPA + DHA. These findings are applicable towards informing achievable dietary guidelines for EPA + DHA intake and improving measurement of EPA + DHA intake in relation to blood n-3 HUFA biomarkers.