Association of dietary omega-3 fatty acids intake with all-cause and cardiovascular disease-specific mortality among individuals with cardiovascular disease

Omega-3 fatty acids (omega-3) are widely recognized for their potential benefits in promoting cardiovascular health. However, the precise relationship between dietary omega-3 fatty acid intake and mortality outcomes in participants with established cardiovascular disease (CVD) remains a subject of ongoing debate and considerable uncertainty. Clinical trials have yielded conflicting results, creating a need for further clarification. To address these uncertainties, we undertook a prospective study to examine the long-term associations between omega-3 fatty acids, including their specific subtypes, and both all-cause and cardiovascular-specific mortality in participants with CVD. This study aimed to explore the possible link between dietary intake of omega-3 fatty acids and both all-cause mortality and CVD-specific mortality in patients with cardiovascular conditions. Utilizing publicly accessible National Health and Nutrition Examination Survey linked mortality files up to December 31, 2019, we identified mortality rates and specific causes of death related to heart disease. To determine the association between omega-3 fatty acid consumption and mortality risk, we employed multivariable Cox regression analyses, generating hazard ratios (HRs) and 95% confidence intervals (CIs) while adjusting for a variety of demographic characteristics, lifestyle factors, and comorbid conditions. Moreover, we utilized Kaplan-Meier survival curves and conducted subgroup analyses to further examine these associations. To assess how varying levels of dietary Omega-3 fatty acids influence the risk of mortality in patients with CVD, we employed restricted cubic spline models under various conditions. A total of 3,826 participants with CVD completed the final cohort, averaging 7.59 years of follow up. Following adjustments for multiple variables, a pronounced inverse association was noted for participants in the highest quintile of total Omega-3 consumption and overall mortality, indicated by the HR of 0.77 (95% CI: 0.60-0.99). Likewise, increased total Omega-3 consumption was correlated with a reduction in CVD-specific mortality, with the HR of 0.63 (95% CI: 0.42-0.95), which was confirmed statistical significance by trend tests (P for Trend < 0.05). In the separate analysis of individual subtypes of the omega-3 fatty acid family, the consumption of alpha-linolenic acid (ALA) was obviously inverse-associated with CVD-specific mortality (HR of 0.64, 95% CI: 0.44-0.95). Nonetheless, the consumption of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and docosapentaenoic acid (DPA) did not show a significant association with mortality risk (P > 0.05). In the dose-response relationship analysis, total omega-3 fatty acid intake and ALA intake were observed to have an "L"-shaped nonlinear relationship with cardiovascular mortality, with the inflection points at 2.12 (g/day) and 2.03 (g/day), respectively. In summary, our research indicates that both total omega-3 fatty acids and ALA are inversely linked to the risk of all-cause mortality and cardiovascular mortality in patients with CVD. We recommend a daily intake of 2.12 g of total omega-3 fatty acids, with an optimal intake of 2.03 g/day for ALA for CVD patients.