Abstract P209: Dose-Response Relationship Between Dietary Intake of Alpha-linolenic Acid and Risk of Coronary Heart Disease: A Meta-analysis of Prospective Studies

Abstract

Introduction: Previous studies show that alpha-linolenic acid (ALA) is associated with reduced risk of coronary heart disease (CHD). However, it remains unclear whether and how dietary ALA doses are related to CHD. Hypothesis: We hypothesized that higher dietary ALA intake is associated with a greater reduction in risk of CHD. Methods: We searched PubMed, EMBASE, and Web of Science for prospective studies examining the association between dietary ALA intake and CHD risk. Dietary ALA intake was assigned or measured by self-report. Outcomes were reported as total and fatal CHD and/or myocardial infarction, which were obtained from blinded endpoint assessments or medical records. Two-stage fixed-effects dose-response meta-analyses were conducted to estimate the association between increasing ALA intake (relative to study-specific referents) and CHD. Results: Fifteen published articles were identified and included in the meta-analysis (13 cohort studies and 2 randomized controlled trials). The pooled analysis was based on 310,768 individuals with 12,049 events with a mean length of follow-up of 9.6 years. The analysis showed a J-shaped curve between ALA intake and relative risk of total CHD (Chi-square=21.08, p<0.001). ALA intake from 0.3-1.4g/day showed reduced risk of total CHD, while intake ≥2.5g/day was associated with increased risk of CHD, compared to people without ALA intake (Figure 1A). Approximately 1g/day of ALA intake was associated with the lowest risk of total CHD. ALA intake was linearly associated with fatal CHD - every 1g/day increase in ALA intake was associated with an 11% decrease in fatal CHD risk (95% CI: -0.16, -0.05) (Figure 1B). Conclusion: The J-shaped dose-response relationship based on our pooled analysis suggests that 1g/day of dietary ALA may be optimal for total CHD prevention. Though a higher dietary ALA intake was associated with reduced risk of fatal CHD, the excess total CHD risk at higher ALA intakes warrants further investigation, especially through randomized controlled trials.