Increased intake omega-3 fatty acids: little or no effects on CV prevention
A Cochrane meta-analysis of 79 randomized, controlled trials (RCTs) did not show positive or negative effects of the long chain omega-3 fatty acids (LCn3) on mortality or CV events. In secondary analyses, these fatty acids from oily fish did reduce serum triglyceride levels and increased HDL concentrations. Alpha-linolenic acid (ALA) from plants was found to lower the risks of CHD mortality, atrial fibrillation and CV events. However, these small effects were only observed in some trials.
RCT’s (1947 to April 2017) focusing on higher omega-3 intake by diet advice or supplementation compared to placebo, no supplementation, usual diet or lower omega-3 dose, with a duration of ≥12 months were eligible for this meta-analysis. Pregnant and critically ill individuals were excluded, leaving a study population of 112,059 participants.
Primary outcomes included all-cause mortality, CV mortality and events, chronic heart disease (CHD) mortality and events, stroke and atrial fibrillation. Secondary outcomes included major cerebrovascular adverse effects or CV events, individual CV events (total, fatal or non-fatal MI, sudden cardiac death, angina, heart failure, revascularization, peripheral arterial disease or acute coronary disease, body weight and lipid levels.
Researchers have suggested CV benefits of omega-3 fatty acids intake, because it lowers blood pressure, reduces triglyceride levels, modulates LPL concentrations, reduces thrombotic risk, acts anti-inflammatory, has anti-arrhythmic effects, improves vascular endothelial function and insulin sensitivity, and it increases plaque stability and paraoxonase levels [1-5]. Current guidelines recommend omega-3 rich diets and supplementation , however, recent trials have not shown the positive effect of omega-3 on CV health.
Altogether, evidence for the positive effect of omega-3 on CV health is still lacking and the effect of ALA on CHD mortality, atrial fibrillation and CV events has to be proven in larger trials.