Omega-3 fatty acids, particularly EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), are well-studied nutrients found primarily in fatty fish and fish oil supplements. There is substantial scientific evidence supporting their role in cardiovascular health. Numerous large-scale observational studies and randomized controlled trials (RCTs) have shown that increased intake of omega-3s is associated with reduced risk of cardiovascular events, especially in individuals with pre-existing heart disease. Mechanisms proposed for these benefits include reduction of triglyceride levels, anti-inflammatory effects, stabilization of atherosclerotic plaques, improvement of endothelial function, and antiarrhythmic properties.

The American Heart Association endorses omega-3 supplementation (specifically EPA and DHA) for patients with coronary heart disease, based on studies such as the GISSI-Prevenzione trial, which demonstrated reduced cardiovascular mortality in individuals who supplemented with fish oil after myocardial infarction. Recent meta-analyses and systematic reviews confirm modest but significant reductions in risk for cardiac death and heart attacks in at-risk populations. However, some newer studies have shown mixed results, particularly in primary prevention (healthy populations), and the benefit appears strongest for secondary prevention (those with established heart disease).

In summary, there is strong scientific validation for the use of omega-3 fatty acids to support heart health, particularly for individuals with existing heart conditions, though the overall effect size is moderate. The evidence base is robust for secondary prevention, while benefits for primary prevention remain less clear.