Fatty acids, particularly omega-3 polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) found in fish oil, have substantial scientific backing for their role in supporting heart health. Multiple randomized controlled trials and meta-analyses have demonstrated that omega-3 fatty acids can reduce triglyceride levels, lower blood pressure modestly, decrease the risk of arrhythmias, and have anti-inflammatory effects—all of which are beneficial for individuals with heart weakness or cardiovascular disease. The American Heart Association endorses the consumption of fatty fish or omega-3 supplements for certain populations, particularly those with existing coronary heart disease or heart failure.

The strongest evidence supports the use of omega-3 fatty acids for reducing triglycerides and possibly lowering cardiovascular event rates in patients with heart disease. For example, the GISSI-Prevenzione trial and the REDUCE-IT trial both reported reduced cardiovascular events in patients taking omega-3 supplements. However, not all studies have shown benefit, particularly in primary prevention, and the benefit may depend on dose, type of fatty acid, and baseline dietary intake.

In summary, there is strong scientific evidence (though not unanimous) for the use of certain fatty acids, especially omega-3s, as supportive therapy for heart health, particularly in individuals with existing heart disease or weakness.