Fish Oil and Heart Disease

The amount of research that has been conducted on the topic of fish oil for the prevention and treatment of heart disease is astounding. Thousands of studies are listed on PubMed, the online repository of peer-reviewed medical journals. Fish oil has been shown to:

• reduce the risk of having a heart attack among high risk patients;
• improve cholesterol levels;
• reduce blood pressure; and
• improve heart function.

The now famous GISSI-⁠Prevenzione trial was a landmark study of patients with established heart disease, that showed benefit from fish-oil supplementation in reducing their risk of having a second, fatal heart attack and reducing their risk of death from heart disease.^[1] This study used a dose of combined eicosapentaenoic acid and docosahexaenoic acid (EPA+DHA) equal to 1 g per day. Since then, additional research has demonstrated other cardiovascular benefits as well. The JELIS study, conducted in Japan, found that higher doses of EPA+DHA, equivalent to 2 g per day, yield higher benefits, with a reduction in risk of nonfatal heart attack as well.^[2]

Higher doses of EPA+DHA have been shown to raise levels of good cholesterol, called high-density lipoprotein (HDL), which protects against heart disease, and lower levels of triglycerides, which are another predictor of heart-disease risk measured on a cholesterol panel.^[3][4] Consumption of fish oil, even at 1 g doses, may reduce systolic blood pressure by up to five points in patients with high blood pressure.^[5] Finally, fish oil may protect against heart arrhythmias (irregular heartbeats). Atrial fibrillation (or “A-⁠fib”) is a common irregularity of heart rhythm, where certain parts of the heart muscle contract in a rapid, ineffective manner; this type of heart irregularity also increases the risk of stroke. Studies have found that having higher blood levels of EPA has been associated with a reduced risk of being diagnosed with a heart condition called atrial fibrillation.^[6][7]

References

1. [No authors listed.] “Dietary supplementation with n-⁠3 polyunsaturated fatty acids and vitamin E after myocardial infarction: Results of the GISSI-Prevenzione trial. Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto miocardico.” Lancet. Vol. 354, No. 9177 (1999): 447–455.
2. Mozaffarian, D. “JELIS, fish oil, and cardiac events.” Lancet. Vol. 369, No. 9567 (2007): 1062–1063.
3. Leslie, M.A., et al. “A review of the effect of omega-⁠3 polyunsaturated fatty acids on blood triacylglycerol levels in normolipidemic and borderline hyperlipidemic individuals.” Lipids in Health and Disease. Vol. 14 (2015): 53.
4. Lee, T.C., et al. “The impact of polyunsaturated fatty acid-based dietary supplements on disease biomarkers in a metabolic syndrome/diabetes population.” Lipids in Health and Disease. Vol. 13 (2014): 196.
5. Minihane, A.M., et al. “Consumption of fish oil providing amounts of eicosapentaenoic acid and docosahexaenoic acid that can be obtained from the diet reduces blood pressure in adults with systolic hypertension: A Retrospective Analysis.” The Journal of Nutrition. Vol. 146, No. 3 (2016): 516–523.
6. Virtanen, J.K., et al. “Serum long-chain n-⁠3 polyunsaturated fatty acids and risk of hospital diagnosis of atrial fibrillation in men.” Circulation. Vol. 120, No. 23 (2009): 2315–2321.
7. Kumar, S., et al. “Long-term omega-⁠3 polyunsaturated fatty acid supplementation reduces the recurrence of persistent atrial fibrillation after electrical cardioversion.” Heart Rhythm. Vol. 9, No. 4 (2012): 483–491.