There's nothing 'fishy' about claims that omega-3 is good for your heart

In April 2014, an article called “’Fishing’ for the origins of the ‘Eskimos and heart disease’ story. Facts or wishful thinking?” was published in the Canadian Journal of Cardiology. This article has grabbed headlines because it questions original research that generated the hypothesis that omega-3 fatty acids are beneficial for heart health.

In the 1970s, researchers reported the interesting paradox that heart disease was rare among Eskimos despite consuming large amounts of fatty seal and whale blubber, which would be expected to have negative health effects. This apparent contradiction led to the finding that Eskimos had high levels of omega-3 fatty acids in their blood, thus triggering extensive research in the area of omega-3 fatty acids. This recently published article alleges that the original research in the 1970s was flawed because the researchers did not properly investigate the heart health of the Eskimo population. The lead author concludes: “To date, more than 5,000 papers have been published studying the alleged beneficial properties of omega-3 fatty acids, not to mention the billion dollar industry producing and selling fish oil capsules based on a hypothesis that was questionable from the beginning.”

However, the relevance of this new review article is questionable. The original research generated a hypothesis that omega-3 fatty acids protect the heart, and this hypothesis has been proven over and over again in scientific studies [1-11]. Systematic reviews and meta-analyses have confirmed that omega-3 fatty acids effectively lower triglycerides [7-9] and blood pressure [10] and reduce the risk of sudden cardiac death [11]. In fact, this new review article cites two meta-analyses that both report a 9% reduction in cardiac death from omega-3s [12, 13]to support their position that omega-3s lack heart health benefits. Who is going to refute the fact that lowering triglycerides, blood pressure, and the risk of cardiac death are extremely beneficial for the heart?

Furthermore, numerous global regulatory bodies and expert scientific organizations have recognized the heart benefits of omega-3 fatty acids, including Health Canada, the American Heart Association, the Academy of Nutrition and Dietetics, and the International Society for the Study of Fatty Acids and Lipids (ISSFAL). Therefore, does it really matter how the hypothesis was generated? The substantial scientific evidence speaks for itself – omega-3 fatty acids confer heart protective effects and the source of the hypothesis is irrelevant (to put it bluntly).

References

1.             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, 1999. 354(9177): p. 447-55.

2.             Marchioli, R., et al., Early protection against sudden death by n-3 polyunsaturated fatty acids after myocardial infarction: time-course analysis of the results of the Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto Miocardico (GISSI)-Prevenzione. Circulation, 2002. 105(16): p. 1897-903.

3.             Yokoyama, M., et al., Effects of eicosapentaenoic acid on major coronary events in hypercholesterolaemic patients (JELIS): a randomised open-label, blinded endpoint analysis. Lancet, 2007.369(9567): p. 1090-8.

4.             Studer, M., et al., Effect of different antilipidemic agents and diets on mortality: a systematic review.Arch Intern Med, 2005. 165(7): p. 725-30.

5.             Djousse, L., et al., Fish consumption, omega-3 fatty acids and risk of heart failure: A meta-analysis. Clin Nutr, 2012.

6.             Mozaffarian, D., et al., Plasma phospholipid long-chain omega-3 fatty acids and total and cause-specific mortality in older adults: a cohort study. Ann Intern Med, 2013. 158(7): p. 515-25.

7.             Wei, M.Y. and T.A. Jacobson, Effects of eicosapentaenoic acid versus docosahexaenoic acid on serum lipids: a systematic review and meta-analysis. Curr Atheroscler Rep, 2011. 13(6): p. 474-83.

8.             Bernstein, A.M., et al., A meta-analysis shows that docosahexaenoic acid from algal oil reduces serum triglycerides and increases HDL-cholesterol and LDL-cholesterol in persons without coronary heart disease. J Nutr, 2012. 142(1): p. 99-104.

9.             Balk, E.M., et al., Effects of omega-3 fatty acids on serum markers of cardiovascular disease risk: a systematic review. Atherosclerosis, 2006. 189(1): p. 19-30.

10.          Miller, P.E., M. Van Elswyk, and D.D. Alexander, Long-Chain Omega-3 Fatty Acids Eicosapentaenoic Acid and Docosahexaenoic Acid and Blood Pressure: A Meta-Analysis of Randomized Controlled Trials. Am J Hypertens, 2014.

11.          Casula, M., et al., Long-term effect of high dose omega-3 fatty acid supplementation for secondary prevention of cardiovascular outcomes: A meta-analysis of randomized, double blind, placebo controlled trials.Atheroscler Suppl, 2013. 14(2): p. 243-51.

12.          Kwak, S.M., et al., Efficacy of omega-3 fatty acid supplements (eicosapentaenoic acid and docosahexaenoic acid) in the secondary prevention of cardiovascular disease: a meta-analysis of randomized, double-blind, placebo-controlled trials. Arch Intern Med, 2012. 172(9): p. 686-94.

13.          Rizos, E.C., et al., Association between omega-3 fatty acid supplementation and risk of major cardiovascular disease events: a systematic review and meta-analysis. JAMA, 2012. 308(10): p. 1024-33.