Omega-3 Fatty Acids and Cardiac Arrhythmias: Prior Studies and Recommendations for Future Research

Compared with prehistoric times, the ratio of n-6 to n-3 fatty acids in the modern diet has increased ≈10-fold to 20:1.1,2 A substantial body of evidence suggests that n-3 polyunsaturated fatty acids (PUFAs) provide cardiovascular protection and prevent arrhythmias.3–5 This has led to the recommendation by the American Heart Association that all adults eat fatty fish at least 2 times per week and that patients with coronary heart disease (CHD) are advised to consume ≈1 g/d of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) combined.6,7 The evidence base is not entirely consistent, and a number of randomized trials have failed to show a protective effect of n-3 PUFAs against arrhythmias.8–10 This has led to some uncertainty regarding the appropriate recommendations for their use.11The present review originates from the Omega-3 Fatty Acids and Their Role in Cardiac Arrhythmogenesis Workshop sponsored by the National Heart, Lung, and Blood Institute and the Office of Dietary Supplements on August 29–30, 2005, and includes the findings from the recently published trials. Data from epidemiological studies, randomized clinical trials, animal studies, and basic science mechanistic studies on the role of n-3 PUFAs in arrhythmia prevention are examined. Areas in which the data are conflicting or our current knowledge is lacking are emphasized.Fatty acids are classified by the length of the carbon chain (long chain, n=20 to 22; intermediate chain, n=18) and the number of double bonds (saturated, monounsaturated, polyunsaturated).1,2 For PUFAs, the location of the first double bond relative to the -CH3 or omega (n-) end is given. Long- and intermediate-chain fatty acids must be ingested as part of the diet because they cannot be synthesized by humans and are therefore referred to as essential. The most common dietary fatty acids include (1) the omega-6 linoleic acid …