Substantial evidence suggests that omega-3 fatty acids from seafood help normalize heart rhythms, and prevent dangerously erratic ones called arrhythmias.
However, this evidence is mostly indirect, as noted by the authors of the most recent evidence review (Liu T et al. 2011).
Several clinical trials show that omega-3s help prevent sudden cardiac death and other arrhythmia-related cardiac events. And omega-3s exert generally beneficial effects on the “ion channels” that help control heart rhythms (Richardson ES et al. 2011).
These lab and clinical findings suggest that omega-3s may hold promise as anti-arrhythmia agents. But scientists still need to identify which kinds and forms of omega-3s exert the best effects, and most the appropriate ways to use them medically.
Despite the impolications of that 2006 headline from this newsletter, a new study suggests that omega-3s may actually help some high-risk heart patients ... namely, diabetics who've had one heart attack.
Clinical data suggest that omega-3s aid diabetic heart attack survivors
The Dutch authors of a modest-size trial show that higher combined intakes of seafood- and plant-source omega-3s may help protect older diabetics who’ve had a heart attack (Kromhout D et al. 2011).
The trial involved 1,014 people with diabetes, aged 60-80, who had experienced a heart attack.
The volunteers were assigned to eat a set amount of one of four margarine products daily, over a 40-month (three-year-plus) period.
Except for the regular, placebo margarine, which had no omega-3s, each margarine product delivered a different daily dose of omega-3s, of varying kinds:
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Marine Omega-3s (from fish fat) – 400 mg of EPA+DHA
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Green Omega-3s (from plant fat) – 2 grams of ALA
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Mixed Omega-3s – 400 mg of EPA+DHA and 2 grams of ALA
The volunteers in all three omega-3-fortified margarine groups enjoyed fewer adverse events associated with severe arrhythmias … sudden death, cardiac arrest, and placement of cardioverter defibrillators.
However, only the Mixed Omega-3s group experienced a statistically significant (84 percent) lower incidence of arrhythmia-related events, versus those who received the omega-3-free (placebo) margarine.
Although there was no significant reduction in fatal heart attacks among any of the groups, the Mixed Omega-3s group had significantly (72 percent) fewer indicators of severe arrhythmia, compared to the placebo group.
The superior outcome for the this group is rather surprising, since almost all of the evidence shows that the “marine” omega-3s from seafood (EPA+DHA) bear greater heart-health benefits, compared with “green”, plant-source omega-3s (ALA).
According to lead researcher Professor Daan Kromhout, MPH, Ph.D., “This is the first study that showed a significant protective effect of omega-3 fatty acids in high-risk patients with diabetes who were on state-of-the-art drug treatment for their heart attack [omega-3s] … seem to provide a benefit to the heart attack patients who also had diabetes.” (ADA 2011)
Omega-3 fatty acids are essential to human health, but the body cannot make them. They are found in fish (such as salmon and tuna), certain plant foods and oils … specifically, dark, leafy greens, walnuts, and flax, hemp, or canola oils.
This study was part of the Alpha Omega Trial, whose results – along with those from other recently published trials – have not proved a consistently positive effect of fish-source omega-3 fatty acids on physiological or clinical signs of ventricular arrhythmias.
The new trial’s positive outcomes may flow from the fact that – compared with non-diabetic heart attack survivors – the participants were diabetics ... a factor that puts them at higher risk of severe arrhythmias.
Harvard expert cites study’s strengths and limitations
We’ve spoken with cardiologist and omega-3 expert Dariush Mozaffarian, M.D., Dr.PH. – an associate professor at Harvard’s School of Public Health and Medical School – at various seafood and health conferences.
As Dr. Mozaffarian told Medscape Medical News, “… this analysis is important because it looked at a population of diabetes and heart attacks at the very high risk for heart disease.” (MMN 2011)
Dr. Mozaffarian continued, “The strength of it is that they're looking at the right outcome: heart disease death in a high-risk group. It supports the idea that omega-3s are beneficial in people at higher risk for heart disease death, but we would ideally see such results from a larger trial.” (MMN 2011)
One limitation of this study was the small number of patients who experienced ventricular arrhythmias or died; 29 and 50 respectively.
However, the study still showed a significant protective effect for the patients in the Mixed Omega-3s margarine group, who got fish-source omega-3s (EPA and DHA) and plant-source omega-3s (ALA).
Almost all participants were taking anti-clotting drugs, blood pressure drugs, and statins.
As Dr. Mozaffarian said, “Personally, as a cardiologist, I recommend fish consumption as the first, primary, and best approach to getting the omega-3s. Fish has other elements that are good for health ...” (MMN 2011)
We couldn’t agree more!
Sources
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American Diabetes Association (ADA). Extra Omega-3 Fatty Acids Reduce Severe Arrhythmia-Related Events in Patients With Diabetes and a Previous Heart Attack. November 21, 2011. Accessed at http://www.thepressreleasewire.com/client/strategic_news_service/release.jsp?actionFor=1532922
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Kromhout D et al. n-3 Fatty Acids, Ventricular Arrhythmia–Related Events, and Fatal Myocardial Infarction in Postmyocardial Infarction Patients With Diabetes. Diabetes Care December 2011 34:2515-2520; doi:10.2337/dc11-0896. Accessed at http://care.diabetesjournals.org/content/34/12/2515.abstract
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Liu T, Korantzopoulos P, Shehata M, Li G, Wang X, Kaul S. Prevention of atrial fibrillation with omega-3 fatty acids: a meta-analysis of randomised clinical trials. Heart. 2011 Jul;97(13):1034-40. Epub 2011 Apr 8. Review.
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Richardson ES, Iaizzo PA, Xiao YF. Electrophysiological mechanisms of the anti-arrhythmic effects of omega-3 fatty acids. J Cardiovasc Transl Res. 2011 Feb;4(1):42-52. Epub 2010 Dec 2. Review.
