What is the omega-3 index?

MUNICH, GERMANY. In an excellent review article Professor Clemens von Schacky of the University of Munich discusses the evidence for a beneficial antiarrhythmic effect of the main components of fish oil, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Dr. Schacky proposes that the omega-3 index can be used as a very powerful indicator of the risk of sudden cardiac death (SCD) – a condition believed to be associated with ventricular fibrillation. The omega-3 index is defined as the percentage of EPA and DHA in total fatty acids contained in the membranes of red blood cells.

EPA and DHA May Have Antiarrhythmic Effects

Studies have shown that the average omega-3 index in the general population of Japan is about 11% compared to about 4% in Germany. Other studies have found that the incidence of SCD is 20 times higher in Germany than in Japan. Dr. von Schacky and other researchers conclude that 8% or higher is a desirable omega-3 index, while an index of less than 4% is associated with a 10-fold increase in the risk of SCD. There is also evidence that supplementation with 850 mg/day of EPA and DHA is associated with a 50% reduction in the risk of developing ventricular arrhythmias. As far as atrial arrhythmias is concerned, epidemiological studies using food frequency questionnaires have yielded conflicting results, while an actual intervention study involving coronary bypass patients found that EPA and DHA supplementation (2 grams/day) halved the risk of post-surgery atrial fibrillation.

Dr. Schacky concludes that the evidence for substantial antiarrhythmic effects of EPA and DHA is overwhelming, while concerns about possible proarrhythmic effects are only theoretical. In an accompanying editorial, Philip Calder of the Institute of Human Nutrition in Southampton, UK points out that omega-3 fatty acids are not created equal, and that the benefits of EPA and DHA are generally far superior to those of alpha-linolenic acid.
von Schacky, C. Omega-3 fatty acids: antiarrhythmic, proarrhythmic or both? Current Opinion in Clinical Nutrition and Metabolic Care, Vol. 11, March 2008, pp. 94-99
Calder, PC and Deckelbaum, RJ. Omega-3 fatty acids: time to get the messages right! Current Opinion in Clinical Nutrition and Metabolic Care, Vol. 11, March 2008, pp. 91-93

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