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Full Title: Health Effects of Omega-3 Fatty Acids on Arrhythmogenic Mechanisms in Animal and Isolated Organ/Cell Culture Studies
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Objectives: To assess the effects of omega-3 fatty acids on the mechanisms producing arrhythmia and arrhythmia outcomes, through a systematic literature review.
Data Sources: MEDLINE®, EMBASE, Biological Abstracts, and the Commonwealth Agricultural Bureau database were searched for potentially relevant, English language studies.
Review Methods: Included research represented comparative studies of omega-3 fatty acid-fed whole animals, or isolated organs, and cells derived from these animals. Other studies included used isolated organs and cell culture to which known amounts of omega-3 fatty acid were introduced. Information was extracted about study design, animal characteristics/model, amount of dietary or culture-medium omega-3 fatty acids introduced, specific agents used, conditions under which the experiments were conducted, and outcomes. Methodological quality (randomization, blinding technique) was assessed for whole-animal studies.
Results: A meta-analysis was performed on 13 whole-animal (rat) studies that compared the anti-arrhythmic effects of alpha-linolenic acid (ALA) or fish oil to those of omega-6 oils. Fish oil supplementation showed a significant risk reduction in the number of deaths (combined risk ratio [RR] = 0.48; 95% confidence interval [CI] = 0.24-0.95), instances of ventricular tachycardia (RR = 0.49; 95% CI = 0.29-0.83), and instances of ventricular fibrillation (RR = 0.21; 95% CI = 0.07-0.63). There was no significant effect for alpha-linolenic acid supplementation.
Twenty-one studies that used isolated organs and cells from whole animals fed omega-3 fatty acids examined contractility and other parameters. Although seven of these studies evaluated the effect of omega-3 fatty acid-enriched diets on contractile parameters, they each compared different diets and used different experimental conditions.
Thirty-nine studies evaluated the effect of free or bound omega-3 fatty acids on isolated organs and cell cultures, measuring parameters similar to those observed in the whole-animal studies. Seven studies of arrhythmia (four from the same collaborative group) reported an apparent protective effect (decreased contraction rate) of omega-3 fatty acids against spontaneous or induced arrhythmias in both rat and guinea pig models in the presence of various arrhythmogenic agents. Results in studies without an arrhythmogenic agent were inconsistent.
Conclusions: Dietary supplementation of various animal species with fish oil might have anti-arrhythmic effects when compared with omega-6, monounsaturated, or saturated fatty-acid supplementation. This protective effect was observed particularly in rats with ischemia- and reperfusion-induced arrhythmias given fish oil, but not if given ALA.
Studies using isolated organs and cells from animals fed omega-3 fatty acids and in studies using isolated organ and cell culture where fatty acids were directly applied to the culture medium were unable to provide plausible biochemical or physiological mechanisms for the effects.
Health Effects of Omega-3 Fatty Acids on Arrhythmogenic Mechanisms in Animal and Isolated Organ/Cell Culture Studies
Evidence-based Practice Center: Tufts-New England Medical Center
Topic Nominator: Office of Dietary Supplements, National Institutes of Health
Current as of March 2004