by Dr. Leo Galland
Fish oil can help increase the chances of survival for people with heart disease, according to research published in the British Medical Journal.
There have been numerous studies on the potential benefits of fish oil supplements for people who have coronary heart disease. Reviews of the published results indicate that taking fish oil supplements could help decrease the risk of cardiac (heart-related) death by 13-20 % in people who already have heart problems.
A review done at Thomas Jefferson University in Philadelphia and published in the journal Clinical Cardiology notes that while the mechanism by which fish oil provides this benefit has not been determined, “Dietary supplementation with omega-3 fatty acids should be considered in the secondary prevention of cardiovascular events.” (Paul Marik)
A review of published research in the British Medical Journal concluded by stating: “Based on the best currently available evidence, the results of this systematic review show a beneficial effect of fish oil in reducing deaths from cardiac causes. The optimal dose or formulation of fish oil is unknown, but it seems reasonable to use a daily formulation similar to that used in the GISSI-Prevenzione trial, of about 465 mg EPA/386 mg DHA.” (Hernando León, et al.)
References and Abstracts:
Clin Cardiol. 2009 Jul;32(7):365-72. Omega-3 dietary supplements and the risk of cardiovascular events: a systematic review.
Marik PE, Varon J.Division of Pulmonary and Critical Care Medicine, Thomas Jefferson University, Philadelphia, PA 19107, USA. firstname.lastname@example.org
BACKGROUND: Epidemiologic data suggest that omega-3 fatty acids derived from fish oil reduce cardiovascular disease. The clinical benefit of dietary fish oil supplementation in preventing cardiovascular events in both high and low risk patients is unclear.
OBJECTIVE: To assess whether dietary supplements of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) decrease cardiovascular events across a spectrum of patients.
DATA SOURCES: MEDLINE, Embase, the Cochrane Database of Systematic Reviews, and citation review of relevant primary and review articles.
STUDY SELECTION: Prospective, randomized, placebo-controlled clinical trials that evaluated clinical cardiovascular end points (cardiovascular death, sudden death, and nonfatal cardiovascular events) and all-cause mortality in patients randomized to EPA/DHA or placebo. We only included studies that used dietary supplements of EPA/DHA which were administered for at least 1 year.
DATA EXTRACTION: Data were abstracted on study design, study size, type and dose of omega-3 supplement, cardiovascular events, all-cause mortality, and duration of follow-up. Studies were grouped according to the risk of cardiovascular events (high risk and moderate risk). Meta-analytic techniques were used to analyze the data.
DATA SYNTHESIS: We identified 11 studies that included a total of 39 044 patients. The studies included patients after recent myocardial infarction, those with an implanted cardioverter defibrillator, and patients with heart failure, peripheral vascular disease, and hypercholesterolemia. The average dose of EPA/DHA was 1.8 +/- 1.2 g/day and the mean duration of follow-up was 2.2 +/- 1.2 years. Dietary supplementation with omega-3 fatty acids significantly reduced the risk of cardiovascular deaths (odds ratio [OR]: 0.87, 95% confidence interval [CI]: 0.79-0.95, p = 0.002), sudden cardiac death (OR: 0.87, 95% CI: 0.76-0.99, p = 0.04), all-cause mortality (OR: 0.92, 95% CI: 0.85-0.99, p = 0.02), and nonfatal cardiovascular events (OR: 0.92, 95% CI: 0.85-0.99, p = 0.02). The mortality benefit was largely due to the studies which enrolled high risk patients, while the reduction in nonfatal cardiovascular events was noted in the moderate risk patients (secondary prevention only). Meta-regression failed to demonstrate a relationship between the daily dose of omega-3 fatty acid and clinical outcome.
CONCLUSIONS: Dietary supplementation with omega-3 fatty acids should be considered in the secondary prevention of cardiovascular events.
BMJ. 2008;337(2931) Effect of Fish Oil on Arrhythmias and Mortality: Systematic Review.
Hernando León; Marcelo C Shibata; Soori Sivakumaran; Marlene Dorgan; Trish Chatterley; Ross T Tsuyuki
Objective: To synthesise the literature on the effects of fish oil — docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) — on mortality and arrhythmias and to explore dose response and formulation effects.
Design: Systematic review and meta-analysis.
Data Sources: Medline, Embase, the Cochrane Library, PubMed, CINAHL, IPA, Web of Science, Scopus, Pascal, Allied and Complementary Medicine, Academic OneFile, ProQuest Dissertations and Theses, Evidence-Based Complementary Medicine, and LILACS.
Studies Reviewed: Randomised controlled trials of fish oil as dietary supplements in humans.
Data Extraction: The primary outcomes of interest were the arrhythmic end points of appropriate implantable cardiac defibrillator intervention and sudden cardiac death. The secondary outcomes were all cause mortality and death from cardiac causes. Subgroup analyses included the effect of formulations of EPA and DHA on death from cardiac causes and effects of fish oil in patients with coronary artery disease or myocardial infarction.
Data Synthesis: 12 studies totalling 32 779 patients met the inclusion criteria. A neutral effect was reported in three studies (n=1148) for appropriate implantable cardiac defibrillator intervention (odds ratio 0.90, 95% confidence interval 0.55 to 1.46) and in six studies (n=31 111) for sudden cardiac death (0.81, 0.52 to 1.25). 11 studies (n=32 439 and n=32 519) provided data on the effects of fish oil on all cause mortality (0.92, 0.82 to 1.03) and a reduction in deaths from cardiac causes (0.80, 0.69 to 0.92). The dose-response relation for DHA and EPA on reduction in deaths from cardiac causes was not significant.
Conclusions: Fish oil supplementation was associated with a significant reduction in deaths from cardiac causes but had no effect on arrhythmias or all cause mortality. Evidence to recommend an optimal formulation of EPA or DHA to reduce these outcomes is insufficient. Fish oils are a heterogeneous product, and the optimal formulations for DHA and EPA remain unclear.