N-3 fatty acids do not prevent restenosis after coronary angioplasty: results from the CART study. Coronary Angioplasty Restenosis Trial

Association Between Omega-3 Fatty Acid Intake and Dyslipidemia: A Continuous Dose-Response Meta-Analysis of Randomized Controlled Trials

Background Previous results provide supportive but not conclusive evidence for the use of omega-3 fatty acids to reduce blood lipids and prevent events of atherosclerotic cardiovascular disease, but the strength and shape of dose-response relationships remain elusive. Methods and Results This study included 90 randomized controlled trials, reported an overall sample size of 72 598 participants, and examined the association between omega-3 fatty acid (docosahexaenoic acid, eicosapentaenoic acid, or both) intake and blood lipid changes. Random-effects 1-stage cubic spline regression models were used to study the mean dose-response association between daily omega-3 fatty acid intake and changes in blood lipids. Nonlinear associations were found in general and in most subgroups, depicted as J-shaped dose-response curves for low-/high-density lipoprotein cholesterol. However, we found evidence of an approximately linear dose-response relationship for triglyceride and non-high-density lipoprotein cholesterol among the general population and more evidently in populations with hyperlipidemia and overweight/obesity who were given medium to high doses (>2 g/d). Conclusions This dose-response meta-analysis demonstrates that combined intake of omega-3 fatty acids near linearly lowers triglyceride and non-high-density lipoprotein cholesterol. Triglyceride-lowering effects might provide supportive evidence for omega-3 fatty acid intake to prevent cardiovascular events.

The ratio of eicosapentaenoic acid to docosahexaenoic acid as a modulator for the cardio-metabolic effects of omega-3 supplements: A meta-regression of randomized clinical trials

BACKGROUND

A large number of studies have demonstrated the effects of omega- 3 supplements containing mixtures of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), known to favorably affect many modifiable risk factors of coronary heart disease (CHD). These studies have used diverse ratios and doses of EPA and DHA. However, it is not known whether the ratio of EPA to DHA in omega-3 supplements affect their efficacy as modulators for cardiovascular risk factors. This meta-regression aimed to investigate the effect of different ratios of EPA to DHA on risk factors associated with CHD including lipid profile, blood pressure, heart rate, and inflammation.

METHOD

A regression analysis was carried out on 92 clinical trials with acceptable quality (Jadad score ≥ 3) that were previously identified from two databases (PubMed and Cochrane Library).

RESULTS

Data from studies that met the inclusion criteria for this analysis showed that the ratio of EPA to DHA was not associated with lipid profile, diastolic blood pressure, or heart rate. With all studies, the ratio of EPA to DHA was associated with C-reactive protein (CRP) (β = -1.3121 (95 % CI: -1.6610 to -0.9543), that is, the higher the EPA to DHA ratio, the greater the reduction. Using only studies that supplied EPA and DHA in the range of 2 g-6 g, the ratio of EPA to DHA was also associated with CRP (β = -2.10429 and 95 % CI: -3.89963 to -0.30895); that is, an even more pronounced reduction in CRP with a higher EPA to DHA ratio. Systolic blood pressure was only associated with an increasing EPA to DHA ratio in the 2 g-6 g range (β = 5.47129 and 95 % CI: 0.40677-10.53580), that is, a higher EPA to DHA ratio within this dose range, the greater the increase in SBP.

CONCLUSION

Current data suggest that the EPA to DHA ratio only correlates to the modulation of CRP by omega-3 supplementation of EPA and DHA, and SBP in studies that supplemented EPA and DHA in the range of 2 g-6 g, shedding light on potential differential effects of EPA vs. DHA on inflammation and systolic blood pressure.

Very Long Chain Marine n-3 Polyunsaturated Fatty Acids in Atherothrombotic Heart Disease. A Brief Review, with a Focus on Metabolic Effects

The global burden of atherothrombotic heart disease should be considered as a life-style disorder where differences in dietary habits and related risk factors like limited physical activity and adiposity together play important roles. Related metabolic changes have been scientifically elucidated in recent decades, and the role of the very-long-chain marine fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been much focused on, especially their possible effects on processes like inflammation and thrombosis. In the present brief review of related metabolic mechanisms, the effects of these fatty acids in a clinical setting have been referred to, including some of the authors' work on this topic. The main focus is the divergent results in the field and the important differences between the study population, the type of supplements and fresh marine sources, the proportion of EPA versus DHA dosages, and the duration of supplementation in clinical trials. We conclude that daily intake of at least 1 g of EPA + DHA may improve a dysmetabolic state in the population. The potential to reduce the risk and progression of atherothrombotic heart disease is still a matter of debate.

Association of Decreased Docosahexaenoic Acid Level After Statin Therapy and Low Eicosapentaenoic Acid Level with In-Stent Restenosis in Patients with Acute Coronary Syndrome

Aim: It is speculated that statin therapy modulates the synthesis of polyunsaturated fatty acids (PUFA), including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, the data available on the effects of statin therapy on the serum levels of PUFA and the subsequent impact on in-stent restenosis (ISR) in patients with acute coronary syndrome (ACS) are limited.

Methods: A total of 120 ACS patients who received emergent coronary stent implantation, follow-up coronary angiography to evaluate ISR, and new statin therapy were enrolled. We measured the serum levels of the PUFA and lipids at the onset of ACS and at the follow-up coronary angiography.

Results: The follow-up coronary angiography revealed 38 ISR cases. New statin therapy significantly reduced the serum levels of DHA and low-density lipoprotein cholesterol (LDL-C), while it did not affect EPA level. Single regression analysis revealed that a decreased serum level of LDL-C was associated with decreased DHA level. The multiple logistic regression analysis revealed that the decreased DHA level after statin therapy and low serum level of EPA on admission were determinants of prevalence of ISR.

Conclusion: Statin therapy decreased the serum level of DHA with a parallel reduction in LDL-C level in patients with ACS. Decreased DHA level after statin therapy and low EPA level on admission are risk factors for ISR, indicating that in patients with ACS, decreased serum levels of DHA may be a residual target for the prevention of ISR.

Safety and tolerability of prescription omega-3 fatty acids: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Omega-3 fatty acids [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] are widely recommended for health promotion. Over the last decade, prescription omega-3 fatty acid products (RxOME3FAs) have been approved for medical indications. Nonetheless, there is no comprehensive analysis of safety and tolerability of RxOME3FAs so far.

METHODS

A systematic review of randomized controlled trials (RCTs) was carried out based on searches in six electronic databases. The studies involving marketed RxOME3FA products were included, and adverse-effect data were extracted for meta-analysis. Subgroup analysis and meta-regression were conducted to explore the sources of potential heterogeneity.

RESULTS

Among the 21 included RCTs (total 24,460 participants; 12,750 from RxOME3FA treatment cohort and 11,710 from control cohort), there was no definite evidence of any RxOME3FA-emerging serious adverse event. Compared with the control group, RxOME3FAs were associated with more treatment-related dysgeusia (fishy taste; p = 0.011) and skin abnormalities (eruption, itching, exanthema, or eczema; p < 0.001). Besides, RxOME3FAs had mild adverse effects upon some non-lipid laboratory measurements [elevated fasting blood sugar (p = 0.005); elevated alanine transaminase (p = 0.022); elevated blood urea nitrogen (p = 0.047); decreased hemoglobin (p = 0.002); decreased hematocrit (p = 0.009)]. Subgroup analysis revealed that EPA/DHA combination products were associated with more treatment-related gastrointestinal adverse events [eructation (belching; p = 0.010); nausea (p = 0.044)] and low-density lipoprotein cholesterol elevation (p = 0.009; difference in means = 4.106mg/dL).

CONCLUSION

RxOME3FAs are generally safe and well tolerated but not free of adverse effects. Post-marketing surveillance and observational studies are still necessary to identify long-term adverse effects and to confirm the safety and tolerability profiles of RxOME3FAs.

Use of supplemental long-chain omega-3 fatty acids and risk for cardiac death: An updated meta-analysis and review of research gaps

BACKGROUND

Randomized controlled trials (RCTs) assessing use of long-chain omega-3 polyunsaturated fatty acids (LC-OM3), primarily eicosapentaenoic acid, and/or docosahexaenoic acid have shown mixed results.

OBJECTIVE

The objectives of the study were to update and further explore the available RCT data regarding LC-OM3 supplementation and risk for cardiac death and to propose testable hypotheses for the mixed results obtained in RCTs regarding supplemental LC-OM3 use and cardiac risk.

METHODS

A literature search was conducted using PubMed and Ovid/MEDLINE for RCTs assessing LC-OM3 supplements or pharmaceuticals with intervention periods of at least 6 months and reporting on the outcome of cardiac death. Meta-analysis was used to compare cumulative frequencies of cardiac death events between the LC-OM3 and control groups, including sensitivity and subset analyses.

RESULTS

Fourteen RCTs were identified for the primary analysis (71,899 subjects). In the LC-OM3 arms, 1613 cardiac deaths were recorded (4.48% of subjects), compared with 1746 cardiac deaths in the control groups (4.87% of subjects). The pooled relative risk estimate showed an 8.0% (95% confidence interval 1.6%, 13.9%, P = .015) lower risk in the LC-OM3 arms vs controls. Subset analyses showed numerically larger effects (12.9%-29.1% lower risks, all P < .05) in subsets of RCTs with eicosapentaenoic acid + docosahexaenoic acid dosages >1 g/d and higher risk samples (secondary prevention, baseline mean or median triglycerides ≥150 mg/dL, low-density lipoprotein cholesterol ≥130 mg/dL, statin use <40% of subjects). Heterogeneity was low (I² ≤ 15.5%, P > .05) for the primary and subset analyses.

CONCLUSION

LC-OM3 supplementation is associated with a modest reduction in cardiac death.

Eicosapentaenoic acid and docosahexaenoic acid containing supplements modulate risk factors for cardiovascular disease: a meta-analysis of randomised placebo-control human clinical trials

BACKGROUND

Over 200 clinical trials have examined the effect of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplements on risk factors associated with cardiovascular disease. However, an updated analysis of the evidence is lacking. The aim of the present meta-analysis was to quantify the effect of supplements containing EPA and DHA on risk factors for cardiovascular disease.

METHODS

An analysis was carried on 171 clinical trials with acceptable quality (Jadad score ≥3) that were identified from a comprehensive electronic search strategy of two databases (Pubmed and Cochrane Library). A random effect model was used to obtain an overall estimate on outcomes of interest. Heterogeneity between trial results was tested for using a standard chi-squared test.

RESULTS

Compared with control, EPA and DHA supplements produced significant reductions of triglycerides of 0.368 mmol L^-1 [95% confidence interval (CI) = -0.427 to -0.309], systolic blood pressure of 2.195 mmHg (95% CI = -3.172 to -1.217), diastolic blood pressure of 1.08 mmHg (95% CI = -1.716 to -0.444), heart rate of 1.37 bpm (95% CI = -2.41 to -0.325) and C-reactive protein of 0.343 mg L^-1 (95% CI = -0.454 to -0.232). This analysis indicates an increase in both low-density lipoprotein cholesterol (mean difference = 0.150 mmol L^-1 ; 95% CI = 0.058-0.243) and high-density lipoprotein cholesterol (mean difference = 0.039 mmol L^-1 ; 95% CI = 0.024-0.054). The triglyceride-lowering effect was dose-dependent.

CONCLUSIONS

The lipid-lowering, hypotensive, anti-arrhythmic and anti-inflammatory actions of EPA and DHA supplements were confirmed in this analysis of randomised placebo-control blinded clinical trials.

Statin Use Mitigate the Benefit of Omega-3 Fatty Acids Supplementation-A Meta-Regression of Randomized Trials

During last 2 decades, multiple studies have evaluated omega-3 polyunsaturated fatty acids (ω-3 PUFA) supplementation for cardiovascular prevention. The benefit found in previous studies was not demonstrated in more contemporary trials. We aimed to investigate effect of study characteristics, particularly concomitant statin therapy on results of randomized controlled trials. We systematically searched electronic databases for randomized controlled trials evaluating ω-3 PUFA supplementation and reporting clinical outcomes. A meta-analysis was performed using a random effect model, followed by a meta-regression of dose, docosahexaenoic acid/eicosapentaenoic acid (DHA/EPA) ratio, and duration of treatment and use of lipid-lowering/statin therapy in control group. Twenty-three studies with 77,776 patients (38,910 PUFA; 38,866 controls) were included. PUFA had no effect on total mortality [risk ratio (RR) = 0.96; 95% confidence interval (CI), 0.92-1.01] and myocardial infarction (RR = 0.87; 95% CI, 0.73-1.02), but marginally reduced cardiovascular mortality (RR = 0.93; 95% CI, 0.87-0.98). Lower control group statin use (b = 0.222, P = 0.027) and higher DHA/EPA (b = -0.105, P = 0.033) ratio was associated with higher reduction in total mortality. Duration and dose had no effect. None of the variables except duration had significant effect on reduction in cardiovascular mortality by PUFA supplementation. There was evidence of publication bias. Statin use may mitigate, and higher DHA/EPA ratio is associated with the beneficial effect of PUFA supplementation.

A Meta-Analysis of Randomized Controlled Trials and Prospective Cohort Studies of Eicosapentaenoic and Docosahexaenoic Long-Chain Omega-3 Fatty Acids and Coronary Heart Disease Risk

OBJECTIVE

To conduct meta-analyses of randomized controlled trials (RCTs) to estimate the effect of eicosapentaenoic and docosahexaenoic acid (EPA+DHA) on coronary heart disease (CHD), and to conduct meta-analyses of prospective cohort studies to estimate the association between EPA+DHA intake and CHD risk.

METHODS

A systematic literature search of Ovid/Medline, PubMed, Embase, and the Cochrane Library from January 1, 1947, to November 2, 2015, was conducted; 18 RCTs and 16 prospective cohort studies examining EPA+DHA from foods or supplements and CHD, including myocardial infarction, sudden cardiac death, coronary death, and angina, were identified. Random-effects meta-analysis models were used to generate summary relative risk estimates (SRREs) and 95% CIs. Heterogeneity was examined in subgroup and sensitivity analyses and by meta-regression. Dose-response was evaluated in stratified dose or intake analyses. Publication bias assessments were performed.

RESULTS

Among RCTs, there was a nonstatistically significant reduction in CHD risk with EPA+DHA provision (SRRE=0.94; 95% CI, 0.85-1.05). Subgroup analyses of data from RCTs indicated a statistically significant CHD risk reduction with EPA+DHA provision among higher-risk populations, including participants with elevated triglyceride levels (SRRE=0.84; 95% CI, 0.72-0.98) and elevated low-density lipoprotein cholesterol (SRRE=0.86; 95% CI, 0.76-0.98). Meta-analysis of data from prospective cohort studies resulted in a statistically significant SRRE of 0.82 (95% CI, 0.74-0.92) for higher intakes of EPA+DHA and risk of any CHD event.

CONCLUSION

Results indicate that EPA+DHA may be associated with reducing CHD risk, with a greater benefit observed among higher-risk populations in RCTs.

Fatty acid profile in erythrocyte membranes and plasma phospholipids affects significantly the extent of inflammatory response to coronary stent implantation

In coronary heart disease, the treatment of significant stenosis by percutaneous coronary intervention (PCI) with stent implantation elicits local and systemic inflammatory responses. This study was aimed at evaluation of the dynamics of inflammatory response and elucidation of the relationship between the fatty acid profile of red blood cell (RBC) membranes or plasma phospholipids and inflammation after PCI. High-sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), serum amyloid A (SAA), malondialdehyde (MDA) and the fatty acid profiles were determined in patients with advanced coronary artery disease undergoing PCI before, 24 h and 48 h after drug-eluting stent implantation (n=36). Patients after PCI exhibited a significant increase in studied markers (hsCRP, IL-6, SAA, MDA). Many significant associations were found between the increase of IL-6, resp. SAA and the amounts of n-6 polyunsaturated fatty acids (namely linoleic, dihomo-gamma-linolenic, docosatetraenoic and docosapentaenoic acid), resp. saturated fatty acids (pentadecanoic, stearic, nonadecanoic) in erythrocyte membranes. The magnitude of the inflammatory response to PCI is related to erythrocyte membrane fatty acid profile, which seems to be a better potential predictor of elevation of inflammatory markers after PCI than plasma phospholipids.

From alga to omega; have we reached peak (fish) oil?

SummaryWhile the Inuit diet was highly cardio-protective and consuming oily fish within a Western diet is to a lesser degree, the case for purified fish oil supplements is less convincing. Purification of fish oil removes lipophilic polyphenols which likely contribute to the health benefits of oily fish; leaving the ω3 highly unsaturated fatty acids exposed and prone to conferring oxidative and inflammatory stress. The authors believe that due to such issues as dietary shift, it may now be inadvisable to prescribe or sell purified ω3 highly unsaturated fatty acids supplements, unless the appropriate co-factors are included.

Effects of Omega-3 fatty acid on major cardiovascular events and mortality in patients with coronary heart disease: a meta-analysis of randomized controlled trials

AIM

There is considerable discrepancy regarding the protective effects of Omega-3 polyunsaturated fatty acids (Omega-3 PUFAs) in patients with coronary heart disease (CHD) from the early-phase clinical randomized controlled trials (RCTs). We conducted a meta-analysis of RCTs to address this issue.

DATA SYNTHESIS

Pubmed, the Cochrane Central Register of Controlled Trials, and EMBASE databases (∼ May 2013) were systematically searched. Odds ratios (OR) and associated 95% CI were retrieved by using random-effect model according to heterogeneity. A total of 14 RCTs involving 16,338 individuals in the Omega-3 PUFAs group and 16,318 in the control group were identified. Patients assigned to Omega-3 PUFAs did not demonstrate satisfactory improvements on major cardiovascular events (OR, 0.93; 95% CI, 0.86 to 1.01; P = 0.08; I(2) = 46%). By contrast, the reduced risks of death from cardiac causes, sudden cardiac death and death from all causes (OR, 0.88; 95% CI, 0.80 to 0.96; P = 0.003; I(2) = 0%; OR, 0.86; 95% CI, 0.76 to 0.98; P = 0.03; I(2) = 29%; and OR, 0.92; 95% CI, 0.85 to 0.99; P = 0.02; I(2) = 6%; respectively) were shown.

CONCLUSIONS

Supplement of Omega-3 PUFAs in patients with CHD is not associated with a protective effect on major cardiovascular events, while it does exert beneficial effects in reducing death from cardiac causes, sudden cardiac death and death from all causes. However, with currently available cardio-protective therapies, whether dietary supplementation with Omega-3 PUFAs should be still considered in patients with CHD is currently debated.

Do omega-3 polyunsaturated fatty acids reduce risk of sudden cardiac death and ventricular arrhythmias? A meta-analysis of randomized trials

INTRODUCTION

Omega-3 polyunsaturated fatty acids (PUFA) have demonstrated to have antiarrhythmic properties. However, randomized studies have shown inconsistent results.

OBJECTIVE

We aimed to analyze the effect of omega-3 PUFA on preventing potentially fatal ventricular arrhythmias and sudden cardiac death.

METHODS

Randomized trials comparing omega-3 PUFA to placebo and reporting sudden cardiac death (SCD) or first implanted cardioverter-defibrillator (ICD) event for ventricular tachycardia or fibrillation were included in this study. A meta-analysis using a random effects model was performed and results were expressed in terms of Odds Ratio (OR) and 95% Confidence Interval (CI) after evaluating for interstudy heterogeneity using I(2). The reported data were extracted on the basis of the intention-to-treat principle.

RESULTS

A total of 32,919 patients were included in nine trials; 16,465 patients received omega-3 PUFA and 16,454 received placebo. When comparing omega-3 PUFA to placebo, there was nonsignificant risk reduction of SCD or ventricular arrhythmias (OR = 0.82 [95% CI: 0.60-1.21], p = 0.21 I(2) = 49.7%).

CONCLUSION

Dietary supplementation with omega-3 PUFA does not affect the risk of SCD or ventricular arrhythmias.

Long chain omega-3 fatty acids and cardiovascular disease: a systematic review

Introduction: Cardiovascular disease remains the commonest health problem in developed countries, and residual risk after implementing all current therapies is still high. The use of marine omega-3 fatty acids (DHA and EPA) has been recommended to reduce cardiovascular risk by multiple mechanisms. Objectives: To update the current evidence on the influence of omega-3 on the rate of cardiovascular events. Review Methods: We used the MEDLINE and EMBASE databases to identify clinical trials and randomized controlled trials of omega-3 fatty acids (with quantified quantities) either in capsules or in dietary intake, compared to placebo or usual diet, equal to or longer than 6 months, and written in English. The primary outcome was a cardiovascular event of any kind and secondary outcomes were all-cause mortality, cardiac death and coronary events. We used RevMan 5·1 (Mantel-Haenszel method). Heterogeneity was assessed by the I2and Chi2tests. We included 21 of the 452 pre-selected studies. Results: We found an overall decrease of risk of suffering a cardiovascular event of any kind of 10 % (OR 0·90; [0·85–0·96],p = 0·001), a 9 % decrease of risk of cardiac death (OR 0·91; [0·83–0·99];p = 0·03), a decrease of coronary events (fatal and non-fatal) of 18 % (OR 0·82; [0·75–0·90];p < 1 × 10− 4), and a trend to lower total mortality (5 % reduction of risk; OR 0·95; [0·89–1·02];p = 0·15. Most of the studies analyzed included persons with high cardiovascular risk. Conclusions: marine omega-3 fatty acids are effective in preventing cardiovascular events, cardiac death and coronary events, especially in persons with high cardiovascular risk.

Effects of omega-3 fatty acid for sudden cardiac death prevention in patients with cardiovascular disease: a contemporary meta-analysis of randomized, controlled trials

PURPOSE

Experimental and epidemiological studies suggest that omega-3 fatty acids have an antiarrhythmic effect. However, evidence from randomized controlled trials (RCTs) for prevention of sudden cardiac death (SCD) remains controversial. This study sought to evaluate the efficacy of omega-3 fatty acids for secondary prevention of SCD in patients with cardiovascular disease (CVD) in the era of guidelines-based therapy.

METHODS

We conducted a PubMed/EMBASE/CENTRAL search for RCTs evaluating omega-3 fatty acids for CVD secondary prevention with at least 6 months follow-up and with data on SCD. Primary outcome was SCD. Secondary outcomes were cardiovascular mortality and all-cause mortality.

RESULTS

Ten randomized controlled trials were identified evaluating a total of 33,429 patients with CVD. In patients with guidelines-adjusted therapy, omega-3 fatty acids did not reduce the risk ratio (RR) of SCD (RR:0.96; 95% CI: 0.84-1.10). In patients with non- guidelines-adjusted therapy, omega-3 fatty acids reduced the RR of SCD (RR: 0.64; 95% CI: 0.51-0.80). Overall, RR for cardiac death and all-cause mortality were 0.81 (95% CI: 0.69-0.95) and 0.89 (95% CI: 0.79-1.01), respectively.

CONCLUSIONS

In the era of guidelines-adjusted treatment for CVD secondary prevention, omega-3 fatty acids do not appear to reduce SCD.

Uses and benefits of omega-3 ethyl esters in patients with cardiovascular disease

Much evidence on the favorable effects of omega-3 ethyl esters on cardiovascular morbidity and mortality has been obtained in studies performed in healthy subjects and in different clinical settings. Here the clinical effects of omega-3 ethyl ester administration in patients with previous myocardial infarction or heart failure are reviewed, together with a discussion of underlying mechanisms of action. The pharmacokinetic and pharmacodynamic properties of omega-3 ethyl esters, as well as evidence concerning their safety and tolerability, are also reported.

Omega-3 fatty acids in high-risk cardiovascular patients: a meta-analysis of randomized controlled trials

BACKGROUND

Multiple randomized controlled trials (RCTs) have examined the cardiovascular effects of omega-3 fatty acids and have provided unexplained conflicting results. A meta-analysis of these RCTs to estimate efficacy and safety and potential sources of heterogeneity may be helpful.

METHODS

The Cochrane library, MEDLINE, and EMBASE were systematically searched to identify all interventional trials of omega-3 fatty acids compared to placebo or usual diet in high-risk cardiovascular patients. The primary outcome was all-cause mortality and secondary outcomes were coronary restenosis following percutaneous coronary intervention and safety. Meta-analyses were carried out using Bayesian random-effects models, and heterogeneity was examined using meta-regression.

RESULTS

A total of 29 RCTs (n = 35,144) met our inclusion criteria, with 25 reporting mortality and 14 reporting restenosis. Omega-3 fatty acids were not associated with a statistically significant decreased mortality (relative risk [RR] = 0.88, 95% Credible Interval [CrI] = 0.64, 1.03) or with restenosis prevention (RR = 0.89, 95% CrI = 0.72, 1.06), though the probability of some benefit remains high (0.93 and 0.90, respectively). However in meta-regressions, there was a >90% probability that larger studies and those with longer follow-up were associated with smaller benefits. No serious safety issues were identified.

CONCLUSIONS

Although not reaching conventional statistical significance, the evidence to date suggests that omega-3 fatty acids may result in a modest reduction in mortality and restenosis. However, caution must be exercised in interpreting these benefits as results were attenuated in higher quality studies, suggesting that bias may be at least partially responsible. Additional high quality studies are required to clarify the role of omega-3 fatty acid supplementation for the secondary prevention of cardiovascular disease.

Blood platelet count and reactivity are associated with restenosis 6 months after coronary angioplasty

OBJECTIVES

Restenosis occurs in 40-50% of patients treated with percutaneous transluminal coronary angioplasty (PTCA). Some data indicate that platelet derived growth factor (PDGF) plays a pathogenetic role. The aims of the present study were to measure the plasma levels of PDGF across the coronary circulation during PTCA and relate them to the development of restenosis.

DESIGN AND RESULTS

Blood samples from the aortic root and coronary sinus were drawn simultaneously before, and after completed PTCA in 26 patients. Plasma levels of PDGF and beta-thromboglobulin (BTG), as well as platelet counts were measured. Restenosis was evaluated by quantitative coronary angiography after 6 months. Significant increases both in PDGF and BTG were encountered in the aortic root after PTCA in patients who developed restenosis as compared to patients without restenosis. Patients who developed restenosis also had significantly higher platelet counts compared to those without.

CONCLUSION

Increases in plasma PDGF and BTG in the aortic root after PTCA seem to be markers for restenosis 6 months after PTCA. This finding may strengthen the hypothesis that platelets contribute to the process of restenosis.

Do vegetarians have to eat fish for optimal cardiovascular protection?

Interest in the cardiovascular protective effects of n-3 (omega-3) fatty acids has continued to evolve during the past 35 y since the original research describing the low cardiovascular event rate in Greenland Inuit was published by Dyerberg et al. Numerous in vitro experiments have shown that n-3 fatty acids may confer this benefit by several mechanisms: they are antiinflammatory, antithrombotic, and antiarrhythmic. The n-3 fatty acids that have received the most attention are those that are derived from a fish source: namely, the longer-chain n-3 fatty acids eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). More limited data are available on the cardiovascular effects of n-3 fatty acids derived from plants such as alpha-linolenic acid (ALA; 18:3n-3). Observational data suggest that diets rich in EPA, DHA, or ALA do reduce cardiovascular events, including myocardial infarction and sudden cardiac death; however, randomized controlled trial data are somewhat less clear. Several recent meta-analyses have suggested that dietary supplementation with EPA and DHA does not provide additive cardiovascular protection beyond standard care, but the heterogeneity of included studies may reduce the validity of their conclusions. No data exist on the potential therapeutic benefit of EPA, DHA, or ALA supplementation on those individuals who already consume a vegetarian diet. Overall, there is insufficient evidence to recommend n-3 fatty acid supplementation for the purposes of cardiovascular protection; however, ongoing studies such as the Alpha Omega Trial may provide further information.

Omega-3 fatty acids: how can they be used in secondary prevention?

Omega-3 fatty acids (FAs) are divided into long-chain fatty acids (eicosapentaenoic acid and docosahexaenoic acid ), which are found in fatty fish, and intermediate-chain FAs (alpha-linolenic acid), which are found in vegetable oils. Omega-3 FAs favorably modulate a variety of vascular risk factors and also exert antiarrhythmic effects. Epidemiologic data suggest that increased consumption of marine omega-3 FAs is associated with reduced coronary heart disease (CHD) mortality. Randomized controlled studies also show that supplementation with EPA and DHA reduces CHD risk, primarily in the secondary prevention setting. Data are more limited on the efficacy of marine omega-3 FAs for the primary prevention of CHD and on the role of alpha-linolenic acid. Increased intake of EPA and DHA represents a valuable tool for vascular disease prevention and should be recommended in all patients with CHD.

Prevention of sudden cardiac death with omega-3 fatty acids in patients with coronary heart disease: a meta-analysis of randomized controlled trials

AIM

To systematically review trials concerning the effects of omega-3 fatty acids on sudden cardiac death (SCD), cardiac death, and all-cause mortality in coronary heart disease (CHD) patients.

METHODS

PubMed, Embase, and the Cochrane database (1966-2007) were searched. We identified randomized controlled trials that compared dietary or supplementary intake of omega-3 fatty acids with control diet or placebo in CHD patients. Eligible studies had at least 6 months of follow-up data, and cited SCD as an end-point. Two reviewers independently assessed methodological quality. Meta-analysis of relative risk was carried out using the random effect model.

RESULTS

Eight trials were identified, comprising 20,997 patients. In patients with prior myocardial infarction (MI), omega-3 fatty acids reduced relative risk (RR) of SCD (RR = 0.43; 95% CI: 0.20-0.91). In patients with angina, omega-3 fatty acids increased RR of SCD (RR = 1.39; 95% CI: 1.01-1.92). Overall, RR for cardiac death and all-cause mortality were 0.71 (95% CI: 0.50-1.00) and 0.77 (95% CI: 0.58-1.01), respectively.

CONCLUSIONS

Dietary supplementation with omega-3 fatty acids reduces the incidence of sudden cardiac death in patients with MI, but may have adverse effects in angina patients.

Effect of fish oils containing different amounts of EPA, DHA, and antioxidants on plasma and brain fatty acids and brain nitric oxide synthase activity in rats

BACKGROUND

The interest in n-3 polyunsaturated fatty acids (PUFAs) has expanded significantly in the last few years, due to their many positive effects described. Consequently, the interest in fish oil supplementation has also increased, and many different types of fish oil supplements can be found on the market. Also, it is well known that these types of fatty acids are very easily oxidized, and that stability among supplements varies greatly.

AIMS OF THE STUDY

In this pilot study we investigated the effects of two different types of natural fish oils containing different amounts of the n-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and antioxidants on plasma and brain fatty acids, blood lipids, vitamin E, and in vivo lipid peroxidation, as well as brain nitric oxide synthase (NOS) activity, an enzyme which has been shown to be important for memory and learning ability.

METHODS

Sprague-Dawley rats were divided into four groups and fed regular rat chow pellets enriched with 5% (w/w) of butter (control group), a natural fish oil (17.4% EPA and 11.7% DHA, referred to as EPA-rich), and a natural fish oil rich in DHA (7.7% EPA and 28.0% DHA, referred to as DHA-rich). Both of the fish oils were stabilized by a commercial antioxidant protection system (Pufanox) at production. The fourth group received the same DHA-rich oil, but without Pufanox stabilization (referred to as unstable). As an index of stability of the oils, their peroxide values were repeatedly measured during 9 weeks. The dietary treatments continued until sacrifice, after 10 days.

RESULTS

Stability of the oils varied greatly. It took the two stabilized oils 9 weeks to reach the same peroxide value as the unstable oil reached after only a few days. Both the stabilized EPA- and DHA-rich diets lowered the triacylglycerols and total cholesterol compared to control (-45%, P < 0.05 and -54%, P < 0.001; -31%, P < 0.05 and -25%, P < 0.01) and so did the unstable oil, but less efficiently. Only the unstable oil increased in vivo lipid peroxidation significantly compared to control (+40%, P < 0.001). Most of the fatty acids in the plasma phospholipids were significantly affected by both the EPA- and DHA-rich diets compared to control, reflecting their specific fatty acid pattern. The unstable oil diet resulted in smaller changes, especially in n-3 PUFAs. In the brain phospholipids the changes were less pronounced, and only the diet enriched with the stabilized DHA-rich oil resulted in a significantly greater incorporation of DHA (+13%, P < 0.01), as well as total n-3 PUFAs (+13%, P < 0.01) compared to control. Only the stabilized DHA-rich oil increased the brain NOS activity (+33%, P < 0.01).

CONCLUSIONS

Both the EPA- and DHA-rich diets affected the blood lipids in a similarly positive manner, and they both had a large impact on plasma phospholipid fatty acids. It was only the unstable oil that increased in vivo lipid peroxidation. However, the intake of DHA was more important than that of EPA for brain phospholipid DHA enrichment and brain NOS activity, and the stability of the fish oil was also important for these effects.

Benefits of fish oil supplementation in hyperlipidemia: a systematic review and meta-analysis

BACKGROUND

Fish oils have been widely reported as a useful supplement to reduce fasting blood triglyceride levels in individuals with hyperlipidemia. We performed an updated meta-analysis to quantitatively evaluate all the randomized trials of fish oils in hyperlipidemic subjects.

METHODS

We conducted a systematic literature search using several electronic databases supplemented by manual searches of published reference lists, review articles and conference abstracts. We included all placebo-controlled randomized trials of parallel design that evaluated any of the main blood lipid outcomes: total, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol or triglycerides (TG). Data were pooled using DerSimonian-Laird's random effects model.

RESULTS

The final analysis comprised of 47 studies in otherwise untreated subjects showed that taking fish oils (weighted average daily intake of 3.25 g of EPA and/or DHA) produced a clinically significant reduction of TG (-0.34 mmol/L, 95% CI: -0.41 to -0.27), no change in total cholesterol (-0.01 mmol/L, 95% CI: -0.03 to 0.01) and very slight increases in HDL (0.01 mmol/L, 95% CI: 0.00 to 0.02) and LDL cholesterol (0.06 mmol/L, 95% CI: 0.03 to 0.09). The reduction of TG correlated with both EPA+DHA intake and initial TG level.

CONCLUSION

Fish oil supplementation produces a clinically significant dose-dependent reduction of fasting blood TG but not total, HDL or LDL cholesterol in hyperlipidemic subjects.

New approaches to therapy with omega-3 fatty acids

With greater focus on chronic disease prevention, renewed attention has been directed toward understanding the pathophysiology of various medical conditions and the development of newer medical treatments to prevent and treat complications. There has been immense interest in evaluating societal lifestyles, cultural attitudes toward health, and dietary influences on health conditions. The omega-3 fatty acids have become a focus of interest, and recent research and trial evidence have highlighted their effects, including potential clinical advantages. Despite this progress, the precise mechanisms through which omega-3 fatty acids act remain poorly understood. These agents are now recommended as secondary prevention after acute myocardial infarction, and ongoing large clinical trials should provide insight into the use of omega-3 fatty acids in heart failure and the primary prevention of cardiovascular disease.

Role of prescription omega-3 fatty acids in the treatment of hypertriglyceridemia

A prescription form of omega-3 fatty acids has been approved by the United States Food and Drug Administration as an adjunct to diet for the treatment of very high triglyceride levels. The active ingredients of omega-3 fatty acids are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are responsible for the triglyceride lowering. The prescription product contains a total of 0.84 g of these two active ingredients in every 1-g capsule of omega-3 fatty acids. The total EPA and DHA dose recommended for triglyceride lowering is approximately 2-4 g/day. Fish oil products containing EPA and DHA are available without a prescription, but the American Heart Association advises that therapy with EPA and DHA to lower very high triglyceride levels should be used only under a physician's care. In patients with triglyceride levels above 500 mg/dl, approximately 4 g/day of EPA and DHA reduces triglyceride levels 45% and very low-density lipoprotein cholesterol levels by more than 50%. Low-density lipoprotein cholesterol levels may increase depending on the baseline triglyceride level, but the net effect of EPA and DHA therapy is a reduction in non-high-density lipoprotein cholesterol level. Alternatively, patients may receive one of the fibrates (gemfibrozil or fenofibrate) or niacin for triglyceride lowering if their triglyceride levels are higher than 500 mg/dl. In controlled trials, prescription omega-3 fatty acids were well tolerated, with a low rate of both adverse events and treatment-associated discontinuations. The availability of prescription omega-3 fatty acids, which ensures consistent quality and purity, should prove to be valuable for the medical management of hypertriglyceridemia.

Differentiating prescription omega-3-acid ethyl esters (P-OM3) from dietary-supplement omega-3 fatty acids

BACKGROUND

A reliable means of treating hyper-triglyceridemia is the use of large doses of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Modest levels of EPA and DHA may be obtained from food, particularly fatty fish.

OBJECTIVES

This article is intended to review clinically relevant differences between dietary-supplement omega-3 fatty acids and prescription omega-3-acid ethyl esters (P-OM3).

METHODS

PubMed and the Food and Drug Administration (FDA) Website were searched for articles published between 1995 and 2007 that contained the terms fish oil, fatty acids, n-3 fatty acids, omega fatty acids, docosahexaenoic acid, or eicosapentaenoic acid. Articles discussing sources, recommended intake, and differences among various formulations of omega-3 fatty acids were selected for review. A limitation to this review is the lack of head-to-head clinical trials using P-OM3 and dietary-supplement omega-3 fatty acids.

RESULTS

Many types of nonprescription dietary supplements of omega-3 fatty acids are available; however, the efficacy, quality, and safety of these products are open to question because they are not regulated by the same standards as pharmaceutical agents. P-OM3 is the only omega-3 fatty acid product (Omacor capsules) approved by the US FDA available in the United States as an adjunct to diet to reduce very high (> or = 500 mg/dL) triglyceride levels in adult patients.

CONCLUSIONS

P-OM3 can be used with confidence by practitioners who want to provide therapeutic doses of omega-3 fatty acids in a preparation that has been documented to be both safe and effective.

Potential of non-antiarrhythmic drugs to provide an innovative upstream approach to the pharmacological prevention of sudden cardiac death

Sudden cardiac death (SCD) is the most common cause of death and often occurs in low-risk patients. Present prevention strategies, mainly confined to high-risk subjects (proposed implantable cardioverter defibrillators recipients), have a limited effect on SCD burden in the general population. A relatively unexplored strategy for extending SCD prevention could imply targeting the early (upstream) processes of the complex cascade leading to SCD by non-antiarrhythmic drugs (i.e., beta-blockers, aldosterone antagonists, angiotensin-converting enzyme inhibitors, angiotensin receptor-blocker agents, statins and omega-3 fatty acids). In this innovative pharmacological perspective, agents with upstream effects may also be used in high-risk patients in association with a strictly downstream intervention, such as the implantable cardioverter defibrillator, in an attempt to obtain an additive/synergetic effect.

Expert opinion: omega-3 fatty acids and bleeding-cause for concern?

Omega-3 fatty acid ethyl esters have well-known triglyceride-lowering properties and were shown >30 years ago to inhibit platelet function. With the recent US Food and Drug Administration (FDA) approval of these agents for treating severe triglyceride elevations, concerns about excess bleeding naturally arise. However, an objective assessment of the evidence for clinically significant bleeding reveals that such concerns are unfounded. As such, the benefits of triglyceride lowering with omega-3 fatty acids more than outweigh any theoretical risks for increased bleeding.

Fatty acids and CHD

During the last century much evidence has accumulated to suggest that from a public health perspective the type of fat is more important than the amount of fat. Saturated andtrans-fatty acids increase and bothn-6 andn-3 PUFA decrease the risk of CHD. Most of the knowledge about the effects of dietary fatty acids on CHD risk is based on observational studies and controlled dietary experiments with intermediate end points (e.g. blood lipoprotein fractions). Information from high-quality randomised controlled trials on fatty acids and CHD is lacking. The Netherlands Institute for Public Health has calculated the potential health gain that can be achieved if the fatty acid composition of the current Dutch diet is replaced by the recommended fatty acid composition. The recommendations of The Netherlands Health Council are: saturated fatty acids <10% energy intake;trans-fatty acids <1% energy intake; fish consumption (an indicator ofn-3 PUFA) once or twice weekly. Implementation of this recommendation could reduce the incidence of CHD in The Netherlands by about 25 000/year and the number of CHD-related deaths by about 6000/year and increase life expectancy from age 40 years onwards by 0.5 year. These projections indicate the public health potential of interventions that modify the fatty acid composition of the diet.

Current clinical applications of omega-6 and omega-3 fatty acids

BACKGROUND

Recent years have brought a resurgence of research interest in fatty acids, with studied fields running the gamut of human disease. This movement has run in parallel with an increased interest in using nutrition modalities as therapeutic measures, as opposed to their conventional role as energy sources. The aim of this manuscript is to provide a basic review of current clinical applications of omega-6 and omega-3 fatty acids, with a particular focus on the latter.

METHODS

A selective review of the voluminous literature, including randomized controlled trials, meta-analyses, population studies, and case reports, was used to compile data and identify trends in pertinent clinical applications of fatty acid therapy.

CONCLUSIONS

There are a myriad of disorders and maladies that seem to benefit from fatty acid supplementation, specifically omega-3 fatty acids. It has clearly been shown that omega-3 fatty acid supplementation provides a protective benefit in heart disease, and in particular sudden cardiac death. Rheumatoid arthritis (RA) is another disease entity that has been proven to benefit from this nutrition intervention, with improvement in symptoms and diminished nonsteroidal antiinflammatory drug (NSAID) usage. In addition, many psychiatric disorders, particularly schizophrenia and major depressive disorder (MDD), have shown positive results when supplementation has been used as an adjunct to standard pharmacotherapy. The remainder of clinical applications for omega-3 fatty acids requires further investigation. Specifically, according to preliminary clinical evidence, parenteral administration of fatty acids warrants further study.

Clinical overview of Omacor: a concentrated formulation of omega-3 polyunsaturated fatty acids

Omacor (omega-3-acid ethyl esters; Reliant Pharmaceuticals, Inc., Liberty Corner, NJ) is a highly purified, prescription omega-3 fatty acid formulation with high concentrations of eicosapentaenoic acid (EPA) (465 mg) and docosahexaenoic acid (DHA) (375 mg) in each 1-g capsule, along with 4 mg (6 IU) of vitamin E. At a typical dose of 4 capsules/day, Omacor significantly lowers plasma triglyceride levels either as monotherapy or in combination with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) or fibrates. Omacor also modestly increases plasma levels of low-density lipoprotein cholesterol, increases high-density lipoprotein cholesterol levels, and has favorable effects on lipoprotein particle size and subclass distribution. Omacor is well tolerated, with few side effects other than mild gastrointestinal symptoms. Hyperglycemia, abnormal bleeding, elevations in muscle or liver enzymes, and/or abnormalities in kidney or nerve function have not been reported. Through its intensive purification process, Omacor has minimal "fishy" smell and taste, and it has not been reported to cause hypervitaminosis or illness due to exposure to environmental toxins. Omacor provides a safe, effective, well-tolerated approach to management of hypertriglyceridemia.

n-3 fatty acids and cardiovascular disease

The results of prospective cohort studies indicate that consuming fish or fish oil containing the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is associated with decreased cardiovascular death, whereas consumption of the vegetable oil-derived n-3 fatty acid a-linolenic acid is not as effective. Randomized control trials (RCTs) in the context of secondary prevention also indicate that the consumption of EPA plus DHA is protective at doses <1 g/d. The therapeutic effect appears to be due to suppression of fatal arrhythmias rather than stabilization of atherosclerotic plaques. At doses >3 g/d, EPA plus DHA can improve cardiovascular disease risk factors, including decreasing plasma triacylglycerols, blood pressure, platelet aggregation, and inflammation, while improving vascular reactivity. Mainly on the basis of the results of RCTs, the American Heart Association recommends that everyone eat oily fish twice per week and that those with coronary heart disease eat 1 g/d of EPA plus DHA from oily fish or supplements. Directions for future research include (1) RCTs to confirm the initial trials showing that EPA plus DHA decreases cardiovascular death and additional studies to determine whether this effect is due to EPA, DHA, or the combination; the dosage of the effective components; and whether the mechanism of action in humans is prevention of fatal arrhythmias. (2) Clinical studies to determine whether the reduction in cardiovascular disease risk factors is due to EPA, DHA, or the combination and the dosage of the effective components. (3) Clinical studies to determine whether vegetable oil-derived alpha-linolenic acid added to a diet enriched in n-6 fatty acids can effectively substitute for fish oil-derived EPA plus DHA.

Omega-3 fatty acids: role in cardiovascular health and disease

Dietary omega-3 polyunsaturated fatty acids, eicosapentaenoic and docosahexaenoic acids, play an important role in cardiovascular health and disease. Clinical trials provide substantial evidence to support current dietary recommendations for omega-3 fatty acids in cardiovascular disease management. The cardioprotective benefits of omega-3 fatty acids may be attributed to multiple physiological effects on lipids, blood pressure, vascular function, cardiac rhythms, platelet function, and inflammatory responses. The metabolism of omega-3 fatty acids, physiological effects, and clinical considerations with current dietary recommendations and sources of omega-3 fatty acids are presented.

Effects of omega-3 fatty acids on coronary restenosis, intima–media thickness, and exercise tolerance: A systematic review

Greater omega-3 fatty acid consumption is associated with reduced cardiovascular disease risk. Though the mechanisms of their effect are unclear, they may involve lesion formation and heart function. We conducted a systematic review of the clinical literature on the effect of omega-3 fatty acids on measures of vascular structure and function. We included studies that assessed fish and plant sources of omega-3 fatty acids on coronary artery restenosis after angioplasty, carotid IMT, and exercise capacity. Compared to placebo, the summary risk ratio of coronary artery restenosis with fish oil is 0.87 (95% CI 0.73, 1.05) across 12 randomized controlled trials. Two prospective studies reported increased carotid IMT, whereas two cross-sectional studies reported a reduction of IMT, with fish, fish oil or ALA consumption. Three randomized trials and three uncontrolled studies reported small non-significant improvements in exercise capacity with fish oil. Overall, little or no effect of fish oil was found for a variety of markers of cardiovascular disease risk. There are insufficient studies to draw conclusions about the effect of ALA. The dearth of long term data on fish consumption or omega-3 fatty acid supplementation on measures of cardiovascular disease risk severely limits our ability to draw definitive conclusions at this time.

Antiarrhythmic Mechanisms of n-3 PUFA and the Results of the GISSI-Prevenzione Trial

The purpose of this paper is twofold: on the one hand, to confirm the positive results on n-3 PUFA from the overall results Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GlSSI)-Prevenzione trial; on the other, to summarize and describe how the results of an important trial can help generate hypotheses either on mechanisms of action or on differential results in particular subgroups of patients, as well as test the pathophysiological hypotheses that have accompanied in the years the story of the hypothesized mechanisms of action of a drug. GISSI-Prevenzione was conceived as a pragmatic population trial on patients with recent myocardial infarction and it was conducted in the framework of the Italian public health system. In GISSI-Prevenzione, 11,323 patients were enrolled in a clinical trial aimed at testing the effectiveness of n-3 polyunsaturated fatty acids (PUFA) and vitamin E. Patients were invited to follow Mediterranean dietary habits, and were treated with up-to-date preventive pharmacological interventions. Long-term n-3 PUFA at 1 g daily, but not vitamin E at 300 mg daily, was beneficial for death and for combined death, non-fatal myocardial infarction, and stroke. All the benefit, however, was attributable to the decrease in risk for overall (-20%), cardiovascular (-30%), and sudden death (-45%). At variance from the orientation of a scientific scenario largely dominated by the "cholesterol-heart hypothesis", GISSI-Prevenzione results indicate n-3 PUFA (virtually devoid of any cholesterol-lowering effect) as a relevant pharmacological treatment for secondary prevention after myocardial infarction.

Fish oils in the care of coronary heart disease patients: a meta-analysis of randomized controlled trials

What is the place of fish oils in the care of coronary heart disease (CHD) patients? As several clinical trials have already addressed this question without giving definitive answers, we did a meta-analysis of trials regarding the efficacy of omega-3 fatty acids in preventing cardiovascular mortality and morbidity. We searched the MEDLINE (1966-2003), EMBASE databases, proceedings abstracts and references of reviewed articles. Randomized controlled trials (RCTs) of the efficacy of omega-3 fatty acids among adults with recent or acute myocardial infarction (MI), or angina were selected. Two reviewers abstracted data independently. Five relevant outcomes, mortality from all causes, fatal and non-fatal MI, non-fatal stroke and angina, were measured. Data were synthesized using a fixed effect model. Ten RCTs with 14,727 patients were included. No significant heterogeneity was detected. Daily intake of omega-3 fatty acids for a mean duration of 37 months decreased all causes of mortality by 16% (relative risk 0.84, 95% confidence interval [0.76; 0.94]) and the incidence of death due to MI by 24% (0.76, [0.66; 0.88]). No significant effect was found for the other outcomes. Because of the suboptimal quality of the studies included into the meta-analysis and the absence of data in patients receiving statins, these results do not justify adding fish oils systematically to the heavy pharmaceutical assortment already recommended in CHD patients.

Omega 3 fatty acids for prevention and treatment of cardiovascular disease

BACKGROUND

It has been suggested that omega 3 (W3, n-3 or omega-3) fats from oily fish and plants are beneficial to health.

OBJECTIVES

To assess whether dietary or supplemental omega 3 fatty acids alter total mortality, cardiovascular events or cancers using both RCT and cohort studies.

SEARCH STRATEGY

Five databases including CENTRAL, MEDLINE and EMBASE were searched to February 2002. No language restrictions were applied. Bibliographies were checked and authors contacted.

SELECTION CRITERIA

RCTs were included where omega 3 intake or advice was randomly allocated and unconfounded, and study duration was at least six months. Cohorts were included where a cohort was followed up for at least six months and omega 3 intake estimated.

DATA COLLECTION AND ANALYSIS

Studies were assessed for inclusion, data extracted and quality assessed independently in duplicate. Random effects meta-analysis was performed separately for RCT and cohort data.

MAIN RESULTS

Forty eight randomised controlled trials (36,913 participants) and 41 cohort analyses were included. Pooled trial results did not show a reduction in the risk of total mortality or combined cardiovascular events in those taking additional omega 3 fats (with significant statistical heterogeneity). Sensitivity analysis, retaining only studies at low risk of bias, reduced heterogeneity and again suggested no significant effect of omega 3 fats. Restricting analysis to trials increasing fish-based omega 3 fats, or those increasing short chain omega 3s, did not suggest significant effects on mortality or cardiovascular events in either group. Subgroup analysis by dietary advice or supplementation, baseline risk of CVD or omega 3 dose suggested no clear effects of these factors on primary outcomes. Neither RCTs nor cohorts suggested increased relative risk of cancers with higher omega 3 intake but estimates were imprecise so a clinically important effect could not be excluded.

REVIEWERS' CONCLUSIONS

It is not clear that dietary or supplemental omega 3 fats alter total mortality, combined cardiovascular events or cancers in people with, or at high risk of, cardiovascular disease or in the general population. There is no evidence we should advise people to stop taking rich sources of omega 3 fats, but further high quality trials are needed to confirm suggestions of a protective effect of omega 3 fats on cardiovascular health. There is no clear evidence that omega 3 fats differ in effectiveness according to fish or plant sources, dietary or supplemental sources, dose or presence of placebo.