Effects of a high-dose concentrate of n-3 fatty acids or corn oil introduced early after an acute myocardial infarction on serum triacylglycerol and HDL cholesterol

The effects of omega-3 polyunsaturated fatty acids on cardiac rhythm: a critical reassessment

Although epidemiological studies provide strong evidence for an inverse relationship between omega-3 polyunsaturated fatty acids (n-3 PUFAs) and cardiac mortality, inconsistent and often conflicting results have been obtained from both animal studies and clinical prevention trials. Despite these heterogeneous results, some general conclusions can be drawn from these studies: 1) n-PUFAs have potent effects on ion channels and calcium regulatory proteins that vary depending on the route of administration. Circulating (acute administration) n-3 PUFAs affect ion channels directly while incorporation (long-term supplementation) of these lipids into cell membranes indirectly alter cardiac electrical activity via alteration of membrane properties. 2) n-3 PUFAs reduce baseline HR and increase HRV via alterations in intrinsic pacemaker rate rather than from changes in cardiac autonomic neural regulation. 3) n-3 PUFAs may be only effective if given before electrophysiological or structural remodeling has begun and have no efficacy against atrial fibrillation. 5) Despite initial encouraging results, more recent clinical prevention and animal studies have not only failed to reduce sudden cardiac death but actually increased mortality in angina patients and increased rather than decreased malignant arrhythmias in animal models of regional ischemia. 6) Given the inconsistent benefits reported in clinical and experimental studies and the potential adverse actions on cardiac rhythm noted during myocardial ischemia, n-3 PUFA must be prescribed with caution and generalized recommendations to increase fish intake or to take n-3 PUFA supplements need to be reconsidered.

Are n-3 fatty acids still cardioprotective?

PURPOSE OF REVIEW

Several recent randomized trials and subsequent meta-analyses have questioned the value of n-3 fatty acid supplementation in cardiovascular disease risk reduction.

RECENT FINDINGS

This report focuses on four clinical trials published between 2010 and 2012 that have failed to show benefits of n-3 fatty acids, and on one meta-analysis from 2012 that used a controversial statistical approach in reaching a conclusion of no effect.

SUMMARY

The question of the extent to which n-3 fatty acid supplementation reduces risk for cardiovascular disease remains open. Future studies must be properly powered, use doses of n-3 fatty acids significantly higher than those provided in background diets, focus on patient populations with low n-3 fatty acid tissue levels, treat for longer periods of time, and consider the effects of these agents in the great majority of patients who are not on guideline-directed therapeutic regimens. The strong evidence-base from prospective cohort studies and the ever-deepening understanding of the cellular effects of long-chain n-3 fatty acids together support the need for these nutrients in reducing cardiovascular risk. Short-term findings from randomized controlled trials need to be interpreted in the light of all the evidence.

Fish oils, coronary heart disease, and the environment

Clinical trials continue to produce conflicting results on the effectiveness of fish oils for the primary and secondary prevention of coronary heart disease. Despite many large, well-performed studies, questions still remain, made even more complex by the addition of early revascularization and statins in our coronary heart disease armamentarium. This is complicated by the reality that fish oil production has a measureable impact on reducing fish populations, which in turn has a negative impact on creating a sustainable product. We review the current data for fish oil usage in the primary and secondary prevention of coronary heart disease with an eye toward future studies, and the effects fish oil production has on the environment and efforts that are currently under way to mitigate these effects.

The role of long-chained marine N-3 polyunsaturated Fatty acids in cardiovascular disease

This paper reviews the current evidence regarding long-chained marine omega-3 polyunsaturated fatty acids (PUFAs) and cardiovascular disease (CVD), their possible mechanisms of action, and results of clinical trials. Also, primary and secondary prevention trials as studies on antiarrhythmic effects and meta-analyses are summarized. However, the individual bioavailability of n-3 PUFAs along with the highly different study designs and estimations of FAs intake or supplementation dosages in patient populations with different background intake of n-3 PUFAs might be some of the reasons for the inconsistent findings of the studies evaluating the impact of n-3 PUFAs on CVD. The question of an optimum dose of n-3 PUFAs or whether there exists a dose-response relation for n-3 PUFA supplementation is widely discussed. Moreover, the difficulties in interpreting meta-analyses are clearly demonstrated by two recently published meta-analyses (Rizos et al. and Delgado Lista et al.), evaluating the efficacy of n-3 PUFAs on CVD, including 12 common studies, but drawing opposite conclusions. We definitely need more large-scale, randomized clinical trials of long duration, also reporting harmful effects of n-3 PUFAs.

Omega-3 index and prognosis in acute coronary chest pain patients with a low dietary intake of omega-3

BACKGROUND

The omega-3 index (eicosapentaenoic acid + docosahexaenoic acid) content in red blood cell membranes has been suggested as a novel risk marker for cardiac death. Objective. To assess the ability of the omega-3 index to predict all-cause mortality, cardiac death and sudden cardiac death following hospitalization with an acute coronary syndrome (ACS), and to include arachidonic acid (AA) in risk assessment.

MATERIAL AND METHODS

The omega-3 index was measured in 572 consecutive patients (median 63 years and 59% males) admitted with chest pain and suspected ACS in an inland Northern Argentinean city with a dietary habit that was essentially based on red meat and a low intake of fish. Clinical endpoints were collected during a 5-year follow-up period, median 3.6 years, range 1 day to 5.5 years. Stepwise Cox regression analysis was employed to compare the rate of new events in the quartiles of the omega-3 index measured at inclusion. Multivariable analysis was performed.

RESULTS

No statistical significant differences in baseline characteristics were noted between quartiles of the omega-3 index. The median of the adjusted omega-3 index was 3.6%. During the follow-up period, 100 (17.5%) patients died. Event rates were similar in all quartiles of the omega-3 index, with no statistical significant differences. AA added no prognostic information.

CONCLUSION

In a population with a low intake of fish and fish oils, the adjusted omega-3 index did not predict fatal events following hospitalization in patients with acute chest pain and suspected ACS.

Why Do We Still Need Large Scale Clinical Trial: The Case of n-3 PUFA

After the first reports about a protective effect on coronary heart disease (CHD) published more than 40 years ago, wide interest in the therapeutic use of n-3 polyunsaturated fatty acids (n-3 PUFA) aroused. Since then, many studies and meta-analyses have reported a significantly reduced risk of CHD and CV death due to fish and n-3 PUFA intake. Some of the overviews reported a significant reduction of risk of sudden cardiac death, all-cause death, and nonfatal CV events. On the other side, recent clinical trials had mixed findings, raising concern about the consistency of the evidence on n-3 PUFA. We critically reviewed recent large clinical trials reporting data on the antiarrhythmic effects of n-3 PUFA in different clinical settings, i.e., patients with CHD, heart failure, with implantable cardioverter defibrillator, and at risk of atrial fibrillation, in order to summarize the results which are available up to date and possibly give "substantiated" fuel to the debate on the conflicting results of n-3 PUFA.

Dietary omega-3 fatty acids and susceptibility to ventricular fibrillation: lack of protection and a proarrhythmic effect

BACKGROUND

Recent clinical studies that evaluated the effects of supplemental omega-3 polyunsaturated fatty acids (n-3 PUFAs) on sudden cardiac death have yielded conflicting results. Our aim was to clarify this issue using an established and clinical relevant canine model of sudden cardiac death.

METHODS AND RESULTS

Susceptibility to ventricular fibrillation (VF) was evaluated using a 2-minute left circumflex artery occlusion during the last minute of an exercise test in 76 dogs (from 2 independent studies) with healed myocardial infarctions (MI); 44 developed VF (susceptible, VF+), whereas 32 did not (resistant, VF-). These dogs were then randomly assigned to either placebo (1 g/d, corn oil; 15 VF+, 11 VF-) or n-3 PUFA (1-4 g/d, docosahexaenoic acid+eicosapentaenoic acid ethyl esters, 29 VF+, 21 VF-) groups. Seven sham (no-MI) dogs were also treated with n-3 PUFA (4 g/d). After treatment (3 months), the exercise+ischemia test was repeated. Dietary n-3 PUFAs produced significant (P<0.01) increases in red blood cell and left ventricular n-3 PUFA levels. Nine post-MI (5 placebo versus 4 n-3 PUFA) and 2 sham dogs died suddenly during the 3-month treatment period. The n-3 PUFA treatment failed to prevent arrhythmias in VF+ dogs (decreased in 27% placebo versus 24% n-3 PUFA, P=0.5646) but induced VT/VF in VF- animals (n-3 PUFA 33% versus placebo 0%, P=0.0442).

CONCLUSIONS

Despite large increases in cardiac tissue n-3 PUFA content, dietary n-3 PUFAs did not prevent ischemia-induced VF and actually increased arrhythmia susceptibility in both noninfarcted and low-risk post-MI dogs.

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.

Fish, n-3 fatty acids, and cardiovascular diseases in women of reproductive age: a prospective study in a large national cohort

Previous studies have indicated a protective effect of long-chain n-3 polyunsaturated fatty acids (LCn3FAs) against cardiovascular disease; however, women are underrepresented in cardiovascular research. The aim of this study was to explore the association between intake of LCn3FAs and the risk of cardiovascular disease in a large prospective cohort of young women (mean age at baseline: 29.9 years [range: 15.7-46.9]). Exposure information on 48 627 women from the Danish National Birth Cohort was linked to the Danish National Patients Registry for information on events of hypertensive, cerebrovascular, and ischemic heart disease used to define a combined measure of cardiovascular diseases. Intake of fish and LCn3FAs was assessed by a food-frequency questionnaire and telephone interviews. During follow-up (1996-2008; median: 8 years), 577 events of cardiovascular disease were identified. Low LCn3FA intake was associated with an increased risk of cardiovascular disease (adjusted hazard ratio for women in lowest versus highest LCn3FA intake group: 1.91 [95% CI: 1.26-2.90]). Restricting the sample to women who had consistently reported similar frequencies of fish intake across 3 different dietary assessment occasions tended to strengthen the relationship (hazard ratio for lowest versus highest intake: 2.91 [95% CI: 1.45-5.85]). Furthermore, the observed associations were consistent in supplementary analyses where LCn3FA intake was averaged across the 3 dietary assessment occasions, and the associations were persistent for all 3 of the individual outcomes. Our findings based on a large prospective cohort of relatively young and initially healthy women indicated that little or no intake of fish and LCn3FAs was associated with an increased risk of cardiovascular disease.

Concordance of randomized and nonrandomized studies was unrelated to translational patterns of two nutrient-disease associations

OBJECTIVE

There are several examples in nutrition of discordance between the results of observational studies and randomized controlled trials (RCTs). We hypothesized that this discordance is attributable to differences in the translational paths of nutrient-disease associations. Translational paths can be assessed using citation analysis.

STUDY DESIGN AND SETTING

We compared the characteristics of citation networks using examples, where RCTs and observational studies agreed (long-chain n-3 polyunsaturated fatty acids [n-3 PUFA]) or disagreed (vitamin E). We performed systematic reviews in each example, constructed citation networks, and compared them with respect to the number of articles and citation relationships between them, as well as the distribution of articles' hub and authority scores.

RESULTS

For n-3 PUFA, meta-analyses of 14 RCTs and 10 observational studies both suggested that higher intake was associated with lower cardiovascular mortality. For vitamin E, the meta-analysis of 14 RCTs excluded a clinically significant effect, whereas 14 observational studies reported a significant inverse association. The respective citation networks consisted of 392 (n-3 PUFA) and 351 (vitamin E) articles. No differences between the characteristics of the two networks were identified. There was no evidence that the observational studies predated RCTs in the translational process in either example.

CONCLUSION

In the two examples, citation network characteristics do not predict concordance in the results of observational studies and RCTs.

Marine n-3 Polyunsaturated Fatty Acids in Adipose Tissue and the Risk of Acute Coronary Syndrome

Background—

Marine n-3 polyunsaturated fatty acids may reduce coronary mortality. Previous data in relation to nonfatal coronary disease, however, have been inconsistent, which may be explained by the use of heterogeneous methods to assess the intake of marine n-3 polyunsaturated fatty acids. We investigated the hypothesis that the content of total and individual marine n-3 polyunsaturated fatty acids in adipose tissue is negatively associated with the incidence of acute coronary syndrome (ACS), including both fatal and nonfatal coronary disease.

Methods and Results—

In the Diet, Cancer and Health, a Danish cohort study, 57 053 subjects were enrolled and had an adipose tissue biopsy taken at inclusion. During a mean follow-up period of 7.6 years, we identified and verified all cases (n=1012) with an incident acute coronary syndrome diagnosis, and a random sample of the cohort (n=1630) had their fatty acid composition in adipose tissue determined by gas chromatography. We found negative dose-response associations between the content of total marine n-3 polyunsaturated fatty acids and individual n-3 polyunsaturated fatty acids in adipose tissue and the risk of acute coronary syndrome. Comparing men in the highest and lowest quintiles gave a hazard ratio of 0.65 (95% confidence interval, 0.45 to 0.95) for total n-3 polyunsaturated fatty acids and 0.51 (95% confidence interval, 0.36 to 0.73) for docosahexaenoic acid. Nonfatal cases constituted >86% of cases, and the association was driven primarily by a reduction in the risk of nonfatal acute coronary syndrome. No consistent associations were found among women.

Conclusion—

Intake of marine n-3 polyunsaturated fatty acids may protect against acute coronary syndrome in men.

Polyunsaturated fatty acids and their effects on cardiovascular disease

Dietary polyunsaturated fatty acids (PUFAs) affect a wide variety of physiological processes. Much attention has been given to the n-3 PUFAs and their role in the prevention and treatment of cardiovascular disease, stemming from evidence obtained through a number of epidemiological studies and clinical trials. Investigators are now focused on elucidating the pathways and mechanisms for the biological action of n-3 PUFAs. Dietary intervention is recognized as a key measure in patient therapy and in the maintenance of human health in general. This review provides a summary of several important clinical trials, and while the exact modes of action of n-3 PUFA are not known, current viewpoints regarding the mechanisms of these fatty acids on atherosclerosis, circulating lipid profile, cell membranes, cell proliferation, platelet aggregation and cardiac arrhythmias are discussed.

Correlation of omega-3 fatty acids intakes with acculturation and socioeconomic status in midwestern Latinas

BACKGROUND

Low socioeconomic status (SES) and acculturation of Latino immigrants in the U.S. are linked to a decrease in diet quality.

METHODS

Interviews were conducted with 162 first generation Latinas to examine the association of SES and acculturation with intake of omega-3 (n - 3) fatty acids. Each participant provided dietary intake by use of a validated n - 3 food frequency questionnaire administered twice, 4 weeks apart, three 24-h recalls, sociodemographic information and completed the 5-item Short Acculturation Scale.

RESULTS

Mean intakes of Total n - 3, α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (g/d) were 1.2 ± 0.7, 1.1 ± 0.6, and 0.1 ± 0.1, respectively. After adjusting for energy intake, education was significantly correlated with EPA + DHA intakes, and acculturation was significantly correlated with Total n - 3, ALA and EPA + DHA intakes. Foods sources of EPA + DHA eaten by at least 50% of participants were chicken, shrimp, tuna and eggs.

DISCUSSION

Given the beneficial cardiovascular effects of n - 3 fatty acids, it is important to understand sociocultural factors affecting adequate intake towards an improvement in diet quality in minorities.

Cardiovascular friendly natural products: a promising approach in the management of CVD

Natural products play an important role as nutritional supplements and provide potential health benefits in cardiovascular diseases (CVD). Compiling data from experimental, epidemiological and clinical studies indicates that dietary nutrients have profound cardioprotective effects in the primary as well as secondary prevention of coronary heart disease, hence they are considered as cardiovascular friendly natural products. The mechanism of cardioprotection produced by dietary nutritional supplements such as flavonoids (citrus fruits, pulses, red wine, tea and cocoa), olive oil, omega-3 (omega-3) fatty acids (fish oil and fish-based products), lycopene (tomato and tomato-based products), resveratrol (grapes and red wine), coffee, and soy in the prevention and treatment of cardiovascular disorders have been discussed in the present review, with the emphasis of epidemiological and clinical studies. Based on the intriguing results of various studies, prophylactic and therapeutic potential of cardiovascular friendly natural products have been suggested. The supplementation of cardiovascular friendly natural products needs to be considered in all populations who have high prevalence of CVD.

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.

The utility of omega-3 fatty acids in cardiovascular disease

We reviewed the use of marine-derived omega-3 fatty acids in cardiovascular disease by discussing key epidemiologic and placebo-controlled studies in people with and without prior cardiovascular disease at baseline. In addition, studies on the antitriglyceridemic, antihypertensive, hemostatic, antiarrhythmic, and antiatherogenic properties of omega-3 fatty acids were examined. Lastly, we discussed current dietary and safety recommendations regarding fish and fish oil capsules as stated by the US Food and Drug Administration and the US Environmental Protection Agency. We found that omega-3 fatty acids have shown to significantly reduce coronary mortality and sudden death in people without prior cardiovascular disease and reduce all-cause death and cardiac mortality in secondary prevention studies. Studies on stroke are still unclear and more studies need to focus on stroke subtypes. The beneficial effects of omega-3 fatty acids might be the result of their ability to reduce triglyceride levels, blood pressure, platelet aggregation, arrhythmia, and atherogenesis. Currently, the general public is recommended to consume two fatty fish meals per week (0.3-0.5 grams per day eicosapentaenoic acid and docosahexaenoic acid). Pregnant mothers and children should refrain from eating fish high in methylmercury levels while limiting their consumption of other fish varieties to 12 ounces per week. Patients with coronary heart disease should have 1 g per day of eicosapentaenoic acid and docosahexaenoic acid, whereas patients with hypertriglyceridemia should take 3 to 5 g per day of eicosapentaenoic acid and docosahexaenoic acid under a physician's supervision.

Omega-3 dietary supplements and the risk of cardiovascular events: a systematic review

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.

Dose-response of n-3 polyunsaturated fatty acids on lipid profile and tolerability in mildly hypertriglyceridemic subjects

The n-3 polyunsaturated fatty acids (PUFAs) are known to reduce risk for coronary heart disease partly by altering blood lipids. The purpose of this study was to determine the effect of low doses of n-3 PUFAs on the lipid profile and their tolerability in mildly hypertriglyceridemic subjects. Subjects with a serum triacylglycerol (TG) level between 100 and 300 mg/dL were placed on a corn oil placebo (seven capsules per day; single-blind) for 4 weeks and then randomized to continue seven capsules per day of placebo (n = 49) or one of the following doses of n-3 PUFAs for 20 weeks: 0.5 g (n = 51), 1 g (n = 23), or 2 g (n = 12). During the treatment period, 48-50% of the 1-g and 2-g dose groups reported noticing burping (P < .05), and only about half as many in the 0.5-g group noticed burping. Interestingly, 2% of those assigned to the placebo did report a fishy burping during the study, but this dropped back to nearly 0% by week 20. There was no significant effect for any dosage group on fasting and postprandial serum TG, chylomicron TG, very-low-density lipoprotein-cholesterol, or high-density lipoprotein-cholesterol concentration. However, 1-g and 2-g n-3 PUFA treatments significantly increased total cholesterol and low-density lipoprotein-cholesterol concentration. In addition, all doses of n-3 PUFA treatments significantly increased plasma phospholipid n-3 PUFAs. We conclude that doses of n-3 PUFAs of 0.5-2 g/day in healthy volunteers with above average TG levels did not have beneficial effects on their lipid profiles.

Novel eicosapentaenoic acid-derived F3-isoprostanes as biomarkers of lipid peroxidation

Isoprostanes (iPs) are prostaglandin (PG) isomers generated by free radical-catalyzed peroxidation of polyunsaturated fatty acids (PUFAs). Urinary F(2)-iPs, PGF(2alpha) isomers derived from arachidonic acid (AA) are used as indices of lipid peroxidation in vivo. We now report the characterization of two major F(3)-iPs, 5-epi-8,12-iso-iPF(3alpha)-VI and 8,12-iso-iPF(3alpha)-VI, derived from the omega-3 fatty acid, eicosapentaenoic acid (EPA). Although the potential therapeutic benefits of EPA receive much attention, a shift toward a diet rich in omega-3 PUFAs may also predispose to enhanced lipid peroxidation. Urinary 5-epi-8,12-iso-iPF(3alpha)-VI and 8,12-iso-iPF(3alpha)-VI are highly correlated and unaltered by cyclooxygenase inhibition in humans. Fish oil dose-dependently elevates urinary F(3)-iPs in mice and a shift in dietary omega-3/omega-6 PUFAs is reflected by an increasing slope [m] of the line relating urinary 8, 12-iso-iPF(3alpha)-VI and 8,12-iso-iPF(2alpha)-VI. Administration of bacterial lipopolysaccharide evokes a reversible increase in both urinary 8,12-iso-iPF(3alpha)-VI and 8,12-iso-iPF(2alpha)-VI in humans on an ad lib diet. However, while excretion of the iPs is highly correlated (R(2) median = 0.8), [m] varies by an order of magnitude, reflecting marked inter-individual variability in the relative peroxidation of omega-3 versus omega-6 substrates. Clustered analysis of F(2)- and F(3)-iPs refines assessment of the oxidant stress response to an inflammatory stimulus in vivo by integrating variability in dietary intake of omega-3/omega-6 PUFAs.

Incremental effects of eicosapentaenoic acid on cardiovascular events in statin-treated patients with coronary artery disease

BACKGROUND

Results from JELIS (Japan EPA Lipid Intervention Study) demonstrated the efficacy of pure eicosapentaenoic acid (EPA) in preventing coronary artery disease (CAD) in hypercholesterolemic patients under statin treatment. The present study examined in detail whether EPA is effective for the secondary prevention of CAD.

METHODS AND RESULTS

Patients with established CAD and a total cholesterol level > or =250 mg/dl were observed with a mean follow-up of 4.6 years. They were randomly assigned to receive either 1,800 mg of EPA + statin (EPA group) or statin alone (control group). The incidence of major coronary events (MCE) were compared in the 2 groups. The incidence of MCE was significantly lower in the EPA group (8.7% vs 10.7%, adjusted hazard ratio =0.77, 95% confidence interval (CI) 0.63-0.96, P=0.017, number needed to treat (NNT) =49). Among 1,050 patients with prior myocardial infarction (MI), the incidence of MCE in the EPA group (15.0%) was significantly lower than that in the control group (20.1%, adjusted hazard ratio =0.73, 95%CI 0.54-0.98, P=0.033, NNT =19).

CONCLUSIONS

EPA is effective for secondary prevention of CAD, especially in individuals with prior MI, and should be added to conventional treatment.

(n-3) Fatty acid content of red blood cells does not predict risk of future cardiovascular events following an acute coronary syndrome

A reduced risk of fatal coronary artery disease has been associated with a high intake of (n-3) fatty acids (FA) and a direct cardioprotective effect by their incorporation into myocardial cells has been suggested. Based on these observations, the omega-3 index (eicosapentaenoic acid + docosahexaenoic acid in cell membranes of RBC expressed as percent of total FA) has been suggested as a new risk marker for cardiac death. In this study, our aim was to evaluate the omega-3 index as a prognostic risk marker following hospitalization with an acute coronary syndrome (ACS). The omega-3 index was measured at admission in 460 patients with an ACS as defined by Troponin-T (TnT) > or = 0.02 microg/L. During a 2-y follow-up, recurrent myocardial infarctions (MI) (defined as TnT > 0.05 microg/L with a typical MI presentation) and cardiac and all-cause mortality were registered. Cox regression analyses were used to relate the risk of new events to the quartiles of the omega-3 index at inclusion. After correction for age, sex, previous heart disease, hypertension, diabetes, smoking, high-sensitivity C-reactive protein, brain natriuretic peptide, creatinine, total cholesterol, HDL-cholesterol, triacylglycerol, homocysteine, BMI, and medication, there was no significant reduction in risk for all-cause mortality, cardiac death, or MI with increasing values of the index. In conclusion, we could not confirm the omega-3 index as a useful prognostic risk marker following an ACS.

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.

Omega 3 : where do we stand?

Omega-3 fatty acids are essential polyunsaturated fatty acids that are crucial components of plasma membrane phospholipids. They influence cell structure and function and have anti-thrombotic and anti-arrhythmic properties, thus potentially exerting a favourable action on primary and secondary prevention of cardiovascular events. However, the supposed beneficial effect of omega-3 fatty acids in the management of cardiovascular risk has been evaluated only in a relatively small number of interventional studies, with results that are not consistent and are only suggestive of a putative beneficial effect of omega-3 supplementation on the prevention of cardiovascular mortality. Benefits have been reported mainly for the prevention of sudden death in patients with recent myocardial infarction and for primary and secondary prevention of nonfatal cardiac events in populations with high fish intake. Therefore, only ongoing trials will provide definitive data to elucidate whether omega-3 fatty acids could represent a new therapeutic approach for cardiovascular disease.

Generic and product-specific health claim processes for functional foods across global jurisdictions

Worldwide consumer interest in functional foods and their potential health benefits has been increasing over the past 10 y. To respond to this interest, regulatory bodies have developed guidelines for assessing health claims on functional foods. The objective of this article is to investigate the type and amount of evidence needed in various jurisdictions on a worldwide basis to substantiate both generic and product-specific health claims. Two types of health claims were examined using separate case studies. Analysis of generic health claims was highlighted by (n-3) fatty acids and their relation to heart health; whereas examination of product-specific health claims was conducted using probiotics and their association with gastrointestinal well-being. Results showed a common core for use of convincing high-quality human data, especially in the form of randomized controlled trials (RCT), but there was significant variability in the type and amount of scientific evidence needed to substantiate health claims, both generic and product specific, across different jurisdictions. Product-specific claims tended to use human RCT as the main basis for claims, whereas generic claims tended to base their statements on a wider spectrum of literature.

Omega-3 fatty acids for cardioprotection

The most compelling evidence for the cardiovascular benefit provided by omega-3 fatty acids comes from 3 large controlled trials of 32,000 participants randomized to receive omega-3 fatty acid supplements containing docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) or to act as controls. These trials showed reductions in cardiovascular events of 19% to 45%. These findings suggest that intake of omega-3 fatty acids, whether from dietary sources or fish oil supplements, should be increased, especially in those with or at risk for coronary artery disease. Patients should consume both DHA and EPA. The target DHA and EPA consumption levels are about 1 g/d for those with known coronary artery disease and at least 500 mg/d for those without disease. Patients with hypertriglyceridemia benefit from treatment with 3 to 4 g/d of DHA and EPA, a dosage that lowers triglyceride levels by 20% to 50%. Although 2 meals of oily fish per week can provide 400 to 500 mg/d of DHA and EPA, secondary prevention patients and those with hypertriglyceridemia must use fish oil supplements if they are to reach 1 g/d and 3 to 4 g/d of DHA and EPA, respectively. Combination therapy with omega-3 fatty acids and a statin is a safe and effective way to improve lipid levels and cardiovascular prognosis beyond the benefits provided by statin therapy alone. Blood DHA and EPA levels could one day be used to identify patients with deficient levels and to individualize therapeutic recommendations.

Omega-3 Fatty Acids: Emerging Role for Cardioprotection

This continuing feature will update readers on recent developments in cardiovascular pharmacotherapy. Cardiovascular disease remains the number one killer in the United States and more clinical outcome trials have been conducted in cardiology than in any other field of medicine. Given this rapidly expanding knowledge base, pharmacists can have a significant impact on prevention and treatment—if they keep current with developments in drug therapy.

Negative confounding in the evaluation of toxicity: the case of methylmercury in fish and seafood

In observational studies, the presence of confounding [corrected] can distort the true association between an exposure and a toxic-effect outcome, if the confounding variable is not controlled for in the study design or analysis phase. While confounding is often assumed to occur in the same direction as the toxicant exposure, the relationship between the benefits and risks associated with fish and seafood consumption is a classic example of negative confounding: the exposure to methylmercury occurs with fish and seafood, which are also associated with beneficial nutrients, and the signs of mercury toxicity [corrected] Mercury and nutrients may affect the same epidemiological outcomes, but most studies addressing one of them have ignored the potential for negative confounding by the other. This article reviews the existing evidence of effects of both nutrient and contaminant intakes as predictors of neurodevelopmental and cardiovascular outcomes. Substantial underestimation of the effects of mercury toxicity and of fish benefits occurs from the lack of confounder adjustment and imprecision of the exposure parameters. Given this inherent bias in observational studies, regulatory agencies should reconsider current dietary advice in order to provide better guidance to consumers in making prudent choices to maintain a nutritious diet with seafood that is low in mercury concentrations. Attention should also be paid to the occurrence of negative confounding in other connections.

Relation of omega-3 Fatty Acid intake to other dietary factors known to reduce coronary heart disease risk

Data supporting the inverse correlation of fish or long-chain omega-3 fatty acid (FA) (eicosapentaenoic acid plus docosahexaenoic acid) supplement consumption and coronary heart disease are inconclusive and may be confounded by other dietary and lifestyle factors. Using the Diabetic Control and Complications Trial (DCCT) database (n = 1,441), correlations between consumption of omega-3 FAs and saturated FAs to dietary variables (kilocalories, macronutrients, sodium, and cholesterol) and to age, gender, exercise level, and tobacco use were tested using Pearson correlation coefficients. Long-chain omega-3 FA intake inversely correlated with consumption of calories (r = -0.16, p <0.0001), percent calories from total fat (r = -0.14, p <0.0001), and percent calories from saturated FAs (r = -0.21, p <0.0001) and directly with dietary fiber intake (grams per 1,000 kcal, r = 0.20, p <0.0001). In the DCCT database, long-chain omega-3 FAs (i.e., fish consumption) inversely correlated with an overall low risk nutritional profile for coronary heart disease. In conclusion, these findings provide evidence that associations observed in studies suggesting a benefit of fish or long-chain omega-3 FAs may be due to a convergence of greater fish intakes with an overall healthier dietary pattern rather than with a specific effect of long-chain omega-3 FAs.

A review of omega-3 ethyl esters for cardiovascular prevention and treatment of increased blood triglyceride levels

The two marine omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), prevalent in fish and fish oils, have been investigated as a strategy towards prophylaxis of atherosclerosis. While the results with fish and fish oils have been not as clear cut, the data generated with the purified ethyl ester forms of these two fatty acids are consistent. Although slight differences in biological activity exist between EPA and DHA, both exert a number of positive actions against atherosclerosis and its complications. EPA and DHA as ethyl esters inhibit platelet aggregability, and reduce serum triglycerides, while leaving other serum lipids essentially unaltered. Glucose metabolism has been studied extensively, and no adverse effects were seen. Pro-atherogenic cytokines are reduced, as are markers of endothelial activation. Endothelial function is improved, vascular occlusion is reduced, and the course of coronary atherosclerosis is mitigated. Heart rate is reduced, and heart rate variability is increased by EPA and DHA. An antiarrhythmic effect can be demonstrated on the supraventricular and the ventricular level. More importantly, two large studies showed reductions in clinical endpoints like sudden cardiac death or major adverse cardiac events. As a consequence, relevant cardiac societies recommend using 1 g/day of EPA and DHA for cardiovascular prevention, after a myocardial infarction and for prevention of sudden cardiac death.

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.

Holotranscobalamin and methylmalonic acid as prognostic markers following an acute myocardial infarction

OBJECTIVE

To evaluate whether low levels of holotranscobalamin (holoTC) or elevated levels of methylmalonic acid (MMA), both indicators of vitamin B(12) deficiency, might predispose to new cardiovascular events following an acute myocardial infarction (MI).

DESIGN

A prospective prognostic study.

SETTING

One hospital center in Stavanger, Norway.

SUBJECTS

A total of 300 patients admitted with an acute MI.

METHODS

Registration of new TnT positive coronary events (defined as TnT>0.05 microg/l and a typical MI pattern) and/or cardiac death during a median follow-up time of 45 months.

RESULTS

We compared the recurrence of events in the lowest quartile of holoTC (Q1<73.9 pmol/l) to the event rate above the 25% percentile (Q2-4). For methylmalonic acid (MMA) the same comparison was carried out for the upper quartile (Q4 > or =0.24 micromol/l) as compared with the event rate below the 75% percentile (Q1-3). After 18 and 45 months of follow-up, the odds ratio (OR) for Q1 vs Q2-4 for holoTC was 1.15 (95% confidence interval (CI) 0.91-1.46, P=0.25) and 1.05 (95% CI 0.86-1.29, P=0.64), respectively. For MMA the OR for Q4 vs Q1-3 was 0.95 (95% CI 0.76-1.19, P=0.67) after 18 months and 1.01 (95% CI 0.83-1.23, P=0.90) after 45 months.

CONCLUSION

This study showed no increased risk of future cardiovascular events associated with low levels of holoTC or high levels of MMA following an acute MI.

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.

Effects of omega-3 fatty acids on serum markers of cardiovascular disease risk: A systematic review

Greater fish oil consumption has been associated with reduced CVD risk, although the mechanisms are unclear. Plant-source oil omega-3 fatty acids (ALA) have also been studied regarding their cardiovascular effect. We conducted a systematic review of randomized controlled trials that evaluated the effect of consumption of fish oil and ALA on commonly measured serum CVD risk factors, performing meta-analyses when appropriate. Combining 21 trials evaluating lipid outcomes, fish oil consumption resulted in a summary net change in triglycerides of -27 (95% CI -33, -20)mg/dL, in HDL cholesterol of +1.6 (95% CI +0.8, +2.3)mg/dL, and in LDL cholesterol of +6 (95% CI +3, +8)mg/dL. There was no effect of fish oil on total cholesterol. Across studies, higher fish oil dose and higher baseline levels were associated with greater reductions in serum triglycerides. Overall, the 27 fish oil trials evaluating Hgb A(1c) or FBS found small non-significant net increases compared to control oils. Five studies of ALA were inconsistent in their effects on lipids, Hgb A(1c) or FBS. Four studies investigating the effects of omega-3 fatty acids on hs-CRP were also inconsistent and non-significant. The evidence supports a dose-dependent beneficial effect of fish oil on serum triglycerides, particularly among people with more elevated levels. Fish oil consumption also modestly improves HDL cholesterol, increases LDL cholesterol levels, but does not appear to adversely affect glucose homeostasis. The evidence regarding the effects of omega-3 fatty acids on hs-CRP is inconclusive, as are data on ALA.

Fish, marine n-3 polyunsaturated fatty acids and coronary heart disease: a minireview with focus on clinical trial data

In this paper, we will briefly deal with the background for the possible effects of long-chain marine n-3 (also called omega-3) polyunsaturated fatty acids (PUFA) in coronary heart disease (CHD) and then focus on findings from clinical trials in humans. We will not deal with effects of alpha-linolenic acid, the non-marine type of n-3 PUFA derived from plant oils.

Antiatherosclerotic and antithrombotic effects of omega-3 fatty acids

Omega-3 fatty acids from both marine and plant sources have been shown to reduce the risk of coronary artery disease death. Although their beneficial cardiovascular effects are thought to be due to their antiarrhythmic properties, omega-3 fatty acids also have been shown to have a wide range of antiatherosclerotic and antithrombotic effects in animal and human studies. Review of the findings of randomized, controlled trials published through August 2005 shows that omega-3 fatty acids of marine origin consistently lower elevated plasma triglyceride levels in a dose-dependent fashion, with greater efficacy at higher triglyceride levels. Smaller effects on lowering blood pressure, improving endothelial function, and increasing plasma levels of high-density lipoprotein cholesterol were also found. No consistent effects on other lipid, hemostatic, inflammatory, glucose tolerance, or plaque stabilization parameters were found. Epidemiologic studies show more consistent reductions in the incidence of nonfatal myocardial infarction and ischemic stroke than do the clinical trials of increased omega-3 fatty acid intake, which suggests important confounding factors in observational studies. Ongoing clinical trials may clarify the non-antiarrhythmic benefits of omega-3 fatty acid supplementation.

Secondary prevention of coronary artery disease with omega-3 fatty acids

Omega-3 fatty acid therapy is a promising intervention for the secondary prevention of coronary artery disease (CAD). Omega-3 fatty acids have properties that promote atherosclerotic plaque stability and decrease the incidence of ischemia-driven cardiac arrhythmias. A large number of clinical trials conducted in patients with CAD or prior myocardial infarction (MI) have examined hard cardiovascular end points, including total mortality, cardiovascular mortality, sudden death, and nonfatal MI. Several intermediate cardiovascular end-point studies have also examined whether ventricular arrhythmias can be suppressed in patients with implantable cardioverter defibrillators (ICDs). Significant reductions in total mortality and sudden death--20% to 50%--have been found in studies using doses of 0.85 to 4.0 g/day, with treatment durations from 12 to 42 months. Favorable trends toward reduction in the incidence of arrhythmic events have been demonstrated in some, but not all, ICD studies. Omega-3 fatty acid therapy shows a general positive trend toward benefit in reducing life-threatening events after MI and in patients with ICDs who have ischemic arrhythmias. Results of the recent Japan EPA Lipid Intervention Study (JELIS) in a large cohort (N = 18,645) of Japanese men and women suggest significant benefits in the reduction of unstable angina and nonfatal coronary events. The totality of evidence supports a strong role for omega-3 fatty acids derived from fish oil in secondary prevention through a presumptive role as an antiarrhythmic agent and through an ability to promote plaque stabilization.

A cost-effectiveness analysis of n-3 PUFA (Omacor) treatment in post-MI patients

This study evaluates the cost-effectiveness of Omacor treatment as a standard prevention measure post-MI in the UK. A cost-effectiveness model was developed based on the GISSI-P trial, combining a survival and a Markov model, over a lifetime period. The base case results for Omacor, at 4 years and over a lifetime, respectively, were: cost [corrected] per QALY gained: pound15,189 and 3,723; [corrected] cost per life years gained (LYG): pound12,011 and pound2,812 [corrected] The cost per death avoided at 4 years was pound31,786. Deterministic and probabilistic sensitivity analyses did not change the base case results substantially. The use of Omacor as a standard post-MI prevention treatment seems warranted in the UK, both on the basis of its efficacy, which is in addition to other prophylactic treatments as evidenced by the results of the GISSI-P trial, and on cost-effectiveness grounds - both at 4 years and over a lifetime's time-horizon, using the current cost-effectiveness thresholds.

(N-3) long-chain polyunsaturated fatty acids prolong survival following myocardial infarction in rats

Many clinical studies report that (n-3) PUFAs decrease the incidence of sudden death in patients with coronary artery disease after myocardial infarction (MI). However, the mechanisms for the beneficial effects of (n-3) PUFAs are unknown. The objectives of the present study were to confirm the findings from clinical trials using an animal model of MI in which dietary intake could be closely controlled and to utilize the model to investigate molecular mechanisms for the beneficial effects of (n-3) PUFAs. Male rats were subjected to coronary ligation to induce MI and were randomly assigned to diets high in (n-6) (58% of lipid) or (n-3) (28% of lipid) PUFAs for 6 mo. A diet high in (n-3) PUFAs was associated with an improvement in 6-mo survival (89.2% vs. 64.9%, P = 0.013) compared with rats consuming a diet high in (n-6) PUFAs (n = 37/group). In a separate study (n = 5 rats/diet group), the (n-3) PUFA diet decreased the (n-6):(n-3) PUFA ratio in plasma (0.6 +/- 0.1 vs. 7.9 +/- 1.8, P < 0.05) and cardiac tissue (0.9 +/- 0.1 vs. 11.8 +/- 1.6, P < 0.05) of rats fed for 4 wk. The increased survival in the (n-3) diet group was associated with decreased cardiac activities of protein kinase A and calcium calmodulin-dependent kinase II by 33-38% (P < 0.05) and a 28% decrease (P < 0.05) in phosphorylation (activation) of the ryanodine receptor calcium release channel. Based upon our results, we speculate that decreased activities of protein kinases induced by diets high in (n-3) PUFAs are associated with a decrease in sudden death after MI in rats.

n-3 Fatty acids from fish or fish-oil supplements, but not alpha-linolenic acid, benefit cardiovascular disease outcomes in primary- and secondary-prevention studies: a systematic review

Studies on the relation between dietary n-3 fatty acids (FAs) and cardiovascular disease vary in quality, and the results are inconsistent. A systematic review of the literature on the effects of n-3 FAs (consumed as fish or fish oils rich in eicosapentaenoic acid and docosahexaenoic acid or as alpha-linolenic acid) on cardiovascular disease outcomes and adverse events was conducted. Studies from MEDLINE and other sources that were of > or =1 y in duration and that reported estimates of fish or n-3 FA intakes and cardiovascular disease outcomes were included. Secondary prevention was addressed in 14 randomized controlled trials (RCTs) of fish-oil supplements or of diets high in n-3 FAs and in 1 prospective cohort study. Most trials reported that fish oil significantly reduced all-cause mortality, myocardial infarction, cardiac and sudden death, or stroke. Primary prevention of cardiovascular disease was reported in 1 RCT, in 25 prospective cohort studies, and in 7 case-control studies. No significant effect on overall deaths was reported in 3 RCTs that evaluated the effects of fish oil in patients with implantable cardioverter defibrillators. Most cohort studies reported that fish consumption was associated with lower rates of all-cause mortality and adverse cardiac outcomes. The effects on stroke were inconsistent. Evidence suggests that increased consumption of n-3 FAs from fish or fish-oil supplements, but not of alpha-linolenic acid, reduces the rates of all-cause mortality, cardiac and sudden death, and possibly stroke. The evidence for the benefits of fish oil is stronger in secondary- than in primary-prevention settings. Adverse effects appear to be minor.

Treatment of hypertriglyceridemia

Hypertriglyceridemia is a disorder commonly encountered in clinical practice. Treatment of this condition aims to prevent the major complications of hypertriglyceridemia, which differ depending on whether triglyceride elevations are moderate or severe. This review discusses the pathophysiology and clinical consequences of hypertriglyceridemia and outlines treatment approaches based on the degree of triglyceride elevation. Special consideration is given to clinical trials using medications that primarily target triglycerides.