Effects of n-3 fatty acids from fish on premature ventricular complexes and heart rate in humans

Melissa officinalis tea favourably affects the frequency of premature ventricular beats and cardiometabolic profile among patients with premature ventricular contraction: A randomised open-label controlled trial

BACKGROUND AND AIMS

Premature ventricular contraction (PVC) as one of the most common arrhythmias could worsen the morbidity of cardiovascular events, particularly concurrent with other risk factors. Considering the probable side effects of antiarrhythmic drugs chronic use, prescribing herbal medicines for such conditions is on the rise. Melissa officinalis (MO) is widely identified as an antiarrhythmic and cardioprotective agent but there is limited evidence for its clinical use. This research, thus, aimed to investigate the effects of MO tea among patients with PVCs.

METHODS

The present 12-week randomised controlled trial enrolled 60 patients with confirmed diagnosis of moderate to low-grade PVCs. The patients in intervention group received MO teabags (containing 2-g dried leaves/250 mL in hot water) two times/day in addition to lifestyle modification recommendations, while control group only received lifestyle modification recommendations. After collecting the data, blood samples were gathered to explore serum concentrations of glucose and lipid markers. The number of premature ventricular beats and heart rates was determined by 24-hour rhythm Holter monitoring.

RESULTS

On average, the patients aged 47 years and approximately 67.8% (n = 40) were women. The ANCOVA adjusted for baseline values and confounders revealed that patients in the MO tea group had significantly lower concentrations of triglyceride (adjusted mean (AM) = 144.75 mg/dL), total cholesterol (AM = 155.35 mg/dL), and fasting blood sugar (AM = 90.85 mg/dL), compared with the controls (AM = 174.27, 171.99, 99.84 mg/dL, respectively (P-value ≤.042). However, the intervention failed to affect LDL-C and HDL-C levels significantly. Significantly reduced frequency of 24-hour premature ventricular beats in the MO tea group (AM = 2142.39) was also noted compared with the controls (AM = 3126.05); (P-value = .017). The 24-hour heartbeats showed only a significant decrease within the intervention group (P-value < .01).

CONCLUSION

Together, these results seem to support the higher cardioprotective effects of MO as a medicinal plant than lifestyle modifications alone. Nevertheless, further exploration of this hypothesis is warranted using large-scaled clinical trials.

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.

Cardiac function in children with premature ventricular contractions: the effect of omega-3 polyunsaturated fatty acid supplementation

BACKGROUND

Premature ventricular contractions are accepted as benign in structurally normal hearts. However, reversible cardiomyopathy can sometimes develop. Omega-3 polyunsaturated fatty acids have anti-arrhythmic properties in animals and humans.AimWe evaluated left ventricular function in children with premature ventricular contractions with normal cardiac anatomy and assessed the impact of omega-3 fatty acid supplementation on left ventricular function in a prospective trial.

METHODS

A total of 25 patients with premature ventricular contraction, with more than 2% premature ventricular contractions on 24-hour Holter electrocardiography, and 30 healthy patients were included into study. All patients underwent electrocardiography, left ventricular M-mode echocardiography, and myocardial performance index testing. Patients with premature ventricular contraction were given omega-3 fatty acids at a dose of 1 g/day for 3 months, and control echocardiography and 24-hour Holter electrocardiography were performed. Neither placebo nor omega-3 fatty acids were given to the control group.

RESULTS

Compared with the values of the control group, the patients with premature ventricular contraction had significantly lower fractional shortening. The myocardial performance index decreased markedly in the patient groups. The mean heart rate and mean premature ventricular contraction percentage of Group 2 significantly decreased in comparison with their baseline values after the omega-3 supplementation.

CONCLUSION

In conclusion, premature ventricular contractions can lead to systolic cardiac dysfunction in children. Omega-3 supplementation may improve cardiac function in children with premature ventricular contractions. This is the first study conducted in children to investigate the possible role of omega-3 fatty acid supplementation on treatment of premature ventricular contractions.

Effect of omega-3 long-chain polyunsaturated fatty acid supplementation on heart rate: a meta-analysis of randomized controlled trials

Background

Elevated resting heart rate (HR) has emerged as a new risk factor for all-cause and cardiovascular mortality. The effect of marine-derived omega-3 long-chain polyunsaturated fatty acid (n−3 LCPUFAs) supplementation on HR was investigated as an outcome in many clinical trials. The present study was to provide an updated meta-analysis on the HR-slowing effect of n−3 LCPUFAs, and to differentiate the chronotropic effect between eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Methods

PubMed and Cochrane databases were searched for relevant articles examining the effects of n−3 PUFAs on HR through May 2017. A random-effects model was used to generate the pooled effect sizes and 95% confidence intervals (CIs). The pooled effect sizes were presented as weighted mean differences (WMDs).

Results

A total of 51 randomized controlled trials (RCTs) with approximately 3000 participants were included in this meta-analysis. Compared to placebo, n−3 PUFA supplementation mildly but significantly reduced HR (−2.23 bpm; 95% CI: −3.07, −1.40 bpm). Moderate evidence of heterogeneity was observed among included trials (I² = 49.1%, P heterogeneity < 0.001). When DHA and EPA were separately administered, modest HR reduction was observed in trials that supplemented with DHA (−2.47 bpm; 95% CI: −3.47, −1.46 bpm), but not in trials with EPA.

Conclusions

The present meta-analysis provides strong clinical evidence demonstrating the effect of heart rate reduction by n−3 LCPUFA supplementation. When DHA or EPA administered alone, heart rate was slowed by DHA rather than by EPA.

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.

n-3 PUFA esterified to glycerol or as ethyl esters reduce non-fasting plasma triacylglycerol in subjects with hypertriglyceridemia: a randomized trial

To date, treatment of hypertriglyceridemia with long-chain n-3 polyunsaturated fatty acids (n-3 PUFA) has been investigated solely in fasting and postprandial subjects. However, non-fasting triacylglycerols are more strongly associated with risk of cardiovascular disease. The objective of this study was to investigate the effect of long-chain n-3 PUFA on non-fasting triacylglycerol levels and to compare the effects of n-3 PUFA formulated as acylglycerol (AG-PUFA) or ethyl esters (EE-PUFA). The study was a double-blinded randomized placebo-controlled interventional trial, and included 120 subjects with non-fasting plasma triacylglycerol levels of 1.7-5.65 mmol/L (150-500 mg/dL). The participants received approximately 3 g/day of AG-PUFA, EE-PUFA, or placebo for a period of eight weeks. The levels of non-fasting plasma triacylglycerols decreased 28% in the AG-PUFA group and 22% in the EE-PUFA group (P < 0.001 vs. placebo), with no significant difference between the two groups. The triacylglycerol lowering effect was evident after four weeks, and was inversely correlated with the omega-3 index (EPA + DHA content in erythrocyte membranes). The omega-3 index increased 63.2% in the AG-PUFA group and 58.5% in the EE-PUFA group (P < 0.001). Overall, the heart rate in the AG-PUFA group decreased by three beats per minute (P = 0.045). High-density lipoprotein (HDL) cholesterol increased in the AG-PUFA group (P < 0.001). Neither total nor non-HDL cholesterol changed in any group. Lipoprotein-associated phospholipase A2 (LpPLA2) decreased in the EE-PUFA group (P = 0.001). No serious adverse events were observed. Supplementation with long-chain n-3 PUFA lowered non-fasting triacylglycerol levels, suggestive of a reduction in cardiovascular risk. Regardless of the different effects on heart rate, HDL, and LpPLA2 that were observed, compared to placebo, AG-PUFA, and EE-PUFA are equally effective in reducing non-fasting triacylglycerol levels.

In-vitro platelet hyperaggregation and hypersecretion associated with the use of fish oil in healthy children

OBJECTIVE

The aim of this study is to evaluate how fish oil supplementation in children affects platelet function tests in vitro.

MATERIALS AND METHODS

The study included 62 children (20 healthy children without any medications and 42 healthy children who volunteered to take fish oil supplementation) aged between 2 and 12 years. In the group of children taking fish oil supplementation, the baseline, fourth week, and eighth week values for platelet function tests were obtained.

RESULTS

In the platelet aggregation tests induced by high dose of ADP after 8 weeks, the values were significantly higher compared with the values measured before the use of fish oil. The fish oil-supplemented group's values showed an increase in the fourth-week measurements compared with the control group and the baseline measurements in terms of platelet secretion test induced by collagen, standard dose of thrombin, and high-dose thrombin. Platelet secretion tests induced by standard dose of ADP at the end of the eighth week showed an increase compared with baseline test values.

CONCLUSION

This study was done in in-vitro conditions wherein the platelet function in the pediatric age group was analyzed and it was found that eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) present in fish oil especially exhibit in-vitro hyperaggregation and increase the secretion of platelets. As a result of this, we consider that it is necessary to be careful while using fish oil supplementation in children as an antithrombotic agent and for a variety of other indications.

A meta-analysis of omega-3 fatty acids and incidence of atrial fibrillation

OBJECTIVES

Atrial fibrillation (AF) is associated with higher health care costs. Although omega-3 (n-3) fatty acids have been associated with a decreased risk of coronary heart disease, their effects on the risk of AF are inconsistent. We therefore sought to review the relation between n-3 fatty acids and the risk of AF.

METHODS

Using an extensive online search, we conducted a meta-analysis of new onset incident/recurrent AF following exposure to fish/fish oil or long-chain n-3 polyunsaturated fatty acids. A random-effect model was used and between-studies heterogeneity was estimated with I(2). The quality of studies was assessed using Jadad and United States Preventive Services Task Force (USPSTF) scoring systems. All analyses were performed with RevMan (version 5.0.20).

RESULTS

Seven cohort studies and 11 randomized controlled trials (RCTs) were included in this meta-analysis. The pooled odds ratio (OR) was 0.79 (95% confidence interval [CI] = 0.56-1.12; p = 0.19) for RCTs and 0.83 (95% CI = 0.59-1.16; p = 0.27) for cohort studies. On sensitivity analysis, no statistically significant difference was noted when stratified by study design or quality of the studies (as graded by Jadad or USPSTF scoring systems).

CONCLUSION

This study does not suggest a major effect of fish/fish oil or n-3 fatty acids on the risk of AF.

Electrophysiological mechanisms of the anti-arrhythmic effects of omega-3 fatty acids

Heart rhythm disorders, or arrhythmias, are a leading cause of morbidity and mortality worldwide. Omega-3 polyunsaturated fatty acids (ω3PUFAs), commonly found in fish oils and plant seeds, have recently emerged as potential anti-arrhythmic agents. The purpose of this review is to summarize the electrophysiological basis of the anti-arrhythmic properties of ω3PUFAs from clinical, animal, and cellular research. Evidence of the anti-arrhythmic effects of ω3PUFAs originated from epidemiological studies that correlated a low incidence of sudden cardiac death with high dietary ω3PUFA intake. Subsequently, multiple clinical trials have confirmed the therapeutic effects of ω3PUFAs in preventing sudden cardiac death and multiple other arrhythmia-related disorders. This has led basic scientists to investigate the effects of ω3PUFAs on several ion channels including sodium, potassium, and calcium channels, as well as Na/Ca exchangers. Therefore, ω3PUFAs may hold promise as safe and effective anti-arrhythmic agents. Nevertheless, further research is needed in areas such as: (1) identifying which form(s) of ω3PUFAs (i.e., phospholipid, triglyceride, or free) is (are) responsible for anti-arrhythmic actions; and (2) developing reproducible methods for delivery so that the appropriate form and concentration may be present at the target site to prevent and treat arrhythmias.

Fish oil in critical illness: mechanisms and clinical applications

Fish oil is rich in omega-3 fatty acids, which have been shown to be beneficial in multiple disease states that involve an inflammatory process. It is now hypothesized that omega-3 fatty acids may decrease the inflammatory response and be beneficial in critical illness. After a review of the mechanisms of omega-3 fatty acids in inflammation, research using enteral nutrition formulas and parenteral nutrition lipid emulsions fortified with fish oil were examined. The results of this research to date are inconclusive for both enteral and parenteral omega-3 fatty acid administration. More research is required before definitive recommendations can be made on fish oil supplementation in critical illness.

Dietary intake of stearidonic acid-enriched soybean oil increases the omega-3 index: randomized, double-blind clinical study of efficacy and safety

BACKGROUND

The benefits of omega-3 (n-3) long-chain polyunsaturated fatty acids to heart health are well established. Stearidonic acid (SDA, 18:4n-3) may contribute to these benefits.

OBJECTIVE

The objective was to evaluate the ability of SDA-containing soybean oil to increase the omega-3 index [erythrocyte eicosapentaenoic acid (EPA) + docosahexaenoic acid, as a percentage of total fatty acids] and to affect other cardiovascular disease risk markers compared with EPA and regular soy oil (control).

DESIGN

This was a randomized, placebo-controlled, double-blind multicenter study in which 252 overweight subjects were randomly assigned to 1 of 3 treatments for 12 wk: 1 g encapsulated soybean oil/d plus 14.7 g liquid soybean oil/d to be mixed in food (control group), 1 g encapsulated EPA/d plus 14.7 g liquid soybean oil/d (EPA group), and 1 g encapsulated soybean oil/d plus 14.7 g liquid SDA-enriched soybean oil/d, providing 4.2 g SDA (SDA group). Subjects consumed treatment oils in exchange for other oils in their diet.

RESULTS

The mean (±SE) baseline omega-3 index was similar between treatments, but after 12 wk of treatment values for this index were 4.15 ± 0.12%, 4.84 ± 0.13%, and 4.69 ± 0.15% for control, EPA, and SDA groups, respectively. Values for the EPA and SDA groups were greater than those for control subjects in the intent-to-treat population (P < 0.001 and P = 0.006, respectively). No adverse treatment-related effects of SDA-enriched soybean oil were reported.

CONCLUSIONS

SDA-enriched soybean oil increased the omega-3 index by raising erythrocyte EPA concentrations. SDA-enriched soybean oil is a land-based n-3 fatty acid that is a sustainable approach to increasing tissue concentrations of long-chain polyunsaturated n-3 fatty acids.

Intake of fish and marine n-3 fatty acids in relation to coronary calcification: the Rotterdam Study

BACKGROUND

Epidemiologic and experimental data suggest a cardioprotective effect of n-3 (omega-3) fatty acids from fish [eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA)].

OBJECTIVE

The objective was to examine the association of fish and EPA plus DHA intakes with coronary calcification in a general older population.

DESIGN

Diet was assessed between 1990 and 1993 by using a semiquantitative 170-item food-frequency questionnaire. Coronary calcification was assessed approximately 7 y later by electron-beam computed tomography in 1570 asymptomatic cardiac subjects with complete dietary data (44% men, mean age of 64 y). Calcium scores according to Agatston's method were divided into < or = 10 (no/minimal coronary calcification), 11-400 (mild/moderate calcification), and > 400 (severe calcification). Prevalence ratios (PRs) for mild/moderate and severe calcification were obtained in categories of fish and EPA plus DHA intake. PRs were adjusted for age, sex, body mass index, diabetes mellitus, socioeconomic status, smoking, alcohol intake, physical activity, and dietary factors.

RESULTS

Subjects with a fish intake > 19 g/d had a significantly lower prevalence of mild/moderate calcification (PR: 0.87; 95% CI: 0.78, 0.98; full model) than did subjects who consumed no fish. Subjects with a high fish intake also had a lower prevalence of severe calcification (PR: 0.88; 95% CI: 0.74, 1.04), which was borderline statistically significant. EPA plus DHA intake showed no significant associations (PR: 0.93 and 0.97, respectively; P > 0.05).

CONCLUSIONS

We found a weak inverse association between fish intake and coronary calcification. If confirmed in other population-based studies, more research is warranted to determine which components in fish can inhibit vascular calcification.

Elevated resting heart rate is an independent risk factor for cardiovascular disease in healthy men and women

BACKGROUND

Elevated resting heart rate (RHR) is known to be associated with reduced survival but inconsistencies remain, including lack of significance in most studies of healthy women, lack of independence from systolic blood pressure (SBP) in some, and the suggestion that RHR is merely functioning as a marker of physical inactivity or other comorbidities. We aimed to clarify these inconsistencies.

METHODS

We analyzed the effect of RHR on end points in the National FINRISK Study; a representative, prospective study using Cox proportional hazards model. Ten-thousand five-hundred nineteen men and 11,334 women were included, excluding those with preexisting coronary heart disease, angina, heart failure, or on antihypertensive therapy.

RESULTS

The hazard ratios for cardiovascular disease (CVD) mortality for each 15 beats/min increase in RHR were 1.24 (1.11-1.40) in men and 1.32 (1.08-1.60) in women, adjusted for age, gender, total cholesterol, physical activity (categorical), SBP, body mass index, and high-density lipoprotein cholesterol. This relationship remained significant after exclusion of those with comorbidities and events occurring within first 2 years of observation. Relationship with coronary mortality was stronger and with total mortality was slightly weaker. Inclusion of nonfatal end points weakened the relationship.

CONCLUSIONS

A strong, graded, independent relationship between RHR and incident CVD was demonstrated. This was consistent in healthy men and women. We have clarified that the relationship is independent of SBP and that the temporal sequence would be compatible with a causal relationship. New findings include independence from both a validated measure of physical activity and comorbidities and the demonstration of a stronger effect for fatal than nonfatal events, supporting increased arrhythmogenicity of one of the mechanisms.

Low dietary fish-oil threshold for myocardial membrane n-3 PUFA enrichment independent of n-6 PUFA intake in rats

Long chain n-3 PUFA docosahexaenoic acid (DHA) is important for heart and brain function. Investigations of biologically plausible mechanisms using animal models associate cardioprotection with DHA incorporation into myocardial membranes that are largely derived from supra-physiological fish oil (FO) intake. We measured the incorporation of DHA into myocardial membranes of rats from low dietary FO intake within human dietary range and quantitatively assessed the influence of dietary n-6 PUFA. With rats fed diets containing 0.16%-5% FO, equal to 0.12%-8.7% energy (%en) as eicosapentaenoic acid (EPA) and DHA (EPA+DHA), and either 1.5%en or 7.5%en n-6 PUFA (linoleic acid) for four weeks, dietary n-6:n-3 PUFA ratios ranged from 74 to 0.3. Myocardial DHA concentration increased in a log-linear fashion with a dietary threshold of 0.019%en as EPA+DHA and half maximal dietary [EPA+DHA] equal to 0.29%en (95% CI, 0.23-0.35). Dietary linoleic acid intake did not influence myocardial DHA. Myocardial membranes are sensitive to absolute dietary intake of long chain n-3 PUFA at low %en in the rat, equivalent to a human intake of one meal of fatty fish per week or less. The dietary ratio of n-6:n-3 PUFA has no influence on long chain n-3 PUFA cellular incorporation from dietary fish oil.

[European Guidelines on Cardiovascular Disease Prevention in Clinical Practice. CEIPC 2008 Spanish Adaptation]

The present CEIPC Spanish adaptation of the European Guidelines on Cardiovascular Disease Prevention in Clinical Practice 2008. This guide recommends the SCORE model for risk evaluation. The aim is to prevent premature mortality and morbidity due to CVD by means of dealing with its related risk factors in clinical practice. The guide focuses on primary prevention and emphasizes the role of the nurses and primary care doctors in promoting a healthy life style, based on increasing physical activity, changing dietary habits, and not smoking. The therapeutic goal is to achieve a Blood Pressure<140/90mmHg, but in patients with diabetes, chronic kidney disease, or definite CVD, the objective is<130/80mmHg. Serum cholesterol should be<200mg/dl and cLDL<130mg/dl, although in patients with CVD or diabetes, the objective is<100mg/dl (80mg/dl if feasible in very high-risk patients). Patients with type 2 diabetes and those with metabolic syndrome must lose weight and increase their physical activity, and drugs must be administered whenever applicable, with the objective guided by body mass index and waist circumference. In diabetic type 2 patients, the objective is glycated haemoglobin<7%. Allowing people to know the guides and developing implementation programs, identifying barriers and seeking solutions for them, are priorities for the CEIPC in order to put the recommendations into practice.

Long-chain n-3 polyunsaturated fatty acids: new insights into mechanisms relating to inflammation and coronary heart disease

Evidence from observational studies, prospective cohort studies and randomized clinical intervention studies indicate that moderate doses of long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) significantly decrease risk of fatal coronary heart disease (CHD). Higher doses and longer duration of intervention may also protect from non-fatal CHD events. The exact mechanisms through which LC n-3 PUFA has an effect on CHD are not well established but may include a decrease in fasting and postprandial triacylglycerol levels, a decrease in arrhythmias, modulation of platelet aggregation and decreased synthesis of pro-inflammatory agents. The mechanistic relation between LC n-3 PUFA and inflammation has attracted great interest, and in vitro studies have revealed that these fatty acids decrease endothelial activation, affect eicosanoid metabolism (including epoxygenation pathways) and induce inflammatory resolution. However, the effects of LC n-3 PUFA on established biomarkers of inflammation and endothelial activation in vivo are not strong. Consequently we need new and more sensitive and systemic biomarkers to reveal the effects of LC n-3 PUFA on localized inflammatory processes.

Association between n-3 fatty acid consumption and ventricular ectopy after myocardial infarction

BACKGROUND

n-3 (omega-3) Fatty acids are associated with a reduced risk of cardiovascular disease; however, the relation between dietary intake of n-3 fatty acids and ventricular arrhythmias has not been investigated among acute post-myocardial infarction (AMI) patients-a group at elevated risk of malignant arrhythmias.

OBJECTIVE

The objective was to examine the association between n-3 fatty acid consumption and ventricular ectopy among AMI patients.

DESIGN

In 260 AMI patients, dietary intake of n-3 fatty acids was assessed by using the Harvard food-frequency questionnaire, and ventricular ectopy was estimated from 24-h electrocardiograph recordings.

RESULTS

A greater intake of n-3 fatty acids (eicosapentaenoic acid + docosahexaenoic acid + docosapentaenoic acid + alpha-linolenic acid) was associated with lower ventricular ectopy (beta = -0.35, P = 0.011), and this effect remained after cardiovascular comorbidities were controlled for (beta = -0.47, P = 0.003). Higher concentrations of both marine-based (eicosapentaenoic acid + docosahexaenoic acid) (beta = -0.21, P = 0.060) and plant-based (alpha-linolenic acid) (beta = -0.33, P = 0.024) fatty acids remained associated with lower ventricular ectopy after cardiovascular comorbidities were controlled for.

CONCLUSION

These findings extend existing evidence linking n-3 fatty acid consumption to a reduced risk of ventricular arrhythmias by showing that a greater intake of n-3 fatty acids may be associated with low ventricular ectopy among AMI patients.

Fish oil reduces heart rate and oxygen consumption during exercise

Dietary omega-3 polyunsaturated fatty acids (PUFAs) are readily incorporated into heart and skeletal muscle membranes where, in the heart, animal studies show they reduce O2 consumption. To test the hypothesis that omega-3 PUFAs alter O2 efficiency in humans, the effects of fish oil (FO) supplementation on O2 consumption during exercise were evaluated. Sixteen well-trained men (cyclists), randomly assigned to receive 8 x 1 g capsules per day of olive oil (control) or FO for 8 weeks in a double-blind, parallel design, completed the study (control: n = 7, age 27.1 +/- 2.7 years; FO: n = 9, age 23.2 +/- 1.2 years). Subjects used an electronically braked cycle ergometer to complete peak O2 consumption tests (VO 2peak) and sustained submaximal exercise tests at 55% of peak workload (from the VO 2peak test) before and after supplementation. Whole-body O2 consumption and indirect measurements of myocardial O2 consumption [heart rate and rate pressure product (RPP)] were assessed. FO supplementation increased omega-3 PUFA content of erythrocyte cell membranes. There were no differences in VO 2peak (mL kg(-1) min(-1)) (control: pre 66.8 +/- 2.4, post 67.2 +/- 2.3; FO: pre 68.3 +/- 1.4, post 67.2 +/- 1.2) or peak workload after supplementation. The FO supplementation lowered heart rate (including peak heart rate) during incremental workloads to exhaustion (P < 0.05). In addition, the FO supplementation lowered steady-state submaximal exercise heart rate, whole-body O2 consumption, and RPP (P < 0.01). Time to voluntary fatigue was not altered by FO supplementation. This study indicates that FOs may act within the healthy heart and skeletal muscle to reduce both whole-body and myocardial O2 demand during exercise, without a decrement in performance.

Omega-3 fatty acids: a comprehensive review of their role in health and disease

Omega-3 fatty acids (omega-3 FAs) are essential fatty acids with diverse biological effects in human health and disease. Reduced cardiovascular morbidity and mortality is a well-established benefit of their intake. Dietary supplementation may also benefit patients with dyslipidaemia, atherosclerosis, hypertension, diabetes mellitus, metabolic syndrome, obesity, inflammatory diseases, neurological/ neuropsychiatric disorders and eye diseases. Consumption of omega-3 FAs during pregnancy reduces the risk of premature birth and improves intellectual development of the fetus. Fish, fish oils and some vegetable oils are rich sources of omega-3 FAs. According to the UK Scientific Advisory Committee on Nutrition guidelines (2004), a healthy adult should consume a minimum of two portions of fish a week to obtain the health benefit. This review outlines the health implications, dietary sources, deficiency states and recommended allowances of omega-3 FAs in relation to human nutrition.

Effect of fish oil on arrhythmias and mortality: systematic review

OBJECTIVE

To synthesise the literature on the effects of fish oil-docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)-on mortality and arrhythmias and to explore dose response and formulation effects.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Medline, Embase, the Cochrane Library, PubMed, CINAHL, IPA, Web of Science, Scopus, Pascal, Allied and Complementary Medicine, Academic OneFile, ProQuest Dissertations and Theses, Evidence-Based Complementary Medicine, and LILACS. Studies reviewed Randomised controlled trials of fish oil as dietary supplements in humans.

DATA EXTRACTION

The primary outcomes of interest were the arrhythmic end points of appropriate implantable cardiac defibrillator intervention and sudden cardiac death. The secondary outcomes were all cause mortality and death from cardiac causes. Subgroup analyses included the effect of formulations of EPA and DHA on death from cardiac causes and effects of fish oil in patients with coronary artery disease or myocardial infarction.

DATA SYNTHESIS

12 studies totalling 32 779 patients met the inclusion criteria. A neutral effect was reported in three studies (n=1148) for appropriate implantable cardiac defibrillator intervention (odds ratio 0.90, 95% confidence interval 0.55 to 1.46) and in six studies (n=31 111) for sudden cardiac death (0.81, 0.52 to 1.25). 11 studies (n=32 439 and n=32 519) provided data on the effects of fish oil on all cause mortality (0.92, 0.82 to 1.03) and a reduction in deaths from cardiac causes (0.80, 0.69 to 0.92). The dose-response relation for DHA and EPA on reduction in deaths from cardiac causes was not significant.

CONCLUSIONS

Fish oil supplementation was associated with a significant reduction in deaths from cardiac causes but had no effect on arrhythmias or all cause mortality. Evidence to recommend an optimal formulation of EPA or DHA to reduce these outcomes is insufficient. Fish oils are a heterogeneous product, and the optimal formulations for DHA and EPA remain unclear.

n-3 fatty acids (fish oil) for epilepsy, cardiac risk factors, and risk of SUDEP: clues from a pilot, double-blind, exploratory study

OBJECTIVE

The goal of the work described here was to determine the effect of high-dose n-3 fatty acids (eicosapentanoic acid+docosahexanoic acid, fish oil) on several outcomes in subjects with refractory epilepsy, including seizure severity, seizure frequency, cardiac risk factors, and heart rate variability, in a pilot, exploratory planning trial.

METHODS

Pilot, randomized, double-blind two-period crossover clinical trial of high-dose fish oil (9600 mg of fish oil/day, 2880 mg of n-3 fatty acids) in 11 subjects with refractory seizures. Outcomes included seizure frequency, seizure severity, lipid panel, and heart rate variability as measured by SDNN and SDANN (defined as the standard deviation of all normal R-R intervals for 1h, and the standard deviation of all R-R intervals in each successive 5-min epoch, respectively).

RESULTS

Preliminary data identified trends towards lower seizure severity, lower triglycerides, higher HDL, and increased SDNN/SDANN in those with low SDNN/SDANN at baseline (Spearman's correlation=-0.65, P=0.03). No positive effect on seizure frequency was identified.

CONCLUSIONS

Further study of the effect of n-3 fatty acids is indicated in people with epilepsy, as favorable trends were identified on cardiac risk factors (triglycerides) and in a subgroup with low heart rate variability (low SDNN/SDANN), a marker of sudden death risk. To our knowledge, this is the first trial to explore the beneficial effects of n-3 fatty acids on cardiac risk factors and heart rate variability in people with epilepsy.

Ultrafast sodium channel block by dietary fish oil prevents dofetilide-induced ventricular arrhythmias in rabbit hearts

Several epidemiologic and clinical studies show that following myocardial infarction, dietary supplements of ω-3 polyunsaturated fatty acids (ω3FA) reduce sudden death. Animal data show that ω3FA have antiarrhythmic properties, but their mechanisms of action require further elucidation. The effects of ω3FA supplementation were studied in female rabbits to analyze whether their antiarrhythmic effects are due to a reduction of triangulation, reverse use-dependence, instability, and dispersion (TRIaD) of the cardiac action potential (TRIaD as a measure of proarrhythmic effects). In Langendorff-perfused hearts challenged by a selective rapidly activating delayed rectifier potassium current inhibitor that has been shown to exhibit proarrhythmic effects (dofetilide; 1 to 100 nM), ω3FA pretreatment (30 days; n = 6) prolonged the plateau phase of the monophasic action potential; did not slow the terminal fast repolarization; reduced the dofetilide-induced prolongation of the action potential duration; reduced dofetilide-induced triangulation; and reduced dofetilide-induced reverse use-dependence, instability of repolarization, and dispersion. Dofetilide reduced excitability in ω3FA-pretreated hearts but not in control hearts. Whereas torsades de pointes (TdP) were observed in five out of six in control hearts, none were observed in ω3FA-pretreated hearts. Docosahexaenoic acid (DHA) inhibited the sodium current with ultrafast kinetics. Dietary ω3FA supplementation markedly reduced dofetilide-induced TRIaD and abolished dofetilide-induced TdP. Ultrafast sodium channel block by DHA may account for the antiarrhythmic protection of the dietary supplements of ω3FA against dofetilide-induced proarrhythmia observed in this animal model.

Fish-oil supplementation in patients with implantable cardioverter defibrillators: a meta-analysis

BACKGROUND

A recent Cochrane meta-analysis did not confirm the benefits of fish and fish oil in the secondary prevention of cardiac death and myocardial infarction. We performed a meta-analysis of randomized controlled trials that examined the effect of fish-oil supplementation on ventricular fibrillation and ventricular tachycardia to determine the overall effect and to assess whether heterogeneity exists between trials.

METHODS

We searched electronic databases (MEDLINE, EMBASE, The Cochrane Central Register of Controlled Trials, CINAHL) from inception to May 2007. We included randomized controlled trials of fish-oil supplementation on ventricular fibrillation or ventricular tachycardia in patients with implantable cardioverter defibrillators. The primary outcome was implantable cardioverter defibrillator discharge. We calculated relative risk [RR] for outcomes at 1-year follow-up for each study. We used the DerSimonian and Laird random-effects methods when there was significant heterogeneity between trials and the Mantel-Hanzel fixed-effects method when heterogeneity was negligible.

RESULTS

We identified 3 trials of 1-2 years' duration. These trials included a total of 573 patients who received fish oil and 575 patients who received a control. Meta-analysis of data collected at 1 year showed no overall effect of fish oil on the relative risk of implantable cardioverter defibrillator discharge. There was significant heterogeneity between trials. The second largest study showed a significant benefit of fish oil (relative risk [RR] 0.74, 95% confidence interval [CI] 0.56-0.98). The smallest showed an adverse tendency at 1 year (RR 1.23, 95% CI 0.92-1.65) and significantly worse outcome at 2 years among patients with ventricular tachycardia at study entry (log rank p = 0.007).

CONCLUSION

These data indicate that there is heterogeneity in the response of patients to fish-oil supplementation. Caution should be used when prescribing fish-oil supplementation for patients with ventricular tachycardia.

European guidelines on cardiovascular disease prevention in clinical practice: executive summary. Fourth Joint Task Force of the European Society of Cardiology and other societies on cardiovascular disease prevention in clinical practice (constituted by representatives of nine societies and by invited experts)

Other experts who contributed to parts of the guidelines: Edmond Walma, Schoonhoven (The Netherlands), Tony Fitzgerald, Dublin (Ireland), Marie Therese Cooney, Dublin (Ireland), Alexandra Dudina, Dublin (Ireland) European Society of Cardiology (ESC) Committee for Practice Guidelines (CPG):, Alec Vahanian (Chairperson) (France), John Camm (UK), Raffaele De Caterina (Italy), Veronica Dean (France), Kenneth Dickstein (Norway), Christian Funck-Brentano (France), Gerasimos Filippatos (Greece), Irene Hellemans (The Netherlands), Steen Dalby Kristensen (Denmark), Keith McGregor (France), Udo Sechtem (Germany), Sigmund Silber (Germany), Michal Tendera (Poland), Petr Widimsky (Czech Republic), José Luis Zamorano (Spain)

Document reviewers: Irene Hellemans (CPG Review Coordinator) (The Netherlands), Attila Altiner (Germany), Enzo Bonora (Italy), Paul N. Durrington (UK), Robert Fagard (Belgium), Simona Giampaoli(Italy), Harry Hemingway (UK), Jan Hakansson (Sweden), Sverre Erik Kjeldsen (Norway), Mogens Lytken Larsen (Denmark), Giuseppe Mancia (Italy), Athanasios J. Manolis (Greece), Kristina Orth-Gomer (Sweden), Terje Pedersen (Norway), Mike Rayner (UK), Lars Ryden (Sweden), Mario Sammut (Malta), Neil Schneiderman (USA), Anton F. Stalenhoef (The Netherlands), Lale Tokgözoglu (Turkey), Olov Wiklund (Sweden), Antonis Zampelas (Greece)

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.