Omega-3 fatty acids in adipose tissue and risk of myocardial infarction: the EURAMIC study

Pharmacokinetic Interaction between Atorvastatin and Omega-3 Fatty Acid in Healthy Volunteers

The interaction between statins and omega-3 fatty acids remains controversial. The aim of this phase 1 trial was to evaluate the pharmacokinetics of drug-drug interaction between atorvastatin and omega-3 fatty acids. Treatments were once-daily oral administrations of omega-3 (4 g), atorvastatin (40 mg), and both for 14 days, 7 days, and 14 days, respectively, with washout periods. The concentrations of atorvastatin, 2-OH-atorvastatin, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) were determined with LC-MS/MS. Parameters of DHA and EPA were analyzed after baseline correction. A total of 37 subjects completed the study without any major violations. The geometric mean ratios (GMRs) and 90% confidence intervals (CIs) of the co-administration of a single drug for the area under the concentration-time curve during the dosing interval at steady state of atorvastatin, 2-OH-atorvastatin, DHA, and EPA were 1.042 (0.971-1.118), 1.185 (1.113-1.262), 0.157 (0.091-0.271), and 0.557 (0.396-0.784), respectively. The GMRs (90% Cis) for the co-administration at steady state of atorvastatin, 2-OH-atorvastatin, DHA, and EPA were 1.150 (0.990-1.335), 1.301 (1.2707-1.1401), 0.320 (0.243-0.422), and 0.589 (0.487-0.712), respectively. The 90% CIs for most primary endpoints were outside the range of typical bioequivalence, indicating a pharmacokinetic interaction between atorvastatin and omega-3.

The Knockout of the ASIP Gene Altered the Lipid Composition in Bovine Mammary Epithelial Cells via the Expression of Genes in the Lipid Metabolism Pathway

Agouti signalling protein (ASIP) is a coat colour-related protein and also is a protein-related to lipid metabolism, which had first been found in agoutis. According to our previous study, ASIP is a candidate gene that affects the lipid metabolism in bovine adipocytes. However, its effect on milk lipid has not been reported yet. This study focused on the effect of the ASIP gene on the lipid metabolism of mammary epithelial cells in cattle. The ASIP gene was knocked out in bMECs by using CRISPR/Cas9 technology. The result of transcriptome sequencing showed that the differentially expressed genes associated with lipid metabolism were mainly enriched in the fatty acids metabolism pathways. Furthermore, the contents of intracellular triglycerides were significantly increased (p < 0.05), and cholesterol tended to rise (p > 0.05) in bMECs with the knockout of the ASIP gene. Fatty acid assays showed a significant alteration in medium and long-chain fatty acid content. Saturated and polyunsaturated fatty acids were significantly up-regulated (p < 0.05), and monounsaturated fatty acids were significantly decreased in the ASIP knockout bMECs (p < 0.05). The Q-PCR analysis showed that knockout of ASIP resulted in a significant reduction of gene expressions like PPARγ, FASN, SCD, and a significant up-regulation of genes like FABP4, ELOVL6, ACSL1, HACD4 prompted increased mid-to long-chain fatty acid synthesis. Overall, ASIP plays a pivotal role in regulating lipid metabolism in bMECs, which could further influence the component of lipid in milk.

Statement on additional scientific evidence in relation to the essential composition of total diet replacement for weight control

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to revise the Opinion on the essential composition of total diet replacements for weight control (TDRs) regarding the minimum content of linoleic acid (LA) and alpha-linolenic acid (ALA) and the maximum content of magnesium (Mg). Through a comprehensive literature search, human studies were retrieved reporting on LA and ALA concentrations in adipose tissue (AT), on weight loss and gallstone formation following TDR consumption and on diarrhoea after supplemental Mg intake. The distribution of the amount of LA and ALA release from AT during weight loss when consuming TDRs was estimated using statistical simulations. Using the fifth percentile, the coverage of the adequate intake (AI) for both FA was estimated. For the risk of developing diarrhoea when consuming TDRs with an Mg content of 350 mg/day, four cross-over studies using 360-368 mg Mg/day were reviewed. The Panel concludes that (1) there is no need to add LA to TDRs, as the amount released from AT during weight loss when consuming TDRs is sufficient to cover the AI for LA; (2) a minimum of 0.8 g/day ALA is needed in TDRs in order to meet the AI for ALA; (3) the minimum fat content of TDRs of 20 g/day as derived in the Panel's previous opinion is proposed to be maintained until the availability of further evidence, given the considerable uncertainty as to the amount of fat required for reducing the risk of gallstone formation; and (4) the likelihood that Mg-induced diarrhoea occurs at a severity that may be considered of concern for overweight and obese individuals consuming TDRs is low when the total maximum Mg content in TDRs is 350 mg/day.

Dietary fatty acids and CHD: from specific recommendations to dietary patterns

Several countries have issued dietary recommendations about total and specific fatty acid (FA) intake for the prevention of CHD. For many years until today, controversies have existed especially about the deleterious effect or not of SFA, and the protective effect or not of n-3 PUFA, so that some authors have criticised these recommendations. There are many reasons for these controversies, including the different conclusions of prospective cohort studies compared with randomised clinical trials (RCT), and the contradictory conclusions of meta-analyses depending on the quality, number and type of studies included. The interrelationships between different FA in the diet make it difficult to analyse the specific effect of a particular class of FA on CHD. Furthermore, based on clinical practice and effectiveness of population-based prevention, it is very difficult at the individual level to assess in personal dietary intake the actual percentage and/or amount of SFA contained in each meal or consumed daily/weekly. In this critical narrative review, we try to answer the question of whether it would not be more relevant, in 2020, to promote dietary patterns, rather than FA intake recommendations. We critically analyse past and recent data on the association of FA with CHD, then propose that the Mediterranean diet and Japanese diet should be revitalised for Westerners and Asian populations, respectively. This does not exclude the usefulness of continuing research about effects of FA towards CHD, and accepting that what seems true today might be revised, at least partially tomorrow.

The memory of the fatty acid system

Mental memory system has sensory memory, short-term memory, working memory, and long-term memory. Working memory "keeps things in mind in parallel" when performing complex tasks. Similar aspects can be found for immunological memory. However, there exists another one, the memory of the fatty acid system. This article shows sensory memory of the fatty acid system, which is the perception apparatus of small intestine enterocytes (CD36, SR-B1, FATP4, FABP1, FABP2) and hepatocytes. In these cells, the fatty acid short-term memory is located, consisting of a cytoplasmic lipid droplet cycle. Similar like a working memory in the brain, the short-term memory of enterocytes and hepatocytes use parallel processing and recourse to long-term fatty acid memory. The fatty acid long-term memory is far away from these primary points of uptake. It is located in the adipocyte and in cellular membranes. The process of building a fatty acid memory is described with constructs like sensing environmental material, encoding, consolidation, long-term storage, retrieval, re-encoding, re-consolidation, and renewed long-term storage. The article illustrates the dynamics of building a fatty acid memory, the information content of fatty acids including the code, the roles of fatty acids in the body, and a new understanding of the expression "you are what you eat". The memory of the fatty acid system, plays a decisive role in integrating environmental signals over time (diet and microbiome).

Adipose tissue content of alpha-linolenic acid and development of peripheral artery disease: a Danish case-cohort study

PURPOSE

The aim of this study was to investigate the association between adipose tissue content of the plant-derived n-3 fatty acid, alpha-linolenic acid, and the rate of incident peripheral artery disease (PAD).

METHODS

We conducted a case-cohort study nested within the Danish Diet, Cancer and Health cohort (n = 57,053), which was established between 1993 and 1997. Potential PAD cases were identified using linkage with The Danish National Patient Register and all potential cases were validated. Adipose tissue samples from the buttock were collected at baseline and fatty acid composition was determined in cases and in a random sample (n = 3500) from the cohort by gas chromatography. Statistical analyses were performed using weighted Cox regression allowing for different baseline hazards among sexes.

RESULTS

During a median of 13.5 years of follow-up, we identified 863 PAD cases with complete information. The median adipose tissue content of ALA in the sub-cohort (n = 3197) was 0.84% (interquartile range 0.73-0.94%) of total fatty acids. In multivariate analyses including adjustment for established risk factors, we observed a U-shaped association between ALA in adipose tissue and rate of PAD, but the association was not statistically significant (P = 0.131). Similar pattern of associations were observed between ALA content in adipose tissue and the rate of PAD among men and women.

CONCLUSIONS

We found indications of a U-shaped association between adipose tissue content of ALA and the rate of PAD, but the association was not statistically significant.

Marine and plant-based n-3 PUFA and atherosclerotic cardiovascular disease

n-3 PUFA may exert favourable effects on several processes that may inhibit the atherosclerotic process. However, the role of n-3 PUFA in lowering the risk of atherosclerotic CVD (ASCVD) has been fiercely debated. In the present paper, we summarise the main findings from previous follow-up studies of intake and studies using adipose tissue as an objective biomarker to investigate exposure to n-3 PUFA in relation to ASCVD risk and discuss some perspectives for further research. The majority of previous studies investigating intake of marine- and plant-based n-3 PUFA have focused on CHD while other ASCVD such as ischaemic stroke and peripheral artery disease have been less studied. However, recent data from Danish Diet, Cancer and Health cohort suggest that marine n-3 PUFA may be inversely associated with risk of myocardial infarction, ischaemic stroke and peripheral arterial disease caused by atherosclerosis. The effect of the plant-derived n-3 PUFA α-linolenic acid on ASCVD is less clear and several gaps in the literature remain to be explored.

Fish Consumption, Omega-3 Fatty Acids, and Risk of Cardiovascular Disease

INTRODUCTION

Data on omega-3 polyunsaturated fatty acids in relation to cardiovascular disease are limited in women. The aim of this study was to examine longitudinal relations of tuna and dark fish, α-linolenic acid, and marine omega-3 fatty acid intake with incident major cardiovascular disease in women.

METHODS

This was a prospective cohort study of U.S. women participating in the Women's Health Study from 1993 to 2014, during which the data were collected and analyzed. A total of 39,876 women who were aged ≥45 years and free of cardiovascular disease at baseline provided dietary data on food frequency questionnaires. Analyses used Cox proportional hazards models to evaluate the association between fish and energy-adjusted omega-3 polyunsaturated fatty acid intake and the risk of major cardiovascular disease, defined as a composite outcome of myocardial infarction, stroke, and cardiovascular death, in 38,392 women in the final analytic sample (96%).

RESULTS

During 713,559 person years of follow-up, 1,941 cases of incident major cardiovascular disease were confirmed. Tuna and dark fish intake was not associated with the risk of incident major cardiovascular disease (p-trend >0.05). Neither α-linolenic acid nor marine omega-3 fatty acid intake was associated with major cardiovascular disease or with individual cardiovascular outcomes (all p-trend >0.05). There was no effect modification by age, BMI, or baseline history of hypertension.

CONCLUSIONS

In this cohort of women without history of cardiovascular disease, intakes of tuna and dark fish, α-linolenic acid, and marine omega-3 fatty acids were not associated with risk of major cardiovascular disease.

Cardioprotective effects of omega 3 fatty acids: origin of the variability

Since 40 years, it is known that omega-3 poly-unsaturated fatty acids (ω3 PUFAs) have cardioprotective effects. These include antiarrhythmic effects, improvements of autonomic function, endothelial function, platelet anti-aggregation and inflammatory properties, lowering blood pressure, plaque stabilization and reduced atherosclerosis. However, recently, conflicting results regarding the health benefits of ω3 PUFAs from seafood or ω3 PUFAs supplements have emerged. The aim of this review is to examine recent literature regarding health aspects of ω3 PUFAs intake from fish or supplements, and to discuss different arguments/reasons supporting these conflicting findings.

Dietary intake and adipose tissue content of α-linolenic acid and risk of myocardial infarction: a Danish cohort study

BACKGROUND

Intake of the plant-derived ω-3 (n-3) fatty acid α-linolenic acid (ALA, 18:3; n-3) may reduce coronary heart disease (CHD) risk, but the results of previous studies have been inconsistent.

OBJECTIVE

We aimed to investigate the association between dietary intake of ALA, adipose tissue content of ALA, and risk of incident myocardial infarction (MI).

DESIGN

A total of 57,053 participants, aged 50-64 y, were enrolled in the prospective Danish cohort study Diet, Cancer and Health between 1993 and 1997. Dietary intake of ALA was assessed with the use of a validated semiquantitative food-frequency questionnaire in the full cohort, whereas the adipose tissue content of ALA was determined with the use of gas chromatography in all incident MI cases and in a random sex-stratified sample of the total cohort (n = 3500).

RESULTS

During a median of 17 y of follow-up, we identified 2177 male and 912 female cases of MI. After appropriate exclusions, we included 2124 men and 854 women for analyses of dietary intake of ALA, whereas 1994 men and 770 women were included in the analysis of the adipose tissue content of ALA. In multivariate analyses that were conducted with the use of restricted cubic splines and adjusted for established CHD risk factors, weak positive associations in men and weak U-shaped associations in women were shown between both dietary intake and the adipose tissue content of ALA and risk of MI, but these associations were not statistically significant. Additional adjustments for dietary factors did not influence the observed associations numerically.

CONCLUSION

This study suggests that ALA has no appreciable association with risk of incident MI in either men or women.

Omega-3 polyunsaturated fatty acids increase plasma adiponectin to leptin ratio in stable coronary artery disease

BACKGROUND

Growing evidence suggests a cardioprotective role of omega-3 polyunsaturated fatty acids (PUFA). However, the exact mechanisms underlying the effects of omega-3 PUFA in humans have not yet been fully clarified.

PURPOSE

We sought to evaluate omega-3 PUFA-mediated effects on adipokines in patients with stable coronary artery disease (CAD) undergoing elective percutaneous coronary intervention (PCI).

METHODS

We conducted a prospective, double-blind, placebo-controlled, randomized study, in which adiponectin, leptin and resistin were determined at baseline, 3-5 days and 30 days during administration of omega-3 PUFA 1 g/day (n=20) or placebo (n=28).

RESULTS

As compared to controls administration of omega-3 PUFA resulted in increase of adiponectin by 13.4% (P<0.0001), reduction of leptin by 22% (P<0.0001) and increase of adiponectin to leptin (A/L) ratio by 45.5% (P<0.0001) at 30 days, but not at 3-5 days. Compared with placebo adiponectin was 12.7% higher (P=0.0042), leptin was 16.7% lower (P<0.0001) and A/L ratio was 33.3% higher (P<0.0001) in the omega-3 PUFA group at 30 days. Resistin decreased similarly in both groups after 1 month, without intergroup differences (P=0.32). The multivariate model showed that the independent predictors of changes in adiponectin at 1 month (P<0.001) were: omega-3 PUFA treatment, baseline platelet count, total cholesterol and those in leptin (P<0.0001) were: omega-3 PUFA treatment and waist circumference. Independent predictors of A/L ratio changes (P<0.0001) were: assigned treatment, current smoking and hyperlipidemia.

CONCLUSIONS

In high risk stable coronary patients after PCI omega-3 PUFA supplementation improves adipokine profile in circulating blood. This might be a novel, favourable mechanism of omega-3 PUFA action.

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.

α-Linolenic acid and risk of cardiovascular disease: a systematic review and meta-analysis

BACKGROUND

Prior studies of α-linolenic acid (ALA), a plant-derived omega-3 (n-3) fatty acid, and cardiovascular disease (CVD) risk have generated inconsistent results.

OBJECTIVE

We conducted a meta-analysis to summarize the evidence regarding the relation of ALA and CVD risk.

DESIGN

We searched multiple electronic databases through January 2012 for studies that reported the association between ALA (assessed as dietary intake or as a biomarker in blood or adipose tissue) and CVD risk in prospective and retrospective studies. We pooled the multivariate-adjusted RRs comparing the top with the bottom tertile of ALA using random-effects meta-analysis, which allowed for between-study heterogeneity.

RESULTS

Twenty-seven original studies were identified, including 251,049 individuals and 15,327 CVD events. The overall pooled RR was 0.86 (95% CI: 0.77, 0.97; I² = 71.3%). The association was significant in 13 comparisons that used dietary ALA as the exposure (pooled RR: 0.90; 95% CI: 0.81, 0.99; I² = 49.0%), with similar but nonsignificant trends in 17 comparisons in which ALA biomarkers were used as the exposure (pooled RR: 0.80; 95% CI: 0.63, 1.03; I² = 79.8%). An evaluation of mean participant age, study design (prospective compared with retrospective), exposure assessment (self-reported diet compared with biomarker), and outcome [fatal coronary heart disease (CHD), nonfatal CHD, total CHD, or stroke] showed that none were statistically significant sources of heterogeneity.

CONCLUSIONS

In observational studies, higher ALA exposure is associated with a moderately lower risk of CVD. The results were generally consistent for dietary and biomarker studies but were not statistically significant for biomarker studies. However, the high unexplained heterogeneity highlights the need for additional well-designed observational studies and large randomized clinical trials to evaluate the effects of ALA on CVD.

Circulating and dietary α-linolenic acid and incidence of congestive heart failure in older adults: the Cardiovascular Health Study

BACKGROUND

Few studies have evaluated the association between the n-3 fatty acid α-linolenic acid (ALA) and the incidence of congestive heart failure (CHF).

OBJECTIVE

We investigated whether plasma phospholipid concentrations and estimated dietary consumption of ALA are associated with incident CHF.

DESIGN

We used data from the Cardiovascular Health Study, a prospective cohort study of cardiovascular diseases among adults aged ≥65 y, from 4 US communities. A total of 2957 participants free of prevalent heart disease and with available fatty acid measurements were included in biomarker analyses (30,722 person-years and 686 incident CHF events). A total of 4432 participants free of prevalent heart disease were included in dietary analyses (52,609 person-years and 1072 events). We investigated the association of ALA with incident CHF by using Cox regression.

RESULTS

After adjustment for age, sex, race, education, smoking status, BMI, waist circumference, and alcohol consumption, plasma phospholipid ALA was not associated with incident CHF (HR for the highest compared with the lowest quartile: 0.97; 95% CI: 0.79, 1.21; P-trend = 0.85). Likewise, dietary ALA was not associated with incident CHF (adjusted HR for the highest compared with the lowest quartile: 0.96; 95% CI: 0.82, 1.20; P-trend = 0.97). We observed no association of biomarker or dietary ALA with nonvalvular CHF subtype. We also found little evidence of an association between ALA and CHF in subgroups based on age, sex, diabetes, fish consumption, BMI, or FADS2 genotype (rs1535).

CONCLUSION

ALA intake is not associated with incident CHF in older adults. This trial was registered at clinicaltrials.gov as NCT00005133.

A double-blind randomized study comparing the efficacy and safety of a composite vs a conventional intravenous fat emulsion in postsurgical gastrointestinal tumor patients

BACKGROUND

Composite intravenous fat emulsion, a fat emulsion composed of soybean oil, medium-chain triglycerides (MCT), olive oil, and fish oil, was evaluated for metabolic efficacy, immune modulation, clinical efficacy, safety, and tolerance in surgical gastrointestinal (GI) tumor patients.

METHODS

In a prospective, randomized, double-blind study, 40 patients were randomized after elective digestive surgery to receive isonitrogenous, isoenergetic parenteral nutrition for 5 days postoperatively with either composite 20% IVFE (composed of soybean, MCT, olive, and fish oils) or a conventional long-chain triglyceride (LCT)/MCT 20% IVFE (LCT/MCT IVFE); IVFE was dosed at 1-2 g/kg body weight. Safety and efficacy parameters were assessed on operation day (day 0) and at the end of study (day 6). Adverse events were documented daily and clinical outcomes were recorded and compared between the groups.

RESULTS

Metabolic parameters, laboratory parameters, proinflammatory cytokine levels, adverse events, and clinical outcomes did not differ between the 2 groups, with the exception that postoperative low-density lipoprotein levels decreased significantly in the composite IVFE group (93.2 ± 24.3 vs 110.5 ± 26.4 mg/dL, P = .038).

CONCLUSIONS

composite IVFE was comparable with conventional LCT/MCT IVFE in efficacy, safety, tolerance, and clinical outcomes in surgical GI tumor patients.

(n-3) fatty acids and cardiovascular health: are effects of EPA and DHA shared or complementary?

Considerable research supports cardiovascular benefits of consuming omega-3 PUFA, also known as (n-3) PUFA, from fish or fish oil. Whether individual long-chain (n-3) PUFA have shared or complementary effects is not well established. We reviewed evidence for dietary and endogenous sources and cardiovascular effects on biologic pathways, physiologic risk factors, and clinical endpoints of EPA [20:5(n-3)], docosapentaenoic acid [DPA, 22:5(n-3)], and DHA [22:6(n-3)]. DHA requires direct dietary consumption, with little synthesis from or retroconversion to DPA or EPA. Whereas EPA is also largely derived from direct consumption, EPA can also be synthesized in small amounts from plant (n-3) precursors, especially stearidonic acid. In contrast, DPA appears principally derived from endogenous elongation from EPA, and DPA can also undergo retroconversion back to EPA. In experimental and animal models, both EPA and DHA modulate several relevant biologic pathways, with evidence for some differential benefits. In humans, both fatty acids lower TG levels and, based on more limited studies, favorably affect cardiac diastolic filling, arterial compliance, and some metrics of inflammation and oxidative stress. All three (n-3) PUFA reduce ex vivo platelet aggregation and DHA also modestly increases LDL and HDL particle size; the clinical relevance of such findings is uncertain. Combined EPA+DHA or DPA+DHA levels are associated with lower risk of fatal cardiac events and DHA with lower risk of atrial fibrillation, suggesting direct or indirect benefits of DHA for cardiac arrhythmias (although not excluding similar benefits of EPA or DPA). Conversely, EPA and DPA, but not DHA, are associated with lower risk of nonfatal cardiovascular endpoints in some studies, and purified EPA reduced risk of nonfatal coronary syndromes in one large clinical trial. Overall, for many cardiovascular pathways and outcomes, identified studies of individual (n-3) PUFA were relatively limited, especially for DPA. Nonetheless, the present evidence suggests that EPA and DHA have both shared and complementary benefits. Based on current evidence, increasing consumption of either would be advantageous compared to little or no consumption. Focusing on their combined consumption remains most prudent given the potential for complementary effects and the existing more robust literature on cardiovascular benefits of their combined consumption as fish or fish oil for cardiovascular benefits.

The global availability of n-3 fatty acids

OBJECTIVES

To assess the validity of FAO data on the availability of fish and vegetable oils as an indicator of national n-3 fatty acid (FA) intake and to estimate the worldwide population living in countries with low n-3 FA intake.

DESIGN

Levels of the essential FA α-linolenic acid (ALA) and DHA, measured by GC in adipose tissue from participants in the present study and from published studies in eleven other countries, were used to validate ALA and fish availability estimated from FAO food balance sheets. On the basis of the validated FAO data for ALA and fish availability, we estimated the global prevalence of low n-3 FA availability.

SETTING

Rural and urban areas of Bulgaria.

SUBJECTS

Fifty men and fifty-eight women.

RESULTS

Adipose tissue ALA and DHA levels (0·34 % and 0·11 % of total FA, respectively) in Bulgaria were lower than those of the eleven other countries with available data. A strong positive correlation was found between adipose tissue DHA and fish availability (r = 0·88) and between adipose tissue ALA and ALA availability (r = 0·92). Approximately half of the world's population lived in middle- and low-income countries with limited access to n-3 FA (fish < 400 g/week and ALA < 4 % of total vegetable oils), with the largest proportion being in South-East Asia (53·6 %), followed by Africa (27·1 %) and Eastern Europe (8·5 %). Of this half, 33 % lived in countries such as Bulgaria where n-3 FA was almost unavailable (fish < 200 g/week and ALA < 2 % of total vegetable oils).

CONCLUSIONS

Very low availability of n-3 FA is extensive worldwide.

Essential fatty acid intake and coronary heart disease risk factors among college students of 3 ethnic groups

OBJECTIVES

Few studies address gender and ethnic variations in essential fatty acid (EFA) intake and risk factors for coronary heart disease (CHD). The purpose of this study was to estimate EFA intake among college students of 3 ethnic groups and compare the relationship between EFA intake and CHD risk factors.

METHODS

Using a cross-sectional design, 300 subjects from 3 ethnic groups--one-third (n = 100) non-Hispanic white, one-third Hispanic, and one-third non-Hispanic black-completed the Cardiovascular Risk Assessment Instruments and a Food Frequency Questionnaire to determine fatty acid intake. Measured CHD risk factors were quantified as CHD Risk Point Standards (CHDRPS).

RESULTS

Results showed that Hispanic females had a significantly higher mean percent intake of arachidonic acid and ratio of linoleic acid to alpha-linolenic acid than non-Hispanic white females, and Hispanic males had significantly higher mean percent intake of EPA and [EPA plus docosahexaenoic acid (DHA)] than non-Hispanic white males. An inverse correlation was found between CHDRPS and DHA among non-Hispanic blacks. A significant positive correlation was found between CHDRPS and linoleic acid among non-Hispanic white females, as well as serum homocysteine (tHcy) concentrations and the ratio of linoleic acid to alpha-linolenic acid intake among non-Hispanic black females.

CONCLUSION

Gender and ethnic differences play a role in adherence to dietary guidelines, demonstrating relevance for future research in this area.

The prognostic value of adipose tissue fatty acids for incident cardiovascular disease: results from 3944 subjects in the Scottish Heart Health Extended Cohort Study

AIMS

Dietary fats are routinely considered key determinants of cardiovascular risk, yet the scientific basis of this association has never been demonstrated using objective measures of fat intakes in a large prospective study in a general population.

METHODS AND RESULTS

Adipose tissue was taken from 3944 participants, predominantly aged 40-59 years, in Scotland, 1984-87. Percentages of individual fatty acids were measured using gas chromatography. Over a median of 19.5 years, 870 incident cardiovascular disease (CVD) events occurred. Hazard ratios (HRs) were obtained from Cox models and the additional prognostic value, accounting for variables in the Framingham and ASSIGN CVD risk scores, were assessed using discrimination indices. Adjusting for age, sex, total and HDL-cholesterol, systolic blood pressure, smoking, hypertensive medication use, diabetes, socio-economic status and family history, the percentage of monounsaturated adipose tissue fatty acids had a positive log-linear relationship with incident CVD: the HR comparing risk between the fourth and first quartiles was 1.29 (95% confidence interval: 1.05, 1.59). n-3 polyunsaturated fat showed the reverse trend, the corresponding result being 0.77 (0.63, 0.94). These two composite variables improved the classification of incident CVD events by 1.0 and 6.4%, respectively, with only the latter being significant at the 5% level.

CONCLUSIONS

A diet which is proportionately rich in polyunsaturated fat, as opposed to other fats, is expected to decrease the risk of CVD independently of the effects of common CVD risk factors, including social deprivation. Taking account of such diets improves the classification of future CVD events.

Cardiovascular effects of marine omega-3 fatty acids

Much evidence shows that the marine omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid have beneficial effects in various cardiac disorders, and their use is recommended in guidelines for management of patients after myocardial infarction. However, questions have been raised about their usefulness alongside optimum medical therapies with agents proven to reduce risk of cardiac events in high-risk patients. Additionally, there is some evidence for a possible pro-arrhythmic effect in subsets of cardiac patients. Some uncertainly exists about the optimum dose needed to obtain beneficial effects and the relative merit of dietary intake of omega-3 polyunsaturated fatty acids versus supplements. We review evidence for the effects of omega-3 polyunsaturated fatty acids on various cardiac disorders and the risk factors for cardiac disease. We also assess areas of uncertainty needing further research.

Persistent organic pollutant exposure leads to insulin resistance syndrome

BACKGROUND

The incidence of the insulin resistance syndrome has increased at an alarming rate worldwide, creating a serious challenge to public health care in the 21st century. Recently, epidemiological studies have associated the prevalence of type 2 diabetes with elevated body burdens of persistent organic pollutants (POPs). However, experimental evidence demonstrating a causal link between POPs and the development of insulin resistance is lacking.

OBJECTIVE

We investigated whether exposure to POPs contributes to insulin resistance and metabolic disorders.

METHODS

Sprague-Dawley rats were exposed for 28 days to lipophilic POPs through the consumption of a high-fat diet containing either refined or crude fish oil obtained from farmed Atlantic salmon. In addition, differentiated adipocytes were exposed to several POP mixtures that mimicked the relative abundance of organic pollutants present in crude salmon oil. We measured body weight, whole-body insulin sensitivity, POP accumulation, lipid and glucose homeostasis, and gene expression and we performed microarray analysis.

RESULTS

Adult male rats exposed to crude, but not refined, salmon oil developed insulin resistance, abdominal obesity, and hepatosteatosis. The contribution of POPs to insulin resistance was confirmed in cultured adipocytes where POPs, especially organochlorine pesticides, led to robust inhibition of insulin action. Moreover, POPs induced down-regulation of insulin-induced gene-1 (Insig-1) and Lpin1, two master regulators of lipid homeostasis.

CONCLUSION

Our findings provide evidence that exposure to POPs commonly present in food chains leads to insulin resistance and associated metabolic disorders.

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.

Are all n-3 polyunsaturated fatty acids created equal?

N-3 Polyunsaturated fatty acids have been shown to have potential beneficial effects for chronic diseases including cancer, insulin resistance and cardiovascular disease. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in particular have been studied extensively, whereas substantive evidence for a biological role for the precursor, alpha-linolenic acid (ALA), is lacking. It is not enough to assume that ALA exerts effects through conversion to EPA and DHA, as the process is highly inefficient in humans. Thus, clarification of ALA's involvement in health and disease is essential, as it is the principle n-3 polyunsaturated fatty acid consumed in the North American diet and intakes of EPA and DHA are typically very low. There is evidence suggesting that ALA, EPA and DHA have specific and potentially independent effects on chronic disease. Therefore, this review will assess our current understanding of the differential effects of ALA, EPA and DHA on cancer, insulin resistance, and cardiovascular disease. Potential mechanisms of action will also be reviewed. Overall, a better understanding of the individual role for ALA, EPA and DHA is needed in order to make appropriate dietary recommendations regarding n-3 polyunsaturated fatty acid consumption.

Alpha-linolenic acid and its conversion to longer chain n-3 fatty acids: benefits for human health and a role in maintaining tissue n-3 fatty acid levels

There is little doubt regarding the essential nature of alpha-linolenic acid (ALA), yet the capacity of dietary ALA to maintain adequate tissue levels of long chain n-3 fatty acids remains quite controversial. This simple point remains highly debated despite evidence that removal of dietary ALA promotes n-3 fatty acid inadequacy, including that of docosahexaenoic acid (DHA), and that many experiments demonstrate that dietary inclusion of ALA raises n-3 tissue fatty acid content, including DHA. Herein we propose, based upon our previous work and that of others, that ALA is elongated and desaturated in a tissue-dependent manner. One important concept is to recognize that ALA, like many other fatty acids, rapidly undergoes beta-oxidation and that the carbons are conserved and reused for synthesis of other products including cholesterol and fatty acids. This process and the differences between utilization of dietary DHA or liver-derived DHA as compared to ALA have led to the dogma that ALA is not a useful fatty acid for maintaining tissue long chain n-3 fatty acids, including DHA. Herein, we propose that indeed dietary ALA is a crucial dietary source of n-3 fatty acids and its dietary inclusion is critical for maintaining tissue long chain n-3 levels.

Omega-3 fatty acids and the cardiometabolic syndrome

Benefits of fish consumption in patients with the cardiometabolic syndrome relate to the high biologic value of protein, omega-3 fatty acids, as well as certain minerals and vitamins in fish. Recently, the American Heart Association issued new guidelines for the intake of omega-3 oils for the prevention of coronary heart disease. The objective of this paper is to evaluate the potential health benefits of fish consumption and/or fish oil supplements in reducing cardiometabolic syndrome risk factors. The consumption of fish or fish oil containing omega-3 polyunsaturated fatty acids reduces the risk of coronary heart disease, decreases triglyceride, blood pressure, and inflammatory markers, improves endothelial function, prevents certain cardiac arrhythmias, reduces platelet aggregation (including reactivity and adhesion), reduces vasoconstriction, enhances fibrinolysis, reduces fibrin formation, and decreases the risk of microalbuminuria and sudden cardiac death. Thus, fish intake or fish oil supplement use is beneficial to reduce cardiometabolic risk factors.

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.

Acute coronary syndrome patients with depression have low blood cell membrane omega-3 fatty acid levels

OBJECTIVE

To determine the extent to which levels of membrane eicosapentaenoic (EPA)+docosahexaenoic acids (DHA) (the omega-3 index) were associated with depression in patients with acute coronary syndrome (ACS). Depression is associated with worse cardiovascular (CV) outcomes in patients with ACS. Reduced levels of blood cell membrane omega-3 (n-3) fatty acids (FAs), an emerging risk factor for both CV disease and depression, may help to explain the link between depression and adverse CV outcomes.

METHODS

We measured membrane FA composition in 759 patients with confirmed ACS. The analysis included not only EPA and DHA but also the n-6 FAs linoleic and arachidonic acids (LA and AA). Depressive symptoms were measured with the Patient Health Questionnaire-9 (PHQ). Multivariable linear regression was used to adjust for demographic and clinical characteristics.

RESULTS

There was a significant inverse relationship between the n-3 index and depressive symptoms (PHQ) in the fully adjusted model (p = .034). For every 4.54% point rise in the n-3 index, there was a 1-point decline in depressive symptoms. In contrast to the n-3 FAs, membrane levels of the n-6 FAs LA and AA were not different between depressed and nondepressed ACS patients.

CONCLUSION

We found an inverse relationship between the n-3 index and the prevalence of depressive symptoms in patients with ACS. Therefore, this study supports the hypothesis that reduced n-3 FA tissue levels are a common and potentially modifiable link between depression and adverse CV outcomes.

n-3 Fatty acids and cardiovascular disease: mechanisms underlying beneficial effects

Dietary n-3 fatty acids, particularly eicosapentaenoic acid and docosahexaenoic acid, are important nutrients through the life cycle. Evidence from observational, clinical, animal, and in vitro studies indicates a beneficial role of n-3 fatty acids in the prevention and management of cardiovascular disease. Although the precise mechanisms are still unclear, clinical and preclinical studies indicate that the cardioprotective effects of n-3 fatty acids may be attributed to a number of distinct biological effects on lipid and lipoprotein metabolism, blood pressure, platelet function, arterial cholesterol delivery, vascular function, and inflammatory responses.

New approaches to therapy with omega-3 fatty acids

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

EPA and DHA in blood cell membranes from acute coronary syndrome patients and controls

BACKGROUND

Increased blood levels of the omega-3 fatty acids (FA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been inversely associated with risk for sudden cardiac death, but their relationship with acute coronary syndromes (ACS) is unclear.

OBJECTIVE

We hypothesized that the EPA+DHA content of blood cell membranes, as a percent of total FAs, is reduced in ACS patients relative to matched controls.

METHODS

We measured the content of EPA+DHA in 768 ACS patients and 768 age-, sex- and race-matched controls. The association with ACS case status of blood cell EPA+DHA [both by a 1 unit change and by category (low, <4%; intermediate 4.1-7.9%; and high, > or =8%)] was assessed using multivariate conditional logistic regression models adjusting for matching variables and smoking status, alcohol use, diabetes, body mass index, serum lipids, education, family history of coronary artery disease, personal histories of myocardial infarction and hypertension, and statin, aspirin, and other antiplatelet drug use.

RESULTS

The combined groups had a mean age of 61+/-12 years, 66% were male, and 92% were Caucasian. The EPA+DHA content was 20% lower in cases than controls (3.4+/-1.6 vs. 4.25+/-2.0%, p<0.001). The multivariable-adjusted odds for case status was 0.77 (95% CI 0.70 to 0.85, p<0.001) for a 1 unit increase in EPA+DHA content. Compared with the lowest EPA+DHA group, the odds ratio for an ACS event was 0.58 (95% CI 0.42-0.80), in the intermediate EPA+DHA group and was 0.31 (95% CI 0.14-0.67; p for trend <0.0001) in the highest EPA+DHA group.

CONCLUSIONS

Odds for ACS case status increased incrementally as the EPA+DHA content decreased suggesting that low EPA+DHA may be associated with increased risk for ACS.

Fish oil significantly alters fatty acid profiles in various lipid fractions but not atherogenesis in apo E-KO mice

BACKGROUND

Consumption of fish oil and n-3 fatty acids is associated with beneficial modifications in plasma lipid levels. The impact of these modifications on development of atherosclerotic lesions merits further investigation.

AIM OF THE STUDY

The aim of this study was to investigate the impact of fish oil consumption on quality and quantity of lipoprotein fatty acids and its influence on atherosclerosis in apolipoprotein E-knockout (apo E-KO) mice.

METHODS

Male apo E-KO mice were treated with 1% dietary fish oil for 14 weeks. Plasma triglycerides (TG), phospholipids, (PL) and cholesteryl ester (CE) fractions were separated using thin layer chromatography. Plasma-free fatty acids (FFA) plus fatty acid contents of TG, PL, CE were determined using gas chromatography. Aortic atherosclerosis was assessed by histological and morphometrical techniques.

RESULTS

Twenty-eight fatty acids were identified in each of the four lipid compartments. High amounts of n-3 fatty acids (eicosapentaenoic (EPA), docosahexaenoic (DHA)) were found in all of these fractions. The levels of EPA and DHA increased by 400 and 150%, respectively, in FFA, TG and PL compartments; higher increases (>500 and 200%) in EPA and DHA were found in CE. This markedly decreased the n-6/n-3 ratios in FFA, TG, PL, and CE by 60, 72, 53, and 61%, respectively. These changes were accompanied by a significant increase in plasma triglyceride levels. Surprisingly, these changes did not affect atherogenesis.

CONCLUSIONS

Elevated levels of EPA and DHA do not appear to prevent development of atherosclerotic plaques in this model. Longer studies warrant investigation of the direct benefits of these fatty acids against myocardial damage as clinical consequences of advanced atherosclerosis.

Tissue n-3 and n-6 fatty acids and risk for coronary heart disease events

BACKGROUND

Tissue proportions of long chain n-6 [especially arachidonic acid (AA)] and n-3 fatty acids [FA; eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) acids], or some ratio of these may be markers of risk for coronary heart disease (CHD). The purpose of this paper is to evaluate the published associations between risk for CHD events and tissue n-3 and n-6 FA composition.

METHODS

Case-control or prospective cohort data sets examining the risk for CHD endpoints as a function of tissue FA composition were identified. Effect sizes were computed for case versus control comparisons using standard meta-analytic methods.

RESULTS

Twenty-five studies were included, 18 examining the FA composition of phospholipid-rich and 7 of triglyceride-rich samples. DHA, with or without EPA, was significantly lower in cases than controls in all studies combined, in those with fatal endpoints, in those with prospective designs, and in both tissue types. The only setting where increased AA was associated with case status was in adipose tissue. The AA/EPA ratio in phospholipid-rich samples did not distinguish cases from controls. Lower linoleic acid content was associated with increased risk for non-fatal events.

CONCLUSIONS

The long-chain n-3 FA, especially DHA, were consistently and significantly reduced in patients experiencing CHD events. These findings add further support to the view that long-chain n-3 FA are cardioprotective.

Effect of Omega-3 Fatty Acid Supplementation on the Arachidonic Acid:Eicosapentaenoic Acid Ratio

STUDY OBJECTIVES

To determine the baseline arachidonic acid:eicosapentaenoic acid (AA:EPA) ratio in patients with coronary artery disease and healthy subjects, and whether supplementation of omega-3 fatty acids, administered as fish oil capsules, affects this ratio.

DESIGN

Prospective, open-label trial.

SETTING

University-affiliated cardiology clinic.

SUBJECTS

Thirty patients with stable coronary artery disease (CAD) and 30 healthy subjects.

INTERVENTION

All participants received omega-3 fatty acids 1.5 g/day for 4 weeks, followed by 3 g/day for an additional 4 weeks.

MEASUREMENTS AND MAIN RESULTS

For each participant, a lipid profile was determined at baseline and after 4 weeks of treatment with each dose. Other laboratory results analyzed were serum AA:EPA ratios, high-sensitivity C-reactive protein (hs-CRP) levels, and blood glucose levels. Mean +/- SD baseline AA:EPA ratios were 39.6 +/- 19.0 in healthy subjects and 23.7 +/- 12.5 in patients with CAD. These ratios decreased significantly in both groups after treatment with 1.5 g/day of omega-3 fatty acids: 9.0 +/- 4.2 in healthy subjects and 10.3 +/- 8.8 in patients with CAD. After treatment with 3 g/day, the ratios were further reduced: 5.1 +/- 3.2 in healthy subjects and 4.9 +/- 2.6 in patients with CAD. Supplementation with omega-3 fatty acids did not significantly affect hs-CRP, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, or blood glucose levels. Triglyceride levels were not reduced in patients with CAD but were significantly decreased in healthy subjects (by 20% decrease with omega-3 fatty acids 1.5 g/day and by 32% decrease with 3 g/day).

CONCLUSION

Treatment with omega-3 fatty acids significantly reduced AA:EPA ratios in both healthy subjects and in patients with stable CAD. The treatment had no effect on hs-CRP levels in either group, and it reduced triglyceride levels in healthy subjects but not in patients with CAD.

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.

Intake and adipose tissue composition of fatty acids and risk of myocardial infarction in a male Portuguese community sample

OBJECTIVE

To evaluate the relation between intake and adipose tissue composition of fatty acids and acute myocardial infarction in Portuguese men.

DESIGN

Case-control study. Diet was assessed using a semiquantitative food frequency questionnaire. In 49 case and 49 control subjects, adipose tissue composition was assessed by gas-liquid chromatography.

SUBJECTS/SETTING

Population-based; subjects were 297 consecutively admitted cases of first acute myocardial infarction in a tertiary care hospital who were aged>or=40 years. Three hundred ten community controls were selected by random-digit dialing.

MAIN OUTCOME MEASURE

Odds ratio (OR).

STATISTICAL ANALYSIS PERFORMED

Logistic regression, adjusting for age, education, family history of acute myocardial infarction, smoking, physical activity, body mass index, and energy intake.

RESULTS

Total fat intake (OR 0.45, fourth quartile, P=0.02), lauric acid (OR 0.44, fourth quartile, P=0.02), palmitic acid (OR 0.58, fourth quartile, P=0.03), and oleic acid (OR 0.42, fourth quartile, P=0.03) were inversely associated with acute myocardial infarction. No significant effects were found for the remaining fatty acids. In the adipose tissue composition data, the adjusted risk estimates of acute myocardial infarction for the highest vs the lowest tertile were 0.16, 0.14, and 0.04 for lauric, oleic, and trans-fatty acids, respectively. A significant direct association was found for palmitic and linoleic acids (adjusted ORs for the highest tertile were 9.02 and 3.63, respectively).

CONCLUSIONS

Low intake of total fat and lauric acid from dairy products was associated with acute myocardial infarction. The association of polyunsaturated fatty acids with risk of acute myocardial infarction was nonsignificant after adjustment for energy intake and confounders. Recommendations on fatty acid intake should aim for both an upper and lower limit.

alpha-Linolenic acid, Delta6-desaturase gene polymorphism, and the risk of nonfatal myocardial infarction

BACKGROUND

Delta(6)-Desaturase (FADS2) is the rate-limiting step in the polyunsaturated fatty acid (PUFA) biosynthetic pathway.

OBJECTIVE

The aim was to test whether the common deletion [T/-] in the promoter of FADS2 affects the PUFA biosynthetic pathway and consequently modifies the effect of alpha-linolenic acid (ALA) on myocardial infarction (MI).

DESIGN

Case subjects (n =1694) with a first nonfatal acute MI were matched by age, sex, and area of residence to 1694 population-based control subjects in Costa Rica. PUFAs were quantified by gas-liquid chromatography from plasma and adipose tissue samples. Least-squares means from generalized linear models and odds ratios (ORs) and 95% CIs from multiple conditional logistic regression models were estimated.

RESULTS

The prevalence of the variant T/- allele was 48%. Eicosapentaenoic acid, gamma-linolenic acid, and arachidonic acid decreased in adipose tissue and plasma with increasing number of copies of the variant allele with a monotonic trend (P < 0.05 for all). Fasting plasma triacylglycerols by genotype were 2.08 mmol/L for TT, 2.16 mmol/L for T-, and 2.26 mmol/L for - - [ie, homozygous for the variant (deletion) allele] (P = 0.03). The FADS2 deletion was not associated with MI and did not significantly modify the association between adipose tissue ALA and the risk of MI.

CONCLUSIONS

The FADS2 deletion may prevent the conversion of ALA into very-long-chain PUFAs. However, this metabolic effect is not translated into an attenuated risk between ALA and MI among carriers of the variant. It is possible that, at current intakes of ALA, any potential defect in the transcription of the gene is masked by the availability of substrate. Further research in populations deficient in ALA intake is warranted.

Blood omega-3 and trans fatty acids in middle-aged acute coronary syndrome patients

We tested the hypothesis that lower blood omega-3 (omega-3) fatty acids (FAs) and/or higher trans FAs are associated with the risk of an acute coronary syndrome (ACS). Higher levels of omega-3 FA have been associated with decreased risk of sudden cardiac death. However, their association with ACS risk is unclear. Although higher self-reported intakes of trans FAs have been linked to increased coronary risk, the association between blood levels of trans FA and ACS risk is also unknown. We analyzed the FA composition of whole blood from 94 subjects with ACS and 94 age-, gender-, and race-matched controls. Omega-3 and trans FA associations with ACS were assessed using multivariable models after adjusting for smoking status, alcohol use, diabetes, body mass index, serum lipids, and history of myocardial infarction or revascularization. Subjects' mean age was 47 years, 54% were men, and 80% were Caucasian. Whole blood long-chain omega-3 FA (eicosapentaenoic acid [EPA] plus docosahexaenoic acid [DHA]) content was 29% lower in patients than in controls (1.7 +/- 0.9% vs 2.4 +/- 1.4%, p <0.001), whereas trans FA content was not different (2.1 +/- 0.7% vs 2.0 +/- 0.9%, p = NS). The multivariable-adjusted odds for case status was 0.67 (95% confidence interval 0.46 to 0.98) for a 1 SD increase in blood EPA + DHA. The inclusion of trans FAs in the EPA + DHA model did not alter this association. In conclusion, low blood EPA + DHA content is an independent predictor of increased risk for ACS, but higher blood trans FA content is not. Blood EPA + DHA may serve as a new, modifiable risk factor for ACS.

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.

Dietary omega-3 fatty acid intake and cardiovascular risk

Dietary omega-3 fatty acids decrease the risk of cardiovascular disease (CVD). Both epidemiologic and interventional studies have demonstrated beneficial effects of omega-3 fatty acids on many CVD end points, including all CVD (defined as all coronary artery disease [CAD], fatal and nonfatal myocardial infarction [MI], and stroke combined), all CAD, fatal and nonfatal MI, stroke, sudden cardiac death, and all-cause mortality. Much of the evidence comes from studies with fish oil and fish; to a lesser extent, data relate to plant-derived omega-3 fatty acids. Cardioprotective benefits have been observed with daily consumption of as little as 25 to 57 g (approximately 1 to 2 oz) of fish high in omega-3 fatty acids, an intake equivalent to >or=1 fish meal weekly or even monthly, with greater intakes decreasing risk further in a dose-dependent manner, up to about 5 servings per week. Fish, including farm-raised fish and their wild counterparts, are the major dietary sources of the longer-chain omega-3 fatty acids. Sources of plant-derived omega-3 fatty acids include flaxseed, flaxseed oil, walnuts, canola oil, and soybean oil. Because of the remarkable cardioprotective effects of omega-3 fatty acids, consumption of food sources that provide omega-3 fatty acids--especially the longer-chain fatty acids (>or=20 carbons) from marine sources--should be increased in the diet to decrease CVD risk significantly.

(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.

Marine macroalgae as sources of polyunsaturated fatty acids

Algae from cold water (Canada) and warm water (China) were analysed for the total lipid content, and for their fatty acid (FA) composition and content. The major findings are that fatty acids (FA) from Canadian algae are generally richer in polyunsaturated FA (PUFA), with a higher n-3/n-6 FA ratio, and a higher degree of total unsaturation. The C 18:4 FA (stearidonic acid, morotic acid as synonym) was detected in greater amounts in cold water samples. The high levels of total PUFA, and especially of n-3 FA in Canadian algae, suggests possible utilization for nutritional purposes.

The incidence of coronary heart disease among Palestinians and Israelis in Jerusalem

BACKGROUND

Lifestyle factors relevant to coronary risk factors differ between Palestinians and Israelis. Both have been exposed, albeit differently, to the stressors of the long-term conflict. We determined the incidence of coronary heart disease, previously unreported in Palestinians, in these Mediterranean populations and made international comparisons with the MONICA Programme.

METHODS

We applied the rigorous World Health Organization MONICA protocol, which enables standardized international population-based comparisons, to determine all acute myocardial infarction events and coronary deaths among Palestinians and Israelis aged 25-74, residents of the Jerusalem district in 1997.

RESULTS

We confirmed a total of 265 coronary events among 76,200 Arabs and 698 among 226,500 Jews. Rates among Arabs were substantially higher than in Jews, particularly so in women. Age-adjusted rate ratios (RRs) for coronary events were 1.58 [95% confidence interval (95% CI) 1.34-1.87] among men and 2.37 (95% CI 1.81-3.10) among women. When restricted to coronary deaths, Arab: Jewish RRs were 2.79 (95% CI 2.09-3.73) in men and 2.66 (95% CI 1.77-4.00) in women. Compared with MONICA populations in 20 countries, Arabs ranked first in total coronary event rates and first in non-fatal myocardial infarction rates, exceeded populations in Finland, Scotland, and Northern Ireland, and showed striking differences from the participating Mediterranean centres.

CONCLUSIONS

Coronary risk appears to be particularly high in Palestinian Arabs. Determinants of these unexpected findings should be sought and prevention programmes initiated.

Influence of alpha-linolenic acid and fish-oil on markers of cardiovascular risk in subjects with an atherogenic lipoprotein phenotype

We tested the hypothesis that dietary alpha-linolenic acid (ALA) can exert effects on markers of cardiovascular risk similar to that produced by its longer chain counterparts in fish-oil. A dietary intervention study was undertaken to examine the effects of an ALA-enriched diet in 57 men expressing an atherogenic lipoprotein phenotype (ALP). Subjects were randomly assigned to one of three diets enriched either with flaxseed oil (FXO: high ALA, n = 21), sunflower oil (SO: high linoleic acid, n = 17), or SO with fish-oil (SOF n = 19) for 12 weeks, resulting in dietary intake ratios of n-6:n-3 PUFA of 0.5, 27.9 and 5.2, respectively. The relative abundance of ALA and EPA in erythrocyte membranes increased on the FXO diet (p < 0.001), whereas both EPA and DHA increased after fish-oil (p < 0.001). There were significant decreases in total plasma cholesterol within (FXO -12.3%, p = 0.001; SOF -7.6%, p = 0.014; SO -7.3%, p = 0.033) and between diets (p = 0.019), and decreases within diets after 12 weeks for HDL cholesterol on flaxseed oil (FXO -10%, p=0.009), plasma TG (-23%, p < 0.001) and small, dense LDL (-22% p = 0.003) in fish-oil. Membrane DHA levels were inversely associated with the changes in plasma TG ( p= 0.001) and small, dense LDL (p<0.05) after fish-oil. In conclusion, fish-oil produced predictable changes in plasma lipids and small, dense LDL (sdLDL) that were not reproduced by the ALA-enriched diet. Membrane DHA levels appeared to be an important determinant of these fish-oil-induced effects.