Heart rate is associated with red blood cell fatty acid concentration: the Genetics of Coronary Artery Disease in Alaska Natives (GOCADAN) study

Omega-3 world map: 2024 update

In 2016, the first worldwide n3 PUFA status map was published using the Omega-3 Index (O3I) as standard biomarker. The O3I is defined as the percentage of EPA + DHA in red blood cell (RBC) membrane FAs. The purpose of the present study was to update the 2016 map with new data. In order to be included, studies had to report O3I and/or blood EPA + DHA levels in metrics convertible into an estimated O3I, in samples drawn after 1999. To convert the non-RBC-based EPA + DHA metrics into RBC we used newly developed equations. Baseline data from clinical trials and observational studies were acceptable. A literature search identified 328 studies meeting inclusion criteria encompassing 342,864 subjects from 48 countries/regions. Weighted mean country O3I levels were categorized into very low ≤4%, low >4-6%, moderate >6-8%, and desirable >8%. We found that the O3I in most countries was low to very low. Notable differences between the current and 2016 map were 1) USA, Canada, Italy, Turkey, UK, Ireland and Greece (moving from the very low to low category); 2) France, Spain and New Zealand (low to moderate); and 3) Finland and Iceland (moderate to desirable). Countries such as Iran, Egypt, and India exhibited particularly poor O3I levels.

Role of Stearoyl-CoA Desaturase 1 in Cardiovascular Physiology

Stearoyl-CoA desaturase is a rate-limiting enzyme in the synthesis of monounsaturated fatty acids. Monounsaturated fatty acids limit the toxicity of exogenous saturated fats. Studies have shown that stearoyl-CoA desaturase 1 is involved in the remodeling of cardiac metabolism. The loss of stearoyl-CoA desaturase 1 reduces fatty acid oxidation and increases glucose oxidation in the heart. Such a change is protective under conditions of a high-fat diet, which reduces reactive oxygen species-generating β-oxidation. In contrast, stearoyl-CoA desaturase 1 deficiency predisposes individuals to atherosclerosis under conditions of hyperlipidemia but protects against apnea-induced atherosclerosis. Stearoyl-CoA desaturase 1 deficiency also impairs angiogenesis after myocardial infarction. Clinical data show a positive correlation between blood stearoyl-CoA Δ-9 desaturation rates and cardiovascular disease and mortality. Moreover, stearoyl-CoA desaturase inhibition is considered an attractive intervention in some obesity-associated pathologies, and the importance of stearoyl-CoA desaturase in the cardiovascular system might be a limitation for developing such therapy. This review discusses the role of stearoyl-CoA desaturase 1 in the regulation of cardiovascular homeostasis and the development of heart disease and presents markers of systemic stearoyl-CoA desaturase activity and their predictive potential in the diagnosis of cardiovascular disorders.

Omega-3 Fatty Acids in Pregnancy-The Case for a Target Omega-3 Index

Scientific societies recommend increasing intake of docosahexaenoic acid (DHA) by 200 mg/day during pregnancy. However, individually, clinical events correlate quite strongly with levels of eicosapentaenoic acid (EPA) and DHA in blood, but these levels poorly correlate with amounts ingested. EPA and DHA in erythrocytes (Omega-3 Index) have a low biologic variability. If analyzed with a standardized analytical procedure (HS-Omega-3 Index^®), analytical variability is low. Thus, the largest database of any fatty acid analytical method was provided. Pregnant women in Germany had a mean Omega-3 Index below the target range suggested for cardiovascular disease of 8–11%, with large interindividual variation, and quite independent of supplementation with EPA and DHA. In Germany, premature birth is a major health issue. Premature birth and other health issues of pregnant women and their offspring correlate with levels of EPA and DHA in blood and can be reduced by increasing intake of EPA and DHA, according to individual trials and pertinent meta-analyses. Very high intake or levels of EPA and DHA may also produce health issues, like bleeding, prolonged gestation, or even premature birth. While direct evidence remains to be generated, evidence from various scientific approaches supports that the target range for the Omega-3 Index of 8–11% might also pertain to pregnancy and lactation.

Omega-3 Polyunsaturated Fatty Acids Improved Arterial Stiffness Parameters in Type 2 Diabetic Patients with Cardiac Autonomic Neuropathy

Background and Aims: Diabetic cardiac autonomic neuropathy (DCAN) in type 2 diabetes (T2D) is among the strongest and independent risk markers for future global and cardiac mortality. Material and Methods: Thirty-six patients suffering from T2D and confirmed DCAN were enrolled in this investigation. Depending on the prescribed therapy, patients were allocated into two groups: group 1 was comprised of 15 patients to whom standard hypoglycemic treatment was prescribed (control group), the second received standard hypoglycemic treatment and omega-3 polyunsaturated fatty acids (ω-3 PUFAs, n = 21). The duration of the study was three month. Results: In subjects with T2D and DСAN prescription of ω-3 PUFAs was associated with a significant decrease of aorta augmentation index (AIxao), pulse wave velocity (PWV) during the active period of the day and decrease of AIxao, brachial augmentation index and PWV during the passive period of the day compared with the control group. Therefore, three month of ω-3 PUFAs supplementation to patients with confirmed DCAN and T2D promotes to improvement of arterial stiffness indices. Conclusions: In patients with T2D and СAN treatment with ω-3 PUFAs improved arterial stiffness parameters. The effectiveness of ω-3 PUFAs is not connected with optimization of glycemic control, but is rather the result of a direct drug action on the studied parameters.

Associations of the serum long-chain n-3 PUFA and hair mercury with resting heart rate, peak heart rate during exercise and heart rate recovery after exercise in middle-aged men

Long-chain n-3 PUFA from fish have been associated with lower risk of CVD. Fish may also contain methylmercury, which may attenuate the inverse associations of the long-chain n-3 PUFA. However, the mechanisms underlying these associations are not fully known. We evaluated the associations of the serum long-chain n-3 PUFA (EPA, DPA and DHA) and hair Hg with resting heart rate (HR), peak HR during cycle ergometer exercise and HR recovery after exercise. A total of 1008 men from the population-based Kuopio Ischaemic Heart Disease Risk Factor Study, aged 42-60 years and free of CVD, were studied. After multivariate-adjustments in ANCOVA, higher serum total long-chain n-3 PUFA concentration was associated with lower resting HR (extreme-quartile difference 2·2 beats/min; 95 % CI 0·2, 4·1, P trend across quartiles=0·02), but not with peak HR or HR recovery. Associations were generally similar when EPA, DPA and DHA were evaluated individually, except for DPA, which was also associated with better HR recovery after exercise (extreme-quartile difference 2·1 beats/min; 95 % CI 0·1, 4·2, P trend=0·06). Higher hair Hg content had a trend towards lower peak HR after adjusting for the long-chain n-3 PUFA (P trend=0·05), but it only slightly attenuated the associations of the serum long-chain n-3 PUFA with HR. These findings suggest that higher serum long-chain n-3 PUFA concentrations are associated with lower resting HR in middle-aged men from Eastern Finland, which may partially explain the potential cardioprotective effect of fish intake.

Red blood cell oleic acid levels reflect olive oil intake while omega-3 levels reflect fish intake and the use of omega-3 acid ethyl esters: The Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico-Heart Failure trial

The Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico-Heart Failure (GISSI-HF) study reported benefits of n-3 fatty acid (FA) treatment on cardiovascular (CV) events, but the effects of treatment on a putative CV disease risk factor, the red blood cell (RBC) n-3 FA level (the omega-3 index), have not been examined in this context. We hypothesized that treatment with prescription omega-3 acid ethyl esters (O3AEE) would increase the omega-3 index to the proposed cardioprotective value of 8%. RBCs were collected from a subset of patients participating in the GISSI-HF study (n=461 out of 6975 randomized), at baseline and after 3 months of treatment with either an olive oil placebo or O3AEE (1 g/d). RBC FA levels were expressed as a percentage of total FA. Patients also reported their typical olive oil and fish intakes. RBC oleic acid levels were directly correlated with reported frequency of olive oil consumption, and the omega-3 index was correlated with reported fish intake (P for trends <0.001 for both). After treatment, the omega-3 index increased from 4.8±1.7% to 6.7±1.9% but was unchanged in the placebo group (4.7±1.7 to 4.8±1.5%) (P<.0001 for changes between groups). At 3 months, more patients reached the proposed target omega-3 index level of 8%-12% in the treated vs placebo group (22.6% vs. 1.3%, P<.0001), however, what omega-3 index levels were ultimately achieved after four years in this trial are unknown.

Global survey of the omega-3 fatty acids, docosahexaenoic acid and eicosapentaenoic acid in the blood stream of healthy adults

Studies reporting blood levels of the omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were systematically identified in order to create a global map identifying countries and regions with different blood levels. Included studies were those of healthy adults, published in 1980 or later. A total of 298 studies met all inclusion criteria. Studies reported fatty acids in various blood fractions including plasma total lipids (33%), plasma phospholipid (32%), erythrocytes (32%) and whole blood (3.0%). Fatty acid data from each blood fraction were converted to relative weight percentages (wt.%) and then assigned to one of four discrete ranges (high, moderate, low, very low) corresponding to wt.% EPA+DHA in erythrocyte equivalents. Regions with high EPA+DHA blood levels (>8%) included the Sea of Japan, Scandinavia, and areas with indigenous populations or populations not fully adapted to Westernized food habits. Very low blood levels (≤4%) were observed in North America, Central and South America, Europe, the Middle East, Southeast Asia, and Africa. The present review reveals considerable variability in blood levels of EPA+DHA and the very low to low range of blood EPA+DHA for most of the world may increase global risk for chronic disease.

Fatty acids linked to cardiovascular mortality are associated with risk factors

Background

Although saturated fatty acids (FAs) have been linked to cardiovascular mortality, it is not clear whether this outcome is attributable solely to their effects on low-density lipoprotein cholesterol (LDL-C) or whether other risk factors are also associated with FAs. The Western Alaskan Native population, with its rapidly changing lifestyles, shift in diet from unsaturated to saturated fatty acids and dramatic increase in cardiovascular disease (CVD), presents an opportunity to elucidate any associations between specific FAs and known CVD risk factors.

Objective

We tested the hypothesis that the specific FAs previously identified as related to CVD mortality are also associated with individual CVD risk factors.

Methods

In this community-based, cross-sectional study, relative proportions of FAs in plasma and red blood cell membranes were compared with CVD risk factors in a sample of 758 men and women aged ≥35 years. Linear regression analyses were used to analyze relations between specific FAs and CVD risk factors (LDL-C, high-density lipoprotein cholesterol, triglycerides, C-reactive protein, systolic blood pressure, diastolic blood pressure, heart rate, body mass index, fasting glucose and fasting insulin, 2-hour glucose and 2-hour insulin).

Results

The specific saturated FAs previously identified as related to CVD mortality, the palmitic and myristic acids, were adversely associated with most CVD risk factors, whereas unsaturated linoleic acid (18:2n-6) and the marine n-3 FAs were not associated or were beneficially associated with CVD risk factors.

Conclusions

The results suggest that CVD risk factors are more extensively affected by individual FAs than hitherto recognized, and that risk for CVD, MI and stroke can be reduced by reducing the intake of palmitate, myristic acid and simple carbohydrates and improved by greater intake of linoleic acid and marine n-3 FAs.

Palmitoleic acid induces the cardiac mitochondrial membrane permeability transition despite the presence of L-carnitine

Although palmitoleic acid (C16:1) is associated with arrhythmias, and increases in an age-dependent matter, the effects of L-carnitine, which is essential for the transport of long-chain fatty acids into the mitochondria, are unclear. It has been postulated that L-carnitine may attenuate palmitate (C16:0)-induced mitochondrial dysfunction and the apoptosis of cardiomyocytes. The aim of this study was to elucidate the activity of L-carnitine in the prevention of the palmitoleic acid-induced mitochondrial membrane permeability transition and cytochrome c release using isolated cardiac mitochondria from rats. Palmitoleoyl-CoA-induced mitochondrial respiration was not accelerated by L-carnitine treatment, and this respiration was slightly inhibited by oligomycin, which is an inhibitor of ATP synthase. Despite pretreatment with L-carnitine, the mitochondrial membrane potential decreased and mitochondrial swelling was induced by palmitoleoyl-CoA. In the presence of a combination of L-carnitine and tiron, a free radical scavenger, there was attenuated mitochondrial swelling and cytochrome c release following palmitoleoyl-CoA treatment. We concluded that palmitoleic acid, but not palmitate, induces the cardiac mitochondrial membrane permeability transition despite the presence of L-carnitine.

Diabetic cardiac autonomic neuropathy: Do we have any treatment perspectives?

Cardiac autonomic neuropathy (CAN) is a serious and common complication of diabetes mellitus (DM). Despite its relationship to an increased risk of cardiovascular mortality and its association with multiple symptoms and impairments, the significance of CAN has not been fully appreciated. CAN among DM patients is characterized review the latest evidence and own data regarding the treatment and the treatment perspectives for diabetic CAN. Lifestyle modification, intensive glycemic control might prevent development or progression of CAN. Pathogenetic treatment of CAN includes: balanced diet and physical activity; optimization of glycemic control; treatment of dyslipoproteinemia; correction of metabolic abnormalities in myocardium; prevention and treatment of thrombosis; use of aldose reductase inhibitors; dihomo-γ-linolenic acid (DGLA), acetyl-L-carnitine, antioxidants, first of all α-lipoic acid (α-LA), use of long-chain ω-3 and ω-6 polyunsaturated fatty acids (ω-3 and ω-6 PUFAs), vasodilators, fat-soluble vitamin B₁, aminoguanidine; substitutive therapy of growth factors, in severe cases-treatment of orthostatic hypotension. The promising methods include research and use of tools that increase blood flow through the vasa vasorum, including prostacyclin analogues, thromboxane A₂ blockers and drugs that contribute into strengthening and/or normalization of Na⁺, K⁺-ATPase (phosphodiesterase inhibitor), α-LA, DGLA, ω-3 PUFAs, and the simultaneous prescription of α-LA, ω-3 PUFA and DGLA.

Omega-3 fatty acids in cardiovascular disease--an uphill battle

In cardiology, results of recent large intervention trials with eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) supplements were neutral. In contrast, in epidemiologic studies, an inverse relation between clinical events and intake of EPA+DHA was found which was steeper for higher levels of EPA+DHA. A standardized way of determining levels is the Omega-3 Index, which is the percentage of EPA+DHA of a total of 26 fatty acids measured in erythrocytes. According to current criteria, a low Omega-3 Index is a cardiovascular risk factor. What can explain this contradiction? Trial participants were recruited irrespective of their baseline status in EPA+DHA - an important predictor of events. Levels of EPA+DHA have a statistically normal distribution; together with the large inter-individual variability of levels' responding to increased intake, this created a large overlap of EPA+DHA levels between intervention and control groups. Moreover, trial participants were advised to take EPA+DHA supplements with breakfast, frequently a low fat meal, resulting in poor bioavailability. As a result, there is an urgent need for new intervention trials in cardiology, for which participants with a low baseline omega-3 index are recruited, and then treated with individually tailored doses of EPA+DHA to a prespecified target range.

Omega-3 index levels and associated factors in a middle-aged French population: the MONA LISA-NUT Study

BACKGROUND/OBJECTIVES

The omega-3 index (the summed percentage content of eicosapentaenoic and docosahexaenoic acids in red blood cells) is associated with a lower risk of fatal coronary heart disease and sudden cardiac death. We aimed to determine which socio-demographic, behavioural or clinical factors are independently associated with the omega-3 index and the extent to which seafood consumption mediates the index's association with socio-economic status (SES).

SUBJECTS/METHODS

As part of the cross-sectional MONA LISA-NUT survey (2005-2007), gas chromatography was used to analyse the red blood cell fatty acid composition in 503 French subjects aged 35-64 years. Dietary data were collected by trained dieticians via a validated food frequency questionnaire and a prospective 3-day food record. Risk factors were estimated with standardised measurements and questionnaires. SES was assessed through the self-reported educational and income tax levels.

RESULTS

The mean ± s.d. omega-3 index was 6.02 ± 1.75%. In the best parsimonious predictive model (which explained 32% of the variability in the omega-3 index), age, educational level and seafood servings were significantly and positively associated with the index. In contrast, waist circumference and smoking were inversely associated with the index. In a mediation analysis that took account of all these factors, seafood servings explained about 40% of the association between educational level and the omega-3 index. Similar results were obtained for the income tax level.

CONCLUSIONS

The inverse association between SES and omega-3 index is largely explained (40%) by an insufficient seafood intake. It remains to be seen which other factors mediate this association.

Omega-3 index and cardiovascular health

Recent large trials with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the cardiovascular field did not demonstrate a beneficial effect in terms of reductions of clinical endpoints like total mortality, sudden cardiac arrest or other major adverse cardiac events. Pertinent guidelines do not uniformly recommend EPA + DHA for cardiac patients. In contrast, in epidemiologic findings, higher blood levels of EPA + DHA were consistently associated with a lower risk for the endpoints mentioned. Because of low biological and analytical variability, a standardized analytical procedure, a large database and for other reasons, blood levels of EPA + DHA are frequently assessed in erythrocytes, using the HS-Omega-3 Index® methodology. A low Omega-3 Index fulfills the current criteria for a novel cardiovascular risk factor. Neutral results of intervention trials can be explained by issues of bioavailability and trial design that surfaced after the trials were initiated. In the future, incorporating the Omega-3 Index into trial designs by recruiting participants with a low Omega-3 Index and treating them within a pre-specified target range (e.g., 8%-11%), will make more efficient trials possible and provide clearer answers to the questions asked than previously possible.

Cardiovascular Disease Among Alaska Native Peoples

Although Alaska Native peoples were thought to be protected from cardiovascular disease (CVD), data now show that this is not the case, despite traditional lifestyles and high omega-3 fatty acid intake. In this article, the current understanding of CVD and its risk factors among Alaska Native peoples, particularly among the Yupik and Inupiat populations, will be discussed, using data from three major studies funded by the National Institutes of Health: Genetics of Coronary Artery Disease among Alaska Natives (GOCADAN), Center for Native Health Research (CANHR), and Education and Research Towards Health (EARTH). Data from these epidemiologic studies have focused concern on CVD and its risk factors among Alaska Native peoples. This review will summarize the findings of these three principal studies and will suggest future directions for research and clinical practice.

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.

Diverse physiological effects of long-chain saturated fatty acids: implications for cardiovascular disease

PURPOSE OF REVIEW

The purpose of this review is to discuss the metabolism of long-chain saturated fatty acids and the ensuing effects on an array of metabolic events.

RECENT FINDINGS

Individual long-chain saturated fatty acids exhibit unique biological properties. Dietary saturated fat absorption varies depending on chain-length and the associated food matrix. The in-vivo metabolism of saturated fatty acids varies depending on the individual fatty acid and the nutritional state of the individual. A variety of fatty acid metabolites are formed, each with their own unique structure and properties that warrant further research. Replacing saturated fatty acids with unsaturated fatty acids improves the blood lipid profile and reduces cardiovascular disease risk, although the benefits depend on the specific saturated fatty acid(s) being replaced.

SUMMARY

Acknowledging the complexity of saturated fatty acid metabolism and associated metabolic events is important when assessing their effects on cardiovascular disease risk. Investigating the biological effects of saturated fatty acids will advance our understanding of how they affect cardiovascular disease risk.

Comparison of erythrocyte membrane fatty acid contents in renal transplant recipients and dialysis patients

BACKGROUND

Alterations of erythrocyte membrane fatty acid (FA) composition play important roles in cellular function because they change the membrane microenvironment, including transmembrane receptors. The erythrocyte membrane oleic acid content is higher among patients with acute coronary syndrome and also in dialysis patients. However, available data are limited concerning erythrocyte membrane FA content in kidney transplant recipients (KTP). We sought to test the hypothesis that erythrocyte membrane FA content among KTP were different from those in dialysis patients.

METHODS

In this cross-sectional study, we recruited 35 hemodialysis, 33 peritoneal dialysis 49 KTP, and 33 normal control subjects (CTL). Their erythrocyte membrane FA content were measured by gas chromatography.

RESULTS

The mean ages of the enrolled dialysis patients, KTP, and CTL were 56.4 ± 10.1, 48.9 ± 10.4, and 49.5 ± 8.3 years, respectively. Mean kidney transplant duration was 89.8 ± 64.8 months and mean dialysis duration, 49.0 ± 32.6 months. The intakes of vegetable lipid and vegetable protein including total calories were significantly increased among KTP versus dialysis patients. Total cholesterol (P < .001) and high density lipoprotein cholesterol (HDL; P < .001) levels were significantly higher and C-reactive protein was significantly lower among KTP compared with dialysis patients. The erythrocyte membrane content of palmitoleic acid (P < .001) was significantly higher but oleic acid (P < .001) significantly lower in KTP compared with dialysis patients. The erythrocyte membrane contents of arachidonic acid and docosahexaenoic acid were significantly higher, and linoleic acid and the omega-6 FA to omega-3 FA ratio (P < .001) significantly lower in KTP compared with dialysis patients. The erythrocyte membrane content of oleic acid was independently associated with monounsaturated fatty acid (beta = 0.771, P < .001), eicosapentaeonic acid (beta = -0.244, P = .010), and HDL (beta = -0.139, P = .049) in KTP.

CONCLUSIONS

FA contents of erythrocyte membranes were significantly different in KTP compared with dialysis patients. These differences may have been associated with improved dietary intake and immunosuppression after kidney transplantation.

Plasma phospholipid fatty acid composition and estimated desaturase activity in heart failure patients with metabolic syndrome

Metabolic syndrome is one of the major factors to increase the incidence of heart failure. In our study, we compared plasma fatty acid compositions among heart failure patients with and without Metabolic syndrome. Fatty acid (FA) composition of plasma phospholipids was analyzed and the activities of desaturase were estimated as the ratio of substrate and product fatty acids in 85 stable heart failure patients. Fatty acid and estimated desaturase activities were further examined for their associations with Metabolic syndrome components. Heart failure patients with Metabolic syndrome showed significant changes in fatty acid composition in comparison to those without Metabolic syndrome, which had a decreased proportion of lauric acid (C12:0) and an increased proportion of dihomo-γ-linolenic acid (C20:3n-6). Also, estimated desaturase activities (D5D and D6D) were closely related to Metabolic syndrome condition among heart failure patients. The content of dihomo-γ-linolenic acid showed positive correlations with BMI, waist circumference, and plasma triglyceride levels. D6D were positively associated with plasma triglyceride levels, whereas D5D showed a negative correlation with plasma triglyceride levels and waist circumferences. The content of dihomo-γ-linolenic acid as well as estimated D6D and D5D were altered in heart failure patients with Metabolic syndrome.

Variants in CPT1A, FADS1, and FADS2 are Associated with Higher Levels of Estimated Plasma and Erythrocyte Delta-5 Desaturases in Alaskan Eskimos

The delta-5 and delta-6 desaturases (D5D and D6D), encoded by fatty acid desaturase 1 (FADS1) and 2 (FADS2) genes, respectively, are rate-limiting enzymes in the metabolism of ω-3 and ω-6 fatty acids. The objective of this study was to identify genes influencing variation in estimated D5D and D6D activities in plasma and erythrocytes in Alaskan Eskimos (n = 761) participating in the genetics of coronary artery disease in Alaska Natives (GOCADAN) study. Desaturase activity was estimated by product: precursor ratio of polyunsaturated fatty acids. We found evidence of linkage for estimated erythrocyte D5D (eD5D) on chromosome 11q12-q13 (logarithm of odds score = 3.5). The confidence interval contains candidate genes FADS1, FADS2, 7-dehydrocholesterol reductase (DHCR7), and carnitine palmitoyl transferase 1A, liver (CPT1A). Measured genotype analysis found association between CPT1A, FADS1, and FADS2 single-nucleotide polymorphisms (SNPs) and estimated eD5D activity (p-values between 10⁻²⁸ and 10⁻⁵). A Bayesian quantitative trait nucleotide analysis showed that rs3019594 in CPT1A, rs174541 in FADS1, and rs174568 in FADS2 had posterior probabilities > 0.8, thereby demonstrating significant statistical support for a functional effect on eD5D activity. Highly significant associations of FADS1, FADS2, and CPT1A transcripts with their respective SNPs (p-values between 10⁻⁷⁵ and 10⁻⁷) in Mexican Americans of the San Antonio Family Heart Study corroborated our results. These findings strongly suggest a functional role for FADS1, FADS2, and CPT1A SNPs in the variation in eD5D activity.

Omega-3 Fatty acids: anti-arrhythmic, pro-arrhythmic, or both?

This review focuses on developments after 2008, when the topic was last reviewed by the author. Pertinent publications were found by medline searches and in the author’s personal data base. Prevention of atrial fibrillation (AF) was investigated in a number of trials, sparked by one positive report on the effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), considerations of upstream therapy, data from electrophysiologic laboratories and animal experiments. If EPA + DHA prevent postoperative AF, the effect is probably smaller than initially expected. The same is probably true for maintenance of sinus rhythm after cardioversion and for new-onset AF. Larger trials are currently ongoing. Prevention of ventricular arrhythmias was studied in carriers of an implanted cardioverter-defibrillator, with no clear results. This might have been due to a broad definition of the primary endpoint, including any ventricular arrhythmia and any action of the device. Epidemiologic studies support the contention that high levels of EPA + DHA prevent sudden cardiac death (SCD). However, since SCD is a rare occurrence, it is difficult to conduct an adequately powered trial. In patients with congestive heart failure, EPA + DHA reduced total mortality and rehospitalizations, but not SCD or presumed arrhythmic death. Of three trials in patients after a myocardial infarction, two were inadequately powered, and in one, the dose might have been too low. Taken together, while epidemiologic studies support an inverse relation between EPA + DHA and occurrence of SCD or arrhythmic death, demonstrating this effect in intervention trials remained elusive so far. A pro-arrhythmic effect of EPA + DHA has not been seen in intervention studies, and results of epidemiologic and animal studies also rather argue against such an effect. A different, and probably more productive, perspective is provided by a standardized analytical assessment of a person’s status in EPA + DHA by use of the omega-3 index, EPA + DHA in red cell fatty acids. In populations with a high omega-3 index, SCD is rare. Intervention trials can become more effective by including a low omega-3 index into the inclusion criteria, thus creating a study population more likely to demonstrate an effect of EPA + DHA. This is especially relevant in case of rare endpoints, like new-onset AF or SCD.

Cis-vaccenic acid and the Framingham risk score predict chronic kidney disease: the multi-ethnic study of atherosclerosis (MESA)

INTRODUCTION

Data on the associations of fatty acids with chronic kidney disease (CKD) are sparse.

MATERIALS AND METHODS

We performed a cross-sectional study of 2792 men and women from the MESA cohort of African-American, Caucasian, Chinese and Hispanic adults without known cardiovascular disease. Plasma phospholipid fatty acid proportions were associated with estimated glomerular filtration rate (eGFR) and the albumin/creatinine ratio.

RESULTS

Cis-vaccenic acid (18:1n-7), adjusted for other fatty acids using multivariate logistic regression (CI: 1.0-1.4), and step-wise logistic regression (CI: 1.02-1.42), was positively associated with reduced eGFR. The Framingham Risk Score, when adjusting for fatty acid proportions and demographic factors, was positively associated with CKD as measured by the eGFR and the albumin/creatinine ratio.

DISCUSSION AND CONCLUSIONS

Plasma phospholipid proportions of the 18 carbon monounsaturated cis-vaccenic acid {18:1n-7}) and the Framingham Risk Score are associated with kidney function. The potential role of 18:1n-7 in the development of CKD warrants further investigation.

Heart rate is associated with markers of fatty acid desaturation: the GOCADAN study

Objectives

To determine if heart rate (HR) is associated with desaturation indexes as HR is associated with arrhythmia and sudden death.

Study design

A community based cross-sectional study of 1214 Alaskan Inuit.

Methods

Data of FA concentrations from plasma and red blood cell membranes from those ≥35 years of age (n =819) were compared to basal HR at the time of examination. Multiple linear regression with backward stepwise selection was employed to analyze the effect of the desaturase indexes on HR, after adjustment for relevant covariates.

Results

The Δ⁵ desaturase index (Δ⁵-DI) measured in serum has recently been associated with a protective role for cardiovascular disease. This index measured here in plasma and red blood cells showed a negative correlation with HR. The plasma stearoyl-CoA-desaturase (SCD) index, previously determined to be related to cardiovascular disease (CVD) mortality, on the other hand, was positively associated with HR, while the Δ⁶ desaturase index (Δ⁶-DI) had no significant effect on HR.

Conclusion

Endogenous FA desaturation is associated with HR and thereby, in the case of SCD, possibly with arrhythmia and sudden death, which would at least partially explain the previously observed association between cardiovascular mortality and desaturase activity.

The legacy of the Alaska Siberia Medical Research Program: a historical perspective

BACKGROUND

The Alaska Siberia Medical Research Program was established at the University of Alaska (UA) at a time when there was no research funded by the National Institutes of Health (NIH) that was concerned with Alaska Native health issues. The program grew out of a dire need for an understanding of the apparently rapidly growing health problems in the Native community. The initial plan included the following objectives.

OBJECTIVES

The objectives are to develop a self-sustaining infrastructure for biomedical research by gaining support from Alaska Natives, UA, national political leaders, NIH and the Russian Academy of Medical Science (RAMS); to identify researchers committed to helping Alaska Natives; to develop meaningful, Native-driven participatory research; to carry out necessary research to form the foundation for future research; and to develop circumpolar collaborations.

RESULTS

The objectives were achieved because of the extraordinary and cheerful contributions by all participants in the program. The collaborative research resulted in some 70 published manuscripts identifying and characterizing research-neglected health problems. Unique risk factors for diabetes, cardiovascular disease, alcoholism and seasonal affective disorders were characterized and institutionalized prevention programs were established. The effort of the program led to U.S. Congressional action establishing the University of Alaska as a minority institution, leading to the funding of a variety of successful NIH-funded research centres and programs at the university that are concerned with Native health problems.

CONCLUSION

A small, visionary investment by the University of Alaska for establishing the program led to a co-operative effort by the UA, RAMS, Alaska Native Health communities and the NIH that resulted in the development of self-sustaining medical research efforts in Alaska and Siberia. The program spawned pilot studies, leading to NIH-funded research that has provided fundamental insights into the etiology of health problems and their reduction by research-based intervention and prevention programs.

The Omega-3 Index as a risk factor for cardiovascular diseases

The Omega-3 Index has been defined as eicosapentaenoic plus docosahexaenoic acids in erythrocytes. Integral part of the definition is a standardized analytical procedure, which conforms to the standards of Clinical Chemistry. This resulted in more than 90 collaborative research projects, concluded and ongoing, and 64 publications so far. The Omega-3 Index is emerging as a risk factor for fatal and non-fatal cardiovascular events. This standardized analysis of fatty acid patterns adds incremental information to standard risk factor algorithms, and it correctly reclassifies persons from intermediate to high or low risk. Circumstantial evidence indicates that determining the Omega-3 Index has a therapeutic consequence. Thus, the Omega-3 Index fulfils important criteria for novel biomarkers, set forth by the American Heart Association and others, and compares well to other novel biomarkers. Future results will add precision to the value of the Omega-3 Index in cardiology, and probably expand its application to other areas, like psychiatry and pregnancy.

Determinants of the omega-3 index in a Mediterranean population at increased risk for CHD

The omega-3 index, defined as the sum of EPA and DHA in erythrocyte membranes expressed as a percentage of total fatty acids, has been proposed as both a risk marker and risk factor for CHD death. A major determinant of the omega-3 index is EPA+DHA intake, but the impact of other dietary fatty acids has not been investigated. In a cross-sectional study on 198 subjects (102 men and 96 women, mean age 66 years) at high cardiovascular risk living in Spain, the country with low rates of cardiac death despite a high prevalence of cardiovascular risk factors, dietary data were acquired from FFQ and blood cell membrane fatty acid composition was measured by GC. The average consumption of EPA+DHA was 0·9 g/d and the mean omega-3 index was 7·1 %. In multivariate models, EPA+DHA intake was the main predictor of the omega-3 index but explained only 12 % of its variability (P < 0·001). No associations with other dietary fatty acids were observed. Although the single most influential determinant of the omega-3 index measured here was the intake of EPA+DHA, it explained little of the former's variability; hence, the effects of other factors (genetic, dietary and lifestyle) remain to be determined. Nevertheless, the high omega-3 index could at least partially explain the paradox of low rates of fatal CHD in Spain despite a high background prevalence of cardiovascular risk factors.

Alpha-linolenic acid: is it essential to cardiovascular health?

There is a large body of scientific evidence that has been confirmed in randomized controlled trials indicating a cardioprotective effect for omega-3 fatty acids from fish. For alpha-linolenic acid (ALA), which is the omega-3 fatty acid from plants, the relation to cardiovascular health is less clear. We reviewed the recent literature on dietary ALA intake, ALA tissue concentrations, and cardiovascular health in humans. Short-term trials (6–12 weeks) in generally healthy participants mostly showed no or inconsistent effects of ALA intake (1.2–3.6 g/d) on blood lipids, low-density lipoprotein oxidation, lipoprotein(a), and apolipoproteins A-I and B. Studies of ALA in relation to inflammatory markers and glucose metabolism yielded conflicting results. With regard to clinical cardiovascular outcomes, there is observational evidence for a protective effect against nonfatal myocardial infarction. However, no protective associations were observed between ALA status and risk of heart failure, atrial fibrillation, and sudden death. Findings from long-term trials of ALA supplementation are awaited to answer the question whether food-based or higher doses of ALA could be important for cardiovascular health in cardiac patients and the general population.