Omega-3 fatty acids and cardiovascular disease

PURPOSE OF REVIEW: Omega-3 fatty acids are gaining acceptance in the cardiovascular field. The present review describes the most recent studies and developments in the field. RECENT FINDINGS: Marine omega-3 fatty acids, that is eicosapentaenoic and docosahexaenoic acids, prevent fatal myocardial infarction and sudden cardiac death by their antiarrhythmic effects and presumably also by their effect on infarct size, the latter mediated by plaque stabilization, improvements in endothelial function and other mechanisms. In contrast, a cardioprotective effect of alpha-linolenic acid, a plant-derived omega-3 fatty acid, remains to be clearly demonstrated in adequate intervention trials. Other forms of applications, like parenteral use or other indications, like in the psychiatric field, are currently being actively investigated. SUMMARY: Eicosapentaenoic and docosahexaenoic acids, but not alpha-linolenic acid, prevent sudden death and other cardiovascular catastrophies, and have therefore been recently incorporated into the pertinent guidelines of European and American cardiologic societies.     

Omega-3 fatty acids and cardiovascular disease

PURPOSE OF REVIEW: In the last 2 years in the cardiovascular field eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been investigated in terms of their epidemiology and vascular biology, and in large-scale intervention trials, and incorporated into the guidelines of cardiac societies. EPA and DHA have advanced from scientific research into everyday practice, a development reviewed here. RECENT FINDINGS: EPA and DHA are antiarrhythmic on the supraventricular and ventricular levels, besides having an anti-atherosclerotic effect. Fish rich in EPA and DHA, contaminated with methyl-mercury, appears less protective. Large-scale clinical trials demonstrated that morbidity can be reduced with EPA even in a population already consuming large amounts of EPA and DHA. Therapy with EPA and DHA can be monitored with the omega-3 index, a risk factor for sudden cardiac death. EPA and DHA appear to be cost-saving in the USA, and, as Omacor, are cost-effective in several European countries. SUMMARY: European and American Cardiac Societies incorporated EPA and DHA into recent treatment guidelines for myocardial infarction, prevention of cardiovascular disease, treatment of ventricular arrhythmias and prevention of sudden cardiac death. Physicians need to reduce the burden of cardiovascular disease by advocating EPA and DHA to all patients likely to benefit.     

Omega-3 fatty acids and anorexia

PURPOSE OF REVIEW: To review the mechanisms of action of omega-3 fatty acids and their role in the brain, as well as their therapeutic implications in anorexia. RECENT FINDINGS: Recent studies have demonstrated that omega-3 fatty acids modulate changes in the concentrations and actions of several orexigenic and anorexigenic neuropeptides in the brain, including neuropeptide Y, alpha-melanocyte stimulating hormone and the neurotransmitters serotonin and dopamine. In patients with acute and chronic inflammatory conditions, low tissue concentrations of omega-3 fatty acids and high concentrations of proinflammatory cytokines are found, in association with anorexia and decreased food intake. The data suggest that omega-3 fatty acid supplementation suppresses proinflammatory cytokine production and improves food intake by normalizing hypothalamic orexigenic peptides and neurotransmitters. SUMMARY: Based on current data, omega-3 fatty acid supplementation has a role in the treatment of anorexia by stimulating the production and release of orexigenic neurotransmitters in food intake regulatory nuclei in the hypothalamus.     

Omega-3 (n-3) fatty acids in health and disease: Part 1--cardiovascular disease and cancer

The omega-3 (n-3) polyunsaturated fatty acids have a wide range of beneficial effects in several human health conditions. Animal and in vitro studies have indicated that omega-3 fatty acids affect blood lipid profiles, cardiovascular health, membrane lipid composition, eicosanoid biosynthesis, cell signaling cascades, and gene expression. Findings from epidemiological studies suggest that intake of omega-3 fatty acids from natural sources or supplements may influence the onset and progression of several disease states, including cardiovascular disease and cancer. This review highlights some recent research findings that help advance our understanding of how omega-3 fatty acids influence cardiovascular disease and cancer.     

Omega-3 fatty acids in health and disease: part 2--health effects of omega-3 fatty acids in autoimmune diseases, mental health, and gene expression

Omega-3 fatty acids from marine and plant sources provide a wide range of benefits in several human health conditions. In vivo studies indicate that omega-3 fatty acids influence the course of several human diseases, including those that involve abnormal immune function, mental disorders, and genetic abnormalities in lipid metabolism. Omega-3 fatty acids are taken up by virtually all body cells and affect membrane composition, eicosanoid biosynthesis, cell signaling cascades, and gene expression. These fatty acids are especially important during human brain development; maternal deficiency of omega-3 fatty acids may lead to several neurological disorders. The review highlights recent findings on omega-3 fatty acids' influence on autoimmune diseases, mental health, and gene expression.     

Omega-3 fatty acids and cardiovascular disease: The epidemiological evidence

Epidemiological studies in the last 40 years suggest that omega-3 fatty acids derived from fish and fish oil decrease the risk of coronary heart disease, hypertension and stroke, and their complications. The beneficial effects of omega-3 fatty acids include effects on lipids, blood pressure, cardiac and vascular function, eicosanoids, coagulation, and immunological responses. However, not all population studies have shown that omega-3 fatty acids are associated with reduced rates of coronary mortality. Such studies suffer either from small numbers of subjects or the population already had a high intake of fish. When comparing the highest intake of fish to that of the lowest fish intake, the beneficial effects of omega-3 fatty acids have been shown. In population-based case-control studies, the patients consuming modest amounts of fish, the equivalent of one fatty fish meal per week, had a significant lower risk of primary cardiac arrest compared with those who did not eat fish at all. In case-control studies, the intake of eicosapentaenoic acid and docosahexaenoic acid as reflected in adipose tissue content is inversely associated with risk of myocardial infarction.     

Omega-3 fatty acids in the prevention and control of cardiovascular disease

Cardiovascular disease is one of the main causes of death in developed countries. Several factors are involved in its appearance and progress, among which nutrition enjoys a certain protagonism. Until recently, the dietetic criteria for preventing and controlling cardiovascular disease were mainly restrictive (at least in terms of energy and fat intake), but such advice is difficult to follow, and without careful monitoring can lead to deficiencies that might negatively affect quality of life and perhaps even life expectancy. Several investigations show that some components of the lipid fraction of the diet, such as omega-3 fatty acids, are beneficial with respect to cardiovascular disease, and these have become the centre of much attention. This paper reviews the results of some of these studies and evaluates the benefit of these fatty acids in the prevention of coronary heart disease. The sources of omega-3 fatty acids, their recommended consumption, possible mechanisms of action and potential adverse effects are discussed.     

Omega-3 fatty acids and blood pressure

Epidemiological and clinical studies suggest that consumption of omega (ω-3) polyunsaturated fatty acids (PUFA) contributes to the reduction of cardiovascular mortality through different mechanisms including modulation of cellular metabolic functions, gene expression and beneficial effects on lipid profile or blood pressure. The aim of the study is to review the effects of ω-3 PUFA supplemented as fish oil or blue fish in blood pressure. The analysis of different studies suggests that high doses ω-3 PUFA ( ≥ 3 g/day) produces a small but significant decrease in blood pressure, especially systolic blood pressure, in older and hypertensive subjects; however, the evidence is not consistent among different studies. ω-3 polyunsaturated fatty acids consumption might have a place in the control of patients with mild hypertension before starting drug treatment and of those who prefer changes of lifestyles like diet.     

Omega-3 fatty acids and inflammatory processes

Long chain fatty acids influence inflammation through a variety of mechanisms; many of these are mediated by, or at least associated with, changes in fatty acid composition of cell membranes. Changes in these compositions can modify membrane fluidity, cell signaling leading to altered gene expression, and the pattern of lipid mediator production. Cell involved in the inflammatory response are typically rich in the n-6 fatty acid arachidonic acid, but the contents of arachidonic acid and of the n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) can be altered through oral administration of EPA and DHA. Eicosanoids produced from arachidonic acid have roles in inflammation. EPA also gives rise to eicosanoids and these often have differing properties from those of arachidonic acid-derived eicosanoids. EPA and DHA give rise to newly discovered resolvins which are anti-inflammatory and inflammation resolving. Increased membrane content of EPA and DHA (and decreased arachidonic acid content) results in a changed pattern of production of eicosanoids and resolvins. Changing the fatty acid composition of cells involved in the inflammatory response also affects production of peptide mediators of inflammation (adhesion molecules, cytokines etc.). Thus, the fatty acid composition of cells involved in the inflammatory response influences their function; the contents of arachidonic acid, EPA and DHA appear to be especially important. The anti-inflammatory effects of marine n-3 PUFAs suggest that they may be useful as therapeutic agents in disorders with an inflammatory component.     

Omega-3 fatty acids EPA and DHA: health benefits throughout life

Omega-3 [(n-3)] fatty acids have been linked to healthy aging throughout life. Recently, fish-derived omega-3 fatty acids EPA and DHA have been associated with fetal development, cardiovascular function, and Alzheimer's disease. However, because our bodies do not efficiently produce some omega-3 fatty acids from marine sources, it is necessary to obtain adequate amounts through fish and fish-oil products. Studies have shown that EPA and DHA are important for proper fetal development, including neuronal, retinal, and immune function. EPA and DHA may affect many aspects of cardiovascular function including inflammation, peripheral artery disease, major coronary events, and anticoagulation. EPA and DHA have been linked to promising results in prevention, weight management, and cognitive function in those with very mild Alzheimer's disease.     

Omega-3 fatty acids, pro-inflammatory signaling and neuroprotection

PURPOSE OF REVIEW: To summarize recent findings that docosahexaenoate (DHA) is the precursor of stereospecific derivatives with anti-inflammatory and cytoprotective properties. RECENT FINDINGS: The docosahexaenoate-derived mediator neuroprotectin D1 is formed in retinal pigment epithelial cells when confronted with oxidative stress, in the brain during experimental stroke, and in the human brain from Alzheimer's disease patients as well as in human brain cells in culture. Neuroprotectin D1 displays potent anti-inflammatory and neuroprotective bioactivity. SUMMARY: Here, we summarize recent studies demonstrating that in brain ischemia-reperfusion and in retinal pigment epithelial cells exposed to oxidative stress stereospecific docosahexaenoate-oxygenation pathways are activated and lead to the formation of docosanoid messengers. Two docosahexaenoate-oxygenation pathways were identified: the first is responsible for the formation of the messenger neuroprotectin D1 and the second pathway, which is active in the presence of aspirin, leads to the formation of the resolvin-type mediators (17R-DHA). Neuroprotectin D1 induces antiapoptotic, anti-inflammatory signaling and is neuroprotective.     

Omega-3 fatty acids and major depression: A primer for the mental health professional

Omega-3 fatty acids play a critical role in the development and function of the central nervous system. Emerging research is establishing an association between omega-3 fatty acids (alpha-linolenic, eicosapentaenoic, docosahexaenoic) and major depressive disorder. Evidence from epidemiological, laboratory and clinical studies suggest that dietary lipids and other associated nutritional factors may influence vulnerability and outcome in depressive disorders. Research in this area is growing at a rapid pace. The goal of this report is to integrate various branches of research in order to update mental health professionals.     

Omega-3 polyunsatured fatty acids role in postmyocardial infarction therapy

Largely initiated by studies among Eskimos in the early 1970s, great attention has been given to possible effects of omega-3 polyunsatured fatty acids (PUFA) in cardiovascular diseases. A series of positive effects on pathogenetic mechanisms of cardiovascular disease has been discovered from laboratory studies in cell cultures, animal models and in humans. omega-3 PUFA can reduce platelets and leucocytes activities as well as plasma triglycerides. Moreover they can have antiarrhythmic properties. Nowadays patients who experienced myocardial infarction have decreased risk of total and cardiovascular mortality by treatment with omega-3 PUFA (1 g daily). This effect is present irrespective of high or low fish intake or simultaneous intake of other drugs for secondary prevention of coronary heart disease. Mainly on the basis of GISSI Prevention trial results, dietary supplementation with omega-3 PUFA is now recommended as a new component of secondary prevention after myocardial infarction in national and international guidelines.