Evidence for the cardioprotective effects of omega-3 Fatty acids

"Unveiling the impacts of climatic cold events on the cardiovascular health in animal models"

Climate change is increasingly driving extreme weather events, leading to drastic temperature fluctuations worldwide. While overall temperatures rise, many regions are simultaneously experiencing severe cold spells that threaten the health of human populations, especially to vulnerable populations including the elderly and those with pre-existing conditions. Exposure to cold stress triggers significant physiological and biochemical disruptions. As cardiovascular diseases (CVDs) rank among the leading causes of global morbidity and mortality, the exacerbation of these conditions by cold exposure underscores critical public health challenges. The complex pathophysiological processes in cold-induced CVDs require careful analysis at an organ-system level, making animal models an ideal tool for replicating human physiological and molecular responses in a controlled environment. However, a detailed mechanism linking cold exposure and cardiovascular dysfunction remains incompletely understood, particularly in the context of animal models. Therefore, this comprehensive review aims to address and analyze from traditional rodent models to less conventional ruminants, broilers, canines, and primate animal models to understand cold stress-induced CVDs, with an extensive account of the potential molecular mechanisms and pathways such as oxidative stress, inflammation, vasomotor dysfunction, and apoptosis, along with emerging roles of cold shock proteins (CSPs), etc. We also delve into various potential therapeutic approaches and preventive measures in cold stress conditions. In conclusion, this review is the first to comprehensively address the underexplored cardiovascular complications arising from cold stress and their underlying mechanisms, particularly using animal models. Furthermore, it provides a foundation for advancing the development of more effective and targeted therapies through translational research.

The effect of omega-3 Polyunsaturated Fatty Acid (PUFA) prescription preparations on the prevention of clinical cardiovascular disease: a meta-analysis of RCTs

IMPORTANCE

Evidence from systematic reviews of the cardioprotective effect of omega-3 polyunsaturated fatty acid (PUFA) remains controversial, and interventions including PUFAs dietary supplements or prescription medications cannot accurately reflect the role of PUFA RX in cardiovascular disease (CVD) prevention.

OBJECTIVE

We conducted a meta-analysis of randomized clinical trials (RCTs) to evaluate the efficacy of PUFA prescription medication in preventing CVD.

METHODS

Two reviewers conducted a literature search of Embase, MEDLINE/PubMed, and the Cochrane Library from their inception to September 2023. The inclusion criteria were RCTs evaluating long-term supplementation (≥ 1 year) with PUFA prescriptions and reporting cardiovascular outcomes. Data were extracted independently by two authors, and the certainty of evidence for each outcome was assessed using the GRADE system. Random-effects models were used to estimate the risk ratios (RRs) and 95% confidence intervals (CIs). The primary outcomes were cardiovascular events. Secondary endpoints included major adverse cardiovascular events (MACEs), cardiac death, all-cause mortality, myocardial infarction, stroke, and revascularization. Subgroup analyses were performed based on PUFA components, dosage, follow-up duration, and risk status.

RESULTS

Twelve RCTs involving 99,830 participants were included. The mean age of participants ranged from 59.4 to 74.0 years, with a follow-up period varying from 1 to 6.2 years. Compared with placebo and statins, PUFA prescription medication was associated with a reduced risk of cardiovascular events (8 RCTs, n = 75,929, RR, 0.88 [95% CI, 0.81-0.95]; P = 0.0007; I2 = 45%), cardiac death (10 RCTs, n = 95,440, RR, 0.91 [95% CI, 0.84-0.99]; P = 0.02; I2 = 23%), myocardial infarction (9 RCTs, n = 94,877, RR, 0.84 [95% CI, 0.73-0.96]; P = 0.009; I2 = 62%), and revascularization (9 RCTs, n = 91,242, RR, 0.91 [95% CI, 0.84-0.99]; P = 0.02; I2 = 63%).

CONCLUSIONS AND RELEVANCE

PUFA prescription medication could lower the risks of cardiovascular events, cardiac death, myocardial infarction and revascularization. This research provides insight into the efficacy of PUFA prescription medications in CVD prevention and contributes to the ongoing debate on the role of PUFA products in cardiovascular outcomes.

Role of omega-3 fatty acids in the prevention and treatment of cardiovascular Diseases: A consensus statement from the Experts' Committee Of National Society Of Cardiometabolic Medicine

Low-density lipoprotein cholesterol (LDL-C) has been considered as the primary target for the prevention and treatment of atherosclerotic cardiovascular disease (ASCVD). However, there are still residual cardiovascular risks in some patients even if LDL-C achieves the target level. Emerging evidence suggestes that elevated triglyceride (TG) level or triglyceride-rich lipoprotein (TRL) cholesterol (TRL-C) is one of the important components of the residual cardiovascular risks. Omega-3 fatty acids have been shown to be one of the effective drugs for reducing TG. However, its efficacy in reducing the risk of ASCVD is inconsistent in large randomized clinical trials. There is lack of consensus among Experts regarding the application of omega-3 fatty acids in cardiovascular diseases including heart failure, arrhythmia, cardiomyopathy, hypertension, and sudden death. Hence, the current consensus will comprehensively and scientifically present the detailed knowledge about the omega-3 fatty acids from a variety of aspects to provide a reference for its management of omega-3 fatty acids application in the Chinese population.

Effect of Flaxseed (Linum usitatissimum L.) Supplementation on Vascular Endothelial Cell Morphology and Function in Patients with Dyslipidaemia—A Preliminary Observation

Context: Flaxseed has a characteristic fatty acids composition and unique phytonutrient profile that may have health-promoting properties. Objective: This study aimed to determine the effects of 10 weeks of supplementation with the flaxseed (28 g/day) on endothelial cells (EC) function, serum lipids and proinflammatory mediators in patients with mild and severe dyslipidaemia. Materials and methods: Eleven lean patients with severe dyslipidaemia treated with apheresis (group 1; 10 weeks treated in four phases: (i) ordinary diet, (ii) ordinary diet + flaxseed, (iii) ordinary diet (wash out), (iv) ordinary diet + placebo) and eleven obese patients with mild dyslipidaemia—not treated with apheresis (group 2; 10 weeks treated in two phases: (i) ordinary diet, (ii) low fat diet + flaxseed). Flaxseed was given blindly. Serum was collected at the end of each phase of the study. ECs were exposed in vitro to the medium supplemented with pooled serum taken from patients from both groups to detect their morphological changes using light and electron microscopy. ECs proliferation was also measured at the end of each study phase. Results: Serum vascular endothelial growth factor was decreased after flaxseed supplementation but only in group 1. ECs proliferation was increased after flaxseed supplementation only in obese patients. ECs exposed to medium supplemented with obese patients’ serum revealed the following cellular abnormalities: accumulation of lipid droplets, changes of rough endoplasmic reticulum and mitochondria, and flaxseed did not reverse observed changes. At the same time, flaxseed supplementation decreases total cholesterol in both tested groups, low-density lipoprotein cholesterol in group 1 and triglycerides in group 2. Conclusions: Our findings support the potential role of flaxseed in treating dyslipidaemia but indicate only a slight impact on endothelial cell function.

Plasma Fatty Acids in Zambian Adults with HIV/AIDS: Relation to Dietary Intake and Cardiovascular Risk Factors

Objective. To determine whether 24 hr dietary recalls (DR) are a good measure of polyunsaturated fatty acid (PUFA) intake when compared to plasma levels, and whether plasma PUFA is associated with markers of HIV/AIDS progression and cardiovascular disease (CVD) risk. Methods. In a cross-sectional study among 210 antiretroviral therapy-naïve HIV-infected adults from Lusaka, Zambia, we collected data on medical history and dietary intake using 24 hr DR. We measured fatty acids and markers of AIDS progression and CVD risk in fasting plasma collected at baseline. Results. PUFA intakes showed modest correlations with corresponding plasma levels; Spearman correlations were 0.36 (p < 0.01) for eicosapentaenoic acid and 0.21 (p = 0.005) for docosahexaenoic acid. While there were no significant associations (p > 0.05) between total plasma PUFA and C-reactive protein (CRP) or lipid levels, plasma arachidonic acid was inversely associated with CRP and triglycerides and positively associated with HDL-C, CD4+ T-cell count, and plasma albumin (p < 0.05). Plasma saturated fatty acids (SFA) were positively associated with CRP (β = 0.24; 95% CI: 0.08 to 0.40, p = 0.003) and triglycerides (β = 0.08; 95% CI: 0.03 to 0.12, p < 0.01). Conclusions. Our data suggest that a single DR is inadequate for assessing PUFA intake and that plasma arachidonic acid levels may modulate HIV/AIDS progression and CVD risk.

The Mediterranean diet, its components, and cardiovascular disease

One of the best-studied diets for cardiovascular health is the Mediterranean diet. This consists of fish, monounsaturated fats from olive oil, fruits, vegetables, whole grains, legumes/nuts, and moderate alcohol consumption. The Mediterranean diet has been shown to reduce the burden, or even prevent the development, of cardiovascular disease, breast cancer, depression, colorectal cancer, diabetes, obesity, asthma, erectile dysfunction, and cognitive decline. This diet is also known to improve surrogates of cardiovascular disease, such as waist-to-hip ratio, lipids, and markers of inflammation, as well as primary cardiovascular disease outcomes such as death and events in both observational and randomized controlled trial data. These enhancements easily rival those seen with more established tools used to fight cardiovascular disease such as aspirin, beta-blockers, angiotensin-converting enzyme inhibitors, and exercise. However, it is unclear if the Mediterranean diet offers cardiovascular disease benefit from its individual constituents or in aggregate. Furthermore, the potential benefit of the Mediterranean diet or its components is not yet validated by concrete cardiovascular disease endpoints in randomized trials or observational studies. This review will focus on the effects of the whole and parts of the Mediterranean diet with regard to both population-based and experimental data highlighting cardiovascular disease morbidity or mortality and cardiovascular disease surrogates when hard outcomes are not available. Our synthesis will highlight the potential for the Mediterranean diet to act as a key player in cardiovascular disease prevention, and attempt to identify certain aspects of the diet that are particularly beneficial for cardioprotection.

Current knowledge and trends in age-related macular degeneration: genetics, epidemiology, and prevention

PURPOSE

To address the most dynamic and current issues concerning human genetics, risk factors, pharmacoeconomics, and prevention regarding age-related macular degeneration.

METHODS

An online review of the database Pubmed and Ovid was performed, searching for the key words: age-related macular degeneration, AMD, pharmacoeconomics, risk factors, VEGF, prevention, genetics and their compound phrases. The search was limited to articles published since 1985 to date. All returned articles were carefully screened and their references were manually reviewed for additional relevant data. The webpage www.clinicaltrials.gov was also accessed in search of relevant research trials.

RESULTS

A total of 366 articles were reviewed, including 64 additional articles extracted from the references and 25 webpages and online databases from different institutions. At the end, only 244 references were included in this review.

CONCLUSION

Age-related macular degeneration is a complex multifactorial disease that has an uneven manifestation around the world but with one common denominator, it is increasing and spreading. The economic burden that this disease poses in developed nations will increase in the coming years. Effective preventive therapies need to be developed in the near future.

N-3 fatty acid supplementation to routine statin treatment inhibits platelet function, decreases patients' daytime blood pressure, and improves inflammatory status

OBJECTIVES

N-3 fatty acids reduce the risks of cardiovascular morbidity and mortality. Administration of N-3 fatty acids to patients treated with statins may potentiate the treatment effects. We examined the operating mechanisms underlying such a combination.

METHODS

Thirty-two hypercholesterolemic patients aged 30-70 years with hypercholesterolemia controlled by statins, received sequential treatments with placebo followed by 1.9 g/day of N-3 fatty acids for 23 weeks. Scheduled clinical visits included physical examination, 24-h blood pressure measurement, endothelial function evaluated by pulse wave analysis, analyses for platelet function, inflammation markers [interleukin (IL)-6, plasminogen activator inhibitor-1 (PAI-1)] and oxidative stress parameters (STAT-8-Isoprostane) were undertaken at baseline, after placebo treatment, and after 6 and 20 weeks of N-3 fatty acid intake.

RESULTS

Platelets functions were significantly inhibited, whereas endothelial function parameters were unaltered. IL-6 significantly decreased whereas PAI-1and STAT-8-Isoprostane levels remained unaffected. Daytime blood pressure significantly decreased; however, nighttime pressure and heart rate remained unchanged. No evidence of lipid-profile improvement was observed following combined treatment with statins and N-3 fatty acids.

CONCLUSIONS

In hypercholesterolemic patients, combination of statins and N-3 fatty acid inhibits platelet aggregation, alters inflammatory status, and positively affects daytime blood pressure. Close long-term follow-up might reveal additional beneficial effects of N-3 fatty acids in this patient population.

Evaluation of protective effects of fish oil against oxidative damage in rats exposed to methylmercury

The present study evaluates a possible protective effect of fish oil against oxidative damage promoted by methylmercury (MeHg) in sub-chronically exposed rats. Reduced glutathione peroxidase and catalase enzyme activity and reduced glutathione levels were observed in MeHg-exposed animals compared to controls. Methylmercury exposure was also associated with DNA damage. Administration of fish oil to the methylmercury-exposed animals did not ameliorate enzyme activity or glutathione levels. On the other hand, a significant DNA protective effect (about 30%) was observed with fish oil treatment. There were no differences in the total mercury concentration in rat liver, kidney, heart or brain after MeHg administration with or without fish oil co-administration. Histopathological analyses showed a significant leukocyte infiltration in rat tissues after MeHg exposure, but this effect was significantly reduced after co-administration of fish oil. Taken together, our findings demonstrate oxidative damage even after low-level MeHg exposure and the protective effect of fish oil. This protection seems not to be related to antioxidant defenses or mercury re-distribution in rat tissues. It is probably due to the anti-inflammatory effects of fish oil.

Long chain omega 3 polyunsaturated fatty acids supplementation in the treatment of elderly depression: effects on depressive symptoms, on phospholipids fatty acids profile and on health-related quality of life

OBJECTIVE

Recent observations showed that long chain omega 3 polyunsaturated fatty acids (n-3 LCPUFA) could represent a potential treatment for elderly depression. To determine if a n-3 LCPUFA containing supplement improves depressive symptoms, changes phospholipids acids profile and ameliorates Health related quality of life (HRQoL) in depressed elderly patients.

DESIGN

Two-months, randomized, double-blind, placebo-controlled trial.

SETTING

Nursing home in Pavia, Italy.

SUBJECTS

Forty-six depressed females, aged 66-95 years.

INTERVENTION

22 depressed females were included in the intervention group (n-3 group, that received 2.5 g/day of n-3 LCPUFA, with 1.67 grams of EPA and 0.83 grams of DHA), and 24 patients in the placebo group. The primary endpoint was the improvement of depressive symptoms as evaluated by Geriatric Depression Scale (GDS). Secondary endpoints were the evaluation of modifications of erythrocyte membrane phospholipids fatty acid profile and of of HRQoL, by using the Short-Form 36-Item Health Survey (SF-36). All parameters were assessed before and after the treatment period of 8 weeks.

RESULTS

The mean GDS at 2 months was significantly lowered only for the n-3 group. SF-36 physical and mental components were significantly increased in the intervention group. Compliance was good, as confirmed by erythrocyte membrane phospholipid FA concentrations, with significant increase of EPA and DHA in the intervention group.

CONCLUSION

The supplementation of n-3 LCPUFA in elderly female patients reduces the occurrence of depressive symptoms, improves phospholipids fatty acids profile and health-related quality of life.

Effect of omega-3 fatty acids supplementation on depressive symptoms and on health-related quality of life in the treatment of elderly women with depression: a double-blind, placebo-controlled, randomized clinical trial

OBJECTIVE

In elderly individuals, depression is one of the most frequently missed diagnoses with negative effects on quality of life. The authors investigated whether a supplement containing long-chain omega-3 polyunsaturated fatty acids (n-3 LCPUFA) improves depressive symptoms and health-related quality of life (HRQoL) in depressed elderly patients.

DESIGN

Eight-week, randomized, double-blind, placebo-controlled trial.

SETTING

Nursing home in Pavia, Italy.

PARTICIPANTS

Forty-six depressed women, aged 66-95 years.

INTERVENTION

Twenty-two depressed women were included in the intervention group (n-3 group, which received 2.5 g/d of n-3 LCPUFA, with 1.67 g of eicosapentaenoic acid [EPA] and 0.83 g of docosahesaenoic acid [DHA]), and 24 patients were included in the placebo group. The primary endpoint was the improvement of depressive symptoms, as evaluated by the Geriatric Depression Scale (GDS). Secondary endpoints were the evaluation of HRQoL, by using the Short-Form 36-Item Health Survey (SF-36), and modifications of erythrocyte membrane phospholipids fatty acid profile. All variables were assessed before and after the treatment period of 8 weeks.

RESULTS

The mean GDS at 8 weeks was significantly lower compared with the n-3 group. The SF-36 physical and mental components were significantly increased in the intervention group. Compliance was good, as confirmed by erythrocyte membrane phospholipid FA concentrations, with a significant increase of EPA and DHA in the intervention group.

CONCLUSION

Supplementation with n-3 LCPUFA is efficacious in the amelioration of depressive symptoms and quality of life in the treatment of depressed elderly female patients.

Prevention of age-related macular degeneration

Age-related macular degeneration (AMD) is one of the leading causes of blindness in the developed world. Although effective treatment modalities such as anti-VEGF treatment have been developed for neovascular AMD, there is still no effective treatment for geographical atrophy, and therefore the most cost-effective management of AMD is to start with prevention. This review looks at current evidence on preventive measures targeted at AMD. Modalities reviewed include (1) nutritional supplements such as the Age-Related Eye Disease Study (AREDS) formula, lutein and zeaxanthin, omega-3 fatty acid, and berry extracts, (2) lifestyle modifications, including smoking and body-mass-index, and (3) filtering sunlight, i.e. sunglasses and blue-blocking intraocular lenses. In summary, the only proven effective preventive measures are stopping smoking and the AREDS formula.

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

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

Comparison of the nutritional-toxicological conflict related to seafood consumption in different regions worldwide

This article discusses the seafood consumption worldwide as well as the related nutritional-toxicological conflict. An exposure assessment was performed using seafood consumption data from the Global Environment Monitoring System and nutrient and contaminant concentration data. The data indicated that the region of Japan, Korea, Madagascar and Philippines have the highest seafood consumption, followed by the Nordic-Baltic countries and South-East Asia. In Japan, Korea, Madagascar, Philippines and the Nordic-Baltic countries, pelagic marine fishes are highly consumed compared to fresh water fishes in South-East Asia. Because pelagic fishes are oily fishes, Japan, Korea, Madagascar, Philippines and the Nordic-Baltic countries have high omega-3 fatty acids and vitamin D intake. Iodine intake is influenced by the demersal fish consumption. The current intake of these nutrients via seafood consumption is still below the recommendations. From the toxicological side, the data indicate that none of the seafood groups had a median contaminant concentration above the EU maximum limits. Though, the results show that in some regions the contaminant intake exceeded the international health-based guidance values, mainly focussing on sensitive subpopulations. In contrast, when using less stringent guidance values relevant for non-sensitive subpopulations, the results show that the benefits of increased seafood consumption outweigh the risks.

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

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

An investigation of the effects of methylmercury in rats fed different dietary fats and proteins: Testicular steroidogenic enzymes and serum testosterone levels

Methylmercury (MeHg) is a testicular toxicant causing reduced steroidogenic enzyme activity, reduced serum testosterone (T) and abnormal spermatogenesis in mammals and fowl. It is also known that certain diets can alter androgen metabolism in rats. Previously we have shown that diets used in the current study impact circulating androgen levels and testicular steroidogenic enzyme activities in Sprague Dawley rats in the absence of MeHg. In the present study, we have investigated the impact of imposing an environmental contaminant (MeHg) commonly found in marine mammals and fish onto the rats' dietary intake of different proteins and lipids in order to determine if the different diets could modify MeHg toxicity in rats. Therefore, we examined the effects of MeHg on testicular steroidogenic enzymes and serum testosterone in rats fed diets containing either different protein sources (casein, fishmeal, whey) or different lipid sources (soybean oil, docosahexaenoic acid (DHA), seal oil, fish oil, lard). Male rats 42-45 days of age (18 per group) were assigned to different experimental diets for 28 days after which 6 rats in each group were gavaged daily with 0, 1 or 3 mg/kg body weight (BW)/day MeHg chloride in 5 mM Na(2)CO(3) solution for 14 days while being maintained on their diets. On the 43rd day of dosing, rats were sacrificed and blood plasma and testes frozen (-80 degrees C) until analysis. Microsomal steroidogenic enzyme activities (3beta-HSD, 17-OHase, C-17, 20-lyase, 17beta-HSD) were measured radiometrically. Serum testosterone was determined using ELISA kits. Testis weights were not affected by MeHg. MeHg at 3 mg/kg BW/day caused a reduction (>50%) in the activity of C-17, 20-lyase in all three protein diets and similar reductions in 17-OHase activity were seen in the casein and whey protein fed rats. At 3 mg/kg BW/day, MeHg reduced 17-OHase activity in the DHA diet but had no effect on 3beta-HSD activity and no inhibitory effects on 17beta-HSD activity. MeHg (3 mg/kg BW/day) caused significant reductions in serum T in the whey, soybean oil and fish oil groups. Interestingly, fishmeal protein but not fish oil offered some protection with respect to maintaining steroidogenic enzyme activities and serum T levels in rats dosed with MeHg. In conclusion, these studies show that different lipid diets can alter the toxic effects of MeHg on male rat steroidogenesis in terms of serum testosterone and steroidogenic enzyme activities.

Comparison of biochemical effects of statins and fish oil in brain: the battle of the titans

Neural membranes are composed of glycerophospholipids, sphingolipids, cholesterol and proteins. The distribution of these lipids within the neural membrane is not random but organized. Neural membranes contain lipid rafts or microdomains that are enriched in sphingolipids and cholesterol. These rafts act as platforms for the generation of glycerophospholipid-, sphingolipid-, and cholesterol-derived second messengers, lipid mediators that are necessary for normal cellular function. Glycerophospholipid-derived lipid mediators include eicosanoids, docosanoids, lipoxins, and platelet-activating factor. Sphingolipid-derived lipid mediators include ceramides, ceramide 1-phosphates, and sphingosine 1-phosphate. Cholesterol-derived lipid mediators include 24-hydroxycholesterol, 25-hydroxycholesterol, and 7-ketocholesterol. Abnormal signal transduction processes and enhanced production of lipid mediators cause oxidative stress and inflammation. These processes are closely associated with the pathogenesis of acute neural trauma (stroke, spinal cord injury, and head injury) and neurodegenerative diseases such as Alzheimer disease. Statins, the HMG-CoA reductase inhibitors, are effective lipid lowering agents that significantly reduce risk for cardiovascular and cerebrovascular diseases. Beneficial effects of statins in neurological diseases are due to their anti-excitotoxic, antioxidant, and anti-inflammatory properties. Fish oil omega-3 fatty acids, eicosapentaenoic acid and docosahexaenoic acid, have similar anti-excitotoxic, antioxidant and anti-inflammatory effects in brain tissue. Thus the lipid mediators, resolvins, protectins, and neuroprotectins, derived from eicosapentaenoic acid and docosahexaenoic acid retard neuroinflammation, oxidative stress, and apoptotic cell death in brain tissue. Like statins, ingredients of fish oil inhibit generation of beta-amyloid and provide protection from oxidative stress and inflammatory processes. Collective evidence suggests that antioxidant, anti-inflammatory, and anti-apoptotic properties of statins and fish oil contribute to the clinical efficacy of treating neurological disorders with statins and fish oil. We speculate that there is an overlap between neurochemical events associated with neural cell injury in stroke and neurodegenerative diseases. This commentary compares the neurochemical effects of statins with those of fish oil.

Plasma n-6 and n-3 polyunsaturated fatty acids as biomarkers of their dietary intakes: a cross-sectional study within a cohort of middle-aged French men and women

OBJECTIVE

To measure the correlations between habitual intakes of individual n-6 and n-3 polyunsaturated fatty acids (PUFA) and their percentages in total plasma fatty acids in a population of adult men and women.

SUBJECTS/METHODS

Two hundred and seventy-six men and 257 women aged 45-60 (men) or 35-60 (women) at baseline, volunteers of the French SU.VI.MAX cohort. Fifteen 24-h record questionnaires were used to estimate the habitual intake of energy, total fat and linoleic, alpha-linolenic acid, arachidonic, eicosapentaenoic (EPA), n-3 docosapentaenoic (DPA) and docosahexaenoic (DHA) acids. Fatty acid composition of fasting plasma total lipids has been determined at baseline.

RESULTS

Dietary intakes of linoleic acid, arachidonic acid, EPA and DHA were weakly but significantly correlated (0.16<r<0.28, P<0.01) with their respective percentages in plasma total fatty acids in both men and women. No correlation was observed between the plasma levels of alpha-linolenic acid and its dietary intake, and between the plasma levels of arachidonic acid and long-chain n-3 PUFA and the intakes of their 18-carbon precursors, linoleic and alpha-linolenic acid, respectively.

CONCLUSIONS

The percentages of linoleic acid, arachidonic acid, EPA and DHA in plasma total fatty acids, but not that of alpha-linolenic acid, are acceptable markers of their habitual levels of intake. The plasma levels of long-chain n-6 and n-3 PUFA are not influenced by the intake levels of their precursors, linoleic and alpha-linolenic acids.

Safety considerations with omega-3 fatty acid therapy

It has been suggested that the potential antithrombotic effect of fish oils may theoretically increase the risk for bleeding, which may be a safety concern for individual patients. However, clinical trial evidence has not supported increased bleeding with omega-3 fatty acid intake, even when combined with other agents that might also increase bleeding (such as aspirin and warfarin). Another potential safety concern is the susceptibility of omega-3 fatty acid preparations to undergo oxidation, which contributes to patient intolerance and potential toxicity. Finally, large amounts of fish consumption may result in adverse experiences due to the potential presence of environmental toxins such as mercury, polychlorinated biphenyls, dioxins, and other contaminants. The risks of exposure to environmental toxins and hypervitaminosis with fish consumption are substantially reduced through purification processes used to develop selected concentrated fish oil supplements and prescription preparations. Thus, in choosing which fish oil therapies to recommend, clinicians should be aware of available information to best assess their relative safety, which includes the US Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) advisory statement regarding fish consumption, the meaning of certain labeling (such as "verification" through the US Pharmacopeia) and the differences in FDA regulatory requirements between nonprescription fish oil supplements and prescription fish oil preparations, and how all of this is important to the optimal treatment of patients.

Diet, serum homocysteine levels and ischaemic heart disease in a Mediterranean population

Homocysteine (Hcy) is recognised as a risk factor for IHD. Serum Hcy is negatively correlated with serum folate levels, the main sources of which are fruits, vegetables and legumes. The present case–control study was designed to examine the relationship between serum Hcy levels and IHD and to assess the role of dietary factors in the southern Mediterranean population of Crete, Greece. Serum Hcy, folate, vitamin B12, creatinine and glucose levels and a full lipid profile were measured in 152 patients with established IHD, median age 64 (range 33–77) years, and 152 healthy control subjects, age- and sex-matched. Dietary data were assessed using a 3 d food intake record. Compared with controls, patients with IHD had significantly higher daily intakes of vitamin B12and MUFA and significantly lower intakes of carbohydrate, fibre, folate, cholesterol,n-3 fatty acids and totaltransunsaturated fatty acids. Moreover, patients had significantly higher serum Hcy, vitamin B12and creatinine levels, but significantly lower folate. Serum folate concentrations in both groups had a significant positive correlation with dietary fibre consumption and a significant inverse correlation with vitamin B12intake. IHD patients should be encouraged to increase their daily dietary intake of fibre, folate andn-3 fatty acids, which are significant components of the traditional Cretan Mediterranean diet. Where dietary folate intake is inadequate, folate supplements are recommended to reduce elevated Hcy levels.

Modulating effects of dietary fats on methylmercury toxicity and distribution in rats

Fish consumption is the most important source of human exposure to methylmercury (MeHg). Since fish is also a rich source of n-3 polyunsaturated fatty acids, this study was conducted to examine the effects of dietary fats on MeHg-induced acute toxicity in rats. Weanling male Sprague Dawley rats were administered semi-purified casein-based isocaloric diet containing soy oil, seal oil, docosahexaenoic acid (DHA), fish oil, or lard for 28 days. Rats were then gavaged with 0, 1, or 3 mg MeHg/kg body weight (BW) per day and fed the same diet for 14 consecutive days. On 43rd day of the experiment, rats were sacrificed and blood samples were collected and analyzed for hematology. Liver and spleen were removed, fixed, and examined for pathological changes. Blood, feces, liver, and brain were analyzed for total mercury and/or MeHg contents. Serum samples were analyzed for clinical markers of hepatic injury and immunoglobulin. Total mercury contents in all tissues measured increased with dose. Mercury excretion in feces increased with dose and duration of MeHg treatment. Both diets and MeHg showed significant effects and interacted significantly on many of the toxicological endpoints measured. Many of the effects of MeHg were diet-dependent. For example, in the rats fed the lard diet, 3mg MeHg/kg BW significantly increased relative liver and spleen weight as compared with vehicle control; whereas in rats fed the fish oil, soy oil, seal oil, or DHA, this effect of MeHg was less obvious or absent, suggesting a protective effect of these diets. MeHg at 3mg/kg BW significantly decreased serum albumin level in all except DHA dietary groups, implying a protection by the DHA diet on this parameter. Only in the lard dietary group, did 3mg MeHg/kg BW significantly increase serum bilirubin level, indicating an enhancing effect of this diet on MeHg toxicity. MeHg suppressed the adaptive immune system and stimulated the innate immune system in rats in a diet-dependent fashion. The seal oil diet provided more resistance, while the fish oil diet rendered greater sensitivity to these effects of MeHg on the immune system. These results imply significant modulating effects of dietary fats on MeHg toxicity which may translate into more severe or protective clinical outcomes. Therefore, dietary fats are important factors to be considered in the risk assessment of MeHg exposure.

Antiarrhythmic effects of omega-3 fatty acids

Fish oil, and omega-3 fatty acids in particular, have been found to reduce plasma levels of triglycerides and increase levels of high-density lipoprotein in patients with marked hypertriglyceridemia, and a pharmaceutical-grade preparation has recently received approval from the US Food and Drug Administration to market for this purpose. However, in both bench research studies and clinical trials, evidence for clinically significant antiarrhythmic properties has also been detected in association with omega-3 fatty acid intake. Arguably the most significant finding in this data set was the reduction in the incidence of sudden death in survivors of myocardial infarction in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI)-Prevenzione trial and the subsequent recommendation for administration of fish oil as part of the postinfarction regimen in Europe. This article reviews in detail the basic and clinical research studies of fish oil as an antiarrhythmic entity, the forms of preparation and/or administration that appear to possess these properties and those that do not, the types of arrhythmias (ventricular ectopy and atrial fibrillation as well as ventricular tachyarrhythmias) that have been beneficially affected by fish oil administration, and the presumed and known mechanisms by which the beneficial actions are exerted.

The effect of dietary fish oil supplementation on exercising horses

Ten horses of Thoroughbred or Standardbred breeding were used to study the effects of dietary fish oil supplementation on the metabolic response to a high-intensity incremental exercise test. Horses were assigned to either a fish oil (n = 6) or corn oil (n = 4) treatment. The fish oil (Omega Protein, Hammond, LA) contained 10.6% eicosapentaenoic acid and 8% docosahexaenoic acid. Each horse received timothy hay and a textured concentrate at a rate necessary to meet its energy needs. The supplemental oil was top-dressed on the concentrate daily at a rate of 324 mg/kg BW. Horses received their assigned diet for 63 d, during which time they were exercised 5 d/wk in a round pen or on a treadmill. During wk 1, horses exercised for 10 min at a trot. After wk 1, exercise time and intensity were increased so that at wk 5, exercise time in the round pen increased to 30 min (10 min of cantering and 20 min of trotting) per day. Starting at wk 6, horses were exercised 3 d/wk in the round pen for 30 min and 2 d/wk on a treadmill for 20 min. After 63 d, all horses performed an exercise test consisting of a 5-min warm-up at 1.9 m/s, 0% grade, followed by a step test on a 10% grade at incremental speeds of 2 to 8 m/s. Blood samples were taken throughout exercise. During exercise, horses receiving fish oil had a lower heart rate (treatment x time interaction; P < 0.05) and tended to have lower packed cell volume (treatment effect; P = 0.087). Plasma lactate concentrations were not affected by treatment. Plasma glucose concentrations were not different between groups during exercise but were lower (treatment x time interaction; P < 0.01) for the fish oil group during recovery. Serum insulin tended to be lower in fish oil horses throughout exercise (treatment effect; P = 0.064). There was a tendency for glucose:insulin ratios to be higher for fish oil-treated horses throughout exercise (treatment effect; P = 0.065). Plasma FFA were lower (treatment x time interaction; P < 0.01) in horses receiving fish oil than in horses receiving corn oil during the initial stages of the exercise test. Serum glycerol concentrations also were lower in fish oil-treated horses (P < 0.05). Serum cholesterol concentrations were lower in horses receiving fish oil (treatment effect; P < 0.05), but serum triglycerides were not affected by treatment (P = 0.55). These data suggest that addition of fish oil to the diet alters exercise metabolism in conditioned horses.

Fish oils in the care of coronary heart disease patients: a meta-analysis of randomized controlled trials

What is the place of fish oils in the care of coronary heart disease (CHD) patients? As several clinical trials have already addressed this question without giving definitive answers, we did a meta-analysis of trials regarding the efficacy of omega-3 fatty acids in preventing cardiovascular mortality and morbidity. We searched the MEDLINE (1966-2003), EMBASE databases, proceedings abstracts and references of reviewed articles. Randomized controlled trials (RCTs) of the efficacy of omega-3 fatty acids among adults with recent or acute myocardial infarction (MI), or angina were selected. Two reviewers abstracted data independently. Five relevant outcomes, mortality from all causes, fatal and non-fatal MI, non-fatal stroke and angina, were measured. Data were synthesized using a fixed effect model. Ten RCTs with 14,727 patients were included. No significant heterogeneity was detected. Daily intake of omega-3 fatty acids for a mean duration of 37 months decreased all causes of mortality by 16% (relative risk 0.84, 95% confidence interval [0.76; 0.94]) and the incidence of death due to MI by 24% (0.76, [0.66; 0.88]). No significant effect was found for the other outcomes. Because of the suboptimal quality of the studies included into the meta-analysis and the absence of data in patients receiving statins, these results do not justify adding fish oils systematically to the heavy pharmaceutical assortment already recommended in CHD patients.

Treatment of hypertriglyceridemia with omega-3 fatty acids: a systematic review

PURPOSE

To (a) critically appraise available randomized controlled trials (RCTs) addressing the efficacy of long-chain omega-3 fatty acids as secondary agents for prevention of hypertriglyceridemia and (b) make recommendations for clinical practice.

DATA SOURCES

Two independent reviewers examined all RCTs from 1994 to 2003 identified in several databases, extracted data from each study, and used the previously tested Boyack and Lookinland Methodological Quality Index (MQI) to determine study quality.

CONCLUSIONS

Ten studies reported long-chain omega-3 fatty acids to be effective in the treatment of hypertriglyceridemia. The average decrease in triglycerides was 29%, total cholesterol 11.6%, very low density lipoprotein (VLDL) 30.2%, and low-density lipoprotein (LDL) 32.5%. One study found LDLs to increase by 25%. The average increase in high-density lipoprotein was 10%. The overall average MQI score was 36% (range = 26% to 54%). Many of the RCTs had serious shortcomings, including short duration, lack of a power analysis, no intention-to-treat analysis, no report of blind assessment of outcome, and lack of dietary control as a confounding variable.

IMPLICATIONS FOR PRACTICE

Overall study methodology was weak. Although the evidence supporting use of long-chain omega-3 fatty acids in the secondary prevention of hypertriglyceridemia is reasonably strong, until there are larger RCTs of better methodological quality, it is not recommended that practitioners treat hypertriglyceridemia with omega-3 fatty acid supplementation in lieu of lipid-lowering medications.

Dietary intakes and food sources of n−6 and n−3 PUFA in french adult men and women

The intake of individual n-6 and n-3 PUFA has been estimated in 4,884 adult subjects (2,099 men and 2,785 women), volunteers from the French SU.VI.MAX intervention trial. The food intakes of each subject were recorded in at least ten 24-h record questionnaires completed over a period of 2.5 yr, allowing the estimation of the daily intake of energy; total fat; and linoleic, alpha-linolenic, arachidonic, eicosapentaenoic (EPA), n-3 docosapentaenoic (DPA), and docosahexaenoic (DHA) acids. The mean total fat intake corresponded to 94.1 g/d (36.3% of total energy intake) in men and 73.4 g/d (38.1% of energy) in women. The intake of linoleic acid was 10.6 g/d in men and 8.1 g/d in women, representing 4.2% of energy intake; that of alpha-linolenic acid was 0.94 g/d in men and 0.74 g/d in women, representing 0.37% of energy intake, with a mean linoleic/alpha-linolenic acid ratio of 11.3. The mean intakes of long-chain PUFA were: arachidonic acid, 204 mg/d in men and 152 mg/d in women; EPA, 150 mg/d in men and 118 mg/d in women; DPA, 75 mg/d in men and 56 mg/d in women; DHA, 273 mg/d in men and 226 mg/d in women; long-chain n-3 PUFA, 497 mg/d in men and 400 mg/d in women. Ninety-five percent of the sample consumed less than 0.5% of energy as alpha-linolenic acid, which is well below the current French recommendation for adults (0.8% of energy). In contrast, the mean intakes of long-chain n-6 and n-3 PUFA appear fairly high and fit the current French recommendations (total long-chain PUFA: 500 mg/d in men and 400 mg/d in women; DHA: 120 mg/d in men and 100 mg/d in women). The intakes of alpha-linolenic acid, and to a lesser extent of linoleic acid, were highly correlated with that of lipids. Whereas the main source of linoleic acid was vegetable oils, all food types contributed to alpha-linolenic acid intake, the main ones being animal products (meat, poultry, and dairy products). The main source of EPA and DHA (and of total long-chain n-3 PUFA) was fish and seafood, but the major source of DPA was meat, poultry, and eggs. Fish and seafood consumption showed very large interindividual variations, the low consumers being at risk of insufficient n-3 PUFA intake.

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.