n-3 fatty acids and lipoproteins: comparison of results from human and animal studies

1H NMR-based metabolomics study of the lipid profile of omega-3 fatty acid supplements and some vegetable oils

Omega-3 fatty acids, which consist of alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), are a type of polyunsaturated fatty acids that are crucial for enhancing human health. These three omega-3s are regarded as vital dietary nutrients because it cannot synthesize them on its own. Therefore, they must be obtained through dietary sources. On the other hands, there are concerns regarding the quality and quantity of omega-3 in dietary sources and supplements. In this study, 1H NMR spectroscopy and multivariate analysis were harnessed for non-destructive profiling of fatty acids in commercially available omega-3 supplements and plant-based oils. Results disclosed substantial disparities in omega-3 content from 8 to over 50 %, with some revealing unexpected adulteration. Notably, in one fish oil sample DHA could not be detected indicating the possibility of adulteration. Additionally, the research delineated the fatty acid composition of plant-based oils, emphasizing variations in alpha-linolenic acid (ALA) and linoleic acid (LA) content among flaxseed, chia seed, and walnut oils. Chia seeds emerged as a rich source of ALA (57-65 %mol), while walnuts contained considerable LA (44-53 % mol). The findings emphasize the power of metabolomics as a rapid and affordable tool for finding omega-3 fatty acids content and adulteration in commercial dietary products.

2023 China Guidelines for Lipid Management

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death among urban and rural residents in China, and elevated low-density lipoprotein cholesterol (LDL-C) is a risk factor for ASCVD. Considering the increasing burden of ASCVD, lipid management is of the utmost importance. In recent years, research on blood lipids has made breakthroughs around the world, hence a revision of China guidelines for lipid management is imperative, especially since the target lipid levels in the general population vary in respect to the risk of ASCVD. The level of LDL-C, which can be regarded as appropriate in a population without frisk factors, can be considered abnormal in people at high risk of developing ASCVD. As a result, the "Guidelines for the prevention and treatment of dyslipidemia" were adapted into the "China Guidelines for Lipid Management" (henceforth referred to as the new guidelines) by an Experts' committee after careful deliberation. The new guidelines still recommend LDL-C as the primary target for lipid control, with CVD risk stratification to determine its target value. These guidelines recommend that moderate intensity statin therapy in adjunct with a heart-healthy lifestyle, be used as an initial line of treatment, followed by cholesterol absorption inhibitors or/and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, as necessary. The new guidelines provide guidance for lipid management across various age groups, from children to the elderly. The aim of these guidelines is to comprehensively improve the management of lipids and promote the prevention and treatment of ASCVD by guiding clinical practice.

2023 Chinese guideline for lipid management

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death among urban and rural residents in China, and elevated low-density lipoprotein cholesterol (LDL-C) is a risk factor for ASCVD. Considering the increasing burden of ASCVD, lipid management is of the utmost importance. In recent years, research on blood lipids has made breakthroughs around the world, hence a revision of Chinese guideline for lipid management is imperative, especially since the target lipid levels in the general population vary in respect to the risk of ASCVD. The level of LDL-C, which can be regarded as appropriate in a population without frisk factors, can be considered abnormal in people at high risk of developing ASCVD. As a result, the "Guidelines for the prevention and treatment of dyslipidemia" were adapted into the "Chinese guideline for Lipid Management" (henceforth referred to as the new guidelines) by an Experts' committee after careful deliberation. The new guidelines still recommend LDL-C as the primary target for lipid control, with cardiovascular disease (CVD) risk stratification to determine its target value. These guidelines recommend that moderate intensity statin therapy in adjunct with a heart-healthy lifestyle, be used as an initial line of treatment, followed by cholesterol absorption inhibitors or/and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, as necessary. The new guidelines provide guidance for lipid management across various age groups, from children to the elderly. The aim of these guidelines is to comprehensively improve the management of lipids and promote the prevention and treatment of ASCVD by guiding clinical practice.

Dietary fat quality impacts metabolic impairments of type 2 diabetes risk differently in male and female CD-1® mice

Metabolic impairments associated with type 2 diabetes, including insulin resistance and loss of glycaemic control, disproportionately impact the elderly. Lifestyle interventions, such as manipulation of dietary fat quality (i.e. fatty acid (FA) composition), have been shown to favourably modulate metabolic health. Yet, whether or not chronic consumption of beneficial FAs can protect against metabolic derangements and disease risk during ageing is not well defined. We sought to evaluate whether long-term dietary supplementation of fish-, dairy- or echium-derived FAs to the average FA profile in a U.S. American diet may offset metabolic impairments in males and females during ageing. One-month-old CD-1^® mice were fed isoenergetic, high-fat (40 %) diets with the fat content composed of either 100 % control fat blend (CO) or 70 % CO with 30 % fish oil, dairy fat or echium oil for 13 months. Every 3 months, parameters of glucose homoeostasis were evaluated via glucose and insulin tolerance tests. Glucose tolerance improved in males consuming a diet supplemented with fish oil or echium oil as ageing progressed, but not in females. Yet, females were more metabolically protected than males regardless of age. Additionally, Spearman correlations were performed between indices of glucose homoeostasis and previously reported measurements of diet-derived FA content in tissues and colonic bacterial composition, which also revealed sex-specific associations. This study provides evidence that long-term dietary fat quality influences risk factors of metabolic diseases during ageing in a sex-dependent manner; thus, sex is a critical factor to be considered in future dietary strategies to mitigate type 2 diabetes risk.

The Effect of Fish Oil-Based Foods on Lipid and Oxidative Status Parameters in Police Dogs

The synthesis, degradation, and reconstruction of the cell membrane as a metabolic pathway of phospholipids is a constant and dynamic process. Fatty acids as bioactive lipid components of plasma and erythrocyte phospholipids as structural lipids have biological roles in the integrity of cell membranes. Fatty acids, depending on the chain length, the degree of saturation, and the synthesis pathways, can alleviate inflammation and oxidative stress caused by excessive exercise. Considering that changing food intake or diet can influence fatty acid phospholipid metabolism, our study aimed to determine the potential benefits of fish-based diets in working (police) dogs undergoing intensive training concerning bioactive lipids such as fatty acids, phospholipids of plasma, and erythrocytes. Fatty acid esters’ composition of plasma and erythrocyte phospholipids as a bioactive lipids, in addition to markers of oxidative stress and metabolic parameters, were analysed by GC chromatography. The food was well tolerated by all dogs, and the compliance to the diet was high throughout the study. After the treatment with fish-based food, blood glucose, total, and LDL cholesterol levels were significantly reduced, indicating positive biochemical profiles of dogs. Correlations of fatty acid phospholipid compositions between plasma and erythrocytes have shown that both plasma and erythrocytes could represent markers of omega-3 eicosapentaenoic and docosahexaenoic acid intake levels in dogs. Morover, fish-based food supplementation caused a significant reduction in lipid peroxidation markers. The enrichment of dogs’ diets with marine fish could improve oxidative status and improve roles and status of bioactive lipids, such as membrane phospholipids and fatty acids, as its components in plasma and erythrocytes in police dogs exposed to intensive exercise.

Hepatoprotective and Anti-Obesity Properties of Sardine By-Product Oil in Rats Fed a High-Fat Diet

Excess lipid intake can trigger liver lipid accumulation and oxidative responses, which can lead to metabolic disturbances and contribute to hepatic steatosis and obesity and increase the risk of cardiovascular disease. Production of fish oil rich in omega-3 is a good opportunity for valorizing fish by-products in the therapeutic field. In this study, we explored the effects of oil from Sardina pilchardus by-products on cardiometabolic and oxidative disorders caused by toxic effects of excess lipids in obese rats. Three groups of obese rats received either 20% sardine by-product oil (SBy-Ob-HS; experimental group), 20% fillet oil (SF-Ob-HS; positive control group), or a high-fat diet (Ob-HS). Normal weight rats received a standard diet (normal). There was a significant decrease in serum total cholesterol (TC), triacylglycerols (TG), and insulin concentrations in the SBy-Ob-HS group compared with the SF-Ob-HS group. Compared with the Ob-HS group, TC and TG, glycemia, glycosylated hemoglobin, and insulinemia were decreased in the SBy-Ob-HS (more notably) and SF-Ob-HS groups. Furthermore, hepatic lipids, low density lipoprotein-cholesterol (C), the non-esterified cholesterol/phos-pholipids ratio, serum transaminases activities and lipid peroxidation were lower and serum high density lipoproteins-C were higher in the SBy-Ob-HS and SF-Ob-HS groups compared with the Ob-HS group. Serum isoprostane concentrations were reduced in the SBy-Ob-HS (more notably) and SF-Ob-HS groups compared with the Ob-HS and normal groups. The activities of antioxidant enzymes in tissues were enhanced, particularly in the by-product oil group. The oil extracted from by-products demonstrate anti-obesity properties (hypolipemiant, hepatoprotective, antiatherogenic, antidiabetic, and antioxidant) that may be beneficial for the management of obesity and its complications, such as hepatic steatosis.

Nutritional adjuvants with antioxidant properties in the treatment of canine leishmaniasis

Clinical improvement of dogs treated for canine leishmaniasis (CanL) requires reducing Leishmania infantum loads, which depend on intracellular oxidant compounds to destroy the parasite. However, oxidative species' excess and antioxidants consumption can culminate in oxidative stress, resulting in increased, widespread inflammation. We aimed to evaluate if early or late addition of nutritional adjuvants (NAs) - omega-3 polyunsaturated fatty acids and B vitamins - to anti-Leishmania drugs (ALDs) in the treatment of CanL would be clinically beneficial. For that, serum biomarkers including oxidative stress parameters were analyzed during 12 months in dogs allocated to two treatment groups: (G1) NAs administered from 30 days prior to the beginning of ALDs; and (G2) NAs administered from 61 days after the beginning of ALDs. Both G1 and G2 continued to receive NAs until the 12th month. The ALDs administered were metronidazole associated with ketoconazole (40 days), followed by allopurinol from day 41 until the 12th month. G1 exhibited superior inflammation control, with reduced globulins (p = 0.025), specific anti-Leishmania immunoglobulins (p = 0.016), total protein (p = 0.031), and an increased serum albumin/globulin ratio (p = 0.033), compared to G2. The early use of NAs associated with ALDs is clinically beneficial in treating dogs with CanL.

Changes in lipoprotein particle subclasses, standard lipids, and apolipoproteins after supplementation with n-3 or n-6 PUFAs in abdominal obesity: A randomized double-blind crossover study

BACKGROUND & AIMS

Marine-derived omega-3 (n-3) polyunsaturated fatty acids (PUFAs), mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), lower circulating levels of triacylglycerols (TAGs), and the plant-derived omega-6 (n-6) PUFA linoleic acid (LA) may reduce cholesterol levels. Clinical studies on effects of these dietary or supplemental PUFAs on other blood fat fractions are few and have shown conflicting results. This study aimed to determine effects of high-dose supplemental n-3 (EPA + DHA) and n-6 (LA) PUFAs from high-quality oils on circulating lipoprotein subfractions and standard lipids (primary outcomes), as well as apolipoproteins, fatty acids, and glycemic control (secondary outcomes), in females and males with abdominal obesity.

METHODS

This was a randomized double-blind crossover study with two 7-wk intervention periods separated by a 9-wk washout phase. Females (n = 16) were supplemented with 3 g/d of EPA + DHA (TAG fish oil) or 15 g/d of LA (safflower oil), while males (n = 23) received a dose of 4 g/d of EPA + DHA or 20 g/d of LA. In fasting blood samples, we investigated lipoprotein particle subclasses by nuclear magnetic resonance spectroscopy, as well as standard lipids, apolipoproteins, fatty acid profiles, and glucose and insulin. Data were analyzed by linear mixed-effects modeling with 'subjects' as the random factor.

RESULTS

The difference between interventions in relative change scores was among the lipoprotein subfractions significant for total very-low-density lipoproteins (VLDLs) (n-3 vs. n-6: -38%∗ vs. +16%, p < 0.001; ∗: significant within-treatment change score), large VLDLs (-58%∗ vs. -0.91%, p < 0.001), small VLDLs (-57%∗ vs. +41%∗, p < 0.001), total low-density lipoproteins (LDLs) (+5.8%∗ vs. -4.3%∗, p = 0.002), large LDLs (+23%∗ vs. -2.1%, p = 0.004), total high-density lipoproteins (HDLs) (-6.0%∗ vs. +3.7%, p < 0.001), large HDLs (+11%∗ vs. -5.3%, p = 0.001), medium HDLs (-24%∗ vs. +6.2%, p = 0.030), and small HDLs (-9.9%∗ vs. +9.6%∗, p = 0.002), and among standard lipids for TAGs (-16%∗ vs. -2.6%, p = 0.014), non-esterified fatty acids (-19%∗ vs. +5.5%, p = 0.033), and total cholesterol (-0.28% vs. -4.4%∗, p = 0.042). A differential response in relative change scores was also found for apolipoprotein (apo)B (+0.40% vs. -6.0%∗, p = 0.008), apoA-II (-6.0%∗ vs. +1.5%, p = 0.001), apoC-II (-11%∗ vs. -1.7%, p = 0.025), and apoE (+3.3% vs. -3.8%, p = 0.028).

CONCLUSIONS

High-dose supplementation of high-quality oils with n-3 (EPA + DHA) or n-6 (LA) PUFAs was followed by reductions in primarily TAG- or cholesterol-related markers, respectively. The responses after both interventions point to changes in the lipoprotein-lipid-apolipoprotein profile that have been associated with reduced cardiometabolic risk, also among people with TAG or LDL-C levels within the normal range.

REGISTRATION

Registered under ClinicalTrials.gov Identifier: NCT02647333.

CLINICAL TRIAL REGISTRATION

Registered at https://clinicaltrials.gov/ct2/show/NCT02647333.

A Whole-Diet Approach Affects Not Only Fasting but Also Postprandial Cardiometabolic Risk Markers in Overweight and Obese Adults: A Randomized Controlled Trial

BACKGROUND

Current dietary recommendations for cardiovascular disease (CVD) prevention focus more on dietary patterns than on single nutrients. However, randomized controlled trials using whole-diet approaches to study effects on both fasting and postprandial CVD risk markers are limited.

OBJECTIVE

This randomized parallel trial compared the effects of a healthy diet (HD) with those of a typical Western diet (WD) on fasting and postprandial CVD risk markers in overweight and obese adults.

METHODS

After a 2-wk run-in period, 40 men and women (50-70 y; BMI: 25-35 kg/m2) consumed the HD (high in fruit and vegetables, pulses, fibers, nuts, fatty fish, polyunsaturated fatty acids; low in salt and high-glycemic carbohydrates; n = 19) or the WD (less fruit, vegetables, and fibers; no nuts and fatty fish; and more saturated fatty acids and simple carbohydrates; n = 21) for 6 wk. Fasting and postprandial cardiometabolic risk markers were assessed as secondary outcome parameters during a 5-h mixed-meal challenge, and a per protocol analysis was performed using 1-factor ANCOVA or linear mixed models.

RESULTS

Differences in diet-induced changes are expressed relative to the HD group. Changes in fasting plasma total cholesterol (-0.57 ± 0.12 mmol/L, P < 0.001), LDL cholesterol (-0.41 ± 0.12 mmol/L, P < 0.01), apolipoprotein B100 (-0.09 ± 0.03 g/L, P < 0.01), and apolipoprotein A1 (-0.06 ± 0.03 g/L, P = 0.05) were significantly different between the diet groups. Changes in postprandial plasma triacylglycerol (diet × time, P < 0.001) and apolipoprotein B48 (P < 0.01) differed significantly between the groups with clear improvements on the HD, although fasting triacylglycerols (-0.24 ± 0.13 mmol/L, P = 0.06) and apolipoprotein B48 (1.04 ± 0.67 mg/L, P = 0.40) did not. Significant differences between the diets were also detected in fasting systolic (-6.9 ± 3.1 mmHg, P < 0.05) and 24-h systolic (-5.0 ± 1.7 mmHg, P < 0.01) and diastolic (-3.3 ± 1.1 mmHg, P < 0.01) blood pressure.

CONCLUSION

A whole-diet approach targeted multiple fasting and postprandial CVD risk markers in overweight and obese adults. In fact, the postprandial measurements provided important additional information to estimate CVD risk. This trial is registered at clinicaltrials.gov as NCT02519127.

Human skeletal muscle metabolic responses to 6 days of high-fat overfeeding are associated with dietary n-3PUFA content and muscle oxidative capacity

Understanding human physiological responses to high-fat energy excess (HFEE) may help combat the development of metabolic disease. We aimed to investigate the impact of manipulating the n-3PUFA content of HFEE diets on whole-body and skeletal muscle markers of insulin sensitivity. Twenty healthy males were overfed (150% energy, 60% fat, 25% carbohydrate, 15% protein) for 6 d. One group (n = 10) received 10% of fat intake as n-3PUFA rich fish oil (HF-FO), and the other group consumed a mix of fats (HF-C). Oral glucose tolerance tests with stable isotope tracer infusions were conducted before, and following, HFEE, with muscle biopsies obtained in basal and insulin-stimulated states for measurement of membrane phospholipids, ceramides, mitochondrial enzyme activities, and PKB and AMPKα2 activity. Insulin sensitivity and glucose disposal did not change following HFEE, irrespective of group. Skeletal muscle ceramide content increased following HFEE (8.5 ± 1.2 to 12.1 ± 1.7 nmol/mg, p = .03), irrespective of group. No change in mitochondrial enzyme activity was observed following HFEE, but citrate synthase activity was inversely associated with the increase in the ceramide content (r=-0.52, p = .048). A time by group interaction was observed for PKB activity (p = .003), with increased activity following HFEE in HF-C (4.5 ± 13.0mU/mg) and decreased activity in HF-FO (-10.1 ± 20.7 mU/mg) following HFEE. Basal AMPKα2 activity increased in HF-FO (4.1 ± 0.6 to 5.3 ± 0.7mU/mg, p = .049), but did not change in HF-C (4.6 ± 0.7 to 3.8 ± 0.9mU/mg) following HFEE. We conclude that early skeletal muscle signaling responses to HFEE appear to be modified by dietary n-3PUFA content, but the potential impact on future development of metabolic disease needs exploring.

Chemical Composition of Urtica simensis Grown in Different Regions of Ethiopia

Leaf samples of Urtica simensis collected from different locations of Ethiopia were analyzed for their proximate compositions, total phenolic and flavonoid contents, antioxidant activities, and fatty acid profiles. The proximate analysis results revealed the presence of ash in the range 17.2–24.3%, crude fat 3.19–3.50%, crude protein 3.42–6.38%, crude fiber 9.37–14.0%, and carbohydrate 56.7–63.7%. The determined total polyphenols, flavonoids, and antioxidant activities ranged 2.18–4.84 mg gallic acid, 1.35–4.46 mg catechin, and 1.58–3.36 mg ascorbic acid, respectively, equivalents per gram of dry sample. High variability was observed for polyphenol and flavonoid contents while only random variation was observed for crude fat and carbohydrate among samples from different locations. In addition, the fatty acid profiles of the leaves were analyzed by using gas chromatography coupled with mass spectrometry. A total of 16 different fatty acids were detected in the samples. Linolenic, palmitic, and linoleic acids were the major fatty acids with average compositions of 36.6, 20.7, and 15.5%, respectively, of the total fatty acid. The result of this study revealed that the carbohydrate and ash contents of leaves of Urtica simensis are exceptionally high to make the leaves a significant source of the dietary important chemicals. Additionally, the lipid fraction of the leaves was found to be rich in essential fatty acids (α-linolenic and linoleic acids) that are critically required in the human diet.

Health Benefits of Whey or Colostrum Supplementation in Adults ≥35 Years; a Systematic Review

Food-health claims are an important method of translating nutrition research to consumers. Whey and colostrum are thought to exert health benefits to adults, but it is unclear what measurable, objective health benefits they impart. This review aimed to identify the objective health benefits of bovine whey or colostrum-based beverages to healthy adults aged ≥35 years to substantiate a food-health claim. Seven databases were systematically searched. Eligible articles were RCTs that involved healthy adults aged ≥35 years, consuming whey or colostrum in beverage form and measuring objective health markers. Quality assessment and data extraction was conducted in duplicate. The searches identified 9943 papers and 16 were included in this review; 13 studies, reported across 15 papers, related to whey, one study to colostrum. The outcomes identified were body composition, bone mineral density, biochemical markers, such as blood glucose and lipids, and muscle strength and synthesis. Heterogeneous outcomes, high risk of bias and inconsistent findings resulted in inconclusive evidence to substantiate a food-health claim. Clearer reporting and consensus on a minimum set of objective measures would allow for more robust recommendations regarding food-health claims. Protecting consumers from misleading health claims will require collaboration between regulators, researchers, and the food industry.

Lipid composition modulates the intestine digestion rate and serum lipid status of different edible oils: a combination of in vitro and in vivo studies

The objective of the present study was to investigate the connections between lipid compositions and the digestion and absorption differences of different lipids. Five typical edible oils (palm oil, PO; leaf lard oil, LO; rapeseed oil, RO; sunflower oil, SO; linseed oil, LINO) were selected to conduct in vitro digestion experiments considering the lipid digestion extent and hydrolysis rate before analyzing the fatty acid composition and TAG profiles using GC and UHPLC-Q-TOF-MS/MS. Meanwhile, the postprandial lipid absorption status after gavage administration was examined in adult male Sprague-Dawley rats with respect to serum lipid profiles. The results showed that the maximum FFA release extent decreased in the order: PO > RO > LINO > SO > LO, and the FFA release apparent constants were PO > SO ≈ RO > LO ≈ LINO. This suggested that the fatty acid species and the location of fatty acids within TAG molecules could significantly affect the lipid digestion fates in the gastrointestinal tract, and short chain saturated fatty acids located at the Sn-1, 3 position could favor the lipid digestion process. PO and LO were both shown to be more likely to affect the serum TG levels and LDL-C : HDL-C ratio compared with RO, SO and LINO. Different fatty acids displayed different correlations with serum lipid profiles when examined by Pearson correlation analysis. This suggested that fatty acid composition and TAG profiles may influence first the digestion rate and then the serum lipid profiles. This further confirmed that lipid composition could modulate the digestion and absorption status under the gastrointestinal conditions. These findings may provide some basic understanding of the connections between lipid composition and their functional difference.

Effect of omega-3 fatty acid plus vitamin E Co-Supplementation on lipid profile: A systematic review and meta-analysis

BACKGROUND

Dyslipidemia is linked to chronic inflammation, which in return leads to a set of chronic disorders. Omega-3 fatty acids have been reported to reduce inflammation. Furthermore, Vitamin E is a fat-soluble vitamin which has antioxidant and anti-inflammatory effects. Vitamin E and omega-3 fatty acids co-supplementations may be more effective than the single supplementation in control dyslipidemia. Therefore, we designed and conducted the current systematic review and meta-analysis to investigate the effect of co-supplementation of vitamin E and omega-3 fatty acids on the lipid profile.

METHODS

A comprehensive search for studies published between January 1990 and July 2018 was performed. The initial search extracted 3015 potentially relevant articles. After studying these publications, 9 RCTs were potentially eligible and retrieved in full text.

RESULTS

The meta-analysis indicate that on total cholesterol, HDL, LDL and triglyceride individually did not show any significant difference between intervention and control groups, but vitamin E an omega-3 fatty acids co-supplementations significantly reduce VLDL levels.

CONCLUSIONS

Based on the available evidence, omega-3 fatty acid and vitamin E co-supplementation can reduce VLDL, although its effect on other lipid profile parameters requires more well-designed studies.

Reprint of: Marine OMEGA-3 fatty acids in the prevention of cardiovascular disease

Omega-6 (ω6) and omega-3 (ω3) fatty acids are two classes of dietary polyunsaturated fatty acids derived from linoleic acid (18:2ω6) and α-linolenic acid (18:3ω3), respectively. Enzymatic metabolism of linoleic and α-linolenic acids generates arachidonic acid (20:4ω6) and eicosapentaenoic acid (20:5ω3; EPA), respectively, both of which are substrates for enzymes that yield eicosanoids with multiple and varying physiological functions. Further elongation and desaturation of EPA yields the 22-carbon fatty acid docosahexaenoic acid (22:6ω3; DHA). The main dietary source of EPA and DHA for human consumption is fish, especially oily fish. There is considerable evidence that EPA and DHA are protective against cardiovascular disease (heart disease and stroke), particularly in individuals with pre-existing disease. ω3 Fatty acids benefit multiple risk factors including blood pressure, blood vessel function, heart function and blood lipids, and they have antithrombotic, anti-inflammatory and anti-oxidative actions. ω3 Fatty acids do not adversely interact with medications. Supplementation with ω3 fatty acids is recommended in individuals with elevated blood triglyceride levels and patients with coronary heart disease. A practical recommendation for the general population is to increase ω3 fatty acid intake by incorporating fish as part of a healthy diet that includes increased fruits and vegetables, and moderation of salt intake. Health authorities recommend the general population should consume at least two oily fish meals per week.

Very long-chain n-3 fatty acids and human health: fact, fiction and the future

EPA and DHA appear to be the most important n-3 fatty acids, but roles for n-3 docosapentaenoic acid are now also emerging. Intakes of EPA and DHA are usually low, typically below those recommended. Increased intakes result in higher concentrations of EPA and DHA in blood lipids, cells and tissues. Increased content of EPA and DHA modifies the structure of cell membranes and the function of membrane proteins. EPA and DHA modulate the production of lipid mediators and through effects on cell signalling can alter the patterns of gene expression. Through these mechanisms, EPA and DHA alter cell and tissue responsiveness in a way that often results in more optimal conditions for growth, development and maintenance of health. DHA has vital roles in brain and eye development and function. EPA and DHA have a wide range of physiological roles, which are linked to certain health or clinical benefits, particularly related to CVD, cancer, inflammation and neurocognitive function. The benefits of EPA and DHA are evident throughout the life course. Future research will include better identification of the determinants of variation of responses to increased intake of EPA and DHA; more in-depth dose-response studies of the effects of EPA and DHA; clearer identification of the specific roles of EPA, docosapentaenoic acid and DHA; testing strategies to enhance delivery of n-3 fatty acids to the bloodstream; and exploration of sustainable alternatives to fish-derived very long-chain n-3 fatty acids.

Marine OMEGA-3 fatty acids in the prevention of cardiovascular disease

Omega-6 (ω6) and omega-3 (ω3) fatty acids are two classes of dietary polyunsaturated fatty acids derived from linoleic acid (18:2ω6) and α-linolenic acid (18:3ω3), respectively. Enzymatic metabolism of linoleic and α-linolenic acids generates arachidonic acid (20:4ω6) and eicosapentaenoic acid (20:5ω3; EPA), respectively, both of which are substrates for enzymes that yield eicosanoids with multiple and varying physiological functions. Further elongation and desaturation of EPA yields the 22-carbon fatty acid docosahexaenoic acid (22:6ω3; DHA). The main dietary source of EPA and DHA for human consumption is fish, especially oily fish. There is considerable evidence that EPA and DHA are protective against cardiovascular disease (heart disease and stroke), particularly in individuals with pre-existing disease. ω3 Fatty acids benefit multiple risk factors including blood pressure, blood vessel function, heart function and blood lipids, and they have antithrombotic, anti-inflammatory and anti-oxidative actions. ω3 Fatty acids do not adversely interact with medications. Supplementation with ω3 fatty acids is recommended in individuals with elevated blood triglyceride levels and patients with coronary heart disease. A practical recommendation for the general population is to increase ω3 fatty acid intake by incorporating fish as part of a healthy diet that includes increased fruits and vegetables, and moderation of salt intake. Health authorities recommend the general population should consume at least two oily fish meals per week.

Membrane Lipid Replacement for chronic illnesses, aging and cancer using oral glycerolphospholipid formulations with fructooligosaccharides to restore phospholipid function in cellular membranes, organelles, cells and tissues

Membrane Lipid Replacement is the use of functional, oral supplements containing mixtures of cell membrane glycerolphospholipids, plus fructooligosaccharides (for protection against oxidative, bile acid and enzymatic damage) and antioxidants, in order to safely replace damaged, oxidized, membrane phospholipids and restore membrane, organelle, cellular and organ function. Defects in cellular and intracellular membranes are characteristic of all chronic medical conditions, including cancer, and normal processes, such as aging. Once the replacement glycerolphospholipids have been ingested, dispersed, complexed and transported, while being protected by fructooligosaccharides and several natural mechanisms, they can be inserted into cell membranes, lipoproteins, lipid globules, lipid droplets, liposomes and other carriers. They are conveyed by the lymphatics and blood circulation to cellular sites where they are endocytosed or incorporated into or transported by cell membranes. Inside cells the glycerolphospholipids can be transferred to various intracellular membranes by lipid globules, liposomes, membrane-membrane contact or by lipid carrier transfer. Eventually they arrive at their membrane destinations due to 'bulk flow' principles, and there they can stimulate the natural removal and replacement of damaged membrane lipids while undergoing further enzymatic alterations. Clinical trials have shown the benefits of Membrane Lipid Replacement in restoring mitochondrial function and reducing fatigue in aged subjects and chronically ill patients. Recently Membrane Lipid Replacement has been used to reduce pain and other symptoms as well as removing hydrophobic chemical contaminants, suggesting that there are additional new uses for this safe, natural medicine supplement. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá.

Effect of Olive Oil-Fried Sardine Consumption on Liver Lipid Composition and Fatty Acid Cholesterol Esterification in Hypercholesterolemic Rats

PUFA n-3 diets have hypolipemic and cardiovascular protection properties, however their effects on liver lipids are not well established. This work aimed to find out the acceptability and effects of diets containing olive oil-fried sardines on serum cholesterol, liver lipid and fatty acids profile in hypercholesterolemic growing Wistar rats. Hypercholesterolemia was induced for three weeks by a casein plus DL-methionine, olive oil and cholesterol plus bovine bileas cholesterol-raising agent. Rats were later transferred for three weeks to semisynthetic diets containing casein plus DL-methionine and olive oil (CO), casein plus DLmethionine, olive oil and the cholesterol-raising agent (COC), sardines fried in olive oil (S), and sardines friedin olive oil and the cholesterol-raising agent (SC). SC or S diets were well accepted by the rats. The SC-diet markedly blocked and reversed the hypercholesterolemic induction of the cholesterol-raising agent. The cholesterol withdrawal decreased serum cholesterol in CO and S dietsby decreasing the serum non-HDL-cholesterol content but the S-diet totally normalised the serum cholesterol. Fried sardines did not change the triacylglycerol, free, esterified and total cholesterol contents of liver. Although long PUFA n-6 and PUFA n-3 were decreased by the dietary cholesterol, olive oil-fried sardine consumption maintained the docosahexaenoic acid and thedocosahexaenoic acid/linolenic acid ratio in liver and cholesterol ester fraction at a high level. Olive oil fried sardines blocked the hypercholesterolemic effect of the diet containing cholesterol and help normalising lipoprotein profile in a rather short period. The oleic acid esterification of cholesterol was kept high in all experimental diets as a mechanism to maintain the liver cholesterol ester/free cholesterol ratio as high as possible. The fat in the oliveoil-fried sardines was used similarly to the oleic acid by the liver of hypercholesterolemic rats but increased its PUFA n-3 content in the total liver and its cholesterol ester fraction.

Functional Roles of Fatty Acids and Their Effects on Human Health

A variety of fatty acids exists in the diet of humans, in the bloodstream of humans, and in cells and tissues of humans. Fatty acids are energy sources and membrane constituents. They have biological activities that act to influence cell and tissue metabolism, function, and responsiveness to hormonal and other signals. The biological activities may be grouped as regulation of membrane structure and function; regulation of intracellular signaling pathways, transcription factor activity, and gene expression; and regulation of the production of bioactive lipid mediators. Through these effects, fatty acids influence health, well-being, and disease risk. The effects of saturated, cis monounsaturated, ω-6 and ω-3 polyunsaturated, and trans fatty acids are discussed. Although traditionally most interest in the health impact of fatty acids related to cardiovascular disease, it is now clear that fatty acids influence a range of other diseases, including metabolic diseases such as type 2 diabetes, inflammatory diseases, and cancer. Scientists, regulators, and communicators have described the biological effects and the health impacts of fatty acids according to fatty acid class. However, it is now obvious that within any fatty acid class, different members have different actions and effects. Thus, it would seem more appropriate to describe biological effects and health impacts of individual named fatty acids, although it is recognized that this would be a challenge when communicating outside of an academic environment (eg, to consumers).

Secondary hypertriglyceridemia in children and adolescents

Secondary dyslipidemia with predominant hypertriglyceridemia may occur as a consequence of both common and rare causes. After accounting for obesity and associated insulin resistance, clinicians should carefully consider other contributing factors and conditions. Genetic background and causative factors prevail during gestation, infancy, and childhood and continue in adults. Elevations in triglyceride (TG) are associated with transfer of TG to high-density lipoprotein (HDL) and low-density lipoprotein (LDL) resulting in lipolysis, HDL degradation, and formation of atherogenic LDL particles. Defining and treating the underlying cause is the first step toward restoring the lipids and lipoproteins to normal, especially in cases with severe hypertriglyceridemia, who are at risk for acute pancreatitis. Disorders involving the liver, kidney, endocrine, and immune systems and medications need to be considered. Rare diseases such as lipodystrophy and glycogen storage disease are particularly challenging, and there have been promising new developments. Treatment depends on the severity; prevention of acute pancreatitis being a priority in severe cases and lifestyle modification being a foundation for general management followed by targeting TG and predictors of coronary artery disease such as LDL cholesterol and non-HDL cholesterol, when they exceed cutpoints.

Associations between Omega-3 Index increase and triacylglyceride decrease in subjects with hypertriglyceridemia in response to six month of EPA and DHA supplementation

INTRODUCTION

Ingestion of long-chain n-3 PUFA effectively decreases serum triacylglycerol (TAG) levels and increases the Omega-3 Index, defined as the % of EPA and DHA in erythrocyte fatty acids. However, it remains unclear whether there is a relationship between the Omega-3 Index increase (ΔO3I increase) and the TAG level decrease (ΔTAG). We hypothesized that TAG reduction is strongly depended on Omega-3 Index increase.

SUBJECTS AND METHODS

Secondary analyses of data from a former double-blind placebo-controlled trial in which 150 dyslipidemic statin-treated subjects were randomized to four capsules of fish oil daily either as re-esterified TAG or ethyl esters in identical doses (1.01 g EPA+0.67 g DHA) or corn oil as a placebo for a period of six month.

RESULTS

108 subjects fulfilled the criteria of the current study protocol and were included in the analyses. A weak but significant negative correlation between ΔO3I and ΔTAG was observed (r=-0.211, p<0.05). However, the relation between ΔO3I and serum ΔTAG was not linear (coefficients of determination R(2): 0.044). After sub-grouping the study population into Omega-3 Index response groups, the group with a mean ΔO3I of>4% after six months of n-3 PUFA treatment demonstrated the greatest TAG reduction.

DISCUSSION AND CONCLUSIONS

A weak association between Omega-3 Index increase and TAG level decrease was found. This may be explained by highly fluctuating TAG levels, a large inter-individual difference in response of the Omega-3 Index, a cohort of subjects with only slightly elevated TAG levels and high Omega-3 Index values at baseline, and possibly to insufficient statistical power. Since there was no strong association between Omega-3 Index increase and the TAG level decrease, we conclude that changes in serum TAG levels are not a viable substitute for the Omega-3 Index to monitor treatment with EPA and DHA.

The effect of nutritional supplements on serum high-density lipoprotein cholesterol and apolipoprotein A-I

One of the factors contributing to the increased risk of developing premature atherosclerosis is low plasma concentrations of high-density lipoprotein (HDL) cholesterol. Multiple potential mechanisms account for the cardioprotective effects of HDL and its main protein apolipoprotein A-I (apo A-I). Diet has an important role in modulating HDL cholesterol level. The widespread use of nutritional supplements may also alter the biology of HDL. In this review, we discuss the effect of select nutritional supplements on serum HDL cholesterol and apo A-I levels. Some nutritional supplements, such as phytosterols, soy proteins, and black seed extracts, may increase HDL cholesterol levels, while others such as cholic acid and high doses of commonly used antioxidant vitamins may downregulate HDL cholesterol levels and reduce its cardioprotection. Multiple mechanisms are involved in the regulation of HDL levels, so changes in production and clearance of HDL may have different clinical implications. The clinical relevance of the changes in HDL and apo A-I caused by nutrient supplementation needs to be tested in controlled clinical trials.

Clinical Strategies for Managing Dyslipidemias

Dyslipidemia is defined as elevated fasting blood levels of total cholesterol (TC), and its primary lipoprotein carrier—low-density lipoprotein (LDL), triglycerides (TG), or reduced high-density lipoprotein (HDL), alone, or in combination (mixed dyslipidemia). Dyslipidemia is well known to be associated with cardiovascular disease (CVD) risk. All patients with dyslipidemia should initiate therapeutic lifestyle changes to target lifestyle-related factors such as physical inactivity, dietary habits, and obesity. The combination of a proper dietary plan and regular aerobic exercise has been reported to lower TC, LDL-C, and TG by 7% to 18%, while increasing HDL-C by 2% to 18%. Numerous pharmacological therapies are available and aggressive therapy using a HMG-CoA reductase (3-hydroxy-3-methyl-glutaryl coenzyme A reductase) inhibitor (statins) should be initiated if lifestyle therapy is not enough to achieve optimal lipid levels with a primary target of lowering LDL-C levels. Aggressive treatment of dyslipidemia with maximal dosage of statin drugs have been reported to reduce LDL-C by 30% to 60%. If mixed dyslipidemia is present, a combination therapy with statin, niacin, cholestyramine, or fibrates should be initiated to reduce the risk of CVD events. These strategies have been shown to reduce CVD risk and optimize LDL-C levels in primary and secondary prevention of CVD.

Omega-3 fatty acids and cardiovascular disease: epidemiology and effects on cardiometabolic risk factors

Clinical and epidemiological studies provide support that the polyunsaturated omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid from fish and fish oils are cardioprotective, particularly in the setting of secondary prevention.

Fish oil supplementation ameliorates fructose-induced hypertriglyceridemia and insulin resistance in adult male rhesus macaques

Fish oil (FO) is a commonly used supplemental source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), 2 n-3 (ω-3) polyunsaturated fatty acids (PUFAs) that have been shown to have a variety of health benefits considered to be protective against cardiometabolic diseases. Although the effects of EPA and DHA on lipid metabolism have been extensively studied, not all of the metabolic effects of FO-derived n-3 PUFAs have been characterized. Our laboratory recently showed that a high-fructose diet in rhesus monkeys induces the features of metabolic syndrome (MetS) similar to those observed in humans. Thus, we specifically wanted to evaluate the effects of FO in rhesus monkeys fed a high-fructose diet and hypothesized that FO supplementation would mitigate the development of fructose-induced insulin resistance, dyslipidemia, and other cardiometabolic risk factors. In this study, adult monkeys (aged 12-20 y) received either a standard unpurified diet plus 75 g fructose/d (control group; n = 9) or a standard unpurified diet, 75 g fructose/d, and 4 g FO (16% EPA + 11% DHA)/d (treatment group; n = 10) for 6 mo. Importantly, our results showed that daily FO supplementation in the monkeys prevented fructose-induced hypertriglyceridemia and insulin resistance as assessed by intravenous-glucose-tolerance testing (P ≤ 0.05). Moreover, FO administration in the monkeys prevented fructose-induced increases in plasma apolipoprotein (Apo)C3, ApoE, and leptin concentrations and attenuated decreases in circulating adropin concentrations (P ≤ 0.05). No differences between the control and FO-treated monkeys were observed in body weight, lean mass, fat mass, or fasting glucose, insulin, and adiponectin concentrations. In conclusion, FO administration in a nonhuman primate model of diet-induced MetS ameliorates many of the adverse changes in lipid and glucose metabolism induced by chronic fructose consumption.

Lipid Replacement Therapy: a natural medicine approach to replacing damaged lipids in cellular membranes and organelles and restoring function

Lipid Replacement Therapy, the use of functional oral supplements containing cell membrane phospholipids and antioxidants, has been used to replace damaged, usually oxidized, membrane glycerophospholipids that accumulate during aging and in various clinical conditions in order to restore cellular function. This approach differs from other dietary and intravenous phospholipid interventions in the composition of phospholipids and their defense against oxidation during storage, ingestion, digestion and uptake as well as the use of protective molecules that noncovalently complex with phospholipid micelles and prevent their enzymatic and bile disruption. Once the phospholipids have been taken in by transport processes, they are protected by several natural mechanisms involving lipid receptors, transport and carrier molecules and circulating cells and lipoproteins until their delivery to tissues and cells where they can again be transferred to intracellular membranes by specific and nonspecific transport systems. Once delivered to membrane sites, they naturally replace and stimulate removal of damaged membrane lipids. Various chronic clinical conditions are characterized by membrane damage, mainly oxidative but also enzymatic, resulting in loss of cellular function. This is readily apparent in mitochondrial inner membranes where oxidative damage to phospholipids like cardiolipin and other molecules results in loss of trans-membrane potential, electron transport function and generation of high-energy molecules. Recent clinical trials have shown the benefits of Lipid Replacement Therapy in restoring mitochondrial function and reducing fatigue in aged subjects and patients with a variety of clinical diagnoses that are characterized by loss of mitochondrial function and include fatigue as a major symptom. This Article is Part of a Special Issue Entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy.

Dietary n-3 PUFA and CVD: a review of the evidence

Many clinical and epidemiological studies have shown that the polyunsaturated n-3 fatty acids EPA and DHA from fish and fish oils, provide cardiovascular protection, particularly in the setting of secondary prevention. n-3 Fatty acids beneficially influence a number of cardiometabolic risk factors including blood pressure, cardiac function, vascular reactivity and lipids, as well as having anti-platelet, anti-inflammatory and anti-oxidative actions. They do not appear to adversely interact with other medications such as statins and other lipid-lowering drugs or antihypertensive medications. n-3 Fatty acids have gained widespread usage by general practitioners and clinicians in a number of clinical settings such as pregnancy and infant development, secondary prevention in CHD patients, treatment of dyslipidaemias and haemodialysis patients. Small doses are achievable with consumption of two to three oily fish meals per week or via purified encapsulated preparations now readily available. n-3 Fatty acids, particularly when consumed as fish, should be considered an important component of a healthy diet. The present paper reviews the effects of n-3 fatty acids on cardiometabolic risk factors, concentrating particularly on the evidence from randomised controlled studies in human subjects.

Acute appearance of fatty acids in human plasma--a comparative study between polar-lipid rich oil from the microalgae Nannochloropsis oculata and krill oil in healthy young males

Background

The long-chain n-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have human health benefits. Alternatives to fish as sources of EPA and DHA are needed. Oil from the micro-algae Nannochloropsis oculata contains a significant amount of EPA conjugated to phospholipids and glycolipids and no DHA. Krill oil contains EPA and DHA conjugated to phospholipids. We compare the appearance of fatty acids in blood plasma of healthy humans after consuming a high fat meal followed by either algal oil or krill oil.

Methods

Ten healthy males aged 18-45 years consumed a standard high fat (55 g) breakfast followed by either algal oil (providing 1.5 g EPA and no DHA) or krill oil (providing 1.02 g EPA and 0.54 g DHA). All participants consumed both oils in random order and separated by 7 days. Blood samples were collected before the breakfast and at several time points up to 10 hours after taking the oils. Fatty acid concentrations (μg/ml) in plasma were determined by gas chromatography.

Results

Fatty acids derived mainly from the breakfast appeared rapidly in plasma, peaking about 3 hours after consuming the breakfast, and in a pattern that reflected their content in the breakfast. There were time-dependent increases in the concentrations of both EPA and DHA with both algal oil (P < 0.001 for EPA; P = 0.027 for DHA) and krill oil (P < 0.001 for both EPA and DHA). The concentration of EPA was higher with algal oil than with krill oil at several time points. DHA concentration did not differ between oils at any time point. The maximum concentration of EPA was higher with algal oil (P = 0.010) and both the area under the concentration curve (AUC) and the incremental AUC for EPA were greater with algal oil (P = 0.020 and 0.006). There was no difference between oils in the AUC or the incremental AUC for DHA.

Conclusion

This study in healthy young men given a single dose of oil indicates that the polar-lipid rich oil from the algae Nannochloropis oculata is a good source of EPA in humans.

Echium oil reduces plasma triglycerides by increasing intravascular lipolysis in apoB100-only low density lipoprotein (LDL) receptor knockout mice

Echium oil (EO), which is enriched in SDA (18:4 n-3), reduces plasma triglyceride (TG) concentrations in humans and mice. We compared mechanisms by which EO and fish oil (FO) reduce plasma TG concentrations in mildly hypertriglyceridemic male apoB100-only LDLrKO mice. Mice were fed one of three atherogenic diets containing 0.2% cholesterol and palm oil (PO; 20%), EO (10% EO + 10% PO), or FO (10% FO + 10% PO). Livers from PO- and EO-fed mice had similar TG and cholesteryl ester (CE) content, which was significantly higher than in FO-fed mice. Plasma TG secretion was reduced in FO vs. EO-fed mice. Plasma very low density lipoprotein (VLDL) particle size was ordered: PO (63 ± 4 nm) > EO (55 ± 3 nm) > FO (40 ± 2 nm). Post-heparin lipolytic activity was similar among groups, but TG hydrolysis by purified lipoprotein lipase was significantly greater for EO and FO VLDL compared to PO VLDL. Removal of VLDL tracer from plasma was marginally faster in EO vs. PO fed mice. Our results suggest that EO reduces plasma TG primarily through increased intravascular lipolysis of TG and VLDL clearance. Finally, EO may substitute for FO to reduce plasma TG concentrations, but not hepatic steatosis in this mouse model.

[Fish by-products oil corrects dyslipidemia, improves reverse cholesterol transport and stimulates paraoxonase-1 activity in obese rat]

AIM OF THE STUDY

To valorize fish by-products oil by investigating its effects on dyslipidemia, hyperglycemia, reverse cholesterol transport and paraoxonase-1 activity in obese rat.

METHODS

Sixteen male Wistar rats were fed a high fat diet. At 400 ± 10 g, obese rats were randomly divided into two groups: the first received 20% of sardine by-products oil and the second 20% of the edible portion oil. At d28, glycemia and serum lipids concentrations were estimated. High density lipoproteins (HDL2 and HDL3) were separated and their contents and composition in lipids and apolipoproteins were analyzed. Lecithin: cholesterol acyltransferase and paraoxonase-1 activities were assessed.

RESULTS

In group which consumed sardine by-products oil, serum cholesterol and triacylglycerols were reduced (-8% and -36%, respectively). However, glycemia was similar. HDL3-phospholipids, HDL3-unesterified cholesterol and HDL3-apolipoproteins were decreased by 56%, 10% and 12%, respectively. Lecithin: cholesterol acyltransferase activity was increased by 35% and the content of HDL2-cholesteryl esters was elevated by 12%. Serum paraoxonase-1 activity was increased by 25%.

CONCLUSION

In obese rat, sardine by-products oil may have a protective effect against cardiovascular risk by improving the anti-atherogenic metabolic pathway of cholesterol and triacylglycerols. This anti-atherogenic action is particularly enhanced by the increase in paraoxonase-1 activity which protects lipoproteins from oxidation.

Oxidation of marine omega-3 supplements and human health

Marine omega-3 rich oils are used by more than a third of American adults for a wide range of purported benefits including prevention of cardiovascular disease. These oils are highly prone to oxidation to lipid peroxides and other secondary oxidation products. Oxidized oils may have altered biological activity making them ineffective or harmful, though there is also evidence that some beneficial effects of marine oils could be mediated through lipid peroxides. To date, human clinical trials have not reported the oxidative status of the trial oil. This makes it impossible to understand the importance of oxidation to efficacy or harm. However, animal studies show that oxidized lipid products can cause harm. Oxidation of trial oils may be responsible for the conflicting omega-3 trial literature, including the prevention of cardiovascular disease. The oxidative state of an oil can be simply determined by the peroxide value and anisidine value assays. We recommend that all clinical trials investigating omega-3 harms or benefits report the results of these assays; this will enable better understanding of the benefits and harms of omega-3 and the clinical importance of oxidized supplements.

Regulation of lipid metabolism-related gene expression in whole blood cells of normo- and dyslipidemic men after fish oil supplementation

Background

Beneficial effects of omega-3 polyunsaturated fatty acids (n-3 PUFAs) on the lipid levels of dyslipidemic subjects are widely described in the literature. However, the underlying molecular mechanisms are largely unknown. The aim of this study was to investigate the effects of n-3 PUFAs on the expression of lipid metabolism-related genes in normo- and dyslipidemic men to unveil potential genes and pathways affecting lipid metabolism.

Methods

Ten normo- and ten dyslipidemic men were supplemented for twelve weeks with six fish oil capsules per day, providing 1.14 g docosahexaenoic acid and 1.56 g eicosapentaenoic acid. The gene expression levels were determined by whole genome microarray analysis and quantitative real-time polymerase chain reaction.

Results

Several transcription factors (peroxisome proliferator-activated receptor α (PPARα), retinoid X receptor (RXR) α, RXRγ, hepatic nuclear factor (HNF) 6, and HNF1ß) as well as other genes related to triacylglycerol (TG) synthesis or high-density lipoprotein (HDL-C) and cholesterol metabolism (phospholipids transfer protein, ATP-binding cassette sub-family G member 5, 2-acylglycerol O-acyltransferase (MOGAT) 3, MOGAT2, diacylglycerol O-acyltransferase 1, sterol O-acyltransferase 1, apolipoprotein CII, and low-density lipoprotein receptor) were regulated after n-3 PUFA supplementation, especially in dyslipidemic men.

Conclusion

Gene expression analyses revealed several possible molecular pathways by which n-3 PUFAs lower the TG level and increase the HDL-C and low-density lipoprotein level, whereupon the regulation of PPARα appear to play a central role.

Trial registration

ClinicalTrials.gov (ID: NCT01089231)

Fatty acids regulate endothelial lipase and inflammatory markers in macrophages and in mouse aorta: a role for PPARγ

OBJECTIVE

Macrophage endothelial lipase (EL) is associated with increased atherosclerosis and inflammation. Because of their anti-inflammatory properties we hypothesized that n-3 fatty acids, in contrast to saturated fatty acids, would lower macrophages and arterial EL and inflammatory markers.

METHODS AND RESULTS

Murine J774 and peritoneal macrophages were incubated with eicosapentaenoic acid or palmitic acid in the presence or absence of lipopolysaccaride (LPS). LPS increased EL mRNA and protein. Palmitic acid alone or with LPS dose-dependently increased EL mRNA and protein. In contrast, eicosapentaenoic acid dose-dependently abrogated effects of LPS or palmitic acid on increasing EL expression. EL expression closely linked to peroxisome proliferator activated receptor (PPAR)γ expression. Eicosapentaenoic acid blocked rosiglitazone (a PPARγ agonist)-mediated EL activation and GW9662 (a PPARγ antagonist)-blocked palmitic acid-mediated EL stimulation. Eicosapentaenoic acid alone or with LPS blunted LPS-mediated stimulation of macrophage proinflammatory interleukin-6, interleukin-12p40, and toll-like receptor-4 mRNA and increased anti-inflammatory interleukin-10 and mannose receptor mRNA. In vivo studies in low density lipoprotein receptor knockout mice showed that high saturated fat rich diets, but not n-3 diets, increased arterial EL, PPARγ, and proinflammatory cytokine mRNA.

CONCLUSIONS

n-3 fatty acids, in contrast to saturated fatty acids, decrease EL in parallel with modulating pro- and anti-inflammatory markers, and these effects on EL link to PPARγ.

Effects of prescription niacin and omega-3 fatty acids on lipids and vascular function in metabolic syndrome: a randomized controlled trial

The metabolic syndrome includes both dyslipidemia and impaired vascular function. Because extended-release niacin (ERN) and prescription omega-3 acid ethyl-esters (P-OM3) independently improve these characteristics, we tested their effects in combination. Sixty metabolic syndrome subjects were randomized to 16 weeks of treatment on dual placebo, P-OM3 (4g/day), ERN (2 g/day), or combination in a double-blind trial. Lipoprotein subfractions and vascular endpoints were measured and tested using ANCOVA. ERN increased HDL cholesterol by 5.4 mg/dl from baseline (P = 0.04), decreased triglycerides (TG) by 39 mg/dl (−21%, P = 0.003), and decreased the augmentation index, which is a measure of vascular stiffness, by 3.5 units (P = 0.04). P-OM3 reduced TG by 26 mg/dl (−13%, P = 0.04). Combination treatment increased HDL cholesterol by 7.8 mg/dl (P = 002) and decreased TG by 72 mg/dl (−34%) but there was no improvement in vascular stiffness. Detailed analysis of lipoprotein subfractions revealed increased large, bouyant HDL₂ (3.3 mg/dl; P = 0.002) and decreased VLDL₁₊₂ (−32%; P < 0.0001), among subjects treated with combination therapy, that were not present with either therapy alone. ERN and P-OM3 alone improved characteristics of metabolic syndrome; however, whereas subjects on combination therapy did not have improved vascular stiffness, TG and HDL levels improved as did certain lipoprotein subfractions.

Arachidonate 5-lipoxygenase gene variants affect response to fish oil supplementation by healthy African Americans

Arachidonate 5-lipoxygenase (ALOX5) gene variants that are common in people of African ancestry are associated with a differential cardiovascular disease (CVD) risk that may be ameliorated by intake of (n-3) PUFA, such as EPA or DHA. We conducted a double-masked, placebo (PL)-controlled trial of fish oil (FO) supplements to determine if changes in erythrocyte (n-3) PUFA composition, heart rate, blood pressure, and plasma lipid and lipoprotein concentrations are modified by genotype. Participants received 5 g/d FO (2 g EPA, 1 g DHA) or 5 g/d corn/soy oil (PL). A total of 116 healthy adults of African ancestry with selected genotypes (genotypes = "dd," "d5," and "55" with "d" representing the deletion of 1 or 2 Sp1 binding sites in the ALOX5 promoter and "5" indicating the common allele with 5 sites) were enrolled and 98 completed the study. FO caused significant increases (relative to PL) in erythrocyte EPA, DHA, and total (n-3) PUFA and a decrease in the (n-6) PUFA:(n-3) PUFA ratio in the low-CVD risk "d5" and "55" genotypes but not in the high-risk "dd" genotype. Similarly, HDL particle concentration decreased with FO relative to PL in the "d5" and "55" but not "dd" genotypes. The plasma TG concentration decreased significantly with FO relative to PL in the "d5" but not "dd" and "55" genotypes. No changes were seen in LDL particle or cholesterol concentrations, heart rate, or blood pressure. These findings indicate that the efficacy of FO supplements vary by ALOX5 genotype.

Transcriptome-based identification of antioxidative gene expression after fish oil supplementation in normo- and dyslipidemic men

Background

The beneficial effects of omega-3 polyunsaturated fatty acids (n-3 PUFAs), especially in dyslipidemic subjects with a high risk of cardiovascular disease, are widely described in the literature. A lot of effects of n-3 PUFAs and their oxidized metabolites are triggered by regulating the expression of genes. Currently, it is uncertain if the administration of n-3 PUFAs results in different expression changes of genes related to antioxidative mechanisms in normo- and dyslipidemic subjects, which may partly explain their cardioprotective effects. The aim of this study was to investigate the effects of n-3 PUFA supplementation on expression changes of genes involved in oxidative processes.

Methods

Ten normo- and ten dyslipidemic men were supplemented for twelve weeks with fish oil capsules, providing 1.14 g docosahexaenoic acid and 1.56 g eicosapentaenoic acid. Gene expression levels were determined by whole genome microarray analysis and quantitative real-time polymerase chain reaction (qRT-PCR).

Results

Using microarrays, we discovered an increased expression of antioxidative enzymes and a decreased expression of pro-oxidative and tissue enzymes, such as cytochrome P450 enzymes and matrix metalloproteinases, in both normo- and dyslipidemic men. An up-regulation of catalase and heme oxigenase 2 in both normo- and dyslipidemic subjects and an up-regulation of cytochrome P450 enzyme 1A2 only in dyslipidemic subjects could be observed by qRT-PCR analysis.

Conclusions

Supplementation of normo- and dyslipidemic subjects with n-3 PUFAs changed the expression of genes related to oxidative processes, which may suggest antioxidative and potential cardioprotective effects of n-3 PUFAs. Further studies combining genetic and metabolic endpoints are needed to verify the regulative effects of n-3 PUFAs in antioxidative gene expression to better understand their beneficial effects in health and disease prevention.

Trial registration

ClinicalTrials.gov (ID: NCT01089231)

Effect of dietary omega-3 fatty acids on red blood cell lipid composition and plasma metabolites in the cockatiel, Nymphicus hollandicus

Although dietary n-3 fatty acids have been extensively studied in poultry, they have not yet been prospectively investigated in psittacines, despite potential benefits for preventing and treating atherosclerosis, osteoarthritis, and other chronic disease processes. The objectives of this study were to investigate the incorporation of dietary n-3 fatty acids into red blood cells (RBC) and to determine the effects of supplementation of psittacine diets with fish or flax oil on plasma lipids and lipoproteins in the cockatiel. Adult cockatiels were fed a custom-formulated diet containing either 4% (wt/wt, as-fed) beef tallow (CON), 3% fish oil + 1% tallow (FSH), or 3.5% flax oil + 0.5% tallow (FLX; n = 20 per diet group). Baseline measurements were obtained for RBC fatty acid composition, triacylglycerides (TAG), and cholesterol. After 8 to 13 wk on the study diets, plasma chemistry profiles, lipoprotein density profiles, and RBC fatty acid composition were determined. At 8 wk, total plasma cholesterol was least in FSH birds (P < 0.05) and TAG concentrations were less in FSH birds than FLX birds (P < 0.05). Total n-3 fatty acids, docosahexaenoic acid, docosapentaenoic acid, and eicosapentaenoic acid were markedly greater in the RBC of FSH birds than FLX or CON birds (P < 0.05). Alpha linolenic acid was greatest in FLX (P < 0.05). Initial and final BW, and nonlipid plasma chemistry values did not differ among diet groups. No adverse effects of dietary supplementation of cockatiels with 3.5% flax oil or 3% fish oil were observed during the 13-wk feeding period. Although fish and flax oils provided similar total n-3 PUFA to the diets, fish oil caused greater reductions in cholesterol and TAG, and greater total RBC n-3 incorporation. Thus, dietary modification of psittacine diets with long chain n-3 PUFA from fish oil appears safe and may be beneficial to these long-lived companion birds.

Attenuation of niacin-induced prostaglandin D(2) generation by omega-3 fatty acids in THP-1 macrophages and Langerhans dendritic cells

Niacin, also known as nicotinic acid, is an organic compound that has several cardio-beneficial effects. However, its use is limited due to the induction of a variable flushing response in most individuals. Flushing occurs from a niacin receptor mediated generation of prostaglandins from arachidonic acid metabolism. This study examined the ability of docosahexaenoic acid, eicosapentaenoic acid, and omega-3 polyunsaturated fatty acids (PUFAs), to attenuate niacin-induced prostaglandins in THP-1 macrophages. Niacin induced both PGD₂ and PGE₂ generation in a dose-dependent manner. Niacin also caused an increase in cytosolic calcium and activation of cytosolic phospholipase A₂. The increase in PGD₂ and PGE₂ was reduced by both docosahexaenoic acid and eicosapentaenoic acid, but not by oleic acid. Omega-3 PUFAs efficiently incorporated into cellular phospholipids at the expense of arachidonic acid, whereas oleic acid incorporated to a higher extent but had no effect on arachidonic acid levels. Omega-3 PUFAs also reduced surface expression of GPR109A, a human niacin receptor. Furthermore, omega-3 PUFAs also inhibited the niacin-induced increase in cytosolic calcium. Niacin and/or omega-3 PUFAs minimally affected cyclooxygenase-1 activity and had no effect on cyclooxygenase -2 activity. The effects of niacin on PGD₂ generation were further confirmed using Langerhans dendritic cells. Results of the present study indicate that omega-3 PUFAs reduced niacin-induced prostaglandins formation by diminishing the availability of their substrate, as well as reducing the surface expression of niacin receptors. In conclusion, this study suggests that the regular use of omega-3 PUFAs along with niacin can potentially reduce the niacin-induced flushing response in sensitive patients.