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

Mechanisms of action of (n-3) fatty acids

(n-3) PUFA are a family of biologically active fatty acids. The simplest member of this family, α-linolenic acid, can be converted to the more biologically active very long-chain (n-3) PUFA EPA and DHA; this process occurs by a series of desaturation and elongation reactions, with stearidonic acid being an intermediate in the pathway. Biological activity of α-linolenic and stearidonic acids most likely relates to their conversion to EPA. The very long-chain (n-3) PUFA have a range of physiological roles that relate to optimal cell membrane structure and optimal cell function and responses. Thus, (n-3) PUFA play a key role in preventing, and perhaps treating, many conditions of poor health and well-being. The multiple actions of (n-3) PUFA appear to involve multiple mechanisms that connect the cell membrane, the cytosol, and the nucleus. For some actions, (n-3) PUFA appear to act via receptors or sensors, so regulating signaling processes that influence patterns of gene expression. Some effects of (n-3) PUFA seem to involve changes in cell membrane fatty acid composition. Changing membrane composition can in turn affect membrane order, formation of lipid rafts, intracellular signaling processes, gene expression, and the production of both lipid and peptide mediators. Under typical Western dietary conditions, human cells tend to have a fairly high content of the (n-6) fatty acid arachidonic acid. Increased oral intake of EPA and DHA modifies the content of arachidonic acid as well as of EPA and DHA. Arachidonic acid is the substrate for eicosanoids involved in physiology and pathophysiology. The eicosanoids produced from EPA frequently have properties that are different from those that are produced from arachidonic acid. EPA and DHA are also substrates for production of resolvins and protectins, which seem to be biologically extremely potent. Increasing the contents of EPA and DHA in membranes modifies the pattern of production of these different lipid mediators.

Dietary supplementation with n-3 PUFA does not promote weight loss when combined with a very-low-energy diet

Obesity is associated with elevated levels of inflammation and metabolic abnormalities which are linked to CVD. The aim of the present study was to investigate whether long-chain n-3 PUFA (LCn-3PUFA), combined with a very-low-energy diet (VLED), facilitated weight loss and weight maintenance, and improvements in blood lipids and inflammatory mediators. This was a double-blind, randomised, controlled trial with two parallel groups. For 14 weeks, one group consumed 6 × 1 g capsules/d of monounsaturated oil (placebo group, PB), and the other group consumed 6 × 1 g capsules/d of LCn-3PUFA (fish oil group, FO), each comprising 70 mg EPA and 270 mg DHA. Both groups were on VLED for 4 weeks (n 14 PB, n 18 FO), which was then followed by 10 weeks of weight maintenance (n 12 PB, n 17 FO). Fasting blood samples, anthropometric measurements and 3 d food diaries were collected at baseline, at 4 and 14 weeks. A greater-than-2-fold increase occurred in plasma levels of EPA and DHA in the FO group (P < 0·001). At 4 weeks, the mean weight loss was − 6·54 (sd 2·08) kg ( − 6·9 %) for PB and − 6·87 (sd 1·83) kg ( − 7·7 %) for FO. At week 14, after the maintenance phase, there was a further mean decrease in weight, − 1·57 (sd 3·7) kg (1·85 %) for PB and − 1·69 (sd 2·32) kg ( − 1·9 %) for FO. Both groups experienced improved metabolic profiles and there was a significant reduction in fat mass for the FO group at week 14 but not for PB. However, it would appear that supplementation with LCn-3PUFA had no significant effect on weight loss or weight maintenance over the 14 weeks.

Health benefits of n-3 polyunsaturated fatty acids: eicosapentaenoic acid and docosahexaenoic acid

Marine-based fish and fish oil are the most popular and well-known sources of n-3 polyunsaturated fatty acids (PUFAs), namely, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These n-3 PUFAs are known to have variety of health benefits against cardiovascular diseases (CVDs) including well-established hypotriglyceridemic and anti-inflammatory effects. Also, various studies indicate promising antihypertensive, anticancer, antioxidant, antidepression, antiaging, and antiarthritis effects. Moreover, recent studies also indicate anti-inflammatory and insulin-sensitizing effects of these fatty acids in metabolic disorders. Classically, n-3 PUFAs mediate some of these effects by antagonizing n-6 PUFA (arachidonic acid)-induced proinflammatory prostaglandin E₂ (PGE₂) formation. Another well-known mechanism by which n-3 PUFAs impart their anti-inflammatory effects is via reduction of nuclear factor-κB activation. This transcription factor is a potent inducer of proinflammatory cytokine production, including interleukin 6 and tumor necrosis factor-α, both of which are decreased by EPA and DHA. Other evidence also demonstrates that n-3 PUFAs repress lipogenesis and increase resolvins and protectin generation, ultimately leading to reduced inflammation. Finally, beneficial effects of EPA and DHA in insulin resistance include their ability to increase secretion of adiponectin, an anti-inflammatory adipokine. In summary, n-3 PUFAs have multiple health benefits mediated at least in part by their anti-inflammatory actions; thus their consumption, especially from dietary sources, should be encouraged.

Moderate doses of EPA and DHA from re-esterified triacylglycerols but not from ethyl-esters lower fasting serum triacylglycerols in statin-treated dyslipidemic subjects: Results from a six month randomized controlled trial

Recently, in a supplementation study over six months, it has been demonstrated that re-esterified omega-3 fatty acid triacylglycerols (n3-FA-rTAGs) led to a higher increase in omega-3-index compared to identical doses of n3-FA ethyl-esters (n3-FA-EEs), suggesting a better long-term bioavailability. The aim of this study was to examine whether differences occur between the two forms in affecting fasting serum lipid levels. 150 dyslipidemic statin-treated participants were randomized to corn oil as a placebo or fish oil either as rTAG or EE in identical doses (1.01g EPA+0.67g DHA). No changes in total cholesterol, HDL or LDL levels were observed. In the rTAG-group, but not in the EE-group, fasting serum TAG levels were significantly reduced from baseline after three and six months. There was no significant difference between the two n3-FA-groups. However, serum TAG levels were significantly lowered after six months in the rTAG-group compared to the placebo-group in contrast to the EE-group.

Fish oil -- how does it reduce plasma triglycerides?

Long chain omega-3 fatty acids (FAs) are effective for reducing plasma triglyceride (TG) levels. At the pharmaceutical dose, 3.4g/day, they reduce plasma TG by about 25-50% after one month of treatment, resulting primarily from the decline in hepatic very low density lipoprotein (VLDL-TG) production, and secondarily from the increase in VLDL clearance. Numerous mechanisms have been shown to contribute to the TG overproduction, but a key component is an increase in the availability of FAs in the liver. The liver derives FAs from three sources: diet (delivered via chylomicron remnants), de novo lipogenesis, and circulating non-esterified FAs (NEFAs). Of these, NEFAs contribute the largest fraction to VLDL-TG production in both normotriglyceridemic subjects and hypertriglyceridemic, insulin resistant patients. Thus reducing NEFA delivery to the liver would be a likely locus of action for fish oils (FO). The key regulator of plasma NEFA is intracellular adipocyte lipolysis via hormone sensitive lipase (HSL), which increases as insulin sensitivity worsens. FO counteracts intracellular lipolysis in adipocytes by suppressing adipose tissue inflammation. In addition, FO increases extracellular lipolysis by lipoprotein lipase (LpL) in adipose, heart and skeletal muscle and enhances hepatic and skeletal muscle β-oxidation which contributes to reduced FA delivery to the liver. FO could activate transcription factors which control metabolic pathways in a tissue specific manner regulating nutrient traffic and reducing plasma TG. This article is part of a Special Issue entitled Triglyceride Metabolism and Disease.

Plasma lipid profiling across species for the identification of optimal animal models of human dyslipidemia

In an attempt to understand the applicability of various animal models to dyslipidemia in humans and to identify improved preclinical models for target discovery and validation for dyslipidemia, we measured comprehensive plasma lipid profiles in 24 models. These included five mouse strains, six other nonprimate species, and four nonhuman primate (NHP) species, and both healthy animals and animals with metabolic disorders. Dyslipidemic humans were assessed by the same measures. Plasma lipoprotein profiles, eight major plasma lipid fractions, and FA compositions within these lipid fractions were compared both qualitatively and quantitatively across the species. Given the importance of statins in decreasing plasma low-density lipoprotein cholesterol for treatment of dyslipidemia in humans, the responses of these measures to simvastatin treatment were also assessed for each species and compared with dyslipidemic humans. NHPs, followed by dog, were the models that demonstrated closest overall match to dyslipidemic humans. For the subset of the dyslipidemic population with high plasma triglyceride levels, the data also pointed to hamster and db/db mouse as representative models for practical use in target validation. Most traditional models, including rabbit, Zucker diabetic fatty rat, and the majority of mouse models, did not demonstrate overall similarity to dyslipidemic humans in this study.

Stearidonic and eicosapentaenoic acids inhibit interleukin-6 expression in ob/ob mouse adipose stem cells via Toll-like receptor-2-mediated pathways

Increased adipose tissue positively correlates with circulating inflammatory cytokines such as IL-6. We previously reported that adipose stem cells from genetically obese ob/ob mice produce significantly higher levels of IL-6 compared with other cell types such as adipocytes and macrophages within adipose tissue. We also demonstrated that (n-3) PUFA have antiinflammatory effects on adipocyte IL-6 secretion. Based on these findings, we hypothesized that EPA [20:5 (n-3)] and stearidonic acid [SDA, 18:4 (n-3)] would decrease LPS (200 μg/L)-induced IL-6 secretion and IL-6 mRNA content in the adipose stem cells. SDA (100 μmol/L) and EPA (100 μmol/L) significantly reduced LPS-induced IL-6 secretion and decreased IL-6 mRNA expression. To determine the underlying intracellular mechanisms, we tested whether LPS-induced Toll-like-receptor (TLR) 4 and TLR2 expression were modulated by these fatty acids using Western-blot analysis. EPA and SDA suppressed LPS-induced TLR2 but not TLR4 protein expression in the adipose stem cells. Furthermore, SDA and EPA significantly lowered the activation and translocation of NF-κB, a TLR2 downstream signaling target, while protein expression of extracellular signal-regulated kinases-1/2 were unaffected. Collectively, our results suggest that EPA and SDA inhibit LPS-induced IL-6 secretion and IL-6 mRNA expression in the adipose stem cells by decreasing TRL2-mediated signaling pathways.

ATP-binding cassette transporter A1 and HDL metabolism: effects of fatty acids

Ample evidence indicates that dietary fatty acids alter the plasma levels of high-density lipoprotein cholesterol (HDL-C). However, the mechanisms underlying the effects of fatty acids still remain elusive. Recent advances in our understanding of ATP-binding cassette transporter A1 (ABCA1) function and regulation have provided a valuable insight into the mechanisms by which fatty acids may affect plasma HDL-C levels. ABCA1 mediates the assembly of phospholipids and free cholesterol with apolipoprotein A-I, which is a critical step for HDL biogenesis. Studies have shown that unsaturated fatty acids, but not saturated fatty acids, repress the expression of ABCA1 in vitro. Although information on mechanisms for the fatty-acid-mediated regulation of ABCA1 expression is still limited and controversial, recent evidence suggests that unsaturated fatty acids inhibit the expression of ABCA1 at the transcriptional and posttranscriptional levels. The transcriptional repression of ABCA1 expression by unsaturated fatty acids is likely liver X receptor dependent. Evidence also suggests that histone deacetylation may play a role in the repression. Posttranscriptionally, unsaturated fatty acids may facilitate ABCA1 protein degradation, which may involve phosphorylation of ABCA1 by protein kinases. Further studies are warranted to better understand the role of dietary fatty acids in HDL metabolism and their effects on cardiovascular health.

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

BACKGROUND

Consumption of omega-3 fatty acids (FAs) is associated with a reduction in deaths from coronary heart disease, arrhythmia, and sudden death. Although these FAs were originally thought to be antiatherosclerotic, recent evidence suggests that their benefits are related to reducing risk for ventricular arrhythmia and that this may be mediated by a slowed heart rate (HR).

METHODS

The study was conducted in Alaskan Eskimos participating in the Genetics of Coronary Artery Disease in Alaska Natives (GOCADAN) Study, a population experiencing a dietary shift from unsaturated to saturated fats. We compared HR with red blood cell (RBC) FA content in 316 men and 391 women ages 35 to 74 years.

RESULTS

Multivariate linear regression analyses of individual FAs with HR as the dependent variable and specific FAs as covariates revealed negative associations between HR and docosahexaenoic acid (22:6n-3; P = .004) and eicosapentaenoic acid (20:5n-3; P = .009) and positive associations between HR and palmitoleic acid (16:1n-7; P = .021), eicosanoic acid (20:1n9; P = .007), and dihomo-gamma-linolenic acid (DGLA; 20:3n-6; P = .021). Factor analysis revealed that the omega-3 FAs were negatively associated with HR (P = .003), whereas a cluster of other, non-omega-3 unsaturated FAs (16:1, 20:1, and 20:3) was positively associated.

CONCLUSIONS

Marine omega-3 FAs are associated with lower HR, whereas palmitoleic and DGLA, previously identified as associated with saturated FA consumption and directly related to cardiovascular mortality, are associated with higher HR. These relations may at least partially explain the relations between omega-3 FAs, ventricular arrhythmia, and sudden death.

n-3 fatty acids prevent whereas trans-fatty acids induce vascular inflammation and sudden cardiac death

n-3 PUFA have well-recognised cardio-beneficial effects. In contrast, premature coronary deaths are associated with consumption of high levels of trans-fatty acids (TFA). The present study determined the effects of n-3 PUFA and TFA on sudden cardiac death and vascular inflammation. A rat coronary ligation model was used to study the effect of fatty acids on sudden cardiac death, whereas a mouse femoral artery ligation model was used to study compensatory vascular remodelling. Human aortic endothelial cells (HAEC) were utilised for the in vitro studies to investigate expression of inflammatory molecules. Feeding animals an n-3 PUFA-enriched diet caused a sevenfold increase in plasma n-3 PUFA compared with that of the TFA-fed group, whereas a TFA-enriched diet caused a 2.5-fold increase in plasma TFA compared with the n-3 PUFA group. Animals on a TFA diet had a lower survival rate due to sudden cardiac death and exhibited variable degrees of aortic atherosclerotic lesions. Animals on a TFA diet had diminished hindlimb collateral growth, whereas animals on the n-3 PUFA diet exhibited extensive collateral growth about ligated regions. HAEC treated with TFA (trans-18 : 2) showed significantly increased expression of intracellular adhesion molecule-1 and nitrosylation of cellular proteins than those treated with DHA (n-3 PUFA, 22 : 6). The in vivo study demonstrates that, in contrast to TFA, n-3 PUFA improve animal survival after myocardial infarction, prevent development of atherosclerotic lesions and stimulate compensatory vascular remodelling. The in vitro study demonstrates that TFA induce, while n-3 PUFA prevent, vascular inflammation.

Understanding omega-3 polyunsaturated fatty acids

Current intakes of very long-chain omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are low in most individuals living in Western countries. A good natural source of these fatty acids is seafood, especially oily fish. Fish oil capsules contain these fatty acids also. Very long-chain omega-3 fatty acids are readily incorporated from capsules into transport (blood lipids), functional (cell and tissue), and storage (adipose) pools. This incorporation is dose-dependent and follows a kinetic pattern that is characteristic for each pool. At sufficient levels of incorporation, EPA and DHA influence the physical nature of cell membranes and membrane protein-mediated responses, lipid-mediator generation, cell signaling, and gene expression in many different cell types. Through these mechanisms, EPA and DHA influence cell and tissue physiology and the way cells and tissues respond to external signals. In most cases the effects seen are compatible with improvements in disease biomarker profiles or health-related outcomes. As a result, very long-chain omega-3 fatty acids play a role in achieving optimal health and in protection against disease. Long-chain omega-3 fatty acids not only protect against cardiovascular morbidity but also against mortality. In some conditions, for example rheumatoid arthritis, they may be beneficial as therapeutic agents. On the basis of the recognized health improvements brought about by long-chain omega-3 fatty acids, recommendations have been made to increase their intake. The plant omega-3 fatty acid, alpha-linolenic acid (ALA), can be converted to EPA, but conversion to DHA appears to be poor in humans. Effects of ALA on human health-related outcomes appear to be due to conversion to EPA, and since this is limited, moderately increased consumption of ALA may be of little benefit in improving health outcomes compared with increased intake of preformed EPA + DHA.

Dose-response of n-3 polyunsaturated fatty acids on lipid profile and tolerability in mildly hypertriglyceridemic subjects

The n-3 polyunsaturated fatty acids (PUFAs) are known to reduce risk for coronary heart disease partly by altering blood lipids. The purpose of this study was to determine the effect of low doses of n-3 PUFAs on the lipid profile and their tolerability in mildly hypertriglyceridemic subjects. Subjects with a serum triacylglycerol (TG) level between 100 and 300 mg/dL were placed on a corn oil placebo (seven capsules per day; single-blind) for 4 weeks and then randomized to continue seven capsules per day of placebo (n = 49) or one of the following doses of n-3 PUFAs for 20 weeks: 0.5 g (n = 51), 1 g (n = 23), or 2 g (n = 12). During the treatment period, 48-50% of the 1-g and 2-g dose groups reported noticing burping (P < .05), and only about half as many in the 0.5-g group noticed burping. Interestingly, 2% of those assigned to the placebo did report a fishy burping during the study, but this dropped back to nearly 0% by week 20. There was no significant effect for any dosage group on fasting and postprandial serum TG, chylomicron TG, very-low-density lipoprotein-cholesterol, or high-density lipoprotein-cholesterol concentration. However, 1-g and 2-g n-3 PUFA treatments significantly increased total cholesterol and low-density lipoprotein-cholesterol concentration. In addition, all doses of n-3 PUFA treatments significantly increased plasma phospholipid n-3 PUFAs. We conclude that doses of n-3 PUFAs of 0.5-2 g/day in healthy volunteers with above average TG levels did not have beneficial effects on their lipid profiles.

omega-3 oil intake during weight loss in obese women results in remodelling of plasma triglyceride and fatty acids

Previous studies have shown that a combination of weight loss and fish oil supplementation reduce cardiovascular disease and diabetes risks by increasing adiponectin and reducing triacylglyceride concentrations, while weight loss alone significantly improves insulin sensitivity and reduces inflammation. Here, a metabolomic approach, using a combination of (1)H-Nuclear Magnetic Resonance spectroscopy, and gas and liquid chromatography and mass spectrometry, was employed to elucidate the metabolic changes in blood plasma following weight loss and fish oil supplementation. The intervention study was conducted over 24 weeks, with 93 female subjects randomised to one of three groups. Two groups followed a 12-week weight loss program, followed by a 12-week weight maintenance period and were randomised to fish or placebo oil capsules; a control group did not follow the weight loss program and were given placebo oil capsules. Lipid profiles changed dramatically upon fish oil intake and subtly across the two weight loss groups. While the fish oil supplementation increased the proportion of various phospholipid species, previously reported reductions in total triacylglycerides (TAGs) upon fish oil intake were shown to be driven by a reduction in a specific subset of the measured TAGs. This remodelling of triglycerides may represent further beneficial effects of fish oil supplementation. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11306-009-0161-7) contains supplementary material, which is available to authorized users.

Toxicology and safety of DHA

Docosahexaenoic acid (DHA) is a long-chain polyunsaturated fatty acid with activities in both infants and adults. The objective of the current work was to evaluate the published literature concerning the toxicological assessment of DHA-rich oils in animals and the safety profile of DHA consumption in humans. Structured literature searches concerning DHA toxicology and DHA effects on platelet function, lipid levels, oxidative potential, glycemic control, and immune function were conducted. The toxicological profile of DHA derived from single-cell organisms demonstrates that these oils are safe in rats (up to a consumption level of 3290 mg/kg body weight/d) in 90-d toxicology evaluations, as well as in reproductive and developmental toxicology studies. The maximum DHA level in human breast milk exceeds 1% of total fatty acids in high-fish-consuming populations. Consumption of DHA-rich human milk as sole source of nutrition provides approximately 315 mg/d in infants 1-6 months of age, and appears to be a safe level of intake. DHA supplementation studies in adults have employed doses ranging from less than 1 to 7.5 g/d, and have not resulted in any consistent adverse responses in platelet function, lipid levels, in vivo oxidation parameters, glycemic control, or immune function. In conclusion, DHA consumption does not result in consistent adverse events in infants or adults. Safe intake levels may be modeled on DHA intake from human milk in infants, and may be at least as high as the upper doses studied in adults.

Responses of LDL and HDL particle size and distribution to omega-3 fatty acid supplementation and aerobic exercise

The purpose of this investigation was to determine the independent and combined effects of aerobic exercise and omega-3 fatty acid (n-3fa) supplementation on lipid and lipoproteins. Sedentary, normoglycemic, nonsmoking men (n = 11) were assigned to perform rest and exercise before and during n-3fa supplementation. Exercise consisted of 3 consecutive days of treadmill walking at 65% maximum O(2) consumption for 60 min. Supplementation consisted of 42 days of 4.55 g/day of n-3fa. A two-way factorial ANOVA with repeated measures revealed significant reductions in total cholesterol (P = 0.001, -9.2%) and triglyceride (P = 0.007, -32.4%) concentrations postexercise. In addition, exercise increased LDL peak particle size (P = 0.001) from 26.2 to 26.4 nm, but not HDL size. The n-3fa supplementation resulted in a significant shift in the distribution of HDL-cholesterol (HDL-C) carried by HDL(2b+2a) (P = 0.001, 14.2%) and HDL(3a+3b) (P = 0.001, -22.8%), despite no significant changes in lipid and lipoprotein-cholesterol concentrations. The majority of the shift in HDL-C was noted in HDL(2b) (P = 0.001, 20.9%) and HDL(3a) (P < 0.001, -31.0%) particles. There were no combined effects of exercise and n-3fa supplementation on lipids and lipoproteins. Three consecutive days of aerobic exercise reduced triglyceride and total cholesterol concentrations with a concomitant increase in LDL peak particle size. In contrast, n-3fa supplementation shifted HDL-C from HDL(3) particles to HDL(2) particles, despite no significant changes in HDL(2)-C and HDL(3)-C concentrations. Exercise and n-3fa supplementation do not synergistically improve serum lipids and lipoproteins, but rather independently affect the metabolism of lipids and lipoproteins.

Omega-3 polyunsaturated fatty acids and human health outcomes

Current intakes of very long chain omega-3 fatty acids, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are low in most individuals living in Western countries. A good natural source of these fatty acids is seafood, especially oily fish. Fish oil capsules contain these fatty acids too. Very long chain omega-3 fatty acids are readily incorporated from capsules into transport, functional, and storage pools. This incorporation is dose-dependent and follows a kinetic pattern that is characteristic for each pool. At sufficient levels of incorporation, EPA and DHA influence the physical nature of cell membranes and membrane protein-mediated responses, eicosanoid generation, cell signaling and gene expression in many different cell types. Through these mechanisms, EPA and DHA influence cell and tissue physiology, and the way cells and tissues respond to external signals. In most cases, the effects seen are compatible with improvements in disease biomarker profiles or in health-related outcomes. As a result, very long chain omega-3 fatty acids play a role in achieving optimal health and in protection against disease. Long chain omega-3 fatty acids protect against cardiovascular morbidity and mortality, and might be beneficial in rheumatoid arthritis, inflammatory bowel diseases, childhood learning, and behavior, and adult psychiatric and neurodegenerative illnesses. DHA has an important structural role in the eye and brain, and its supply early in life is known to be of vital importance. On the basis of the recognized health improvements brought about by long chain omega-3 fatty acids, recommendations have been made to increase their intake.

Dyslipidemia and Risk of Coronary Heart Disease: Role of Lifestyle Approaches for Its Management

Multiple risk factors have a causative relationship to the etiology of coronary heart disease (CHD). However, it is clear that dyslipidemia plays a central role. The chain of evidence is strongest for elevated levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). An inverse association has also been demonstrated between levels of high-density lipoprotein cholesterol (HDL-C) and its principal apolipoprotein, A-1, and risk of CHD. Elevated levels of fasting triglyceride (TG) also are a predictor of CHD, but the independent contribution of TG is difficult to prove because of its usual association with reduced levels of HDL-C; elevated levels of small, dense, highly-atherogenic LDL particles; and the metabolic syndrome. Elevated fasting levels of non—HDL-C (TC — LDL-C) and apolipoprotein B also are strongly predictive of the risk of CHD. Therapeutic lifestyle changes are important adjuncts to pharmacologic management of dyslipidemia. The purpose of this article is to review these contributions with an emphasis on dietary habits (particularly lipid intake), weight management, and aerobic exercise.

Nonpharmacologic treatment of hypertriglyceridemia: focus on fish oils

Early studies in Greenland Eskimos stimulated interest in evaluating the effect of Omega-3 fatty acids on coronary artery disease. Subsequent studies showed a significant decrease in triglyceride levels in patients receiving high doses of fish oil containing DHA and EPA. Slight increases in LDL were also observed in patients receiving fish oil supplements. These studies have also shown a dose-response effect which persists as long as supplementation continues. Later trials, specifically the Diet and Reinfarction Trial and the Indian Experiment of Infarct Survival, have demonstrated a reduction in cardiac death rates and in the incidence of cardiac symptoms in patients receiving fish oil.

Acute consumption of fish oil improves postprandial VLDL profiles in healthy men aged 50–65 years

Dietary supplementation with fish oil induces beneficial changes in the size and concentration of plasma lipoproteins, although the underlying mechanism is unclear. We have investigated the effect of increasing the amount of fish oil in a single meal on the size and concentration of VLDL, LDL and HDL particles during the postprandial period. Healthy men aged 58 (sd 5) years (n 11) consumed isoenergetic, mixed macronutrient test meals containing either 0·3 g (reference, REF) or 2·2 g (high fish oil, HFO) fish oil in a randomised order, and blood samples were collected over the following 6 h. Plasma lipoprotein size and concentration were measured by NMR spectroscopy. There was a significant interaction effect of time and meal composition on the VLDL, but not on the LDL or HDL, concentration (P = 0·036) and particle size (P = 0·005). Consuming the HFO meal significantly increased the VLDL concentration (P < 0·05) and reduced VLDL particle size (P < 0·05) when compared with the REF meal and baseline. LDL particle size decreased slightly during the postprandial period, but there was no difference between the meals. There was no effect of time or meal composition in the LDL concentration. The HDL concentration decreased and size increased slightly during the postprandial period, but there were no significant differences between the meals. Increased consumption of fish oil induces acute changes in the VLDL, but not in the LDL or HDL, metabolism.

Effects of krill oil on serum lipids of hyperlipidemic rats and human SW480 cells

BACKGROUND

Cardiovascular disease (CVD) and colon cancer incidence are known to be closely related to dietary factors. This article evaluated effects of krill oil (KO) on serum lipids of hyperlipidemia rats and human colon cancer cells (SW480). Serum lipids of rats fed with high fat diet (HFD) and different doses of KO were measured by automatic analyzer. Effect of KO on viability of cells was determined by methyl thiazolyl tetrazolium (MTT) assay.

RESULTS

Except for higher dose group, body weights decreased significantly. Total cholesterol (TC), LDL-cholesterol (LDL-C) of all dose groups, Triglycerides (TG) of low and mid dose groups descended significantly, while there were no significant differences of HDL-cholesterol (HDL-C), compared with control group. Treatment of colon cancer cells with KO also resulted in time-dependent inhibition of cell growth.

CONCLUSION

Our findings indicated that the consumption of KO may provide benefits to control serum lipid levels in certain diseases and inhibit growth of colon cancer cells. Therefore, KO may be a good candidate for development as a functional food and nutraceutical.

Combination of fish oil and fish protein hydrolysate reduces the plasma cholesterol level with a concurrent increase in hepatic cholesterol level in high-fat-fed Wistar rats

OBJECTIVE

This study investigated the potential additive or synergistic effect of fish oil (FO) and fish protein hydrolysate (FPH) on cholesterol concentration in plasma and the liver.

METHODS

Male Wistar rats were fed high-fat diets (30% fat, 20% protein, wt/wt) containing FO (5%), FPH (10%), a combination of FO and FPH, or a high-fat control diet. After 7 wk of feeding, the rats were fasted for 12 h before lipid levels in plasma and the liver and hepatic activities of acyl-coenzyme A:cholesterol acyltransferase, 3-hydroxy-3-methylglutaryl coenzyme A reductase, and fatty acid synthase were measured.

RESULTS

The combination of FO and FPH in the diet profoundly reduced the plasma cholesterol level, mainly due to lowering of high-density lipoprotein cholesterol, whereas the hepatic total cholesterol concentration was elevated compared with control rats and rats fed diets containing FPH or FO alone. The elevated cholesterol concentration in the liver was caused by an increased amount of cholesteryl esters and was in correlation to an increased activity of acyl-coenzyme A:cholesterol acyltransferase. There was a reduced fatty acid synthase activity that could lead to a reduced lipogenesis in the rats fed a combination of FO and FPH.

CONCLUSION

A dietary combination of FO and FPH resulted in lower levels of plasma cholesterol and higher levels of hepatic cholesterol compared with dietary FO or FPH alone. Further studies are warranted to confirm whether the hypocholesterolemic effect was due to a reduced secretion of very low-density lipoprotein from the liver.

Modulation of enzymatic activities by n-3 polyunsaturated fatty acids to support cardiovascular health

Epidemiological evidence from Greenland Eskimos and Japanese fishing villages suggests that eating fish oil and marine animals can prevent coronary heart disease. Dietary studies from various laboratories have similarly indicated that regular fish oil intake affects several humoral and cellular factors involved in atherogenesis and may prevent atherosclerosis, arrhythmia, thrombosis, cardiac hypertrophy and sudden cardiac death. The beneficial effects of fish oil are attributed to their n-3 polyunsaturated fatty acid (PUFA; also known as omega-3 fatty acids) content, particularly eicosapentaenoic acid (EPA; 20:5, n-3) and docosahexaenoic acid (DHA; 22:6, n-3). Dietary supplementation of DHA and EPA influences the fatty acid composition of plasma phospholipids that, in turn, may affect cardiac cell functions in vivo. Recent studies have demonstrated that long-chain omega-3 fatty acids may exert beneficial effects by affecting a wide variety of cellular signaling mechanisms. Pathways involved in calcium homeostasis in the heart may be of particular importance. L-type calcium channels, the Na+-Ca2+ exchanger and mobilization of calcium from intracellular stores are the most obvious key signaling pathways affecting the cardiovascular system; however, recent studies now suggest that other signaling pathways involving activation of phospholipases, synthesis of eicosanoids, regulation of receptor-associated enzymes and protein kinases also play very important roles in mediating n-3 PUFA effects on cardiovascular health. This review is therefore focused on the molecular targets and signaling pathways that are regulated by n-3 PUFAs in relation to their cardioprotective effects.

Polymorphisms in the CD36 gene modulate the ability of fish oil supplements to lower fasting plasma triacyl glycerol and raise HDL cholesterol concentrations in healthy middle-aged men

Five SNPs in the CD36 gene, 25444G>A, 27645del>ins, 30294G>C, -31118G>A and -33137A>G in haplotypic combinations, link to fasting plasma NEFA concentrations. Fish oil lowers TAG concentrations. The influence of CD36 SNPs on hypotriglyceridemic effects is unknown. The study examines how four of the SNPs modify the effects of fish oil on fasting plasma TAG, NEFA, glucose LDL and HDL cholesterol concentrations in 111 healthy, middle-aged, Caucasian men. Subjects consumed habitual diets while taking 6g MaxEPA daily for 12 weeks. TAG decreased from 1.48 mol/l to 0.11 mmol/l, and glucose and HDL rose from 5.92 to 0.15 mmol/l and from 1.27 to 0.04 mmol/l, respectively, irrespective of genotype. NEFA was unaffected. Significant falls in TAG only occurred in individuals with the GG variant of the 25444, 30294, -31118 or -33137 SNPs. The TAG-lowering effects may be via stimulation of CD36 activity in extrahepatic tissue in individuals with the GG variants of these SNPs.

Obesity-related changes in high-density lipoprotein metabolism

Obesity is associated with a 3-or-more-fold increase in the risk of fatal and nonfatal myocardial infarction (1,2,3,4,5,6). The American Heart Association has reclassified obesity as a major, modifiable risk factor for coronary heart disease (7). The increased prevalence of premature coronary heart disease in obesity is attributed to multiple factors (8,9,10). A principal contributor to this serious morbidity is the alterations in plasma lipid and lipoprotein levels. The dyslipidemia of obesity is commonly manifested as high plasma triglyceride levels, low high-density lipoprotein cholesterol (HDLc), and normal low-density lipoprotein cholesterol (LDLc) with preponderance of small dense LDL particles (7,8,9,10). However, there is a considerable heterogeneity of plasma lipid profile in overweight and obese people. The precise cause of this heterogeneity is not entirely clear but has been partly attributed to the degree of visceral adiposity and insulin resistance. The emergence of glucose intolerance or a genetic predisposition to familial combined hyperlipidemia will further modify the plasma lipid phenotype in obese people (11,12,13,14,15).

The potential role of nutritional components in the management of Alzheimer's Disease

Epidemiological evidence linking nutrition to the incidence and risk of Alzheimer Disease is rapidly increasing. The specific nutritional deficiencies in Alzheimer patients may suggest a relative shortage of specific macro- and micronutrients. These include omega-3 fatty acids, several B-vitamins and antioxidants such as vitamins E and C. Recent mechanistic studies in cell systems and animal models also support the idea that nutritional components are able to counteract specific aspects of the neurodegenerative and pathological processes in the brain. In addition, it has been shown that several nutritional components can also effectively stimulate membrane formation and synapse formation as well as improve behavior and cerebrovascular health. The suggested synergy between nutritional components to improve neuronal plasticity and function is supported by epidemiological studies as well as experimental studies in animal models. The ability of nutritional compositions to stimulate synapse formation and effectively reduce Alzheimer Disease neuropathology in these preclinical models provides a solid basis to predict potential to modify the disease process, especially during the early phases of Alzheimer Disease.

HDL-cholesterol modulation and its impact on the management of cardiovascular risk

There is strong epidemiological evidence that HDL-cholesterol (HDL-C) is an independent cardiovascular risk factor. A low HDL-C is a common finding in the general population, and is a feature of metabolic syndrome, the prevalence of which is increasing globally. The importance of HDL-C as a coronary risk factor is generally accepted, and has been incorporated into most of the commonly applied risk engines. There are several causes of a low HDL-C, including rare genetic abnormalities, and more common conditions associated with lifestyle and drug therapy. Not all of these are associated with an increased risk of coronary disease. A better understanding of HDL metabolism and the mechanisms by which it may exert its protective effects has revealed why this may be the case. New therapeutic targets have also been identified that may allow HDL-C to be raised in patients with low levels. However, good clinical endpoint studies are still required to enable the setting of absolute target values for HDL-C in patients at high cardiovascular risk.

Echium oil reduces plasma lipids and hepatic lipogenic gene expression in apoB100-only LDL receptor knockout mice

We tested the hypothesis that dietary supplementation with echium oil (EO), which is enriched in stearidonic acid (SDA; 18:4 n-3), the product of Delta-6 desaturation of 18:3 n-3, will decrease plasma triglyceride (TG) concentrations and result in conversion of SDA to eicosapentaenoic acid (EPA) in the liver. Mildly hypertriglyceridemic mice (apoB100-only LDLrKO) were fed a basal diet containing 10% calories as palm oil (PO) and 0.2% cholesterol for 4 weeks, after which they were randomly assigned to experimental diets consisting of the basal diet plus supplementation of 10% of calories as PO, EO or fish oil (FO) for 8 weeks. The EO and FO experimental diets decreased plasma TG and VLDL lipid concentration, and hepatic TG content compared to PO, and there was a significant correlation between hepatic TG content and plasma TG concentration among diet groups. EO fed mice had plasma and liver lipid EPA enrichment that was greater than PO-fed mice but less than FO-fed mice. Down-regulation of several genes involved in hepatic TG biosynthesis was similar for mice fed EO and FO and significantly lower compared to those fed PO. In conclusion, EO may provide a botanical alternative to FO for reduction of plasma TG concentrations.

Dietary α-linolenic acid and health-related outcomes: a metabolic perspective

α-Linolenic acid (αLNA; 18: 3n-3) is essential in the human diet, probably because it is the substrate for the synthesis of longer-chain, more unsaturatedn-3 fatty acids, principally EPA (20: 5n-3) and DHA (22: 6n-3), which confer important biophysical properties on cell membranes and so are required for tissue function. The extent to which this molecular transformation occurs in man is controversial. The present paper reviews the recent literature on the metabolism of αLNA in man, including the use of dietary αLNA in β-oxidation, recycling of carbon by fatty acid synthesisde novoand conversion to longer-chain PUFA. Sex differences in αLNA metabolism and the possible biological consequences are discussed. Increased consumption of EPA and DHA in fish oil has a number of well-characterised beneficial effects on health. The present paper also reviews the efficacy of increased αLNA consumption in increasing the concentrations of EPA and DHA in blood and cell lipid pools, and the extent to which such dietary interventions might be protective against CVD and inflammation. Although the effects on CVD risk factors and inflammatory markers are variable, where beneficial effects have been reported these are weaker than have been achieved from increasing consumption of EPA+DHA or linoleic acid. Overall, the limited capacity for conversion to longer-chainn-3 fatty acids, and the lack of efficacy in ameliorating CVD risk factors and inflammatory markers in man suggests that increased consumption of αLNA may be of little benefit in altering EPA+DHA status or in improving health outcomes compared with other dietary interventions.

Nutrients: the environmental regulation of cardiovascular gene expression

The complexity of nutrient-gene interactions has led to the development of a new branch in the nutrition sciences, the nutrigenomics. The individual susceptibility to nutrients based on environment --> genotype --> phenotype interplay makes this new research field extremely promising although complex. In this review, we highlight and examine recent findings and the most relevant hypotheses on the role of the diet in the onset and progression of cardiovascular diseases. The effect of unbalanced diets on the cardiovascular system is considered one of the most important risk factors both for ischemic and degenerative myocardial pathologies. The concept that nutrigenomics could help in improving public and personal health is becoming tangible indicating future directions for basic and applied research in the pathophysiology of cardiovascular disease.

Docosahexaenoic acid supplementation improves fasting and postprandial lipid profiles in hypertriglyceridemic men

BACKGROUND

The effects of docosahexaenoic acid (DHA) on the mean size and concentrations of VLDL, LDL, and HDL subclasses have not been previously studied.

OBJECTIVE

We determined the effects of DHA supplementation on the concentrations of apoproteins; large, medium, and small VLDL, LDL, and HDL particles; and the mean diameters of these particles in fasting and postprandial plasma.

DESIGN

Hypertriglyceridemic men aged 39-66 y (n = 34) participated in a double-blind, randomized, placebo-controlled parallel study. They received no supplements for the first 8 d and received either 7.5 g DHA oil/d (3 g DHA/d) or olive oil (placebo) for the last 90 d. Lipoprotein particle diameters and concentrations were measured by nuclear magnetic resonance spectroscopy.

RESULTS

DHA supplementation for 45 d significantly (P < 0.05) decreased concentrations of fasting triacylglycerol (24%), large VLDL (92%), and intermediate-density lipoproteins (53%) and the mean diameter of VLDL particles (11.1 nm). It elevated concentrations of LDL cholesterol (12.6%), small VLDL particles (133%), and large LDL particles (120%) and the mean diameter of LDL particles (0.6 nm) in fasting plasma. Similar changes were observed for area under the curve for postprandial samples (0-6 h); however, the number of small dense LDL particles decreased significantly (21%), and the change in LDL cholesterol was not significant. Continued supplementation with DHA beyond 45 d caused no further changes; placebo treatment altered none of the responses tested.

CONCLUSION

DHA supplementation may improve cardiovascular health by lowering concentrations of triacylglycerols and small, dense LDL particles.

Age- and dose-dependent effects of an eicosapentaenoic acid-rich oil on cardiovascular risk factors in healthy male subjects

Supplementation with fish oils, rich in n-3 polyunsaturated fatty acids, modifies cardiovascular risk factors. However, dose-response relationships are poorly defined and whether similar effects are seen in young and older subjects is not known. This study determined the effect of supplementing the diet of young and older male subjects with different amounts of an eicosapentaenoic acid (EPA)-rich oil. Healthy young (18-42 years) and older (53-70 years) males were randomized to placebo or 1.35, 2.7 or 4.05 g EPA/day for 12 weeks. There was no effect of EPA on blood pressure or on plasma total, LDL or HDL cholesterol. EPA lowered plasma triacylglycerols, with the maximal effect at the lowest dose. Plasma lipoperoxides decreased in all groups. EPA decreased the lag time of copper-induced lipoprotein peroxidation and the ratio of reduced to total glutathione in the older subjects. The highest dose of EPA increased soluble E-selectin in young subjects, while increasing EPA tended to decrease soluble intercellular adhesion molecule 1 in young and older subjects. Young and older males will gain cardiovascular benefit from increased intake of EPA. Young males are unlikely to suffer adverse consequences from high EPA intake, whereas older males may have an increased risk of lipoprotein peroxidation.

HDL Cholesterol: Physiology, Pathophysiology, and Management

Numerous epidemiological studies have identified high-density lipoprotein cholesterol (HDL) to be an independent risk factor for coronary heart disease (CHD). HDL is an emerging therapeutic target that could rival the impact of 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibitors (statins) on LDL and CHD risk reduction. HDL metabolism, HDL kinetics, the concentration of various HDL subclasses, and other genetic factors affecting HDL functionality may all contribute to the anti-atherogenic properties of HDL; thus, standard plasma measurement may not capture the full range of HDL effects. Algorithms have been suggested to treat low HDL levels in subgroups of patients; however, no formal HDL target goals or treatment guidelines have been implemented as there is a lack of strong clinical evidence to support effective pharmacologic therapy for primary risk reduction. Available therapies have a modest impact on serum HDL levels; however, emerging therapies could have a more significant influence.

Differentiating prescription omega-3-acid ethyl esters (P-OM3) from dietary-supplement omega-3 fatty acids

BACKGROUND

A reliable means of treating hyper-triglyceridemia is the use of large doses of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Modest levels of EPA and DHA may be obtained from food, particularly fatty fish.

OBJECTIVES

This article is intended to review clinically relevant differences between dietary-supplement omega-3 fatty acids and prescription omega-3-acid ethyl esters (P-OM3).

METHODS

PubMed and the Food and Drug Administration (FDA) Website were searched for articles published between 1995 and 2007 that contained the terms fish oil, fatty acids, n-3 fatty acids, omega fatty acids, docosahexaenoic acid, or eicosapentaenoic acid. Articles discussing sources, recommended intake, and differences among various formulations of omega-3 fatty acids were selected for review. A limitation to this review is the lack of head-to-head clinical trials using P-OM3 and dietary-supplement omega-3 fatty acids.

RESULTS

Many types of nonprescription dietary supplements of omega-3 fatty acids are available; however, the efficacy, quality, and safety of these products are open to question because they are not regulated by the same standards as pharmaceutical agents. P-OM3 is the only omega-3 fatty acid product (Omacor capsules) approved by the US FDA available in the United States as an adjunct to diet to reduce very high (> or = 500 mg/dL) triglyceride levels in adult patients.

CONCLUSIONS

P-OM3 can be used with confidence by practitioners who want to provide therapeutic doses of omega-3 fatty acids in a preparation that has been documented to be both safe and effective.

Long-chain n-3 fatty acid supplementation in men increases resistance to activated protein C

It has recently and controversially been demonstrated that fish oil supplementation may not be beneficial for everyone, but to date there have been no biological explanations. We suggest that resistance to the anticoagulant, activated protein C (APC), be considered as a potential mechanism, because it has been demonstrated that the type of fatty acids on phospholipids modulates function of the APC pathway. The APC ratio in plasma was decreased by 7% after fish oil supplementation in healthy men (P<.005; n=35). The decrease in APC ratio equates to an increase in APC resistance. Fish oil lowered the APC ratio by (1) increasing low-density lipoprotein (LDL) cholesterol (P<.01) and apolipoprotein B (P<.05) and (2) increasing platelet microparticles (P<.05). In vitro, purified LDL decreased the APC ratio and increased microparticle formation. These changes affecting the anticoagulant APC could contribute toward a prothrombotic state, potentially explaining the recent observation that fish oil supplementation may not always be of benefit. These findings will need to be repeated in different disease states.

A review of omega-3 ethyl esters for cardiovascular prevention and treatment of increased blood triglyceride levels

The two marine omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), prevalent in fish and fish oils, have been investigated as a strategy towards prophylaxis of atherosclerosis. While the results with fish and fish oils have been not as clear cut, the data generated with the purified ethyl ester forms of these two fatty acids are consistent. Although slight differences in biological activity exist between EPA and DHA, both exert a number of positive actions against atherosclerosis and its complications. EPA and DHA as ethyl esters inhibit platelet aggregability, and reduce serum triglycerides, while leaving other serum lipids essentially unaltered. Glucose metabolism has been studied extensively, and no adverse effects were seen. Pro-atherogenic cytokines are reduced, as are markers of endothelial activation. Endothelial function is improved, vascular occlusion is reduced, and the course of coronary atherosclerosis is mitigated. Heart rate is reduced, and heart rate variability is increased by EPA and DHA. An antiarrhythmic effect can be demonstrated on the supraventricular and the ventricular level. More importantly, two large studies showed reductions in clinical endpoints like sudden cardiac death or major adverse cardiac events. As a consequence, relevant cardiac societies recommend using 1 g/day of EPA and DHA for cardiovascular prevention, after a myocardial infarction and for prevention of sudden cardiac death.

Eicosapentaenoic acid and docosahexaenoic acid from fish oils: differential associations with lipid responses

Fish-oil supplementation can reduce circulating triacylglycerol (TG) levels and cardiovascular risk. This study aimed to assess independent associations between changes in platelet eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and fasting and postprandial (PP) lipoprotein concentrations and LDL oxidation status, following fish-oil intervention. Fifty-five mildly hypertriacylglycerolaemic (TG 1·5–4·0 mmol/l) men completed a double-blind placebo controlled cross over study, where individuals consumed 6 g fish oil (3 g EPA+DHA) or 6 g olive oil (placebo)/d for two 6-week intervention periods, with a 12-week wash-out period in between. Fish-oil intervention resulted in a significant increase in the platelet phospholipid EPA (+491 %,P<0·001) and DHA (+44 %,P<0·001) content and a significant decrease in the arachidonic acid (-10 %,P<0·001) and γ-linolenic acid (-24 %,P<0·001) levels. A 30 % increase inex vivoLDL oxidation (P<0·001) was observed. In addition, fish oil resulted in a significant decrease in fasting and PP TG levels (P<0·001), PP non-esterified fatty acid (NEFA) levels, and in the percentage LDL as LDL-3 (P=0·040), and an increase in LDL-cholesterol (P=0·027). In multivariate analysis, changes in platelet phospholipid DHA emerged as being independently associated with the rise in LDL-cholesterol, accounting for 16 % of the variability in this outcome measure (P=0·030). In contrast, increases in platelet EPA were independently associated with the reductions in fasting (P=0·046) and PP TG (P=0·023), and PP NEFA (P=0·015), explaining 15–20 % and 25 % of the variability in response respectively. Increases in platelet EPA+DHA were independently and positively associated with the increase in LDL oxidation (P=0·011). EPA and DHA may have differential effects on plasma lipids in mildly hypertriacylglycerolaemic men.

Effect of n-3 fatty acids on metabolism of apoB100-containing lipoprotein in type 2 diabetic subjects

The effect of long-chain n-3 PUFA on the metabolism of apoB100-containing lipoprotein in diabetic subjects is not fully understood. The objective of the present study was to determine the effect of a daily intake of 1080 mg EPA and 720 mg DHA for diabetic subjects on the kinetics of apoB100-containing lipoprotein in the fasting state. A kinetic study was undertaken to determine the mechanisms involved in the effects of n-3 fatty acids in terms of a decrease in triacylglycerol level in type 2 diabetic patients. We have studied the effect of fish oils on the metabolism of apoB100 endogenously labelled by [5,5,5-2H3]-leucine in type 2 diabetic patients in the fasting state. The kinetic parameters of apoB100 in VLDL, intermediate-density lipoprotein and LDL were determined by compartmental modelling in five diabetic subjects before and 8 weeks after n-3 fatty acid treatment. Treatment did not change the plasma cholesterol level (0.801 (sd 0.120) v. 0.793 (sd 0.163) mmol/l) but lowered the plasma triacylglycerol level (1.776 (sd 0.280) v.1.356 (sd 0.595) mmol/l; P < 0.05). Treated patients showed a decrease in VLDL apoB100 concentration (0.366 (sd 0.030) v.0.174 (sd 0.036) g/l; P < 0.05) related to a decrease in VLDL 1 production (1.49 (sd 0.23) v.0.44 (sd 0.19) mg/kg per h; P < 0.05) and an increase in the VLDL conversion rate (0.031 (sd 0.024) v.0.052 (sd 0.040) per h; P < 0.05), with no change in fractional catabolic rates. Treatment led to a higher direct production of intermediate-density lipoprotein (0.02 (sd 0.01) v.0.24 (sd 0.12) mg/kg per h; P < 0.05). In conclusion, the present study, conducted in the fasting state, showed that supplementation with n-3 fatty acids in type 2 diabetic patients induced beneficial changes in the metabolism of apoB100-containing lipoprotein.

Evaluation of clinical safety and beneficial effects of a fish oil containing lipid emulsion (Lipoplus, MLF541): Data from a prospective, randomized, multicenter trial*

OBJECTIVE

To prove safety and effectiveness of a lipid emulsion enriched with n-3 fatty acids from fish oil (Lipoplus) within the setting of parenteral nutrition of patients after major abdominal surgery and to determine whether there are effects on outcome parameters.

DESIGN

Prospective, randomized, double-blind, multicenter trial.

SETTING

University and surgical teaching hospitals.

PATIENTS

After obtaining informed consent, 256 patients undergoing major abdominal surgery were randomized. Parameters of safety, effectiveness, and outcome were routine laboratory parameters, complication rates, length of stay in the intensive care unit, and length of hospital stay. In addition we determined in patient subgroups of 30 patients each, the changes of the content of selected long-chain polyunsaturated fatty acids, the leukotriene synthetic capacity and the antioxidant alpha-tocopherol.

INTERVENTIONS

Participating patients were randomized to receive either Lipoplus (group I; n = 127 patients) or Intralipid (group II; n = 129 patients). Parenteral nutrition was initiated immediately after surgery and ended on day 5 after surgery.

MEASUREMENTS AND MAIN RESULTS

No significant differences between groups I and II were observed when comparing routine laboratory parameters during the perioperative period. Plasma levels of eicosapentaenoic acid, leukotriene B5, and antioxidant content were significantly increased in group I. Furthermore, there was a significantly shorter length of hospital stay of approximately 21% (17.2 vs. 21.9 days; p = .0061) in group I.

CONCLUSIONS

Our findings indicate that the administration of Lipoplus in the postoperative period after major abdominal surgery is safe and results in a significantly shorter length of hospital stay. Administration of n-3 polyunsaturated fatty acids in the postoperative period can be considered a valuable choice for patients requiring parenteral nutrition after major abdominal surgery.

Effect of eicosapentaenoic/docosahexaenoic fatty acids and soluble fibers on blood lipids of individuals classified into different levels of lipidemia

OBJECTIVE

This study evaluated the effect of a formulation containing eicosapentaenoic acid and docosahexaenoic acid combined with soluble fibers (beta-glucan and guar gum) on fasting blood lipids used as coronary heart disease biomarkers of individuals classified into different levels of lipidemia by multivariate techniques.

METHODS

Serum total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triacylglycerol, plasma glucose concentrations, body mass index, age, and waist circumference were determined in 99 healthy volunteers. Three clusters or subgroups were identified according to coronary heart disease risk levels. Within each cluster, individuals were randomly assigned to one of four experimental groups, with each group receiving samples of a functional formulation containing 460 mg of omega-3 polyunsaturated fatty acids and/or 580 mg of soluble fibers, and placebo to be consumed in one bottle per day (200 mL) for 6 wk.

RESULTS

No significant changes were observed for triacylglycerol (P = 0.281) and total cholesterol (P = 0.082) concentrations across the three subgroups. Soluble dietary fibers improved the sensory quality of the formulation containing eicosapentaenoic acid and docosahexaenoic acid. The efficiency of cluster analysis to discriminate individuals in subgroups was confirmed by one-way analysis of variance (P < 0.003).

CONCLUSION

The omega-3 polyunsaturated fatty acid supplementation equivalent to fish consumed 2.5 to 3 times per week by a functional food-containing soluble dietary fiber showed no beneficial result in terms of changes in blood lipids in individuals classified according to different levels of lipidemia. Small numbers of patients in each cluster and possibly the low dose of fish oil and soluble dietary fibers used in this study may have also contributed to the lack of these differences. Multivariate techniques proved to be a very efficient tool to solve the heterogeneity problem usually observed in human designs and to evaluate the results within subgroups categorized by n variables extracted from the same population.

Suplementação de ácidos graxos ômega 3 em atletas de competição: impacto nos mediadores bioquímicos relacionados com o metabolismo lipídico

OBJETIVO: Avaliar o efeito da suplementação dos ácidos graxos ômega 3 em atletas de natação sobre indicadores bioquímicos. MÉTODOS: Nadadores de elite (n = 14) do sexo masculino foram avaliados em estudo randomizado, controlado por placebo pelo período de seis semanas (45 dias). O grupo placebo (GP) recebeu óleo mineral (n = 6) e o grupo suplementado (n = 8), óleo de peixe (GOP) contendo, no total, 950mg de ácido eicosapentaenóico e 500mg de ácido docosapentaenóico. Amostras de sangue foram coletadas imediatamente antes (T0), aos 15 (T15), aos 30 (T30) e aos 45 (T45) dias de suplementação para análise da composição dos ácidos graxos por cromatografia gasosa e para quantificação das lipoproteínas plasmáticas através de kits comerciais específicos. RESULTADOS: Os resultados revelaram um desajuste na dieta dos atletas considerando a ingestão g/kg de massa corporal dos macronutrientes. A análise do questionário de freqüência de consumo mostrou que os atletas não ingeriram regularmente fontes alimentares de ômega 3 e que o consumo de peixes, em 85% da amostra, era inferior ou igual a uma vez na semana. O perfil de ácidos graxos plasmáticos evidenciou aumento dos ácidos graxos poliinsaturados ômega 3 (P < 0,05) e redução do ácido araquidônico no grupo suplementado (P < 0,05). A suplementação com óleo de peixe ocasionou efeito hipocolesterolêmico, com redução nos teores sanguíneos de VLDL, LDL e colesterol total. Os valores de HDL não apresentaram diferenças significativas entre os grupos em nenhum momento estudado (P > 0,05). CONCLUSÃO: A suplementação de ácidos graxos N-3 em atletas nadadores altera os indicadores bioquímicos do metabolismo lipídico, influenciando na redução das lipoproteínas plasmáticas, ricas em colesterol e na prevenção de doenças cardiovasculares.