Susceptibility of LDL to oxidative modification in healthy volunteers supplemented with low doses of n-3 polyunsaturated fatty acids

Broader and safer clinically-relevant activities of pentadecanoic acid compared to omega-3: Evaluation of an emerging essential fatty acid across twelve primary human cell-based disease systems

A growing body of evidence supports that pentadecanoic acid (C15:0), an odd-chain saturated fat found in butter, is an essential fatty acid that is necessary in the diet to support long-term metabolic and heart health. Here, dose dependent and clinically relevant cell-based activities of pure C15:0 (FA15TM) were compared to eicosapentaenoic acid (EPA), a leading omega-3 fatty acid, as well as to an additional 4,500 compounds. These studies included 148 clinically relevant biomarkers measured across 12 primary human cell systems, mimicking various disease states, that were treated with C15:0 at four different concentrations (1.9 to 50 μM) and compared to non-treated control systems. C15:0 was non-cytotoxic at all concentrations and had dose dependent, broad anti-inflammatory and antiproliferative activities involving 36 biomarkers across 10 systems. In contrast, EPA was cytotoxic to four cell systems at 50 μM. While 12 clinically relevant activities were shared between C15:0 and EPA at 17 μM, C15:0 had an additional 28 clinically relevant activities, especially anti-inflammatory, that were not present in EPA. Further, at 1.9 and 5.6 μM, C15:0 had cell-based properties similar to bupropion (Pearson’s scores of 0.78), a compound commonly used to treat depression and other mood disorders. At 5.6 μM, C15:0 mimicked two antimicrobials, climabazole and clarithromycin (Pearson’s scores of 0.76 and 0.75, respectively), and at 50 μM, C15:0 activities matched that of two common anti-cancer therapeutics, gemcitabine and paclitaxel (Pearson’s scores of 0.77 and 0.74, respectively). In summary, C15:0 had dose-dependent and clinically relevant activities across numerous human cell-based systems that were broader and safer than EPA, and C15:0 activities paralleled common therapeutics for mood disorders, microbial infections, and cancer. These studies further support the emerging role of C15:0 as an essential fatty acid.

The potential toxic effects of magnesium oxide nanoparticles and valproate on liver tissue

The liver is the main organ responsible for drug and xenobiotic metabolism and detoxification in the body. There are many antiepileptic drugs and nanoparticles that have been reported to cause serious untoward biological responses and hepatotoxicity. The aim of this study is to investigate the potential toxic effect of aspartic acid-coated magnesium oxide nanoparticles (Mg nano) and valproate (valp) using an in vitro three-dimensional (3D) human liver organoid model and an in vivo pentylenetetrazole (PTZ)-induced convulsion model in rats. Here, 3D human liver organoids were treated with valp or valp + Mg nano for 24 h and then incubated with PTZ for an extra 24 h. As the in vivo model, rats were treated with valp, Mg nano, or valp + Mg nano for 4 weeks and then they were treated with PTZ for 24 h. Toxicity in the liver organoids was demonstrated by reduced cell viability, decreased ATP, and increased reactive oxygen species. In the rat convulsion model, results revealed elevated serum alanine aminotransferase and aspartate aminotransferase levels. Both the in vitro and in vivo data demonstrated the potential toxic effects of valp + Mg nano on the liver tissues.

Nutritional Neuroscience as Mainstream of Psychiatry: The Evidence- Based Treatment Guidelines for Using Omega-3 Fatty Acids as a New Treatment for Psychiatric Disorders in Children and Adolescents

Omega-3 polyunsaturated fatty acids (or omega-3 PUFAs, n-3 PUFAs) are essential nutrients throughout the life span. Recent studies have shown the importance of n-3 PUFAs supplementation during prenatal and perinatal period as a potential protective factor of neurodevelopmental disorders. N-3 PUFAs have been reported to be lower in youth with attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD) and major depressive disorder (MDD). N-3 PUFAs supplementation has shown potential effects in the improvement of clinical symptoms in youth with ADHD, ASD, and MDD, especially those with high inflammation or a low baseline n-3 index. Moreover, it has been suggested that n-3 PUFAs had positive effects on lethargy and hyperactivity symptoms in ASD. For clinical application, the following dosage and duration are recommended in youth according to available randomized controlled trials and systemic literature review: (1) ADHD: a combination of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) ≥ 750 mg/d, and a higher dose of EPA (1,200 mg/d) for those with inflammation or allergic diseases for duration of 16−24 weeks; (2) MDD: a combination of a EPA + DHA of 1,000−2,000 mg/d, with EPA:DHA ratio of 2 to 1, for 12−16 weeks; (3) ASD: a combination of EPA + DHA of 1,300−1,500 mg/d for 16−24 weeks as add-on therapy to target lethargy and hyperactivity symptoms. The current review also suggested that n-3 index and inflammation may be potential treatment response markers for youth, especially in ADHD and MDD, receiving n-3 PUFA.

The beneficial effects of nutraceuticals and natural products on small dense LDL levels, LDL particle number and LDL particle size: a clinical review

Cardiovascular diseases (CVDs) are globally the major causes of morbidity and mortality. Evidence shows that smaller and denser low-dense lipoprotein (sdLDL) particles are independent atherogenic risk factors for CVD due to their greater susceptibility to oxidation, and permeability in the endothelium of arterial walls. sdLDL levels are an independent risk factor and of more predictive value than total LDL-C for the assessment of coronary artery disease and metabolic syndrome. Functional food ingredients have attracted significant attention for the management of dyslipidemia and subsequently increase cardio-metabolic health. However, to date there is no study that has investigated the effect of these bioactive natural compounds on sdLDL levels. Therefore, the aim of the present review is to summarize the evidence accrued on the effect of special dietary ingredients such as omega-3 polyunsaturated fatty acids, nutraceuticals and herbal medicines on the levels of sdLDL, LDL particle number, and LDL particle size. Based on the results of the existing clinical trials this review suggests that natural products such as medicinal plants, nutraceuticals and omega-3 fatty acids can be used as adjunct or complementary therapeutic agents to reduce sdLDL levels, LDL particle numbers or increase LDL particle size and subsequently may prevent and treat CVD, with the advantage that theses natural agents are generally safe, accessible, and inexpensive.

Effect of Low Dose Docosahexaenoic Acid-Rich Fish Oil on Plasma Lipids and Lipoproteins in Pre-Menopausal Women: A Dose⁻Response Randomized Placebo-Controlled Trial

Omega-3 long chain polyunsaturated fatty acid (n-3 LCPUFA) supplementation has been shown to improve plasma lipid profiles in men and post-menopausal women, however, data for pre-menopausal women are lacking. The benefits of intakes less than 1 g/day have not been well studied, and dose–response data is limited. The aim of this study was to determine the effect of low doses of docosahexaenoic acid (DHA)-rich tuna oil on plasma triglyceride (TG) lowering in pre-menopausal women, and investigate if low dose DHA-rich tuna oil supplementation would increase the low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particle sizes. A randomized, double-blind, placebo-controlled trial was conducted, in which 53 healthy pre-menopausal women with mildly elevated plasma TG levels consumed 0, 0.35, 0.7, or 1 g/day n-3 LCPUFA as HiDHA™ tuna oil or placebo (Sunola oil) capsules for 8 weeks. Supplementation with 1 g/day n-3 LCPUFA, but not lower doses, reduced plasma TG by 23% in pre-menopausal women. This was reflected in a dose-dependent reduction in very-low-density lipoprotein (VLDL)-TG (R² = 0.20, p = 0.003). A weak dose-dependent shift in HDL (but not LDL) particle size was identified (R² = 0.05, p = 0.04). The results of this study indicate that DHA-rich n-3 LCPUFA supplementation at a dose of 1 g/day is an effective TG-lowering agent and increases HDL particle size in pre-menopausal women.

Modulatory effects of some natural products on hepatotoxicity induced by combination of sodium valproate and paracetamol in rats

Possible hepatoprotective effect of Curcuma longa and/or Nigella sativa against hepatotoxicity induced by coadministration of sodium valproate (SV) and paracetamol was studied. Rats were divided into 10 groups, control groups 1, 2, 3, and 4 received vehicles, C. longa (200 mg/kg, p.o.), N. sativa (250 mg/kg, p.o.), or both herbs for 21 days, respectively. Toxicity groups 5, 6, and 7 received SV (300 mg/kg, i.p.), paracetamol (1000 mg/kg, p.o.) for the last 4 days or both for 21 days, respectively. Protection groups 8, 9, and 10 received C. longa, N. sativa, or both, respectively, 1 h before the administration of both the drugs for 21 days. SV and/or paracetamol significantly increased aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total bilirubin, relative liver/body weight ratio, malondialdehyde (MDA), tumor necrosis factor alpha (TNF-α), and caspase-3 (Casp-3) while significantly decreased albumin, total protein, glutathione (GSH) reduced, GSH peroxidase, and superoxide dismutase (SOD). Preadministration of C. longa and/or N. sativa caused protective effect against the hepatotoxicity induced by both drugs.

Low-density lipoprotein oxidation biomarkers in human health and disease and effects of bioactive compounds

Based on the significance of oxidized low-density lipoprotein (LDL) in health and disease, this review focuses on human studies addressing oxidation of LDL, including three lines of biomarkers, (i) ex vivo LDL resistance to oxidation, a "challenge test" model, (ii) circulating oxidized LDL, indicating the "current in vivo status", and (iii) autoantibodies against oxidized LDL as fingerprints of an immune response to oxidized LDL, along with circulating oxysterols and 4-hydroxynonenal as biomarkers of lipid peroxidation. Lipid peroxidation and oxidized LDL are hallmarks in the development of various metabolic, cardiovascular and other diseases. Changes further occur across life stages from infancy to older age as well as in athletes and smokers. Given their responsiveness to targeted nutritional interventions, markers of LDL oxidation have been employed in a rapidly growing number of human studies for more than 2 decades. There is growing interest in foods, which, besides providing energy and nutrients, exert beneficial effects on human health, such as protection of DNA, proteins and lipids from oxidative damage. Any health claim, however, needs to be substantiated by supportive evidence derived from human studies, using reliable biomarkers to demonstrate such beneficial effects. A large body of evidence has accumulated, demonstrating protection of LDL from oxidation by bioactive food compounds, including vitamins, other micronutrients and secondary plant ingredients, which will facilitate the selection of oxidation biomarkers for future human intervention studies and health claim support.

Valproate-induced liver injury: modulation by the omega-3 fatty acid DHA proposes a novel anticonvulsant regimen

Background

The polyunsaturated, ω-3 fatty acid, docosahexaenoic acid (DHA), claims diverse cytoprotective potentials, although via largely undefined triggers. Thus, we currently first tested the ability of DHA to ameliorate valproate (VPA)-evoked hepatotoxicity, to modulate its anticonvulsant effects, then sought the cellular and molecular basis of such actions. Lastly, we also verified whether DHA may kinetically alter plasma levels/clearance rate of VPA.

Methods and Results

VPA (500 mg/kg orally for 14 days in rats) evoked prominent hepatotoxicity that appeared as a marked rise (2- to 4-fold) in serum hepatic enzymes (γ-glutamyl transferase [γ-GT], alanine aminotransferase [ALT], and alkaline phosphatase [ALP]), increased hepatic lipid peroxide (LPO) and tumor necrosis factor-alpha (TNFα) levels, as well as myeloperoxidase (MPO) activity (3- to 5-fold), lowering of serum albumin (40 %), and depletion of liver reduced-glutathione (GSH, 35 %). Likewise, histopathologic examination revealed hepatocellular degeneration, replacement by inflammatory cells, focal pericentral necrosis, and micro/macrovesicular steatosis. Concurrent treatment with DHA (250 mg/kg) markedly blunted the elevated levels of liver enzymes, lipid peroxides, TNFα, and MPO activity, while raising serum albumin and hepatic GSH levels. DHA also alleviated most of the cytologic insults linked to VPA. Besides, in a pentylenetetrazole (PTZ) mouse convulsion model, DHA (250 mg/kg) markedly increased the latency in convulsion evoked by VPA, beyond their individual responses. Lastly, pharmacokinetic studies revealed that joint DHA administration did not alter serum VPA concentrations.

Conclusions

DHA substantially ameliorated liver injury induced by VPA, while also markedly boosted its pharmacologic effects. DHA manipulated definite cellular machinery to curb liver oxidative stress and inflammation, without affecting VPA plasma levels. Collectively, these protective and synergy profiles for DHA propose a superior VPA-drug combination regimen.

Effect of EPA and vitamin C on superoxide dismutase, glutathione peroxidase, total antioxidant capacity and malondialdehyde in type 2 diabetic patients

OBJECTIVES

The aim of this study is to investigate the effect of eicosapentaenoic acid combined with vitamin C in comparison with the pure form of eicosapentaenoic acid on the serum concentration of malondialdehyde, erythrocyte activity of superoxide dismutase, glutathione peroxidase, and the serum level of total antioxidant capacity in patients with type 2 diabetes.

METHODS

Eighty one male diabetic patients, aged 33-63 years, were randomly assigned to one of 4 groups. The subjects consumed 500 mg/d pure eicosapentaenoic acid, 200 mg/d vitamin C, 500 mg eicosapentaenoic acid and 200 mg/d vitamin C or placebo depending on their groups. In fasting blood samples, superoxide dismutase and glutathione peroxidase activities were determined via the enzymatic method (Randox kit) and the serum total antioxidant capacity, malondialdehyde and vitamin C concentrations were estimated by colorimetric methods.

RESULTS

Administration of pure eicosapentaenoic acid in diabetic patients increased superoxide dismutase by 4%, glutathione peroxidase 53%, total antioxidant capacity 36% and decreased malondialdehyde significantly by 25%. Prescription of eicosapentaenoic acid combined with vitamin C demonstrated a significant increment for superoxide dismutase activity by 3% and for glutathione peroxidase activity by 52% during the study, but no significant change was seen for total antioxidant capacity and malondialdehyde, respectively. There was a significant decrease in FBS and HbA1c following prescription of eicosapentaenoic acid with/without vitamin C along the study, although these changes were not significant between the study groups.

CONCLUSION

It is concluded that prescription of eicosapentaenoic acid in the pure form reduces oxidative stress in type 2 diabetic patients; albeit, it does not alleviate hyperglycemia. Combination of vitamin C and eicosapentaenoic acid does not improve antioxidant property of eicosapentaenoic acid.

The impact of long-chain n-3 polyunsaturated fatty acids on human health

A considerable literature has been published on the health benefits of fish, oil-rich fish and fish oils and their constituent long-chain (LC) n-3 PUFA. Evidence from epidemiological studies highlights the cardioprotective attributes of diets rich in fish, especially oil-rich fish. Data from intervention trials are consistent in suggesting that LC n-3 PUFA lower the risk of CVD, probably by the multiple mechanisms of lowering serum triacylglycerols, improving the LDL:HDL ratio, anti-arrhythmic effects on heart muscle, improved plaque stability, anti-thrombotic effects and reduced endothelial activation. Research indicates LC n-3 PUFA provision has an impact during development, and there is preliminary evidence that docosahexaenoic acid supplementation during pregnancy could optimise brain and retina development in the infant. LC n-3 PUFA are also postulated to ameliorate behavioural and mental health disturbances such as depression, schizophrenia, dementia and attention deficit hyperactivity disorder. However, despite some positive evidence in each of these areas, use of LC n-3 PUFA in these conditions remains at the experimental stage. In the case of immune function, there is little doubt that LC n-3 PUFA have a positive effect. Although intervention trials in rheumatoid arthritis show strong evidence of benefit, evidence for efficacy in other inflammatory conditions, including Crohn's disease, ulcerative colitis, psoriasis, lupus, multiple sclerosis, cystic fibrosis and asthma, is inconsistent or inadequate. More promising evidence in some conditions may come from studies which attempt to modify the fetal environment using LC n-3 PUFA supplementation during pregnancy.

Dietary methods and biomarkers of omega 3 fatty acids: a systematic review

The aims of the present study were to review the validity of dietary methods used to measure the usual long chain (LC) omega-3 polyunsaturated fatty acid (n-3 PUFA) intake of a population and to assess the usefulness of different biomarkers of n-3 PUFA in healthy humans. Two systematic literature searches were conducted until May 2011 to update previous systematic reviews. The first literature search aimed to find studies validating the methodology used for measuring the dietary intake of n-3 PUFA. The second search aimed to find human intervention studies in which n-3 PUFA status changed after 2 weeks of n-3 PUFA supplementation. Sixteen studies were identified for inclusion in the first review. Correlation coefficients between fatty acids in subcutaneous fat or blood lipids and dietary intake of n-3 PUFA from different questionnaires were similar. Subcutaneous fat has been reported as the best reference method for some authors, and these studies showed moderate correlation coefficients with no dietary intake method being superior to any other. As for the evaluation of biomarkers of docosahexaenoic acid (DHA, 22 : 6 n-3) and eicosapentaenoic acid (EPA, 20 : 5n-3) status in response to supplementation, the new search reaffirmed and reinforced the evidence supporting that plasma phospholipid DHA, erythrocyte DHA, and platelet DHA were all effective and robust biomarkers of DHA status. Our findings only confirmed earlier studies and did not provide evidence for reaching new conclusions.

Methods of assessment of n-3 long-chain polyunsaturated fatty acid status in humans: a systematic review

BACKGROUND

The availability of reliable biomarkers of n-3 (omega-3) long-chain polyunsaturated fatty acid (LCPUFA) status is a prerequisite for linking dietary n-3 LCPUFA status to clinical outcomes.

OBJECTIVE

The objective of this meta-analysis was to assess the usefulness of different biomarkers of n-3 LCPUFA status in healthy humans.

DESIGN

We searched Ovid MEDLINE, EMBASE (Ovid), and Cochrane databases from inception to September 2007 for human intervention studies in which n-3 LCPUFA status changed after > or =2 wk of n-3 LCPUFA supplementation. We used formal inclusion/exclusion criteria and applied standard procedures for data extraction, validity assessment, and meta-analysis.

RESULTS

We included 41 studies (34 randomized controlled trials and 7 before-after studies) reporting on 18 different biomarkers. The data allowed specific evaluation of biomarkers of docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3) status in response to supplementation. There were sufficient data to determine that plasma DHA, plasma phospholipid DHA, plasma triacylglycerol DHA, plasma cholesteryl ester DHA, plasma nonesterified DHA, erythrocyte DHA, erythrocyte phospholipid DHA, and platelet DHA were all effective biomarkers of DHA status and that plasma phospholipid EPA was an effective marker of EPA status. Plasma phospholipid DHA appears to be a good marker of DHA status in adult men and women irrespective of DHA baseline status or supplementation dose, but its usefulness in other population subgroups is unclear.

CONCLUSION

There appears to be a range of useful biomarkers of DHA status in humans, but further research is needed to characterize which work best in particular population subgroups.

Omega-3 fatty acids: how can they be used in secondary prevention?

Omega-3 fatty acids (FAs) are divided into long-chain fatty acids (eicosapentaenoic acid and docosahexaenoic acid ), which are found in fatty fish, and intermediate-chain FAs (alpha-linolenic acid), which are found in vegetable oils. Omega-3 FAs favorably modulate a variety of vascular risk factors and also exert antiarrhythmic effects. Epidemiologic data suggest that increased consumption of marine omega-3 FAs is associated with reduced coronary heart disease (CHD) mortality. Randomized controlled studies also show that supplementation with EPA and DHA reduces CHD risk, primarily in the secondary prevention setting. Data are more limited on the efficacy of marine omega-3 FAs for the primary prevention of CHD and on the role of alpha-linolenic acid. Increased intake of EPA and DHA represents a valuable tool for vascular disease prevention and should be recommended in all patients with CHD.

Long-chainn-3 polyunsaturated fatty acid from fish oil modulates aortic nitric oxide and tocopherol status in the rat

In spite of their high oxidisability, long-chainn-3 PUFA protect against CVD. Dietary fatty acids modulate the fatty acid composition of lipoproteins involved in atherosclerosis. We thought that if long-chainn-3 PUFA were able to increase NO production by the aorta, then by its antioxidant activity the NO will prevent lipid peroxidation. However, the beneficial effect of NOin vivoon VLDL+LDL oxidation would only be possible if NO could diffuse to their lipidic core. Rats were fed maize oil- or fish oil as menhaden oil- (MO) rich diets for 8 weeks, to study the effects of MO on aortic NO production, NO diffusion into VLDL+LDL, the extent of oxidation in native VLDL+LDL and their oxidisabilityex vivo. Aortic NO production and its α-tocopherol content were increased andn-3 PUFA were incorporated into the VLDL+LDL. In spite of the higher peroxidisability and the low α-tocopherol in native VLDL+LDL from rats fed MO, native VLDL+LDL from the two groups shared similar electrophoretic patterns, conjugated dienes, thiobarbituric acid-reactive substances, total antioxidant capacity, and NO diffusibility on VLDL+LDL, indicative of anin vivoprotection against oxidation. However, these results do not correlate with theex vivooxidisability of VLDL+LDL, as NO is lacking. Thus, thein vivobeneficial effects can be explained by increased α-tocopherol in aorta and by a compensatory effect of NO on VLDL+LDL against the low α-tocopherol levels, which may contribute to the anti-atherogenic properties of fish oil.

The pig as an experimental model for elucidating the mechanisms governing dietary influence on mineral absorption

This review highlights the similarities between pigs and humans and thereby the value of the porcine human nutritional model, and reviews some of the more recent applications of this model for nutritional research.

Indigestible Material Attenuated Changes in Apoptosis in the Fasted Rat Jejunal Mucosa

We have previously demonstrated that fasting induced apoptosis and decreased cell proliferation in the rat intestinal mucosa. The aim was to investigate the effect of expanded polystyrene as indigestible material on apoptosis and cell proliferation in rat small intestinal mucosa during fasting. Male SD rats were divided into 3 groups. The first group was fed with chow and water ad libitum. The second group fasted for 72 hrs. The third group was fasted for 24 hrs and was fed expanded polystyrene. Intestinal apoptosis was evaluated by percent fragmented DNA assay, terminal deoxynucleotidyl transferase–mediated dUDP-biotin nick end-labeling (TUNEL) staining, and caspase-3 assay. Cell proliferation was analyzed by 5-bromo-2′-deoxyuridine (5-BrdU) uptake. Truncal vagotomy was performed to evaluate a role of the central nervous system. In the 72-hr fasted rat, mucosal height of the rat jejunum was decreased to 73% of that in rats fed ad libitum, and this decrease was partly restored to 90% in rats fed expanded polystyrene. The fragmented DNA was increased in fasted rats (28.0%) when compared with that in rats fed ad libitum (2.6%). The increase in fragmented DNA in fasted rats was recovered by feeding them expanded polystyrene (8.3%). TUNEL staining confirmed this result. The effect of polystyrene on apoptosis was decreased by truncal vagotomy. Expression of cleaved caspase-3 was increased in fasted rats, which was then decreased by feeding of expanded polystyrene. In contrast to apoptosis, feeding of expanded polystyrene had no reconstructive effect on 5-BrdU uptake in the intestinal epithelium, which was decreased by fasting to 60% of that in rats fed ad libitum. In conclusion, feeding of indigestible material partly restored the decrease in intestinal mucosal length in the fasted rats through the apoptotic pathway without any influence on BrdU uptake. Further exploration focused on the mechanism of this effect of indigestible material is required.

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.

Effects of Lactobacillus casei Shirota, Bifidobacterium breve, and oligofructose-enriched inulin on colonic nitrogen-protein metabolism in healthy humans

Pre- and/or probiotics can cause changes in the ecological balance of intestinal microbiota and hence influence microbial metabolic activities. In the present study, the influence of oligofructose-enriched inulin (OF-IN), Lactobacillus casei Shirota, and Bifidobacterium breve Yakult on the colonic fate of NH3 and p-cresol was investigated. A randomized, placebo-controlled, crossover study was performed in 20 healthy volunteers to evaluate the influence of short- and long-term administration of OF-IN, L. casei Shirota, B. breve Yakult, and the synbiotic L. casei Shirota + OF-IN. The lactose[15N,15N]ureide biomarker was used to study the colonic fate of NH3. Urine and fecal samples were analyzed for 15N content by combustion-isotope ratio mass spectrometery and for p-cresol content by gas chromatography-mass spectrometry. RT-PCR was applied to determine the levels of total bifidobacteria. Both short- and long-term administration of OF-IN resulted in significantly decreased urinary p-cresol and 15N content. The reduction of urinary 15N excretion after short-term OF-IN intake was accompanied by a significant increase in the 15N content of the fecal bacterial fraction. However, this effect was not observed after long-term OF-IN intake. In addition, RT-PCR results indicated a significant increase in total fecal bifidobacteria after long-term OF-IN intake. Long-term L. casei Shirota and B. breve Yakult intake showed a tendency to decrease urinary 15N excretion, whereas a significant decrease was noted in p-cresol excretion. In conclusion, dietary addition of OF-IN, L. casei Shirota, and B. breve Yakult results in a favorable effect on colonic NH3 and p-cresol metabolism, which, in the case of OF-IN, was accompanied by an increase in total fecal bifidobacteria.

Influence of three rapeseed oil-rich diets, fortified with alpha-linolenic acid, eicosapentaenoic acid or docosahexaenoic acid on the composition and oxidizability of low-density lipoproteins: results of a controlled study in healthy volunteers

OBJECTIVE

To compare the individual effects of dietary alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) on low-density lipoprotein (LDL) fatty acid composition, ex vivo LDL oxidizability and tocopherol requirement.

DESIGN, SETTING AND SUBJECTS

A randomized strictly controlled dietary study with three dietary groups and a parallel design, consisting of two consecutive periods. Sixty-one healthy young volunteers, students at a nearby college, were included. Forty-eight subjects (13 males, 35 females) completed the study.

INTERVENTIONS

Subjects received a 2-week wash-in diet rich in monounsaturated fatty acids (21% energy) followed by experimental diets enriched with about 1% of energy of ALA, EPA or DHA for 3 weeks. The omega-3 (n-3) fatty acids were provided with special rapeseed oils and margarines. The wash-in diet and the experimental diets were identical, apart from the n-3 fatty acid composition and the tocopherol content, which was adjusted to the content of dienoic acid equivalents.

RESULTS

Ex vivo oxidative susceptibility of LDL was highest after the DHA diet, indicated by a decrease in lag time (-16%, P<0.001) and an increase in the maximum amount of conjugated dienes (+7%, P<0.001). The EPA diet decreased the lag time (-16%, P<0.001) and the propagation rate (-12%, P<0.01). Tocopherol concentrations in LDL decreased in the ALA group (-13.5%, P<0.05) and DHA group (-7.3%, P<0.05). Plasma contents of tocopherol equivalents significantly decreased in all three experimental groups (ALA group: -5.0%, EPA group: -5.7%, DHA group: -12.8%). The content of the three n-3 polyunsaturated fatty acid differently increased in the LDL: on the ALA diet, the ALA content increased by 89% (P<0.001), on the EPA diet the EPA content increased by 809% (P<0.001) and on the DHA diet, the DHA content increased by 200% (P<0.001). In addition, the EPA content also enhanced (without dietary intake) in the ALA group (+35%, P<0.01) and in the DHA group (+284%, P<0.001).

CONCLUSIONS

Dietary intake of ALA, EPA or DHA led to a significant enrichment of the respective fatty acid in the LDL particles, with dietary EPA preferentially incorporated. In the context of a monounsaturated fatty acid-rich diet, ALA enrichment did not enhance LDL oxidizability, whereas the effects of EPA and DHA on ex vivo LDL oxidation were inconsistent, possibly in part due to further changes in LDL fatty acid composition.

Associations between hypertriglyceridemia, dietary fat intake, oxidative stress, and endothelial activation in men

OBJECTIVE

We examined the associations between intake of different types of dietary fat and plasma levels of oxidative stress and endothelial activation markers in men.

METHODS

For that purpose, a complete physical and metabolic profile was assessed. Dietary habits of subjects were determined with a 3-d food record. We also measured fasting plasma 8-iso-prostaglandin F2alpha and oxidized low-density lipoprotein concentrations and soluble forms of vascular cell adhesion molecule-1 (sVCAM-1), intercellular adhesion molecule-1 (sICAM-1), and E-selectin. All these measurements were performed with commercial enzyme-linked immunosorbent assay kits and standards.

RESULTS

We found that a high total dietary fat intake was associated with high plasma sICAM-1 (r = 0.40, P < 0.005), sVCAM-1 (r = 0.31, P < 0.05), and E-selectin (r = 0.28, P < 0.05) levels. We also found that in men matched for plasma triacylglycerol levels, those consuming a diet rich in total fat (>105 g/d, n = 21) were characterized by higher circulating levels of sICAM-1 (P < 0.05) and E-selectin (P < 0.05) compared with triacylglycerol-matched individuals with a low total dietary fat intake (<105 g/d, n = 21). However, no significant difference was noted in plasma oxidized low-density lipoprotein levels between groups. Further, we conducted multivariate analyses and found that saturated fatty acid intake was the only dietary variable after inclusion of other dietary variables that contributed to circulating sICAM-1 (P < 0.05) and sVCAM-1 (P < 0.05).

CONCLUSION

Our study suggests that high dietary fat consumption is associated with endothelial activation in men and that this detrimental effect is likely attributable to the saturated fatty acid content of the diet.

The influence of moderate red wine consumption on antioxidant status and indices of oxidative stress associated with CHD in healthy volunteers

The effects of moderate red wine consumption on the antioxidant status and indices of lipid peroxidation and oxidative stress associated with CHD were investigated. A randomised, controlled study was performed with twenty free-living healthy volunteers. Subjects in the red wine group consumed 375 ml red wine daily for 2 weeks. We measured the total concentration of phenolics and analysed the individual phenolics in the wine and plasma by HPLC with tandem MS. The antioxidant capacity of plasma was measured with electron spin resonance spectroscopy while homocysteine and fasting plasma lipids were also determined. The production of conjugated dienes and thiobarbituric acid-reactive substances (TBARS) were measured in Cu-oxidised LDL. Plasma total phenolic concentrations increased significantly after 2 weeks of daily red wine consumption (P< or =0.001) and trace levels of metabolites, mainly glucuronides and methyl glucuronides of (+)-catechin and (-)-epicatechin, were detected in the plasma of the red wine group. These flavan-3-ol metabolites were not detected in plasma from the control group. The maximum concentrations of conjugated dienes and TBARS in Cu-oxidised LDL were reduced (P< or =0.05) and HDL cholesterol concentrations increased (P< or =0.05) following red wine consumption. The findings from the present study provide some evidence for potential protective effects of moderate consumption of red wine in healthy volunteers.

Effect of fish and fish oil-derived omega-3 fatty acids on lipid oxidation

There is evidence that omega-3 (omega3) fatty acids derived from fish and fish oils reduce the risk of cardiovascular disease via mechanisms underlying atherosclerosis, thrombosis and inflammation. Despite these benefits, there has been concern that these fatty acids may increase lipid peroxidation. However, the in vivo data to date are inconclusive, due in part to limitations in the methodologies. In this regard, our findings using the measurement of F(2)-isoprostanes, a reliable measure of in vivo lipid peroxidation and oxidant stress, do not support adverse effects of omega3 fatty acids on lipid peroxidation.

The role of omega-3 long-chain polyunsaturated fatty acids in health and disease of the retina

In this work we advance the hypothesis that omega-3 (omega-3) long-chain polyunsaturated fatty acids (LCPUFAs) exhibit cytoprotective and cytotherapeutic actions contributing to a number of anti-angiogenic and neuroprotective mechanisms within the retina. omega-3 LCPUFAs may modulate metabolic processes and attenuate effects of environmental exposures that activate molecules implicated in pathogenesis of vasoproliferative and neurodegenerative retinal diseases. These processes and exposures include ischemia, chronic light exposure, oxidative stress, inflammation, cellular signaling mechanisms, and aging. A number of bioactive molecules within the retina affect, and are effected by such conditions. These molecules operate within complex systems and include compounds classified as eicosanoids, angiogenic factors, matrix metalloproteinases, reactive oxygen species, cyclic nucleotides, neurotransmitters and neuromodulators, pro-inflammatory and immunoregulatory cytokines, and inflammatory phospholipids. We discuss the relationship of LCPUFAs with these bioactivators and bioactive compounds in the context of three blinding retinal diseases of public health significance that exhibit both vascular and neural pathology. How is omega-3 LCPUFA status related to retinal structure and function? Docosahexaenoic acid (DHA), a major dietary omega-3 LCPUFA, is also a major structural lipid of retinal photoreceptor outer segment membranes. Biophysical and biochemical properties of DHA may affect photoreceptor membrane function by altering permeability, fluidity, thickness, and lipid phase properties. Tissue DHA status affects retinal cell signaling mechanisms involved in phototransduction. DHA may operate in signaling cascades to enhance activation of membrane-bound retinal proteins and may also be involved in rhodopsin regeneration. Tissue DHA insufficiency is associated with alterations in retinal function. Visual processing deficits have been ameliorated with DHA supplementation in some cases. What evidence exists to suggest that LCPUFAs modulate factors and processes implicated in diseases of the vascular and neural retina? Tissue status of LCPUFAs is modifiable by and dependent upon dietary intake. Certain LCPUFAs are selectively accreted and efficiently conserved within the neural retina. On the most basic level, omega-3 LCPUFAs influence retinal cell gene expression, cellular differentiation, and cellular survival. DHA activates a number of nuclear hormone receptors that operate as transcription factors for molecules that modulate reduction-oxidation-sensitive and proinflammatory genes; these include the peroxisome proliferator-activated receptor-alpha (PPAR-alpha) and the retinoid X receptor. In the case of PPAR-alpha, this action is thought to prevent endothelial cell dysfunction and vascular remodeling through inhibition of: vascular smooth muscle cell proliferation, inducible nitric oxide synthase production, interleukin-1 induced cyclooxygenase (COX)-2 production, and thrombin-induced endothelin 1 production. Research on model systems demonstrates that omega-3 LCPUFAs also have the capacity to affect production and activation of angiogenic growth factors, arachidonic acid (AA)-based vasoregulatory eicosanoids, and MMPs. Eicosapentaenoic acid (EPA), a substrate for DHA, is the parent fatty acid for a family of eicosanoids that have the potential to affect AA-derived eicosanoids implicated in abnormal retinal neovascularization, vascular permeability, and inflammation. EPA depresses vascular endothelial growth factor (VEGF)-specific tyrosine kinase receptor activation and expression. VEGF plays an essential role in induction of: endothelial cell migration and proliferation, microvascular permeability, endothelial cell release of metalloproteinases and interstitial collagenases, and endothelial cell tube formation. The mechanism of VEGF receptor down-regulation is believed to occur at the tyrosine kinase nuclear factor-kappa B (NFkappaB). NFkappaB is a nuclear transcription factor that up-regulates COX-2 expression, intracellular adhesion molecule, thrombin, and nitric oxide synthase. All four factors are associated with vascular instability. COX-2 drives conversion of AA to a number angiogenic and proinflammatory eicosanoids. Our general conclusion is that there is consistent evidence to suggest that omega-3 LCPUFAs may act in a protective role against ischemia-, light-, oxygen-, inflammatory-, and age-associated pathology of the vascular and neural retina.

Fatty acids and atherosclerotic risk

Most research concerning the effects of dietary fatty acids on atherosclerotic risk has focused on their effects on lipid and lipoprotein metabolism. However, it is known that fatty acids also influence a number of other relevant mechanisms involved in atherosclerosis such as lipid peroxidation, inflammation and haemostasis. The most favourable distribution of cholesterol over the various lipoproteins is achieved when saturated and trans fatty acids are replaced by a mixture of cis-unsaturated fatty acids. Furthermore, fatty acids from fish oil lower triacylglycerol concentrations. Effects on other atherosclerotic risk markers are less evident. Monounsaturated fatty acids maybe preferable above other fatty acids with respect to low-density lipoprotein oxidation as measured by indirect in vitro assays. The relevance of these assays for the in vivo situation is, however, limited. With respect to inflammation, mainly the effects of n-3 polyunsaturated fatty acids from fish oil have been studied, but results were inconsistent. Also results from studies evaluating the effects of fatty acids on haemostatic risk markers were inconsistent, which may be partly related to the use of different analytical methods. The most consistent finding however is the potential beneficial effect of moderate intakes of fish oil on platelet aggregation. Furthermore, reducing total fat intake rather than changing the fatty acid composition of the diet may beneficially affect the coagulation system. In conclusion, while beneficial effects on atherosclerotic risk are mainly ascribed to cis-unsaturated fatty acids, it remains debateable whether trans and saturated fatty acids in the diet have to be replaced by cis-unsaturated fatty acids or by carbohydrates. To answer this question adequately more validated methods are needed that reflect in vivo lipid peroxidation, inflammation and haemostasis.

LDL cholesterol-raising effect of low-dose docosahexaenoic acid in middle-aged men and women

BACKGROUND

Long-chain n-3 polyunsaturated fatty acids have variable effects on LDL cholesterol, and the effects of docosahexaenoic acid (DHA) are uncertain.

OBJECTIVE

The objective of the study was to determine the effect on blood lipids of a daily intake of 0.7 g DHA as triacylglycerol in middle-aged men and women.

DESIGN

Men and women aged 40-65 y (n = 38) underwent a double-blind, randomized, placebo-controlled, crossover trial of treatment with 0.7 g DHA/d for 3 mo.

RESULTS

DHA supplementation increased the DHA concentration in plasma by 76% (P < 0.0001) and the proportion in erythrocyte lipids by 58% (P < 0.0001). Values for serum total cholesterol, LDL cholesterol, and plasma apolipoprotein B concentrations were 4.2% (0.22 mmol/L; P = 0.04), 7.1% (0.23 mmol/L; P = 0.004), and 3.4% (P = 0.03) higher, respectively, with DHA treatment than with placebo. In addition, the LDL cholesterol:apolipoprotein B ratio was 3.1% higher with DHA treatment than with placebo (P = 0.04), which suggested an increase in LDL size. Plasma lathosterol and plant sterol concentrations were unaffected by treatment.

CONCLUSION

A daily intake of approximately 0.7 g DHA increases LDL cholesterol by 7% in middle-aged men and women. It is suggested that DHA down-regulates the expression of the LDL receptor.

Effects of Scandinavian caviar paste enriched with a stable fish oil on plasma phospholipid fatty acids and lipid peroxidation

OBJECTIVE

To study the possibility of increasing the very long-chain n-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in humans by means of consumption of a common food product, Scandinavian caviar paste, suitable for strategic enrichment with a high concentration of these fatty acids, and to measure the potential inducement of lipid peroxidation.

DESIGN

A randomized double blind repeated measures experiment.

SUBJECTS AND INTERVENTIONS

In total, 16 healthy, nonsmoking subjects (eight men and eight women, age 42+/-12 y) were included in the study. Eight consumed 25 g ordinary caviar paste daily for 3 weeks, and eight the same amount of caviar paste enriched with a very stable fish oil (7%, wt/wt). Blood lipids, plasma phospholipid fatty acids and lipid peroxidation were measured.

RESULTS

alpha-Linoleic acid was significantly decreased after intake of both ordinary (-8%, P<0.05) and fish oil caviar (-10%, P<0.05), as was the sum of all n-6 fatty acids (-6%, P<0.05 and -8%, P<0.001, respectively). The fatty acids EPA and DHA, as well as the sum of all n-3 fatty acids, increased significantly in both caviar groups but more in the group given fish oil caviar paste (EPA: +51%, P<0.05 and +100%, P<0.001, respectively; DHA: +24%, P<0.01 and +29%, P<0.001, respectively; sum of n-3:+27%, P<0.05 and +40%, P<0.001, respectively). Lipid peroxidation, measured as the thiobarbituric acid-malondialdehyde adduct, was increased by 26% (P<0.05) after intake of ordinary caviar paste, but was unchanged after intake of fish oil-enriched caviar paste.

CONCLUSION

Scandinavian caviar paste is a spread naturally enriched with n-3 polyunsaturated fatty acids that can be included in the diet to achieve an increase in these fatty acids. However, changing to caviar paste enriched with stable fish oil will lead to a considerably greater increase in EPA and DHA.

SPONSORSHIP

Swedish Medical Research Council; Cardinova AB, Uppsala, Sweden.

Plant- and marine-derived n-3 polyunsaturated fatty acids have differential effects on fasting and postprandial blood lipid concentrations and on the susceptibility of LDL to oxidative modification in moderately hyperlipidemic subjects

BACKGROUND

Dietary alpha-linolenic acid (ALA) can be converted to long-chain n-3 polyunsaturated fatty acids (PUFAs) in humans and may reproduce some of the beneficial effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on cardiovascular disease risk factors.

OBJECTIVE

This study aimed to compare the effects of increased dietary intakes of ALA and EPA+DHA on a range of atherogenic risk factors.

DESIGN

This was a placebo-controlled, parallel study involving 150 moderately hyperlipidemic subjects randomly assigned to 1 of 5 interventions: 0.8 or 1.7 g EPA+DHA/d, 4.5 or 9.5 g ALA/d, or an n-6 PUFA control for 6 mo. Fatty acids were incorporated into 25 g of fat spread and 3 capsules to be consumed daily.

RESULTS

The change in fasting or postprandial lipid, glucose, or insulin concentrations or in blood pressure was not significantly different after any of the n-3 PUFA interventions compared with the n-6 PUFA control. The mean (+/- SEM) change in fasting triacylglycerols after the 1.7-g/d EPA+DHA intervention (-7.7 +/- 4.99%) was significantly (P < 0.05) different from the change after the 9.5-g/d ALA intervention (10.9 +/- 4.5%). The ex vivo susceptibility of LDL to oxidation was higher after the 1.7-g/d EPA+DHA intervention than after the control and ALA interventions (P < 0.05). There was no significant change in plasma alpha-tocopherol concentrations or in whole plasma antioxidant status in any of the groups.

CONCLUSION

At estimated biologically equivalent intakes, dietary ALA and EPA+DHA have different physiologic effects.

n-3 long-chain FA decrease serum levels of TG and remnant-like particle-cholesterol in humans

A large number of papers have reported that administration of n-3 FA reduced serum TG concentrations in hypertriglyceridemic patients. However, few studies have examined the effect of n-3 FA on serum concentrations of remnant-like particle (RLP) cholesterol. Volunteers (n = 41) whose serum TG concentrations were 100-300 mg/dL were recruited and randomly assigned to either an n-3 FA group or a control group with stratification by sex, age, and serum TG level in a double-blind manner. The subjects in the n-3 FA group were administered 125 mL of fermented soybean milk with fish oil containing 600 mg of EPA and 260 mg of DHA/d for 12 wk. The controls consumed control soybean milk with olive oil. Fasting blood samples were obtained before the start of administration and at 4, 8, and 12 wk. EPA concentrations in red blood cells increased significantly in all but one subject in the n-3 FA group, with no significant changes in the control group. TG levels decreased more in the n-3 FA group than in the control group at weeks 4 (P < 0.05), 8 (P < 0.01), and 12 (P < 0.05) with their baseline as covariate. RLP cholesterol levels decreased more in the n-3 FA group than in the control at weeks 8 (P < 0.01) and 12 (P < 0.05) with their baseline as covariate. The groups did not differ in the other lipid levels. It is likely that n-3 long-chain FA may exert anti-atherosclerotic effects by lowering serum TG and RLP-cholesterol levels even at the dose of 860 mg/d.

The degree of unsaturation of dietary fatty acids and the development of atherosclerosis (review)

Atherosclerosis is the principal contributor to the pathogenesis of myocardial and cerebral infarction, gangrene and loss of function in the extremities. It results from an excessive inflammatory-fibroproliferative response to various forms of insult to the endothelium and smooth muscle of the artery wall. Atherosclerotic lesions develop fundamentally in three stages: dysfunction of the vascular endothelium, fatty streak formation and fibrous cap formation. Each stage is regulated by the action of vasoactive molecules, growth factors and cytokines. This multifactorial etiology can be modulated through the diet. The degree of unsaturation of dietary fatty acids affects lipoprotein composition as well as the expression of adhesion molecules and other pro-inflammatory factors, and the thrombogenicity associated with atherosclerosis development. Thus, the preventive effects of a monounsaturated-fatty acid-rich diet on atherosclerosis may be explained by the enhancement of high-density lipoprotein-cholesterol levels and the impairment of low-density lipoprotein-cholesterol levels, the low-density lipoprotein susceptibility to oxidation, cellular oxidative stress, thrombogenicity and atheroma plaque formation. On the other hand, the increase of high-density lipoprotein cholesterol levels and the reduction of thrombogenicity, atheroma plaque formation and vascular smooth muscle cell proliferation may account for the beneficial effects of polyunsaturated fatty acid on the prevention of atherosclerosis. Thus, the advantages of the Mediterranean diet rich in olive oil and fish on atherosclerosis may be due to the modulation of the cellular oxidative stress/antioxidant status, the modification of lipoproteins and the down-regulation of inflammatory mediators.

Pro- and antioxidant activities of docosahexaenoic acid on human blood platelets

n - 3 polyunsaturated fatty acids may protect against vascular diseases, however, their high accumulation in membranes may increase lipid peroxidation and subsequently induce deleterious effects in patients suffering from oxidative stress. This led us to investigate in vitro the dose-dependent effect of docosahexaenoic acid (DHA) on the redox status of human platelets. We have compared the effect of different DHA concentrations (0.5, 5 and 50 micro mol L(-1)) corresponding to DHA/albumin ratios of 0.01, 0.1 and 1. At the highest concentration, DHA elicited a marked oxidative stress, as evidenced by high malondialdehyde and low vitamin E levels whereas the lowest DHA concentration significantly decreased the malondialdehyde formation, with no change in vitamin E. The proportion of DHA was only increased in plasmalogen phosphatidylethanolamine at low concentration to rise in all phosphatidyl-choline and -ethanolamine subclasses at high concentration. Thus, the results show a biphasic effect of DHA with antioxidant and prooxidant effects at low and high concentrations, respectively, with a possible relationship with the phospholipid subclass in which it accumulates.

Cardiovascular disease and long-chain omega-3 fatty acids

PURPOSE OF REVIEW

Of all known dietary factors, long-chain omega-3 fatty acids may be the most protective against death from coronary heart disease. New evidence has confirmed and refined the cardioprotective role of these fatty acids.

RECENT FINDINGS

Omega-3 fatty acid supplementation reduces the risk of sudden cardiac death and death from any cause within 4 months in post-myocardial infarction patients. Evidence continues to accrue for benefits in the primary prevention of coronary heart disease and stroke, and an anti-arrhythmogenic mechanism is emerging as the most likely explanation.

SUMMARY

Current evidence suggests that individuals with coronary artery disease may reduce their risk of sudden cardiac death by increasing their intake of long-chain omega-3 fatty acids by approximately 1 g per day.

Docosahexaenoic acid abundance in the brain: a biodevice to combat oxidative stress

Docosahexaenoic acid (DHA) (22:6) is a polyunsaturated fatty acid of the n - 3 series which is believed to be a molecular target for lipid peroxides (LPO) formation. Its ubiquitous nature in the nervous tissue renders it particularly vulnerable to oxidative stress, which is high in brain during normal activity because of high oxygen consumption and generation of reactive oxygen species (ROS). Under steady state conditions potentially harmful ROS and LPO are maintained at low levels due to a strong antioxidant defense mechanism, which involves several enzymes and low molecular weight reducing compounds. The present review emphasizes a paradox: a discrepancy between the expected high oxidability of the DHA molecule due to its high degree of unsaturation and certain experimental results which would indicate no change or even decreased lipid peroxidation when brain tissue is supplied or enriched with DHA. The following is a critical review of the experimental data relating DHA levels in the brain to lipid peroxidation and oxidative damage there. A neuroprotective role for DHA, possibly in association with the vinyl ether (VE) linkage of plasmalogens (pPLs) in combating free radicals is proposed.