Erythrocyte omega-3 fatty acids increase and linoleic acid decreases with age: Observations from 160,000 patients

BackgroundThe fatty acid (FA) composition of the red blood cell (RBC) has been reported to provide prognostic information regarding risk for coronary heart disease (CHD). In particular, the Omega-3 Index (RBC eicosapentaenoic acid+docosahexaenoic acid, EPA+DHA) has been shown to be independently and inversely related to risk for sudden cardiac death and for acute coronary syndromes. Higher linoleic acid (n-6) and lower trans FA levels have also been associated with improved CHD outcomes. Accordingly, the RBC FA panel has recently been introduced in routine clinical laboratory testing.ObjectiveThe purpose of this study was to define age- and gender-based norms for RBC FA levels.MethodsRBC FA profiles from about 160,000 patients (48% from males, 52% from females) were measured at Health Diagnostic Laboratory. These data were used to create age decade and gender-specific norms (percentiles). FA values were expressed as a percent of total identified FA.ResultsCompared to men, women generally had higher C18 trans levels, and between the ages of 10–29 years, they had DHA and lower EPA levels. Among the major FA classes, saturated (41% of total) and trans (～0.85%) fats did not vary appreciably by age, whereas monounsaturated fats tended to rise slightly. Of the two major n-6 polyunsaturates, arachidonic and linoleic acids, the former was unchanged across decades (16.4% abundance) whereas the latter decreased by about 2 percentage points (13.0–11.1%). The overall median Omega-3 Index was 4.5%, and across the decades it increased by about 1.5 percentage points. The Omega-3 Index and linoleic acid stabilized after age 70.ConclusionWhereas RBC saturated, mono- and polyunsaturated FA levels are generally stable across the lifespan, there is a shift in the composition of the latter, with an increase in the Omega-3 Index and a decrease in linoleic acid. Higher DHA and lower EPA levels in younger women is consistent with enhanced conversion of EPA to DHA during the early reproductive years. The availability of RBC FA norms will facilitate research into the relationships between altered FA status and human disease, and will help physicians evaluate the n-3 FA status of their patients.     

Unexpected similarity in RBC DHA and AA levels between bottlenose dolphins and humans

BackgroundThe Omega-3 Index [red blood cell (RBC) content of eicosapentaenoic acid (EPA)+docosahexaenoic acid (DHA)] is inversely related to risk of cardiovascular disease in humans. In the U.S., the average Omega-3 Index is about 4–6% of RBC fatty acids, whereas in Japan it is 9–10%. The range of physiologically-possible levels for the Omega-3 Index in other mammals is unknown.ObjectiveTo compare the RBC fatty acid composition of a common piscivorous mammal, the bottlenose dolphin (Tursiops truncatus), with that of (U.S.) humans, and to examine the extent to which dietary fatty acid patterns were reflected in RBCs.MethodsRBCs were isolated from routine blood samples collected from 35 healthy dolphins at two display facilities and were analyzed by gas chromatography. For humans, historic, deidentified RBC fatty acid data from our laboratory were used (n=11,329; mean age 58).ResultsThe mean Omega-3 Index of the dolphins was 19.9% compared with 6.0% for humans. EPA levels were 15.3% vs 1.2%, respectively, but DHA levels were virtually identical (4.6% vs 4.8%). Linoleic acid (LNA) levels were much lower in dolphins vs humans (0.5% vs 12.5%) whereas arachidonic acid (ARA) levels were similar (12.3% vs 14.5%). In a subgroup of humans with an Omega-3 Index in the >99.2 percentile, the mean index was similar to that of the dolphins. Based on an analysis of their food, the dolphins consumed about 60 g of EPA+DHA per day as compared to about 0.1 g in humans.ConclusionDolphins have an Omega-3 Index that is (only) 3–4× higher than that of U.S. adults despite their intake of EPA+DHA being about 165× higher (as a percent of kcal). RBC, EPA and LNA levels are relatively more reflective of dietary intakes than are DHA and ARA levels. The mechanisms by which certain fatty acid levels appear to be fixed and others may vary in RBC membranes are unknown.     

Omega-3 fatty acids from fish oils and cardiovascular disease

Fish and fish oils contain the omega-3 fatty acids known as eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA). Epidemiological studies have shown an inverse relation between the dietary consumption of fish containing EPA/DHA and mortality from coronary heart disease. These relationships have been substantiated from blood measures of omega-3 fatty acids including DHA as a physiological biomarker for omega-3 fatty acid status. Controlled intervention trials with fish oil supplements enriched in EPA/DHA have shown their potential to reduce mortality in post-myocardial infarction patients with a substantial reduction in the risk of sudden cardiac death. The cardioprotective effects of EPA/DHA are widespread, appear to act independently of blood cholesterol reduction, and are mediated by diverse mechanisms. Their overall effects include anti-arrhythmic, blood triglyceride-lowering, anti-thrombotic, anti-inflammatory, endothelial relaxation, plus others. Current dietary intakes of EPA/DHA in North America and elsewhere are well below those recommended by the American Heart Association for the management of patients with coronary heart disease. (Mol Cell Biochem 263: 217–225, 2004)     

Effects of long-term supplementation with omega-3 fatty acids on longitudinal changes in bone mass and microstructure in mice

A diet rich in omega-3s has previously been suggested to prevent bone loss. However, evidence for this has been limited by short exposure to omega-3 fatty acids (FAs). We investigated whether a diet enriched in eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) for the entire adult life of mice could improve bone microstructure and strength. Thirty female mice received a diet enriched in DHA or EPA or an isocaloric control diet from 3 to 17 months of age. Changes in bone microstructure were analyzed longitudinally and biomechanical properties were analysed by a three-point bending test. Bone remodelling was evaluated by markers of bone turnover and histomorphometry. Trabecular bone volume in caudal vertebrae was improved by EPA or DHA at 8 months (+26.6% and +17.2%, respectively, compared to +3.8% in controls, P=.01), but not thereafter. Trabecular bone loss in the tibia was not prevented by omega-3 FAs (BV/TV −94%, −93% and −97% in EPA, DHA and controls, respectively). EPA improved femur cortical bone volume (+8.1%, P<.05) and thickness (+4.4%, P<.05) compared to controls. EPA, but not DHA, reduced age-related decline of osteocalcin (−70% vs. −83% in controls, P<.05). EPA and DHA increased leptin levels (7.3±0.7 and 8.5±0.5 ng ml⁻¹, respectively, compared to 4.5±0.9 ng ml⁻¹ in controls, P=.001); however, only EPA further increased IGF-1 levels (739±108 ng ml⁻¹, compared to 417±58 ng ml⁻¹ in controls, P=.04). These data suggest that long-term intake of omega-3 FA, particularly EPA, may modestly improve the structural and mechanical properties of cortical bone by an increase in leptin and IGF-1 levels, without affecting trabecular bone loss.     

Fatty acid composition of the postmortem prefrontal cortex of adolescent male and female suicide victims

Prior epidemiological, prospective intervention, and peripheral and central fatty acid composition studies suggest that omega-3 fatty acid deficiency may be associated with the pathoaetiology of depression and suicide. In the present study, we determined the fatty acid composition of the postmortem prefrontal cortex (PFC) of adolescent male and female suicide victims and age-matched controls. Fatty acid composition (wt% total fatty acids) and concentrations (μmol/g) were determined in the postmortem PFC (Brodmann area 10) of male and female adolescent (aged 13–20 years) suicide victims (n=20) and age-matched controls (n=20) by gas chromatography. None of the major polyunsaturated fatty acids including the principle brain omega-3 fatty acid, docosahexaenoic acid (DHA), monounsaturated fatty acids, or saturated fatty acids differed significantly between adolescent suicide victims and controls before or after segregation by gender. The arachidonic acid (AA, 20:4n-6): DHA ratio and adrenic acid (22:4n-6) composition were negatively correlated with age at death in controls but not in suicides, and males exhibited a greater AA:DHA ratio irrespective of cause-of-death. These results demonstrate that adolescent male and female suicide victims do not exhibit DHA deficits in the postmortem PFC relative to age-matched controls, and suggest that suicide victims do not exhibit the normal age-related decrease in adrenic acid composition and the AA:DHA ratio.     

Enhancing LC-PUFA production in <Emphasis Type="Italic">Thalassiosira pseudonana</Emphasis> by overexpressing the endogenous fatty acid elongase genes

The health beneficial omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) are naturally synthesized by diatoms through consecutive steps of fatty acid elongase and desaturase enzymes. In Thalassiosira pseudonana, these fatty acids constitute about 10–20 % of the total fatty acids, with EPA accumulation being five to ten times higher than DHA. In order to identify the subcellular localization of enzymes in the pathway of LC-PUFA biosynthesis in T. pseudonana and to manipulate the production of EPA and DHA, we generated constructs for overexpressing each of the T. pseudonana long-chain fatty acid elongase genes. Full-length proteins were fused to GFP, and transgenic lines were generated. In addition, overexpressed native proteins with no GFP fusion were tested. The subcellular localization of each elongase protein was determined. We then examined the total amount of lipids and analyzed the fatty acid profile in each of the transgenic lines compared to wild type. Lines with overexpressed elongases showed an increase of up to 1.4-fold in EPA and up to 4.5-fold in DHA, and the type of fatty acid that was increased (EPA vs. DHA) depended on the type of elongase that was overexpressed. This data informs future metabolic engineering approaches to further improve EPA and DHA content in diatoms.     

Towards the Industrial Production of Omega-3 Long Chain Polyunsaturated Fatty Acids from a Genetically Modified Diatom Phaeodactylum tricornutum

The marine diatom Phaeodactylum tricornutum can accumulate up to 30% of the omega-3 long chain polyunsaturated fatty acid (LC-PUFA) eicosapentaenoic acid (EPA) and, as such, is considered a good source for the industrial production of EPA. However, P. tricornutum does not naturally accumulate significant levels of the more valuable omega-3 LC-PUFA docosahexaenoic acid (DHA). Previously, we have engineered P. tricornutum to accumulate elevated levels of DHA and docosapentaenoic acid (DPA) by overexpressing heterologous genes encoding enzyme activities of the LC-PUFA biosynthetic pathway. Here, the transgenic strain Pt_Elo5 has been investigated for the scalable production of EPA and DHA. Studies have been performed at the laboratory scale on the cultures growing in up to 1 L flasks a 3.5 L bubble column, a 550 L closed photobioreactor and a 1250 L raceway pond with artificial illumination. Detailed studies were carried out on the effect of different media, carbon sources and illumination on omega-3 LC-PUFAs production by transgenic strain Pt_Elo5 and wild type P. tricornutum grown in 3.5 L bubble columns. The highest content of DHA (7.5% of total fatty acids, TFA) in transgenic strain was achieved in cultures grown in seawater salts, Instant Ocean (IO), supplemented with F/2 nutrients (F2N) under continuous light. After identifying the optimal conditions for omega-3 LC-PUFA accumulation in the small-scale experiments we compared EPA and DHA levels of the transgenic strain grown in a larger fence-style tubular photobioreactor and a raceway pond. We observed a significant production of DHA over EPA, generating an EPA/DPA/DHA profile of 8.7%/4.5%/12.3% of TFA in cells grown in a photobioreactor, equivalent to 6.4 μg/mg dry weight DHA in a mid-exponentially growing algal culture. Omega-3 LC-PUFAs production in a raceway pond at ambient temperature but supplemented with artificial illumination (110 μmol photons m^-2s^-1 ) on a 16:8h light:dark cycle, in natural seawater and F/2 nutrients was 24.8% EPA and 10.3% DHA. Transgenic strain grown in RP produced the highest levels of EPA (12.8%) incorporated in neutral lipids. However, the highest partitioning of DHA in neutral lipids was observed in cultures grown in PBR (7.1%). Our results clearly demonstrate the potential for the development of the transgenic Pt_Elo5 as a platform for the commercial production of EPA and DHA.     

Common and differential effects of docosahexaenoic acid and eicosapentaenoic acid on helper T-cell responses and associated pathways

Our understanding of the differential effects between specific omega-3 fatty acids is incomplete. Here, we aimed to evaluate the effects of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on T-helper type 1 (Th1) cell responses and identify the pathways associated with these responses. Naïve CD4⁺ T cells were co-cultured with bone marrow-derived dendritic cells (DCs) in the presence or absence of palmitate (PA), DHA, or EPA. DHA or EPA treatment lowered the number of differentiated IFN-γ-positive cells and inhibited the secretion of IFN-γ, whereas only DHA increased IL-2 and reduced TNF-α secretion. There was reduced expression of MHC II on DCs after DHA or EPA treatment. In the DC-independent model, DHA and EPA reduced Th1 cell differentiation and lowered the cell number. DHA and EPA markedly inhibited IFN-γ secretion, while only EPA reduced TNF-α secretion. Microarray analysis identified pathways involved in inflammation, immunity, metabolism, and cell proliferation. Moreover, DHA and EPA inhibited Th1 cells through the regulation of diverse pathways and genes, including Igf1 and Cpt1a. Our results showed that DHA and EPA had largely comparable inhibitory effects on Th1 cell differentiation. However, each of the fatty acids also had distinct effects on specific cytokine secretion, particularly according to the presence of DCs.     

Cardiovascular disease prevention and treatment

The incidence of fatal and non-fatal cardiovascular disease (sudden cardiac death (SCD), myocardial infarction, others) varies, depending on conventional risk factors. However, in Western countries, like the US or Germany, incidences of fatal and non-fatal cardiovascular disease are far higher than in countries like Japan. In the present article, these differences are discussed and related to eicosapentaenoic acid (C20:5omega-3 or C20:5n-3; EPA) and docosahexaenoic acid (C22:6omega-3; DHA). Dietary intake of EPA and DHA and a number of other factors determine levels of EPA and DHA in an individual—best assessed as the omega-3 index, defined as the percentage of EPA and DHA in red cells, and analyzed in a standardized fashion. A review of the literature, expanded by measurements of the omega-3 index, indicates that the risk of sudden cardiac death correlates inversely with the omega-3 index. For persons with an omega-3 index <4%, risk is tenfold, as compared to persons with an omega-3 index >8%. A similar, less-pronounced, correlation exists for non-fatal cardiovascular disease. EPA and DHA have anti-arrhythmic and anti-atherosclerotic mechanisms of action. In large-scale intervention studies, intake of EPA and DHA has been demonstrated to reduce SCD and non-fatal cardiovascular events. Assessing or recommending dietary intake of EPA and DHA does not predict the resulting omega-3 index. Taken together, the omega-3 index is a biomarker to assess a person's content of omega-3 fatty acids, and thus the risk for sudden cardiac death, as well as non-fatal cardiovascular events. EPA and DHA prevent fatal and non-fatal cardiovascular disease and complications of congestive heart failure.     

Antarctic microorganisms as source of the omega-3 polyunsaturated fatty acids

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are long-chain polyunsaturated fatty acids (PUFAs) that belong to the omega-3 group. They are essential fatty acids found in phospholipid of cell membranes. There is strong evidence that these nutrients may also favorably modulate many diseases. Primary sources of omega-3 PUFAs in the human diet are fish and fish-derived products. The fishing industry worldwide, however, is becoming unable to satisfy the growing demand for these PUFAs. A promising cost-effective alternative source of PUFAs is bacterial production. We identified 40 Antarctic marine bacterial isolates by 16S rRNA gene sequence analysis. Fifteen genera in three phyla were represented in the collection. Isolates were tested for ability to produce EPA using a method in which their ability to reduce 2,3,5-triphenyltetrazolium chloride (TTC) is determined and by gas chromatography coupled to mass spectrometry (GC–MS). All isolates could reduce TTC, and GC–MS analysis showed that four produced EPA and that six produced DHA. We show for the first time that isolates identified as Cellulophaga, Pibocella and Polaribacter can produce EPA and DHA, only DHA or only EPA, respectively. One isolate, Shewanella sp. (strain 8-5), is indicated to be a good candidate for further study to optimize growth and EPA production. In conclusion, a rapid method was tested for identification of new EPA producing strains from marine environments. New EPA and DHA producing strains were found as well as a potentially useful PUFA production strain.     

Effect of randomized supplementation with high dose olive, flax or fish oil on serum phospholipid fatty acid levels in adults with attention deficit hyperactivity disorder

Dietary intake of omega-3 fatty acids has been positively correlated with cardiovascular and neuropsychiatric health in several studies. The high seafood intake by the Japanese and Greenland Inuit has resulted in low ratios of the omega-6 fatty acid arachidonic acid (AA, 20:4n-6) to eicosapentaenoic acid (EPA, 20:5n-3), with the Japanese showing AA:EPA ratios of approximately 1.7 and the Greenland Eskimos showing ratios of approximately 0.14. It was the objective of this study to determine the effect of supplementation with high doses (60 g) of flax and fish oils on the blood phospholipid (PL) fatty acid status, and AA/EPA ratio of individuals with Attention Deficit Hyperactivity Disorder (ADHD), commonly associated with decreased blood omega-3 fatty acid levels. Thirty adults with ADHD were randomized to 12 weeks of supplementation with olive oil (< 1% omega-3 fatty acids), flax oil (source of alpha-linolenic acid; 18:3n-3; alpha-LNA) or fish oil (source of EPA and docosahexaenoic acid; 22:6n-3; DHA). Serum PL fatty acid levels were determined at baseline and at 12 weeks. Flax oil supplementation resulted in an increase in alpha-LNA and a slight decrease in the ratio of AA/EPA, while fish oil supplementation resulted in increases in EPA, DHA and total omega-3 fatty acids and a decrease in the AA/EPA ratio to values seen in the Japanese population. These data suggest that in order to increase levels of EPA and DHA in adults with ADHD, and decrease the AA/EPA ratio to levels seen in high fish consuming populations, high dose fish oil may be preferable to high dose flax oil. Future study is warranted to determine whether correction of low levels of long-chain omega-3 fatty acids is of therapeutic benefit in this population.     

Hexadecenoic Fatty Acid Isomers in Human Blood Lipids and Their Relevance for the Interpretation of Lipidomic Profiles

Monounsaturated fatty acids (MUFA) are emerging health biomarkers, and in particular the ratio between palmitoleic acid (9cis-16:1) and palmitic acid (16:0) affords the delta-9 desaturase index that is increased in obesity. Recently, other positional and geometrical MUFA isomers belonging to the hexadecenoic family (C16 MUFA) were found in circulating lipids, such as sapienic acid (6cis-16:1), palmitelaidic acid (9trans-16:1) and 6trans-16:1. In this work we report: i) the identification of sapienic acid as component of human erythrocyte membrane phospholipids with significant increase in morbidly obese patients (n = 50) compared with age-matched lean controls (n = 50); and ii) the first comparison of erythrocyte membrane phospholipids (PL) and plasma cholesteryl esters (CE) in morbidly obese patients highlighting that some of their fatty acid levels have opposite trends: increases of both palmitic and sapienic acids with the decrease of linoleic acid (9cis,12cis-18:2, omega-6) in red blood cell (RBC) membrane PL were reversed in plasma CE, whereas the increase of palmitoleic acid was similar in both lipid species. Consequentially, desaturase enzymatic indexes gave different results, depending on the lipid class used for the fatty acid content. The fatty acid profile of morbidly obese subjects also showed significant increases of stearic acid (C18:0) and C20 omega-6, as well as decreases of oleic acid (9cis-18:1) and docosahexaenoic acid (C22:6 omega-3) as compared with lean healthy controls. Trans monounsaturated and polyunsaturated fatty acids were also measured and found significantly increased in both lipid classes of morbidly obese subjects. These results highlight the C16 MUFA isomers as emerging metabolic marker provided that the assignment of the double bond position and geometry is correctly performed, thus identifying the corresponding lipidomic pathway. Since RBC membrane PL and plasma CE have different fatty acid trends, caution must also be used in the choice of lipid species for the interpretation of lipidomic profiles.     

Omega-3 fatty acids regulate gene expression levels differently in subjects carrying the PPARα L162V polymorphism

Omega-3 fatty acids (FAs) are natural ligands of the peroxisome proliferator-activated receptor-α (PPARα), a nuclear receptor that modulates expression levels of genes involved in lipid metabolism. The L162V polymorphism of the PPARα gene is associated with a deteriorated metabolic profile. We postulate that subjects carrying the PPARα-V162 allele exhibit differences in the expression of PPARα and its target genes after incubation with omega-3 FAs compared with L162 homozygotes. Peripheral blood monocytes from six men carrying the PPARα-V162 allele paired for age and for body mass index with six L162 homozygotes were differentiated into macrophages and activated with eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), or mixtures of EPA:DHA. Data demonstrates that gene expression levels of PPARα and apolipoprotein AI (APOA1) were significantly lower for carriers of the PPARα-V162 allele compared to L162 homozygotes after the addition of DHA and a mixture of EPA:DHA. Additionally, lipoprotein lipase (LPL) gene expression displayed a tendency to be lower in the PPARα L162V polymorphism subgroup after the addition of a mixture of EPA:DHA. Consequently, individuals carrying the PPARα-V162 allele may demonstrate inferior improvements in their lipid profile due to alterations in gene expression rates in response to omega-3 FA supplementation.     

Acute effects of unsaturated fatty acids in splanchnic artery occlusion shock

Diets enriched with omega-3 unsaturated fatty acids are associated with decreased hypercholesterolemia and decreased risk of ischemic and atherosclerotic diseases. We studied the acute intravascular effects of some of these unsaturated fatty acids (i.e., eicosapentaenoic acid, EPA; docosahexaenoic acid, DHA) along with omega-6 unsaturated fatty acids, (i.e., linoleic and linolenic acid) in splanchnic artery occlusion (SAO) shock in rats. Anesthetized rats subjected to total occlusion of the celiac and superior mesenteric arteries for 40 minutes followed by reperfusion usually resulted in a fatal outcome 90-120 minutes after releasing the clamps. SAO shock rats treated with the omega-3 unsaturated fatty acid, EPA, exhibited an improved survival time and rate (p less than 0.05 from vehicle) compared to those receiving only vehicle (i.e., 50% ethanol). EPA and DHA treated SAO rats also exhibited lower plasma activities of the lysosomal protease, cathepsin D, free amino-nitrogen compounds, and the cardiotoxic peptide, myocardial depressant factor. These results indicate that omega-3 unsaturated fatty acids, especially EPA, have some acute beneficial effects in SAO shock in rats.     

Cloning and functional characterisation of a fatty acyl elongase from southern bluefin tuna (Thunnus maccoyii)

The synthesis of long chain polyunsaturated fatty acids (LCPUFA), such as eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3), involves fatty acyl desaturase and elongase enzymes. The marine fish species southern bluefin tuna (SBT) can accumulate large quantities of omega-3 (n-3) LCPUFA in its flesh but their capacity to synthesize EPA and DHA is uncertain. A cDNA, sbtElovl5, encoding a putative fatty acyl elongase was amplified from SBT liver tissue. The cDNA included an open reading frame (ORF) encoding 294 amino acids. Sequence comparisons and phylogenetic analyses revealed a high level of sequence conservation between sbtElovl5 and fatty acyl elongase sequences from other fish species. Heterologous expression of the sbtElovl5 ORF in Saccharomyces cerevisiae confirmed that it encoded a fatty acyl elongase capable of elongating C_18/20 polyunsaturated fatty acid (PUFA) substrates, but not C₂₂ PUFA substrates. For the first time in an Elovl5, the substrate competition occurring in nature was investigated. Higher activity towards n-3 PUFA substrates than omega-6 (n-6) PUFA substrates was exhibited, regardless of substrate chain length. The sbtElovl5 preferentially elongated 18:4n-3 and 18:3n-6 rather than 20:5n-3 and 20:4n-6. The sbtElovl5 enzyme also elongated saturated and monounsaturated fatty acids.     

Omega-3 index determined by gas chromatography with electron impact mass spectrometry

Omega-3 index is a relatively new concept, defined as the sum of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) expressed as a percentage of the total fatty acids in red blood cell membranes. This index reflects medium to long-term intake of omega-3 polyunsaturated fatty acids and could be a useful tool in epidemiological studies. The standard technique used for fatty acid analysis and quantification has been gas chromatography (GC) with flame ionization detection. This method is robust and has good precision and sensitivity. However, a major disadvantage is inability to confirm spectrometrically the identity of fatty acids detected, which is important especially in complex biological samples. The current study measures omega-3 index in 12 healthy human volunteers using GC-mass spectrometry (MS). Both the intra-assay and day-to-day variations were well within 5% with linearity of response extending to a concentration of 250 μg/ml (830 μmol/L) of EPA. The limit of detection of EPA was 0.36 μg/ml (1.2 μmol/L). About 25 fatty acids were consistently detected in red blood cells from healthy volunteers including cis and trans isomers. The omega-3 index ranged from 2.4% to 6.2% among the 12 volunteers examined and there was no difference between samples taken in the fasting and postprandial states. EPA and DHA concentrations ranged from 3.53 to 105.89 μg/ml (11.7–350 μmol/L) and 12.19 to 214.42 μg/ml (37.1–652.7 μmol/L), respectively. Thus a GC–MS method has been developed for measuring the omega-3 index. Further studies are required to determine the role of this index as a predictor of disease.     

Microalgal biofactories: a promising approach towards sustainable omega-3 fatty acid production

ABSTRACT: Omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) provide significant health benefits and this has led to an increased consumption as dietary supplements. Omega-3 fatty acids EPA and DHA are found in animals, transgenic plants, fungi and many microorganisms but are typically extracted from fatty fish, putting additional pressures on global fish stocks. As primary producers, many marine microalgae are rich in EPA (C20:5) and DHA (C22:6) and present a promising source of omega-3 fatty acids. Several heterotrophic microalgae have been used as biofactories for omega-3 fatty acids commercially, but a strong interest in autotrophic microalgae has emerged in recent years as microalgae are being developed as biofuel crops. This paper provides an overview of microalgal biotechnology and production platforms for the development of omega-3 fatty acids EPA and DHA. It refers to implications in current biotechnological uses of microalgae as aquaculture feed and future biofuel crops and explores potential applications of metabolic engineering and selective breeding to accumulate large amounts of omega-3 fatty acids in autotrophic microalgae.     

Acute supplementation with eicosapentaenoic acid reduces platelet microparticle activity in healthy subjects

BackgroundDietary supplementation with omega-3 fatty acids has been associated with reduced incidence in thrombotic events. In addition, administration of n-3 polyunsaturated fatty acids (PUFAs) has been shown to rectify elevated platelet microparticle (MP) number and procoagulant activity in post myocardial infarction patients. However, it is unknown whether supplementation can alter these parameters in healthy individuals and if such effects are immediate or require long-term supplementation. We have previously demonstrated a gender-specific effect of LCn-3PUFA supplementation on platelet aggregation in healthy human subjects. Here we extend these findings to include the acute effects of supplementation with EPA- or DHA-rich oils on circulating MP levels and activity in healthy subjects.DesignA placebo-controlled trial was conducted in healthy males and females (n=30). MP activity, MP levels and platelet aggregation were measured at 0 and 24 h postsupplementation with either a placebo or EPA- or DHA-rich oil.ResultsBoth EPA and DHA effectively reduced platelet aggregation at 24 h postsupplementation relative to placebo (?13.3%, P=.006 and ?11.9%, P=.016, respectively), but only EPA reduced MP activity (?19.4%, P=.003). When grouped by gender, males showed a similar reduction in both platelet aggregation and MP activity (?20.5%, P=.008; ?22%, P=.008) following EPA, while females showed significantly reduced platelet aggregation (?13.7%, P=.04) but not MP activity after DHA only.ConclusionEPA and DHA exert gender-dependent effects on platelet aggregation and platelet MP activity, but not on MP levels. With respect to thrombotic disease risk, males may benefit more from EPA supplementation.     

Long-Chain Omega-3 Polyunsaturated Fatty Acids Have Developmental Effects on the Crop Pest,the Cabbage White Butterfly Pieris rapae

Nutritional enhancement of crops using genetic engineering can potentially affect herbivorous pests. Recently, oilseed crops have been genetically engineered to produce the long-chain omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) at levels similar to that found in fish oil; to provide a more sustainable source of these compounds than is currently available from wild fish capture. We examined some of the growth and development impacts of adding EPA and DHA to an artificial diet of Pieris rapae, a common pest of Brassicaceae plants. We replaced 1% canola oil with EPA: DHA (11:7 ratio) in larval diets, and examined morphological traits and growth of larvae and ensuing adults across 5 dietary treatments. Diets containing increasing amounts of EPA and DHA did not affect developmental phenology, larval or pupal weight, food consumption, nor larval mortality. However, the addition of EPA and DHA in larval diets resulted in progressively heavier adults (F _{4, 108} = 6.78; p = 0.011), with smaller wings (p < 0.05) and a higher frequency of wing deformities (R = 0.988; p = 0.001). We conclude that the presence of EPA and DHA in diets of larval P. rapae may alter adult mass and wing morphology; therefore, further research on the environmental impacts of EPA and DHA production on terrestrial biota is advisable.     

Omega-3 fatty acids modulate ATPases involved in duodenal Ca absorption

Dietary supplementation with fish oil that contains omega-3 polyunsaturated fatty acids has been shown to enhance bone density as well as duodenal calcium uptake in rats. The latter process is supported by membrane ATPases. The present in vitro study was undertaken to test the effect of omega-3 fatty acids on ATPase activity in isolated basolateral membranes from rat duodenal enterocytes. Ca-ATPase in calmodulin-stripped membranes was activated in a biphasic manner by docosahexanoic acid (DHA) (10-30 microg/ml) but not by eicosapentanoic acid (EPA). This effect was blocked partially by 0.5 microM calphostin (a protein kinase C blocker). DHA inhibited Na,K-ATPase (-49% of basal activity, [DHA]=30 microg/ml, P <0.01). This effect could be reversed partially by 50 microM genistein, a tyrosine kinase blocker. EPA also inhibited Na,K-ATPase: (-47% of basal activity, [EPA]=30 microg/ml, P <0.01), this effect was partially reversed by 100 microM indomethacin, a cyclo-oxygenase blocker. Omega-3 fatty acids are thus involved in multiple signalling effects that effect ATPases in BLM.