Proportions Of EPA Research Articles

Lipid and fatty acid yield of nine stationary-phase microalgae: Applications and unusual C24–C28 polyunsaturated fatty acids

Nine microalgal species from the classes Bacillariophyceae, Cryptophyceae, Prymnesiophyceae and Dinophyceae were isolated from Australian waters, cultured to stationary phase and analyzed for their lipid and fatty acid composition and yield. Five species (Pavlova pinguis, Heterocapsa niei, Proteomonas sulcata, Navicula jeffreyi and Thalassiosira pseudonana) produced high proportions of triacylglycerol (TAG: 22–57% total lipid). An unidentified Navicula-like diatom (CS-786), despite having a low TAG content, had the highest EPA yield (5.8 mg L−1), due to high biomass and a high relative proportion of EPA. Heterocapsa niei had the highest DHA yield (2.9 mg L−1), due to a high cellular lipid and DHA content (171 pg cell−1 and 13.7 pg cell−1, respectively) despite its relatively low biomass. The desirable PUFA composition and yield of both diatom CS-786 and H. niei make them potential candidates for optimization of biomass and PUFA production for use as live-feeds in aquaculture. In addition, H. niei may have potential as a source of DHA for other uses. Low proportions (< 1.2%) of 24:6(n−3) accompanied by trace proportions of 24:5(n−6) were detected in most strains, while 28:8(n−3) was found in dinoflagellates and also in the prymnesiophyte P. pinguis. All non-diatomaceous species contained 26:7(n−3) in minor quantities. This is the first time these unusual C24 and C26 PUFA have been reported in microalgae and the first report of C28 PUFA in a microalga other than dinoflagellates. Possible biosynthetic reasons why these might occur in stationary phase cultures are considered and the likely dietary transfer of these PUFA to higher aquatic life is discussed.

The influence of different combinations of gamma-linolenic acid, stearidonic acid and EPA on immune function in healthy young male subjects.

To determine the effects of EPA, stearidonic acid (STA) or gamma-linolenic acid (GLA) on immune outcomes, healthy male subjects consumed one of seven oil blends for 12 weeks. EPA consumption increased the EPA content of peripheral blood mononuclear cells (PBMC). Consumption of GLA (2.0 g/d) in the absence of STA or EPA increased di-homo-GLA content in PBMC. Neither STA nor its derivative 20 : 4n-3 appeared in PBMC when STA (<1.0 g/d) was consumed. However, STA (1.0 g/d), in combination with GLA (0.9 g/d), increased the proportion of EPA in PBMC. None of the treatments altered neutrophil or monocyte phagocytosis or respiratory burst, production of inflammatory cytokines by monocytes, T lymphocyte proliferation or the delayed-type hypersensitivity response. Production of cytokines by T lymphocytes increased in all groups, with no differences among them. The proportion of lymphocytes that were natural killer cells decreased significantly in subjects receiving 2.0 g EPA or GLA/d. There were no other effects on lymphocyte sub-populations. Plasma IgE concentration decreased in most groups, but not in the control group. Plasma IgG2 concentration increased in the EPA group. Thus, EPA or GLA at a dose of 2.0 g/d have little effect on key functions of neutrophils, monocytes and T lymphocytes, although at this dose these fatty acids decrease the number of natural killer cells. At this dose EPA increases IgG2 concentrations. STA can increase immune cell EPA status, but at 1.0 g/d does not affect human immune function.

The influence of different combinations of γ-linolenic, stearidonic and eicosapentaenoic acids on the fatty acid composition of blood lipids and mononuclear cells in human volunteers

This study set out to identify whether stearidonic acid (18:4n-3; STA) can be used to increase the eicosapentaenoic acid (20:5n-3; EPA) content of plasma lipids and cells in humans and to understand more about the effects of increased consumption of γ-linolenic acid (18:3n-3; GLA), STA and EPA in humans. Healthy young males were randomised to consume one of seven oil blends for a period of 12 weeks (9 g oil/day) ( n =8–12 subjects/group). Palm oil, sunflower oil, an EPA-rich oil, borage oil (rich in GLA), and Echium oil (rich in STA) were blended in various combinations to generate a placebo oil and oils providing approximately 2 g GLA + STA + EPA per day, but in different combinations. Blood was collected at 0, 4, 8 and 12 weeks and the fatty acid compositions of plasma triacylglycerols, cholesteryl esters and phospholipids and of peripheral blood mononuclear cells (PBMCs) determined. Significant effects were observed with each lipid fraction. Neither STA nor its derivative 20:4n-3 appeared in any of the lipid fractions studied when STA (up to 1 g/day) was consumed. However, STA (1 g/day), in combination with GLA (0.9 g/day), increased the proportion of EPA in some lipid fractions, suggesting that STA-rich plant oils may offer a novel means of increasing EPA status. Furthermore, this combination tended to increase the dihomo- γ-linolenic acid (20:3n-6; DGLA) content of PBMCs, without an increase in arachidonic acid (AA) (20:4n-6) content. EPA consumption increased the EPA content of all lipid fractions studied. Consumption of GLA (2 g/day), in the absence of STA or EPA, increased DGLA content with a tendency to increase AA content in some fractions. This effect was prevented by inclusion of EPA in combination with GLA. Thus, this study indicates that STA may be used as a precursor to increase the EPA content of human lipids and that combinations of GLA, STA and EPA can be used to manipulate the fatty acid compositions of lipid pools in subtle ways. Such effects may offer new strategies for manipulation of cell composition in order to influence cellular responses and functions in desirable ways.

Association of n-3 polyunsaturated fatty acids with stability of atherosclerotic plaques: a randomised controlled trial

N-3 polyunsaturated fatty acids (PUFAs) from oily fish protect against death from cardiovascular disease. We aimed to assess the hypothesis that incorporation of n-3 and n-6 PUFAs into advanced atherosclerotic plaques increases and decreases plaque stability, respectively. We did a randomised controlled trial of patients awaiting carotid endarterectomy. We randomly allocated patients control, sunflower oil (n-6), or fish-oil (n-3) capsules until surgery. Primary outcome was plaque morphology indicative of stability or instability, and outcome measures were concentrations of EPA, DHA, and linoleic acid in carotid plaques; plaque morphology; and presence of macrophages in plaques. Analysis was per protocol. 188 patients were enrolled and randomised; 18 withdrew and eight were excluded. Duration of oil treatment was 7-189 days (median 42) and did not differ between groups. The proportions of EPA and DHA were higher in carotid plaque fractions in patients receiving fish oil compared with those receiving control (absolute difference 0.5 [95% CI 0.3-0.7], 0.4 [0.1-0.6], and 0.2 [0.1-0.4] g/100 g total fatty acids for EPA; and 0.3 [0.0-0.8], 0.4 [0.1-0.7], and 0.3 [0.1-0.6] g/100 g total fatty acids for DHA; in plaque phospholipids, cholesteryl esters, and triacylglycerols, respectively). Sunflower oil had little effect on the fatty acid composition of lipid fractions. Fewer plaques from patients being treated with fish oil had thin fibrous caps and signs of inflammation and more plaques had thick fibrous caps and no signs of inflammation, compared with plaques in patients in the control and sunflower oil groups (odds ratio 0.52 [95% CI 0.24-0.89] and 1.19 [1.02-1.57] vs control; 0.49 [0.23-0.90] and 1.16 [1.01-1.53] vs sunflower oil). The number of macrophages in plaques from patients receiving fish oil was lower than in the other two groups. Carotid plaque morphology and infiltration by macrophages did not differ between control and sunflower oil groups. Atherosclerotic plaques readily incorporate n-3 PUFAs from fish-oil supplementation, inducing changes that can enhance stability of atherosclerotic plaques. By contrast, increased consumption of n-6 PUFAs does not affect carotid plaque fatty-acid composition or stability over the time course studied here. Stability of plaques could explain reductions in non-fatal and fatal cardiovascular events associated with increased n-3 PUFA intake.

Production of structured triglycerides rich in n-3 polyunsaturated fatty acids by the acidolysis of cod liver oil and caprylic acid in a packed-bed reactor: equilibrium and kinetics

Structured triglycerides (ST) enriched in n-3 polyunsaturated fatty acids (PUFAs) (eicosapentaenoic acid, EPA, and docosahexaenoic acid, DHA) in position 2 of the triglyceride backbone were synthesised by acidolysis of cod liver oil (CLO) and caprylic acid (CA) catalysed by the 1,3-specific immobilised lipase Lipozyme IM. The reaction was carried out in three ways: (1) in a batch reactor (where the influence of temperature on the incorporation of CA into the CLO triglyceride was studied); (2) in an immobilised lipase packed-bed reactor (PBR) by recirculating the reaction mixture from the exit of the bed to the substrate reservoir (product recirculation) to determine the equilibrium composition; and (3) in a PBR without recirculation. A “lag” period of duration inversely proportional to the initial water amount of the lipase, was observed when new lipase was used. Apparently, during this “lag” period the hydro-enzymatic layer that surrounds the lipase surface reaches its water equilibrium content. A reaction scheme, where only the fatty acid in the positions 1 and 3 of the glycerol backbone were exchanged by CA, was proposed. The exchange equilibrium constants between CA and the native fatty acids of CLO were determined. The n-3 PUFAs (EPA and DHA) were the most resistant native fatty acids to exchange with exchange equilibrium constants of 1.32 and 0.28, respectively. Also, average reaction rates and kinetic constants of exchange of CA and native fatty acid of CLO were calculated. Low kinetic constants were observed for EPA, DHA and palmitic acid. For acidolysis reaction in the continuous mode PBR, the lipase amount/(flow rate × substrate concentration) ratio ( m L / q[TG] 0) could be considered as the intensive variable of the process for use in scale up of the PBR. A simple equation was proposed for the prediction of the fatty acid composition of the ST at the exit of the PBR as a function of the intensive variable m L / q[TG] 0. At equilibrium, the ST produced had the following composition: CA 57%, EPA 5.1%, DHA 10.0% and palmitic acid 6.3% (only considering the major fatty acids). In addition, the proportion of EPA and DHA that esterified the position 2 of the ST was 13.5%, which represented 44% of the total fatty acids in the position 2 of the resultant ST.

High levels of n−3 polyunsaturated fatty acids in Euphausia pacifica and its role as a source of docosahexaenoic and icosapentaenoic acids for higher trophic levels

In Euphausia pacifica specimens, phospholipids (PL, 44.1–81.2%) such as phosphatidylethanolamine (PE, mean±standard error, 26.1±2.1%) and phosphatidylcholine (PC, 29.0±2.3%) were found to be the dominant lipids. Compared to many other marine organisms, the level of PL was markedly high. The major fatty acids in the TAG of E. pacifica were saturated fatty acids (SFA, 14:0 and 16:0), monounsaturated fatty acids (MUFA, 16:1 and 18:1), and polyunsaturated fatty acids (PUFA, 18:4 n−3 and 20:5 n−3, icosapentaenoic acid: EPA). The only fatty acids found in the tissue PL were SFA (16:0), MUFA (18:1), and PUFA (20:4 n−6, arachidonic acid: AA, EPA, and 22:6 n−3, docosahexaenoic acids: DHA). The comparatively high levels of 14:0, 16:0, 16:1 n−7, 16:2 n−4, 16:4 n−1, 18:1 n−7, 18:1 n−9, 18:4 n−3, and EPA in the TAG may be affected by the lipid composition of its phytoplankton prey, such as diatoms, which generally contain high amounts of these fatty acids. The levels of short chain 14:0, 16:1 n−7, 16:2 n−4, 16:4 n−1, 18:1 n−9, and 18:4 n−3 decreased in PL, while AA, EPA, and DHA increased. In particular, the levels of n−3 PUFA in PL were markedly high in all specimens. The mean proportion of EPA plus DHA accounted for more than 45% (55.0% in PE and 47.7% in PC) of the total fatty acids. These results suggest that E. pacifica, which contains markedly high levels of EPA and DHA, may biosynthesize these PUFA by carbon chain elongation and desaturation or selectively accumulate n−3 PUFA. In addition, their lipids may be an important source of n−3 PUFA for higher marine animals, such as the pelagic marine fishes (sardines, anchovies, and other small fishes), which mainly prey on these euphausiids. Marine fish accumulate high levels of these n−3 PUFA because they are unable to synthesize DHA.

Nutritional regulation of hepatocyte fatty acid desaturation and polyunsaturated fatty acid composition in zebrafish (Danio rerio) and tilapia (Oreochromis niloticus)

The desaturation and elongation of [1-14C]18:3n-3 was investigated in hepatocytes of the tropical warm freshwater species, zebrafish (Danio rerio) and Nile tilapia (Oreochromis niloticus). The hepatocyte fatty acid desaturation/elongation pathway was assayed before and after the fish were fed two experimental diets, a control diet containing fish oil (FO) and a diet containing vegetable oil (VO; a blend of olive, linseed and high oleic acid sunflower oils) for 10 weeks. The VO diet was formulated to provide 1% each of 18:2n-6 and 18:3n-3, and so satisfy the possible EFA requirements of zebrafish and tilapia. At the end of the dietary trial, the lipid and fatty acid composition was determined in whole zebrafish, and liver, white muscle and brain of tilapia. Both zebrafish and tilapia expressed a hepatocyte fatty acid desaturation/elongation pattern consistent with them being freshwater and planktonivorous fish. The data also showed that hepatic fatty acid desaturation/elongation was nutritionally regulated with the activities being higher in fish fed the VO diet compared to fish fed the FO diet. In zebrafish, the main effect of the VO diet was increased fatty acid Δ6 desaturase activity resulting in the production of significantly more 18:4n-3 compared to fish fed the FO diet. In tilapia, all activities in the pathway were greater in fish fed the VO diet resulting in increased amounts of all fatty acids in the pathway, but primarily eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). However, the fatty acid compositional data indicated that despite increased activity, desaturation of 18:3n-3 was insufficient to maintain tissue proportions of EPA and DHA in fish fed the VO diet at the same level as in fish fed the FO diet. Practically, these results indicate that manipulation of tilapia diets in commercial culture in response to the declining global fish oil market would have important consequences for fish fatty acid composition and the health of consumers. Scientifically, zebrafish and tilapia, both the subject of active genome mapping projects, could be useful models for studies of lipid and fatty acid metabolism at a molecular biological and genetic level.

Production of eicosapentaenoic acid (EPA) in Monodus subterraneus grown in a helical tubular photobioreactor as affected by cell density and light intensity

The effect of cell density (1–4.5 g L-1) and light intensity (44 and 82 μmol m-2 s-1) on fatty acid composition andeicosapentaenoic acid (EPA, 20:5 ω3) production was studied ina semi-continuous culture of Monodus subterraneus grown in a helicaltubular photobioreactor (`Biocoil') under laboratory conditions. Under lowlight, the highest proportion of EPA (31.5% of total fatty acids) and EPAcontent (3.5% of dry weight), biomass productivity (1.3 g L-124 h-1) and EPA productivity (44 mg L-1 24 h-1)occurred at optimal cell density of about 1.7 g L-1. Cell densityhad no effect on the total fatty acid (TFA) content and was maintained atca. 11% of dry weight. Under high light, the highest proportion ofEPA to fatty acids (31.8%), the total fatty acids content (13.4%) andEPA content (4.3% of dry weight) occurred at cell density of about 3.4gL-1. But the highest biomass productivity (1.7 g L-124 h-1) and EPA productivity (56 mg L-1 24 h-1) wereobtained at a cell density of 1.6 and 2.6g L-1, respectively. Ourresults suggest that manipulating the cell density and light intensity canmodify the composition of fatty acid and production of eicosapentaenoicacid (EPA) in M. subterraneus.

Seasonal variation in the fatty acid composition and quality of sardine oil from Sardinops sagax caeruleus of the Gulf of California.

One of the few sources of long-chain n-3 polyunsaturated fatty acids is fish oil, but considerable variation may exist according to species and season. In this study, the fatty acid profiles of sardine oils from Sardinops sagax caeruleus of the Gulf of California, Mexico, were evaluated in three seasonal catch periods. Oil quality was also evaluated by peroxide and free acid values. The most abundant fatty acids found in the oils were palmitic acid (19.3%), oleic acid (14.3%), eicosapentaenoic acid (EPA, 20.4%), and docosahexaenoic acid (DHA, 12.2%). There was no significant difference in the composition and quality among the six reduction plants where the samples were obtained. However, a significant difference in the proportion of EPA and DHA in one of the catch seasons analyzed was observed.

Effects of monospecific and mixed-algae diets on survival, development and fatty acid composition of penaeid prawn ( Penaeus spp.) larvae

Four species of microalgae (Chaetoceros muelleri, Tetraselmis suecica, Tahitian Isochrysis sp. (T-iso) and Dunaliella tertiolecta) with distinctly different fatty acid profiles were grown in continuous culture and fed to prawn larvae (Penaeus japonicus, P. semisulcatus and P. monodon) as monospecific diets. The best two diets (C. muelleri and T. suecica) were also fed as a mixed diet. Experiments were run until the larvae fed the control diet of C. muelleri metamorphosed to Mysis 1. The survival and development (i.e. performance) of the larvae were affected by algal diet, and the diets were ranked in the order of decreasing nutritional value: C. muelleri ≥ T. suecica > T-iso > D. tertiolecta. Larvae fed a mixed diet of C. muelleri and T. suecica (2:3 by dry weight) performed as well or better than those fed C. muelleri, and the performance of both these groups of larvae was better than those fed T. suecica. The lipid and carbohydrate compositions of the algae had little or no effect on the lipid and carbohydrate compositions of the larvae or their performance. However, the larvae that performed best (i.e. those fed C. muelleri) had significantly more lipid and carbohydrate than those that performed worst (i.e. those fed D. tertiolecta). Larvae fed C. muelleri or the mixed-algae diet had higher proportions of the essential fatty acids eicosapentaenoic acid [EPA, 20:5(n-3)] and arachidonic acid [ARA, 20:4(n-6)] than the larvae fed on other diets. Furthermore, the larvae fed T. suecica, which showed intermediate performance between larvae fed C. muelleri and T-iso or D. tertiolecta, also had higher proportions of EPA and ARA. Both C. muelleri and T. suecica contained EPA and ARA, but T-iso and D. tertiolecta did not, except for trace amounts of EPA in T-iso. The fatty acid ARA appears to be much more important in the diet of larval prawns than has so far been considered. The level of the essential fatty acid docosahexaenoic acid [DHA, 22:6(n-3)] in the algal diet and the larvae was not related to the performance of the larvae; only C. muelleri and T-iso contained DHA. However, the nauplii contained large proportions of DHA, suggesting that these were sufficient to meet the larval requirements for DHA during their development to Mysis 1. Mixed-algae diets could improve the performance of larvae by providing a more comprehensive range of fatty acids.

The relationships between dietary alpha-linolenic:linoleic acid and rat platelet eicosapentaenoic and arachidonic acids.

Increased dietary intake of alpha-linolenic acid (ALA) may be desirable to enrich tissue eicosapentaenoic acid (EPA; 20:5n-3) but competition between n-3 and n-6 fatty acids for enzymes involved in elongation and subsequent acylation will determine the relative proportions of phospholipid fatty acids. The aim of the present study was to examine the effects of altering the dietary ALA:linoleic acid (LA) ratio on rat platelet EPA and arachidonic acid (AA; 20:4n-6) concentrations. Sprague-Dawley rats were fed on diets containing 30% total energy as fat with approximately 10% each of saturated, monounsaturated and polyunsaturated fatty acids with one of the following ALA:LA values; 1:7, 1:4, 1:1 or 1.3:1 (nine rats per group). After 4 weeks, blood was withdrawn from the abdominal aorta and platelet fatty acids analysed. The proportion of EPA was greater at the 1:1 and 1.3:1 ratios compared with the 1:7 and 1:4 (P < 0.05), and a decrease in AA was observed (P < 0.05) at the higher ratios. It was established that the platelet EPA:AA value increased (P < 0.05) as the dietary ALA:LA value increased.

A study of the distribution of eicosapentaenoic acid and docosahexaenoic acid between the α and β glycerol chains in fish oils by 13C-NMR spectroscopy

Using the 13C-NMR signals for the C1 and C2 carbon atoms it is possible to determine the proportion of EPA and of DHA in the α and β chains of triacylglycerols. This has been applied to seven fish oils and to EPA/DHA enriched fractions obtained from four of these. The results show that these two important n-3 polyene acids are distributed differently in fish oil triacylglycerols. DHA is concentrated in the β position (59–87%), but EPA is more randomly distributed between the α and β chains. These results accord with those obtained for other fish oils by stereospecific gas chromatographic procedures.

Manipulation of polyunsaturated, branchedchain and trans-fatty acid production in Shewanella putrefaciens strain ACAM 342

Shewanella putrefaciens strain ACAM 342 produced a range of polyunsaturated fatty acids (PUFA) including 18:2ω6, 18:3ω3, 18:3ω6, 18:4ω3 and 20:5ω3 (EPA). Under culture in Zobell&apos;s broth at 15 °C exponential-phase cultures produced 3.2 + 0.3% EPA, or 1.2 + 0.2 mg (g bacterial dry wt)-1. Alteration of growth phase, addition of biotin to the medium or a 10-fold decrease in nutrient levels had no significant effect (P&gt;0.05) on levels of EPA. Growth in 7.0% NaCl medium markedly decreased the overall degree of fatty acid unsaturation (P&lt;0.01), while growth on acetate as the sole carbon source increased the level of 18:2.6 from 0.4 + 0.1% to 7.1 % of total fatty acids through inhibition of branched-chain fatty acid synthesis. Addition of desaturase cofactors to the growth medium increased the proportion of EPA from 3.2 + 0.3% to 4.6%, but decreased the quantitative yield from 1.2. 0.2 to 0.9 mg (g bacterial dry wt)-1. This bacterium represents a model organism to study bacterial PUFA production. The trans-monounsaturated fatty acid 16:1ω7t was also produced under all culture conditions, together with four other trans-isomers, namely 14:1ω5t, 15:1ω6t, 17:1ωt and 18:1ω7t. Although the relative levels of trans-acids also changed under various culture conditions, there was no evidence that they were produced as a starvation or stress response.

The influence of different amounts ofn-3 polyunsaturated fatty acids on bleeding time and invivovascular reactivity

Mesenteric bleeding time, mesenteric vascular reactivity, platelet and erythrocyte lipid fatty acid composition were measured at 2-3 weeks, 5-6 weeks and 11-22 weeks in normotensive Wistar rats, fed on high (6.5% energy) or moderate (1.6% energy) intakes of eicosapentaenoic acid (20:5n-3; EPA) as fish oil, compared with controls fed on a diet devoid of EPA. All diets contained the same level of linoleic acid (4% energy): the moderate- and high-EPA diets also contained 1.1 and 4.4% of the energy as docosahexaenoic acid (22:6n-3) respectively. Moderate, but not high, intakes of EPA increased mesenteric bleeding time. Similar reductions in erythrocyte and platelet arachidonic acid (20:4n-6) occurred in animals fed on either high or low amounts of EPA, but the proportion of EPA increased dose-dependently. At high intakes of EPA the proportion of oleic acid in platelets and erythrocytes was decreased. Blood pressure platelet counts, mesenteric vessel diameter and mesenteric vascular reactivity to vasopressin were unaffected by treatment. High intakes of fish oil led to a slight fall in packed cell volume. In a second experiment bleeding time and mesenteric vascular reactivity to noradrenaline were increased 2-4 weeks after receiving a moderate intake of EPA and these effects persisted 5-21 d after switching to a control diet. A similar increase in vascular reactivity to noradrenaline was observed in animals given indomethacin (6 mg/kg) but not in those given aspirin (20 mg/kg).

Production of Eicosapentaenoic Acid (20:5 n-3) by Vibrio pelagius Isolated from Turbot ( Scophthalmus maximus (L.)) Larvae

Fourteen bacterial strains isolated from turbot, Scophthalmus maximus (L.), larvae were screened for eicosapentaenoic acid (20:5 n-3) (EPA) production. Gas chromatography analysis revealed that one bacterial species, Vibrio pelagius, contained a high proportion of EPA in cellular lipid. This finding was confirmed by gas chromatography-mass spectrometry analysis. A higher concentration of EPA was detected when the bacterium was cultured at 4 degrees C.

The influence of a fish oil high in docosahexaenoic acid on plasma lipoprotein and vitamin E concentrations and haemostatic function in healthy male volunteers.

Nine healthy male subjects consumed a daily fish oil supplement providing 2.1 g docosahexaenoic acid (22:6 n-3; DHA) and 0.8 g eicosapentaenoic acid (20:5 n-3; EPA) for 6 weeks. The proportion of EPA and DHA in plasma, erythrocytes, leucocytes and platelet phospholipids was increased by the supplement. Plasma concentration of triacylglycerol and very-low-density-lipoprotein-cholesterol were lowered and those of high-density-lipoprotein (HDL)- and HDL2-cholesterol and apoprotein B were increased. Platelet aggregation and thromboxane B2 production induced by collagen were partially inhibited. Both systolic and diastolic blood pressure fell during treatment and rose following withdrawal of the supplement. Statistically significant reductions in erythrocyte counts, packed cell volume and haemoglobin and increases in total leucocyte and monocyte counts occurred with the supplement. Plasma alpha-tocopherol concentrations fell below the normal range during the period of supplementation. It is suggested that future studies consider components other than EPA in fish oil. Further studies are needed to investigate the extent to which fish oil increases the requirement for antioxidant nutrients.

Production of eicosapentaenoic acid by freshwaterVibrio

AbstractArctic charr,Salvelinus alpinus (L.), were fed a moist pellet diet based on casein, dextrin and coconut oil in fresh water. The diet contained substantial amounts of saturated fatty acids, especially 12∶0. Polyunsaturated fatty acids in the n−3 series were not detected in the diet, but analysis of the intestinal liquor stripped from the charr showed that eicosapentaenoic acid (EPA, 20∶5n−3) accounted for 3.5% of fatty acids in total lipid. Colony forming units (CFU) of aerobic microorganisms were approximately 104 per mL intestinal liquor. Seventeen bacterial strains isolated from the intestinal liquor were screened for EPA production. Four isolates contained a high proportion of EPA in their total lipid. These isolates belong to the speciesVibrio.

Erythrocyte eicosapentaenoic acid versus docosahexaenoic acid as a marker for fish and fish oil consumption

The fatty acid composition of erythrocyte membranes was investigated in 21 healthy men after 6 wk of varying intakes of eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). In one experiment, 12 subjects were fed three diets in a 3 × 3 crossover design: an essentially fish-free control diet, a fish diet (0.15 g EPA/d, 0.41 g DHA/d) and the same fish-based diet supplemented with 5 g/d fish oil (Fish + Oil: 0.99 g EPA/d, 0.99 g DHA/d). A 6 wk wash-out period was allowed between each diet. In another experiment, 11 subjects were supplemented with 5 g/d fish oil alone for 6 wk (0.84 g EPA/d, 0.48 g DHA/d). After fish or fish oil feeding, the percent proportion of EPA and DHA in the erythrocyte membranes rose at the expense of linoleic and arachidonic acids. After 6 wk on the fish-based diets, EPA incorporation approached saturation, with the incremental increases being proportional to the amounts supplied by the diets. In contrast, parallel increases were observed for erythrocyte DHA even though the Fish + Oil diet was supplying twice as much DHA as the fish alone diet. These observations imply different metabolic rates for EPA and DHA and their importance is discussed in terms of the value of erythrocyte EPA versus DHA as markers for fish and fish oil consumption.

Preparation of Omega‐3 PUFA Concentrates from Fish Oils via Urea Complexation

AbstractThe effect of weight ratio of urea to fatty acids and the urea‐fatty acid adduct crystallization temperature on the enrichment of eicosapentaenoic acid from marine oil fatty acids was studied. The optimum ratio of urea to fatty acids was found to be 3 : 1 for laboratory scale preparations and the optimum temperature for the formation of urea‐fatty acid adduct was 1°C. At very low temperatures (−12, −18, −35°C) the recovery efficiency for EPA was reduced. Using these optimum values, enrichment of EPA and other n‐3 polyunsaturated fatty acids via urea complexation was carried out on a pilot plant scale in a variety of North Atlantic and North Pacific fist oils and a seal oil. Irrespective of hte type of starting oil, all the oils gave a concentrate with 69–85% total n‐3 PUFA with an overall yield of 17–20%. Menhaden is clearly an ideal oil for preparation of EPA concentrate, as the starting oil usually has a higher proportion of EPA to DHA than most of the other commercial fish oils.