Stearidonic Acid-Enriched Soybean Oil Increased the Omega-3 Index, an Emerging Cardiovascular Risk Marker

A plant source of omega-3 fatty acid (FA) that can raise tissue eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA) is needed. A soybean oil (SBO) containing approximately 20% stearidonic acid [SDA; the delta-6 desaturase product of alpha-linolenic acid (ALA)] derived from genetically modified soybeans is under development. This study compared the effects of EPA to SDA-SBO on erythrocyte EPA+DHA levels (the omega-3 index). Overweight healthy volunteers (n=45) were randomized to SDA-SBO (24 ml/day providing approximately 3.7 g SDA) or to regular SBO (control group) without or with EPA ethyl esters (approximately 1 g/day) for 16 weeks. Serum lipids, blood pressure, heart rate, platelet function and safety laboratory tests were measured along with the omega-3 index. A per-protocol analysis was conducted on 33 subjects (11 per group). Compared to baseline, average omega-3 index levels increased 19.5% in the SDA group and 25.4% in the EPA group (p<0.05 for both, vs. control). DHA did not change in any group. Relative to EPA, SDA increased RBC EPA with about 17% efficiency. No other clinical endpoints were affected by SDA or EPA treatment (vs. control). In conclusion, SDA-enriched SBO significantly raised the omega-3 index. Since EPA supplementation has been shown to raise the omega-3 index and to lower risk for cardiac events, SDA-SBO may be a viable plant-based alternative for providing meaningful intakes of cardioprotective omega-3 FAs.     

Decreasing the Linoleic Acid to α-Linolenic Acid Diet Ratio Increases Eicosapentaenoic Acid in Erythrocytes in Adults

The n-6/n-3 fatty acid (FA) ratio has increased in the Western-style diet to ~10–15:1 during the last century, which may have contributed to the rise in cardiovascular disease (CVD). Prior studies have evaluated the effects on CVD risk factors of manipulating the levels of n-6 and n-3 FA using food and supplements or investigated the metabolic fate of linoleic acid (LNA) and α-linolenic acid (ALA) by varying the n-6/n-3 ratios. However, no previous studies have investigated the potential interaction between diet ratios and supplementation with eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). We used a factorial design approach with adults (n = 24) in a controlled feeding trial to compare the accretion of EPA and DHA into red blood cell membranes (RBC) by adding a direct source (algal oil supplement) of EPA and DHA in a diet with a 10:1 versus 2:1 ratio of n-6/n-3 FA. Subjects were randomized into 8-week crossover diet sequences and each subject consumed three of four diets [10:1, 10:1 plus supplement (10:1 + S), 2:1 and 2:1 + S]. LNA and ALA intakes were 9.4 and 7.7%, and 1.0 and 3.0% during the low and high ALA diets, respectively. Compared to the Western-style 10:1 diet, the 2:1 diet increased EPA by 60% (P < 0.0001) in RBC membranes without the direct EPA source and a 34% increase (P = 0.027) was observed with the 10:1 + S diet; however, DHA levels increased in both diet ratios only with a direct DHA source. Shifting towards a 2:1 diet is a valid alternative to taking EPA-containing supplements.     

Peripheral Artery Disease Is Associated with a Deficiency of Erythrocyte Membrane n-3 Polyunsaturated Fatty Acids

Population-based data suggest that individuals who consume large dietary amounts of n-3 polyunsaturated fatty acids (PUFA) have lower odds of peripheral artery disease (PAD); however, clinical studies examining n-3 PUFA levels in patients with PAD are sparse. The objective of this study is to compare erythrocyte membrane fatty acid (FA) content between patients with PAD and controls. We conducted a cross-sectional study of 179 vascular surgery outpatients (controls, 34; PAD, 145). A blood sample was drawn and the erythrocyte FA content was assayed using capillary gas chromatography. We calculated the ratio of the n-3 PUFA eicosapentaenoic acid (EPA) to the n-6 PUFA arachidonic acid (ARA) as well as the omega-3 index (O3I), a measure of erythrocyte content of the n-3 PUFA, EPA, and docosahexaenoic acid (DHA), expressed as a percentage of total erythrocyte FA. Compared with controls, patients with PAD smoked more and were more likely to have hypertension and hyperlipidemia (p < 0.05). Patients with PAD had a lower mean O3I (5.0 ± 1.7% vs 6.0 ± 1.6%, p < 0.001) and EPA:ARA ratio (0.04 ± 0.02 vs 0.05 ± 0.05, p < 0.001), but greater mean total saturated fats (39.5 ± 2.5% vs 38.5 ± 2.6%, p = 0.01). After adjusting for several patient characteristics, comorbidities, and medications, an absolute decrease of 1% in the O3I was associated with 39% greater odds of PAD (odds ratio [OR] 1.39, 95% confidence interval [CI] 1.03–1.86, and p = 0.03). PAD was associated with a deficiency of erythrocyte n-3 PUFA, a lower EPA:ARA ratio, and greater mean total saturated fats. These alterations in FA content may be involved in the pathogenesis or development of poor outcomes in PAD.     

Docosahexaenoic acid supplementation in vegetarians effectively increases omega-3 index: A randomized trial

Low red blood cell (RBC) membrane content of FPA+DHA (hereafter called omega-3 index) has recently been described as an indicator for increased risk of death from coronary heart disease. The relationship between plasma and RBC FA, focusing on omega-3 index, and the response to DHA supplementation were investigated in a double-blind, randomized, placebo-controlled, intervention study. Healthy vegetarians (87 f, 17 m) consumed daily a microalgae oil from Ulkenia sp. (0.94 g DHA/d) or olive oil (placebo) for 8 wk. DHA supplementation significantly increased DHA in RBC total lipids (7.9 vs. 4.4 wt%), in RBC PE (12.1 vs. 6.5 wt%), in RBC PC (3.8 vs. 1.4 wt%), and in plasma phospholipids (PL) (7.4 vs. 2.8 wt%), whereas EPA levels rose to a much lesser extent. Microalgae oil supplementation increased the omega-3 index from 4.8 to 8.4 wt%. After intervention, 69% of DHA-supplemented subjects (but no subject of the placebo group) reached an omega-3 index above the desirable value of 8 wt%. Omega-3 index and EPA+DHA levels in RBC PE, RBC PC, and plasma PL were closely correlated (r always >0.9). We conclude that an 8-wk supplementation with 0.94 g DHA/d from microalgae oil achieves a beneficial omega-3 index of ≥8% in most subjects with low basal EPA+DHA status. RBC total FA analyses can be used instead of RBC lipid fraction analyses for assessing essential FA status, e.g., in clinical studies.     

n-3 Polyunsaturated Fatty Acids and Atopy in Korean Preschoolers

Atopy is a growing problem for Korean children. Since eicosapentaenoic acid is a precursor of less active inflammatory eicosanoids, n-3 polyunsaturated fatty acids (PUFA) may have a protective effect on atopy. This study was undertaken to determine whether n-3 PUFA in red blood cells (RBC) is lower in atopic than in non-atopic preschoolers. Three hundred and eight Korean children aged 4–6 years were enrolled. Total RBC fatty acid composition was measured by gas chromatography. The prevalence of atopic dermatitis, allergic rhinitis, or asthma was 29%. Total RBC n-3 PUFA were lower in preschoolers with atopy than controls (9.8 ± 1.2 vs. 11.4 ± 1.6%; P < 0.05), while n-6 PUFA (33.0 ± 1.4 vs. 32.2 ± 1.0%; P < 0.05) and n-6/n-3 PUFA ratio (3.4 ± 0.6 vs. 2.8 ± 0.5; P < 0.05) were greater. The following factors were also associated with an increase in atopy: higher saturated fatty acids (39.6 ± 1.4 vs. 40.6 ± 1.9; P < 0.05) and arachidonic acid (15.3 ± 1.6 vs. 16.0 ± 2.9; P < 0.05), and lower total PUFA (43.8 ± 0.7 vs. 42.8 ± 1.4; P < 0.05) and omega-3 index (EPA + DHA; 9.1 ± 0.8 vs. 7.8 ± 0.5; P < 0.05) in RBC. Maternal history of atopy was a significant (P < 0.05) risk factor, while lactation was not. The results suggest that a reduced content of n-3 PUFA in the RBC membrane could play a role in early children atopy.     

Lipid Content and Fatty Acid Composition of 15 Marine Fish Species from the Southeast Coast of Brazil

Lipid content and fatty acid composition were determined in edible meat of fifteen marine fish species caught on the Southeast Brazilian coast and two from East Antarctic. Most of the fish had lipid amounts lower than 10% of their total weight. Palmitic acid (C16:0) predominated, accounting for 54–63% of the total amount of saturated fatty acids. Oleic acid (C18:1n-9) was the most abundant (49–69%) monounsaturated fatty acid, and docosahexaenoic acid (DHA) was the predominant polyunsaturated fatty acid (PUFA), accounting for 31–84% of n-3 PUFA. n-3 PUFA level were highest in Antarctic fish meat, comprising 45% of the total fatty acid content, which consisted of mainly EPA (16.1 ± 1.5 g/100 g lipids) and DHA (24.8 ± 2.4 g/100 g lipids). The amounts of EPA + DHA in g/100 g of lipids on the Southeast Brazilian coast and Antarctic fish species investigated were found to be similar: 42.0 ± 1.7 for Bonito cachorro, 41.0 ± 2.3 for Atum, and 39.4 ± 1.8 for peixe porco, respectively. All the studied species exhibited an n-3/n-6 ratio higher than 3, which confirms the great importance of Southeast Brazilian coast fish as a significant dietary source of n-3 PUFA.     

Low Levels of the Omega-3 Index are Associated with Sudden Cardiac Arrest and Remain Stable in Survivors in the Subacute Phase

In previous studies, low blood levels of n-3 fatty acids (FA) have been associated with increased risk of cardiac death, and the omega-3 index (red blood cell (RBC) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) expressed as weight percentage of total FA) has recently been proposed as a new risk factor for death from coronary artery disease, especially following sudden cardiac arrest (SCA). As blood samples often haven been harvested after the event, the aim of our study was to evaluate the stability of RBC fatty acids following SCA. The total FA profile, including the omega-3 index, was measured three times during the first 48 h in 25 survivors of out-of-hospital cardiac arrest (OHCA), in 15 patients with a myocardial infarction (MI) without SCA and in 5 healthy subjects. We could not demonstrate significant changes in the FA measurements in any of the groups, this also applied to the omega-6/omega-3 ratio and the arachidonic acid (AA)/EPA ratio. Furthermore, we compared the omega-3 index in 14 OHCA-patients suffering their first MI with that of 185 first-time MI-patients without SCA; mean values being 4.59% and 6.48%, respectively (p = 0.002). In a multivariate logistic regression analysis, a 1% increase of the omega-3 index was associated with a 58% (95% CI: 0.25–0.76%) reduction in risk of ventricular fibrillation (VF). In conclusion, the omega-3 index remained stable after an event of SCA and predicted the risk of VF.     

Dietary Source of Stearidonic Acid Promotes Higher Muscle DHA Concentrations than Linolenic Acid in Hybrid Striped Bass

Rapid expansion of aquacultural production is placing increasing demand on fish oil supplies and intensified the search for alternative lipid sources. Many of the potential alternative sources contain low concentrations of long chain n-3 fatty acids and the conversion of dietary linolenic acid to longer chain highly unsaturated fatty acids is a relatively inefficient process in some species. A 6-week study was conducted to compare tissue fatty acid (FA) concentrations in hybrid striped bass fed either 18:3n-3 (α-linolenic acid; ALA) or 18:4n-3 (stearidonic acid; SDA). Hybrid striped bass were fed either a control diet containing fish oil, or diets containing ALA or SDA at three different levels (0.5, 1 and 2% of the diet). There were no significant differences in whole animal responses between fish fed ALA or SDA. Liver and muscle concentrations of ALA and SDA were responsive to dosages fed. However, only 22:6n-3 concentrations in muscle were significantly affected by dietary source of 18 carbon precursors. Muscle 22:6n-3 concentrations were significantly higher in fish fed SDA compared to fish fed ALA. Based on these data, it appears that feeding SDA can increase long chain n-3 fatty acid concentrations in fish muscle.     

Low-dose eicosapentaenoic or docosahexaenoic acid administration modifies fatty acid composition and does not affect susceptibility to oxidative stress in rat erythrocytes and tissues

In view of the promising future for use of n-3 polyunsaturated fatty acids (PUFA) in the prevention of cancer and cardiovascular diseases, it is necessary to ensure that their consumption does not result in detrimental oxidative effects. The aim of the present work was to test a hypothesis that low doses of eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) do not induce harmful modifications of oxidative cell metabolism, as modifications of membrane fatty acid composition occur. Wistar rats received by gavage oleic acid, EPA, or DHA (360 mg/kg body weight/day) for a period of 1 or 4 wk. Fatty acid composition and α-tocopherol content were determined for plasma, red blood cell (RBC) membranes, and liver, kidney, lung, and heart microsomal membranes. Susceptibility to oxidative stress induced by tert-butylhydroperoxide was measured in RBC. EPA treatment increased EPA and docosapentaenoic acid (DPA) content in plasma and in all the membranes studied. DHA treatment mainly increased DHA content. Both treatments decreased arachidonic acid content and n-6/n-3 PUFA ratio in the membranes, without modifying the Unsaturation Index. No changes in tissue α-tocopherol content and in RBC susceptibility to oxidative stress were induced by either EPA or DHA treatment. The data suggest that EPA and DHA treatments can substantially modify membrane fatty acids, with-out increasing susceptibility to oxidative stress, when administered at low doses. This opens the possibility for use of low doses of n-3 PUFA for chemoprevention without risk of detrimental secondary effects.     

Blood pressure,serum lipids,and fatty acids in populations on a lake-fish diet or on a vegetarian diet in Tanzania

Major risk factors for coronary heart disease were assessed in two populations of Tanzania, one on a fish diet (FD) living along the coast of Lake Nyasa, and the other, mainly on a vegetarian diet (VD), living in a farming area. Lower blood pressure values were found in the FD subjects (n=618) vs. VD (n=618) (systolic blood pressure, SBP, 120±15 vs. 135±20,P<0.01; diastolic blood pressure, DBP, 70±9 vs. 78±11,P<0.01, respectively). In an FD subgroup (n=61), total cholesterol (TC) (122 vs. 136 mg/dL,P<0.01); triglycerides (TG) (82 vs. 105 mg/dL,P<0.01); and lipoprotein (a) [Lp(a)] (19.9±18.4 vs. 32.3±22.4,P<0.001) were lower than in a VD subgroup (n=55). Serum fatty acids (FA) in the FD subgroup were as follows: eicosapentaenoic acid (EPA) (20∶5) 2.48 vs. 0.72%, docosahexaenoic acid (DHA) (22∶6) 5.93 vs. 1.49%, vs. the VD, respectively. Arachidonic acid (AA) (20∶4n-6) also was higher in the FD vs. the VD group (9.85 vs. 8.30%,P<0.05), whereas 18∶2n-6 was about double (23.97 and 14.85%) in VD vs. FD. The peculiar serum FA pattern in FD reflected the FA of dietary fish. In fact, in four main species of lake fish, DHA was 8–19%, higher than EPA (1.8–4.2%), in contrast with the situation in cold-water fish, and AA was 5.8–8%, higher than in cold-water fish. The data, obtained in populations strictly on natural, unprocessed, low-fat diets, show that a diet based on freshwater fish results in lower BP, serum TC, TG, and Lp(a), and suggests that serum AA is not reduced when the major dietary n-3 is DHA rather than EPA.     

Matrix Extension Validation of AOCS Ce 2c-11 for Omega-3 Polyunsaturated Fatty Acids in Conventional Foods and Dietary Supplements Containing Added Marine Oil

Marine oils are commonly added to conventional foods and dietary supplements to enhance their contents of omega-3 polyunsaturated fatty acids (PUFA), including eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3), which have been associated with numerous potential health benefits. This study compared American Oil Chemists’ Society (AOCS) Official Methods Ce 2b-11 and Ce 2c-11 for determining EPA and DHA in foods and dietary supplements and found that AOCS Ce 2c-11 produces significantly higher analyzed values, which could be attributed to a more comprehensive breakdown of the sample matrix and derivatization of fatty acids. Our subsequent food matrix extension validation of AOCS Ce 2c-11 demonstrated that the method produces true, accurate, sensitive, and precise determinations of EPA, DHA, and total omega-3 PUFA in foods and dietary supplements containing added marine oil, including those formulated with emulsified and microencapsulated oils. The method detection limits for EPA and DHA were 0.012 ± 0.002 and 0.011 ± 0.003 mg g⁻¹, respectively (means ± SD). The analyzed contents of EPA (1.26–386 mg serving⁻¹), DHA (1.37–563 mg serving⁻¹), and total omega-3 PUFA (2.69–1270 mg serving⁻¹) were reported for 27 conventional food and dietary supplement products. Eighteen products declared contents of DHA, EPA + DHA, or total omega-3 PUFA on product labels, and the analyzed contents of those fatty acids varied from 95 to 162% of label declarations for all but two of the products.     

Mammary Uptake of Fatty Acids Supplied by Intravenous Triacylglycerol Infusion to Lactating Dairy Cows

Supplementing dairy cows with n-3 fatty acid-rich feeds does not easily increase quantities in milk fat. Previous results demonstrated very long-chain n-3 fatty acids are primarily transported in the PL fraction of blood, making them largely unavailable to the mammary gland for enrichment of milk fat. Our objective was to compare mammary uptake of fatty acids of increasing chain length and unsaturation delivered intravenously as TAG emulsions. Late lactation dairy cows were assigned to a completely randomized block design. Treatments were intravenous TAG emulsions enriched with oleic acid (OLA), linoleic acid (LNA), alpha-linolenic acid (ALA), or docosahexaenoic acid (DHA) and were delivered continuously at 16 mL/h for 72 h. Each treatment supplied 30 g/day of the target fatty acid. Treatment did not affect feed intake, milk yield, or milk composition, but all treatments reduced intake and yield. The proportion of DHA increased in plasma FFA, TAG, and PL with infusion. Increases of n-3 fatty acids, ALA, EPA, and DHA, were evident in the plasma PL fraction, suggesting re-esterification in the liver. Transfer efficiencies were 37.8 ± 4.1, 27.6 ± 5.4, and 10.9 ± 4.1 %, and day 3 total milk fatty acyl yields were 37.0 ± 3.4, 10.8 ± 0.4, and 3.3 ± 0.3 g for LNA, ALA, and DHA. Variation in oleic acyl yield prevented calculation of OLA transfer efficiency. Mammary uptake of fatty acids was reduced with increased chain length and unsaturation. Both liver and mammary mechanisms may regulate transfer of long-chain polyunsaturates.     

Higher Increase in Plasma DHA in Females Compared to Males Following EPA Supplementation May Be Influenced by a Polymorphism in ELOVL2: An Exploratory Study

Young adult females have higher blood docosahexaenoic acid (DHA), 22:6n-3 levels than males, and this is believed to be due to higher DHA synthesis rates, although DHA may also accumulate due to a longer half-life or a combination of both. However, sex differences in blood fatty acid responses to eicosapentaenoic acid (EPA), 20:5n-3 or DHA supplementation have not been fully investigated. In this exploratory analysis, females and males (n = 14–15 per group) were supplemented with 3 g/day EPA, 3 g/day DHA, or olive oil control for 12 weeks. Plasma was analyzed for sex effects at baseline and changes following 12 weeks' supplementation for fatty acid levels and carbon-13 signature (δ¹³C). Following EPA supplementation, the increase in plasma DHA in females (+23.8 ± 11.8, nmol/mL ± SEM) was higher than males (−13.8 ± 9.2, p < 0.01). The increase in plasma δ¹³C-DHA of females (+2.79 ± 0.31, milliUrey (mUr ± SEM) compared with males (+1.88 ± 0.44) did not reach statistical significance (p = 0.10). The sex effect appears driven largely by increased plasma DHA in the AA genotype of females (+58.8 ± 11.5, nmol/mL ± SEM, n = 5) compared to GA + GG in females (+4.34 ± 13.5, n = 9) and AA in males (−29.1 ± 17.2, n = 6) for rs953413 in the ELOVL2 gene (p < 0.001). In conclusion, EPA supplementation increases plasma DHA levels in females compared to males, which may be dependent on the AA genotype for rs953413 in ELOVL2.     

Lipid Metabolic Dose Response to Dietary Alpha-Linolenic Acid in Monk Parrot (Myiopsitta monachus)

Monk parrots (Myiopsitta monachus) are susceptible to atherosclerosis, a progressive disease characterized by the formation of plaques in the arteries accompanied by underlying chronic inflammation. The family of n-3 fatty acids, especially eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA), have consistently been shown to reduce atherosclerotic risk factors in humans and other mammals. Some avian species have been observed to convert α-linolenic acid (18:3n-3, ALA) to EPA and DHA (Htin et al. in Arch Geflugelk 71:258–266, 2007; Petzinger et al. in J Anim Physiol Anim Nutr, 2013). Therefore, the metabolic effects of including flaxseed oil, as a source of ALA, in the diet at three different levels (low, medium, and high) on the lipid metabolism of Monk parrots was evaluated through measuring plasma total cholesterol (TC), free cholesterol (FC), triacylglycerols (TAG), and phospholipid fatty acids. Feed intake, body weight, and body condition score were also assessed. Thus the dose and possible saturation response of increasing dietary ALA at constant linoleic acid (18:2n-6, LNA) concentration on lipid metabolism in Monk parrots (M. monachus) was evaluated. Calculated esterified cholesterol in addition to plasma TC, FC, and TAG were unaltered by increasing dietary ALA. The high ALA group had elevated levels of plasma phospholipid ALA, EPA, and docosapentaenoic acid (DPAn-3, 22:5n-3). The medium and high ALA groups had suppressed plasma phospholipid 20:2n-6 and adrenic acid (22:4n-6, ADA) compared to the low ALA group. When the present data were combined with data from a previous study (Petzinger et al. in J Anim Physiol Anim Nutr, 2013) a dose response to dietary ALA was observed when LNA was constant. Plasma phospholipid ALA, EPA, DPAn-3, DHA, and total n-3 were positively correlated while 20:2n-6, di-homo-gamma-linoleic acid (20:3n-6Δ7), arachidonic acid (20:4n-6), ADA, and total n-6 were inversely correlated with dietary en% ALA.     

Estradiol Favors the Formation of Eicosapentaenoic Acid (20:5n-3) and n-3 Docosapentaenoic Acid (22:5n-3) from Alpha-Linolenic Acid (18:3n-3) in SH-SY5Y Neuroblastoma Cells

Whether neurosteroids regulate the synthesis of long chain polyunsaturated fatty acids in brain cells is unknown. We examined the influence of 17-β-estradiol (E2) on the capacity of SH-SY5Y cells supplemented with α-linolenic acid (ALA), to produce eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA). Cells were incubated for 24 or 72 h with ALA added alone or in combination with E2 (ALA + E2). Fatty acids were analyzed by gas chromatography of ethanolamine glycerophospholipids (EtnGpl) and phosphatidylcholine (PtdCho). Incubation for 24 h with ALA alone increased EPA and DPA in EtnGpl, by 330 and 430% compared to controls (P < 0.001) and DHA by only 10% (P < 0.05). Although DHA increased by 30% (P < 0.001) in ALA + E2-treated cells, the difference between the ALA and ALA + E2 treatments were not significant after 24 h (Anova-1, Fisher’s test). After 72 h, EPA, DPA and DHA further increased in EtnGpl and PtdCho of cells supplemented with ALA or ALA + E2. Incubation for 72 h with ALA + E2 specifically increased EPA (+34% in EtnGpl, P < 0.001) and DPA (+15%, P < 0.001) compared to ALA alone. Thus, SH-SY5Y cells produced membrane EPA, DPA and DHA from supplemental ALA. The formation of DHA was limited, even in the presence of E2. E2 significantly favored EPA and DPA production in cells grown for 72 h. Enhanced synthesis of ALA-elongation products in neuroblastoma cells treated with E2 supports the hypothesis that neurosteroids could modulate the metabolism of PUFA.     

Accretion of Dietary Docosahexaenoic Acid in Mouse Tissues Did Not Differ between Its Purified Phospholipid and Triacylglycerol Forms

Recent studies suggest that dietary krill oil leads to higher omega-3 polyunsaturated fatty acids (n-3 PUFA) tissue accretion compared to fish oil because the former is rich in n-3 PUFA esterified as phospholipids (PL), while n-3 PUFA in fish oil are primarily esterified as triacylglycerols (TAG). Tissue accretion of the same dietary concentrations of PL- and TAG-docosahexaenoic acid (22:6n-3) (DHA) has not been compared and was the focus of this study. Mice (n = 12/group) were fed either a control diet or one of six DHA (1%, 2%, or 4%) as PL-DHA or TAG-DHA diets for 4 weeks. Compared with the control, DHA concentration in liver, adipose tissue (AT), heart, and eye, but not brain, were significantly higher in mice consuming either PL- or TAG-DHA, but there was no difference in DHA concentration in all tissues between the PL- or TAG-DHA forms. Consumption of PL- and TAG-DHA at all concentrations significantly elevated eicosapentaenoic acid (20:5n-3) (EPA) in all tissues when compared with the control group, while docoshexapentaenoic acid (22:5n-6) (DPA) was significantly higher in all tissues except for the eye and heart. Both DHA forms lowered total omega-6 polyunsaturated fatty acids (n-6 PUFA) in all tissues and total monounsaturated fatty acids (MUFA) in the liver and AT; total saturated fatty acid (SFA) were lowered in the liver but elevated in the AT. An increase in the DHA dose, independent of DHA forms, significantly lowered n-6 PUFA and significantly elevated n-3 PUFA concentration in all tissues. Our results do not support the claim that the PL form of n-3 PUFA leads to higher n-3 PUFA tissue accretion than their TAG form.     

n-3 Fatty Acids Abrogate Dyslipidemia-Induced Changes in Bile Acid Uptake,Synthesis, and Transport in Young and Aged Dyslipidemic Rats

In this study, the effect of n-3 fatty acids (FA) [α-linolenic acid (ALA) and eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA)] on the intestinal bile acid (BA) uptake, hepatic BA synthesis, and enterohepatic bile acid transporters (BAT) was assessed in young and aged dyslipidemic rats. Dyslipidemia was induced in young and aged rats by feeding a high-fat (HF) diet. Experimental groups received diets containing canola oil (HF + CNO) and fish oil (HF + FO) as a source of ALA and EPA + DHA, respectively. After 60 days of feeding, intestinal BA uptake and expression of apical sodium-dependent bile acid transporter (Asbt), organic solute transporter-alpha/beta (Osta/b) messenger RNA (mRNA), and hepatic expression of Na⁺ taurocholate cotransporting polypeptide (Ntcp), bile salt export pump (Bsep), cholesterol 7-α hydroxylase A1 (Cyp7a1), Farnesoid X receptor (Fxr), small heterodimer partner-1 (Shp), liver receptor homolog-1 (Lrh-1), and hepatic nuclear factor-4 alpha (Hnf4a) mRNA were measured. Hepatic 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase activity and total BA in serum, liver, and feces were assessed. The dyslipidemic HF group had: (1) increased intestinal BA uptake and Asbt and Osta/b mRNA expression, (2) increased BA in serum, (3) decreased hepatic expression of Ntcp, Bsep, and Cyp7a1 mRNA, (4) increased activity of HMG-CoA reductase, (5) increased hepatic expression of Fxr and Shp mRNA, (6) decreased hepatic expression of Lrh-1 and Hnf4a mRNA, and (7) decreased BA in feces, when compared to control, HF + CNO, and HF + FO groups. Immunostaining revealed increased expression of intestinal Asbt and hepatic Ntcp protein in the HF group when compared to control, HF + CNO, and HF + FO groups. n-3 FA abrogated dyslipidemia-induced changes in the intestinal uptake, hepatic synthesis, and enterohepatic transporters of BA in both young and aged rats. EPA + DHA was more effective than ALA in modulating dyslipidemia-induced changes.     

Lipidic pattern of 25 Mexican marine fishes with special emphasis in their n-3 fatty acids as nutraceuticals components

The aim of this study was to characterize and to evaluate the lipidic composition of mexican marine fishes with special emphasis in n-3 fatty acids as nutraceuticals. The edible portion of 25 species: humidity (H), crude protein (CP), total lipids (TL) and fatty acids (FA). The average content (g/100g edible portion) of H was 75.20, PC was 18.40, TL was 3.60. Four n-3 FA were identified in all the samples and they were found in the next abundance order (mg/100g edible portion): C22:6n-3 (DHA)(229.60), C20:5 n-3 (EPA)(52.10), C18:3 n-3 (ALA)(11.80) and C20:3 n-3 (2.25). By their origin and climate there were no difference. By their biologycal classification, n-3 FA content was higher in bony fishes than cartilaginous fishes. It was detected a proportional relation with the n-3 FA concentration and total lipid content. According to their ecotic distribution there were numerical differences in DHA content (mg/100g edible portion) between pelagics (420.70), benthopelagics (125.30) and demersals fishes (225.40). Fatty fishes had higher content of EPA and DHA (mg/100g edible portion) (109.27 and 552.72) than semifatty fishes (56.12 and 226.29) and leanness (15.95 and 96.52), respectively. Bony, fatty and pelagic fishes had a higher content of EPA+DHA. According with the international recommendation values (200 to 600 mg EPA+DHA/day) the 44% of the analyzed species could be considered as functional foods due to their high content of EPA + DHA in a range of 220 to 1300 mg/100g.     

Enzymatic Incorporation of Selected Long-Chain Fatty Acids into Triolein

Acidolysis of triolein (tri C18:1) with selected long-chain fatty acids (LCFA) was carried out using Candida antarctica (Novozym 435), Rhizomucor miehei (Lipozyme RM IM), Pseudomonas sp. (PS-30), Aspergillus niger (AP-12), and Candida rugosa (AY-30). A better incorporation of stearic acid (SA), α-linolenic acid (ALA), γ-linolenic acid (GLA), arachidonic acid (AA), and docosapentaenoic acid (DPA) was achieved using lipase from Rhizomucor miehei. Lipase from Pseudomonas sp. catalyzed a better incorporation of linoleic acid (LA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) into triolein. Thus, Rhizomucor miehei and to a lesser extent Pseudomonas sp. might be considered as providing the most effective enzymes for acidolysis of triolein with selected LCFA. In general, incorporation of LCFA into triolein (tri C18:1) may be affected by chain length, number of double bonds, and the location and geometry of the double bonds as well as reaction conditions and reactivity and specificity of lipases used. As the ratio of the number of moles of a mixture of equimole quantities of C18 FA to triolein changed from 1 to 3, incorporation of C18 FA into triolein increased accordingly with Rhizomucor miehei lipase. Similarly, incorporation of n-3 FA into triolein increased when ALA, DPA, DHA, and EPA were used. The same trend was noticed for a mixture of n-6 FA (LA + GLA + AA) and triolein.     

Eicosapentaenoic acid is primarily responsible for hypotriglyceridemic effect of fish oil in humans

The aim of this study was to determine whether eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), or both, were responsible for the triglyceride (TG)-lowering effects of fish oil. EPA (91% pure) and DHA (83% pure), a fish oil concentrate (FOC; 41% EPA and 23% DHA) and an olive oil (OO) placebo (all ethyl esters) were tested. A total of 49 normolipidemic subjects participated. Each subject was given placebo for 2–3 wk and one of the n-3 supplements for 3 wk in randomized, blinded trials. The target n-3 fatty acid (FA) intake was 3 g/day in all studies. Blood samples were drawn twice at the end of each supplementation phase and analyzed for lipids, lipoproteins, and phospholipid FA composition. In all groups, the phospholipid FA composition changed to reflect the n-3 FA given. On DHA supplementation, EPA levels increased to a small but significant extent, suggesting that some retroconversion may have occurred. EPA supplementation did not raise DHA levels, however, FOC and EPA produced significant decreases in both TG and very low density lipoprotein (VLDL) cholesterol (C) levels (P<0.01) and increases in low density lipoprotein (LDL) cholesterol levels (P<0.05). DHA supplementation did not affect cholesterol, triglyceride, VLDL, LDL, or high density lipoprotein (HDL) levels, but it did cause a significant increase in the HDL₂/HDL₃ cholesterol ratio. We conclude that EPA appears to be primarily responsible for TG-lowering (and LDL-C raising) effects of fish oil.