Dietary ALA,But not LNA,Increase Growth,Reduce Inflammatory Processes,and Increase Anti‐Oxidant Capacity in the Marine Finfish Larimichthys crocea

Whilst aquaculture feed is increasingly formulated with the inclusion of plant oils replacing fish oil, and increasing research effort has been invested in understanding the metabolic effects of reduced dietary n‐3 long chain poly unsaturated fatty acids (n‐3 LC‐PUFA), relatively little information is available on the potential direct metabolic roles of dietary alpha‐linolenic acid (ALA, 18:3n‐3) and alpha‐linolenic acid/linoleic acid (LNA, 18:2n‐6) ratio in cultured marine finfish species. In this study, four plant oil based diets, with varying ALA/LNA ratio (0.0, 0.5, 1.0 and 1.5) were fed to juvenile large yellow croakers (Larimichthys crocea) and compared to a fish oil‐based control diet (CD) to evaluate the resulting effects on growth, nonspecific immunity, anti‐oxidant capacity and related gene expression. High dietary LNA negatively impacted fish growth performance, nonspecific immunity and antioxidant capacity, but growth and immunity were maintained to levels comparable to CD by increasing the ratio of dietary ALA/LNA. The over‐expression of genes associated with inflammation (cyclooxygenase‐2 and interleukin‐1β) and fatty acid oxidation (carnitine palmitoyl transferase I and acyl CoA oxidase) in croakers fed high concentrations of LNA were reduced to levels comparable to those fed CD by increasing dietary ALA/LNA. This study showed that dietary ALA, by increasing the overall n‐3/n‐6 PUFA ratio, exerts direct anti‐inflammatory and antioxidant effects, similar to those exerted by dietary n‐3 LC‐PUFA.     

Dietary High‐Oleic Acid Soybean Oil Dose Dependently Attenuates Egg Yolk Content of n‐3 Polyunsaturated Fatty Acids in Laying Hens Fed Supplemental Flaxseed Oil

Chickens can hepatically synthesize eicosapentaenoic acid (20:5 n‐3) and docosahexaenoic acid (22:6 n‐3) from α‐linolenic acid (ALA; 18:3 n‐3); however, the process is inefficient and competitively inhibited by dietary linoleic acid (LNA; 18:2 n‐6). In the present study, the influence of dietary high‐oleic acid (OLA; 18:1 n‐9) soybean oil (HOSO) on egg and tissue deposition of ALA and n‐3 polyunsaturated fatty acids (PUFA) synthesized from dietary ALA was investigated in laying hens fed a reduced‐LNA base diet supplemented with high‐ALA flaxseed oil (FLAX). We hypothesized that reducing the dietary level of LNA would promote greater hepatic conversion of ALA to very long‐chain (VLC; >20C) n‐3 PUFA, while supplemental dietary HOSO would simultaneously further enrich eggs with OLA without influencing egg n‐3 PUFA contents. Nine 51‐week‐old hens each were fed 0, 10, 20, or 40 g HOSO/kg diet for 12 weeks. Within each group, supplemental dietary FLAX was increased every 3 weeks from 0 to 10 to 20 to 40 g/kg diet. Compared to controls, dietary FLAX maximally enriched the total n‐3 and VLC n‐3 PUFA contents in egg yolk by 9.4‐fold and 2.2‐fold, respectively, while feeding hens 40 g HOSO/kg diet maximally attenuated the yolk deposition of ALA, VLC n‐3 PUFA, and total n‐3 PUFA by 37, 15, and 32%, respectively. These results suggest that dietary OLA is not neutral with regard to the overall process by which dietary ALA is absorbed, metabolized, and deposited into egg yolk, either intact or in the form of longer‐chain/more unsaturated n‐3 PUFA derivatives.     

Incorporation of Omega-3 Fatty Acids in Nile Tilapia (Oreochromis niloticus) Fed Chia (Salvia hispanica L.) Bran

This study evaluated the effect of the inclusion of chia bran in the diet of Nile tilapia on the composition of n‐3 fatty acids (FA). Omega‐3 fatty acids provide health benefits such as reducing the risks of coronary heart disease, hypertension and inflammation, and the precursor alpha‐linolenic acid is considered strictly essential because it cannot be synthesized by humans, therefore must be ingested. Tilapias grown in tanks for a period of 45 days were treated with diets supplemented with either soybean oil (TI) or chia bran (TII). Proximal composition analysis of the feeds showed no significant difference. Feed FA quantification showed that the chia diet (TII) had a higher alpha‐linolenic acid (LNA) content. A significant increase was observed in the concentrations of LNA (8.38–81.31 mg 100 g^?1 fillets), eicosapentaenoic acid (1.12–1.56 mg 100 g^?1 fillets) and docosahexaenoic acid (19.55–26.55 mg 100 g^?1 fillets) in tilapia fillets between 0 and 45 days for TII. Total lipids at 45 days under TII were fractionated into neutral lipids (67.66 %) and polar lipids (18.90 %). Thus, dietary supplementation with chia bran contributed to raising the nutritional quality of Nile tilapia fillets.     

Effects of the flaxseed oil on the fatty acid composition of tilapia heads

The objective of this study was to evaluate the effects of adding flaxseed oil (FO) to feed on the incorporation of n‐3 PUFA in tilapia heads. Tilapia were given diets with increasing levels of FO (0.00, 1.25, 2.50, 3.75 and 5.00% for treatments A, B, C, D and E, respectively), as a source of LNA for 150 days. The proximate composition of the heads indicated high nutritional value and 40 FA (fatty acids) common to all treatments were identified in total lipids. Intake of LNA caused storage of LNA and sequential desaturation‐elongation to eicosapentaenoic acid (EPA) and DHA. With increasing levels of FO in the diet, the content of LNA in tilapia heads increased (1.7 and 14.0% for diets A and E, respectively), as well as the contents of EPA (0.1 and 0.9% for diets A and E, respectively) and DHA (0.5 and 1.8% for diets A and E, respectively). Adding FO to tilapia feed markedly increased the total content of n‐3 PUFA (3.0 and 21.1% for diets A and E, respectively), decreased the total content of n‐6 PUFA (41.3 and 24.9% for diets A and E, respectively), and consequently resulted in a decrease in the n‐6/n‐3 ratio (13.8 and 1.2 for diets A and E, respectively). Therefore, feeding tilapia with FO is a good way of valorizing this part of the fish by creating a valuable nutritional food source.     

Effect of Dietary Replacement of Soybean Oil with Different Sources of Gamma‐Linolenic Acid on Fatty Acid Composition of Nile Tilapia

Gamma‐linolenic acid (GLA) plays an important role in the prevention and/or treatment of certain diseases. In this work, we investigate the incorporation of GLA from supplemented feed diets with borage oil (BO) and evening primrose oil (EPO) as substitutes for soybean oil (SO) into the composition of tilapia fillet lipids. High contents of PUFA and n‐6 fatty acids were quantified in fish fillet after 30 days of treatment with SO, BO, and EPO. Feed diets containing BO and EPO were efficient in the incorporation of GLA into fish. Compared to the initial day of the experiment, the increase of GLA was significant (from 6.43 to 13.99 and 15.12 mg g^?1, in lipids of fish treated for 30 days with BO and EPO, respectively). The increase of GLA was also observed in fish which were fed with SO diet (6.43–11.43 mg g^?1). Principal component analysis (PCA) allowed the separation of the treatments and discriminated BO and EPO in a group of fish that received the GLA supplemented diet. In addition to GLA, n‐3 fatty acids were important in the characterization of SO diet and affected the separation of BO and EPO from SO in the PCA score plot.     

Dietary Unsaturated Fatty Acids Modulate Maternal Dyslipidemia‐Induced DNA Methylation and Histone Acetylation in Placenta and Fetal Liver in Rats

The present study assessed the role of dietary unsaturated fatty acids in maternal dyslipidemia‐induced DNA methylation and histone acetylation in placenta and fetal liver and accumulation of lipids in the fetal liver. Weanling female Wistar rats were fed control and experimental diets for 2 months, mated, and continued on their diets during pregnancy. At gestation days of 18–20, rats were euthanized to isolate placenta and fetal liver. DNA methylation, DNA methyl transferase‐1 (DNMT1) activity, acetylation of histones (H2A and H2B), and histone acyl transferase (HAT) activity were evaluated in placenta and fetal liver. Fetal liver lipid accumulation and activation of peroxisome proliferator‐activated receptor‐α (PPAR‐α) were assessed. Maternal dyslipidemia caused significant epigenetic changes in placenta and fetal liver. In the placenta, (1) global DNA methylation increased by 37% and DNMT1 activity by 86%, (2) acetylated H2A and H2B levels decreased by 46% and 24% respectively, and (3) HAT activity decreased by 39%. In fetal liver, (1) global DNA methylation increased by 52% and DNMT1 activity by 78%, (2) acetylated H2A and H2B levels decreased by 28% and 26% respectively, and (3) HAT activity decreased by 37%. Maternal dyslipidemia caused a 4.75‐fold increase in fetal liver triacylglycerol accumulation with a 78% decrease in DNA‐binding ability of PPAR‐α. Incorporation of dietary unsaturated fatty acids in the maternal high‐fat diet significantly (p < 0.05) modulated dyslipidemia‐induced effects in placenta and fetal liver. Eicosapentaenoic acid (EPA, 20:5n‐3) + docosahexaenoic acid (DHA, 22:6n‐3) exhibited a profound effect followed by alpha‐linolenic acid (ALA, 18:3n‐3) than linoleic acid (LNA, 18:2n‐6) in modulating the epigenetic parameters in placenta and fetal liver.     

Application of Silver Ion High-Performance Liquid Chromatography for Quantitative Analysis of Selected n-3 and n-6 PUFA in Oil Supplements

The aim of this study was to develop a simple method for simultaneous determination of selected cis/cis PUFA–LNA (18:2), ALA (18:3), GLA (18:3), EPA (20:5), and DHA (22:6) by silver ion high‐performance liquid chromatography coupled to a diode array detector (Ag‐HPLC‐DAD). The separation was performed on three Luna SCX Silver Loaded columns connected in series maintained at 10 °C with isocratic elution by 1 % acetonitrile in n‐hexane. The applied chromatographic system allowed a baseline separation of standard mixture of n‐3 and n‐6 fatty acid methyl esters containing LNA, DHA, and EPA and partial separation of ALA and GLA positional isomers. The method was validated by means of linearity, precision, stability, and recovery. Limits of detection (LOD) for considered PUFA standard solutions ranged from 0.27 to 0.43 mg L^?1. The developed method was used to evaluate of n‐3 and n‐6 fatty acids contents in plant and fish softgel oil capsules, results were compared with reference GC‐FID based method.     

Postprandial Lipid Responses do not Differ Following Consumption of Butter or Vegetable Oil when Consumed with Omega-3 Polyunsaturated Fatty Acids

Dietary saturated fat (SFA) intake has been associated with elevated blood lipid levels and increased risk for the development of chronic diseases. However, some animal studies have demonstrated that dietary SFA may not raise blood lipid levels when the diet is sufficient in omega‐3 polyunsaturated fatty acids (n‐3PUFA). Therefore, in a randomised cross‐over design, we investigated the postprandial effects of feeding meals rich in either SFA (butter) or vegetable oil rich in omega‐6 polyunsaturated fatty acids (n‐6PUFA), in conjunction with n‐3PUFA, on blood lipid profiles [total cholesterol, low density lipoprotein cholesterol (LDL‐C), high density lipoprotein cholesterol (HDL‐C) and triacylglycerol (TAG)] and n‐3PUFA incorporation into plasma lipids over a 6‐h period. The incremental area under the curve for plasma cholesterol, LDL‐C, HDL‐C, TAG and n‐3PUFA levels over 6 h was similar in the n‐6PUFA compared to SFA group. The postprandial lipemic response to saturated fat is comparable to that of n‐6PUFA when consumed with n‐3PUFA; however, sex‐differences in response to dietary fat type are worthy of further attention.     

Uncoupling EPA and DHA in Fish Nutrition: Dietary Demand is Limited in Atlantic Salmon and Effectively Met by DHA Alone

Due to the scarcity of marine fish oil resources, the aquaculture industry is developing more efficient strategies for the utilization of dietary omega‐3 long‐chain polyunsaturated fatty acids (n‐3 LC‐PUFA). A better understanding of how fish utilize EPA and DHA, typically provided by fish oil, is needed. However, EPA and DHA have different physiological functions, may be metabolized and incorporated into tissues differently, and may vary in terms of their importance in meeting the fatty acid requirements of fish. To address these questions, Atlantic salmon were fed experimental diets containing, as the sole added dietary lipid source, fish oil (positive control), tallow (negative control), or tallow supplemented with EPA, DHA, or both fatty acids to ~50 or 100 % of their respective levels in the positive control diet. Following 14 weeks of feeding, the negative control diet yielded optimum growth performance. Though surprising, these results support the notion that Atlantic salmon requirements for n‐3 LC‐PUFA are quite low. EPA was largely β‐oxidized and inefficiently deposited in tissues, and increasing dietary levels were associated with potential negative effects on growth. Conversely, DHA was completely spared from catabolism and very efficiently deposited into flesh. EPA bioconversion to DHA was largely influenced by substrate availability, with the presence of preformed DHA having little inhibitory effect. These results clearly indicate EPA and DHA are metabolized differently by Atlantic salmon, and suggest that the n‐3 LC‐PUFA dietary requirements of Atlantic salmon may be lower than reported and different, if originating primarily from EPA or DHA.     

Fish Oil and Microalga Omega-3 as Dietary Supplements: A Comparative Study on Cardiovascular Risk Factors in High-Fat Fed Rats

Dietary supplementation with marine omega‐3 polyunsaturated fatty acids (n‐3 PUFA) can have beneficial effects on a number of risk factors for cardiovascular disease (CVD). We compared the effects of two n‐3 PUFA rich food supplements (freeze‐dried Odontella aurita and fish oil) on risk factors for CVD. Male rats were randomly divided into four groups of six animals each and fed with the following diets: control group (C) received a standard diet containing 7 % lipids; second group (HF high fat) was fed with a high‐fat diet containing 40 % lipids; third group (HFFO high fat+fish oil) was fed with the high‐fat diet supplemented with 0.5 % fish oil; and fourth group (HFOA high fat+O. aurita) received the high‐fat diet supplemented with 12 % of freeze‐dried O. aurita. After 8 weeks rats fed with the high‐fat diet supplemented with O. aurita displayed a significantly lower bodyweight than those in the other groups. Both the microalga and the fish oil significantly reduced insulinemia and serum lipid levels. O. aurita was more effective than the fish oil in reducing hepatic triacyglycerol levels and in preventing high‐fat diet‐induced steatosis. O. aurita and fish oil also reduced platelet aggregation and oxidative status induced by high fat intake. After an OA supplementation, the adipocytes in the HFOA group were smaller than those in the HF group. Freeze‐dried O. aurita showed similar or even greater biological effects than the fish oil. This could be explained by a potential effect of the n‐3 PUFA but also other bioactive compounds of the microalgae.     

Dietary Supplementation of Tetracarpidium conophorum (African Walnut) Seed Enhances Muscle n‐3 Fatty Acids in Broiler Chickens

The influence of dietary Tetracarpidium conophorum (African Walnut) seed meal (TCSM) on fatty acids, productivity parameters, and physicochemical properties of breast and thigh muscles in broiler chickens are assessed. A total of 180, 28‐d‐old Arbor acre broiler chickens are randomly assigned to dietary treatments containing 0% (control), 2.5%, and 5% w/w TCSM, fed for 28 d, and euthanized. Dietary TCSM reduces (p < 0.05) feed intake, body weight gain (BWG), carcass weight, and abdominal fat. Diet does not affect feed efficiency and hematological parameters. The control birds have higher (p < 0.05) serum total cholesterol and triglycerides than do the supplemented birds. Diet has no effect on pH, water holding capacity, carbonyl and malondialdehyde contents, and organoleptic properties of breast and thigh muscles. The 5% TCSM has higher redness in breast muscle than do other treatments. Dietary TCSM improves (p < 0.05) the concentration of C18:3n‐3 (4.80–8.76% vs 1.56%), C20:5n‐3 (0.54–0.79% vs 0.39%), C22:5n‐3 (0.64–0.89% vs 0.18%), and C22:6n‐3 (0.75–0.97% vs 0.19%), and reduces (p <  0.05) the fat content (2.15–2.45% vs 3.15%) in breast and thigh muscles. Dietary TCSM enhances muscle n‐3 fatty acids without instigating oxidative deterioration, but reduces BWG in broiler chickens. Practical Application: Albeit that broiler meat is rich in polyunsaturated fatty acids (PUFA), its omega 6 (n‐6)/omega 3 (n‐3) is >4. Elevated n‐6/n‐3 could have adverse effect on human physiology thereby promoting the pathogenesis of certain diseases. This heightens the need to enhance the n‐3 PUFA content of broiler meat. Dietary TCSM induced up to a fourfold increase in n‐3 PUFA content of the breast and thigh muscles in broiler chickens. Moreover, dietary TCSM induced up to a tenfold decrease in the n‐6/n‐3 of the breast and thigh muscles in broiler chickens. This finding assumes great significance because the health concerns regarding dietary fat are the foremost factors responsible for the bad image suffered by meat. These results provide insights on the potential of TCSM to improve the nutritional quality without compromising the oxidative shelf life, organoleptic traits, and physicochemical properties of broiler meat.     

n‐3 PUFA Esterified to Glycerol or as Ethyl Esters Reduce Non‐Fasting Plasma Triacylglycerol in Subjects with Hypertriglyceridemia: A Randomized Trial

To date, treatment of hypertriglyceridemia with long‐chain n‐3 polyunsaturated fatty acids (n‐3 PUFA) has been investigated solely in fasting and postprandial subjects. However, non‐fasting triacylglycerols are more strongly associated with risk of cardiovascular disease. The objective of this study was to investigate the effect of long‐chain n‐3 PUFA on non‐fasting triacylglycerol levels and to compare the effects of n‐3 PUFA formulated as acylglycerol (AG‐PUFA) or ethyl esters (EE‐PUFA). The study was a double‐blinded randomized placebo‐controlled interventional trial, and included 120 subjects with non‐fasting plasma triacylglycerol levels of 1.7–5.65 mmol/L (150–500 mg/dL). The participants received approximately 3 g/day of AG‐PUFA, EE‐PUFA, or placebo for a period of eight weeks. The levels of non‐fasting plasma triacylglycerols decreased 28 % in the AG‐PUFA group and 22 % in the EE‐PUFA group (P < 0.001 vs. placebo), with no significant difference between the two groups. The triacylglycerol lowering effect was evident after four weeks, and was inversely correlated with the omega‐3 index (EPA + DHA content in erythrocyte membranes). The omega‐3 index increased 63.2 % in the AG‐PUFA group and 58.5 % in the EE‐PUFA group (P < 0.001). Overall, the heart rate in the AG‐PUFA group decreased by three beats per minute (P = 0.045). High‐density lipoprotein (HDL) cholesterol increased in the AG‐PUFA group (P < 0.001). Neither total nor non‐HDL cholesterol changed in any group. Lipoprotein‐associated phospholipase A2 (LpPLA2) decreased in the EE‐PUFA group (P = 0.001). No serious adverse events were observed. Supplementation with long‐chain n‐3 PUFA lowered non‐fasting triacylglycerol levels, suggestive of a reduction in cardiovascular risk. Regardless of the different effects on heart rate, HDL, and LpPLA2 that were observed, compared to placebo, AG‐PUFA, and EE‐PUFA are equally effective in reducing non‐fasting triacylglycerol levels.     

In vitro antioxidant and in vivo antidiabetic,antihyperlipidemic activity of linseed oil against streptozotocin‐induced toxicity in albino rats

The intake of omega‐3 unsaturated fatty acids has a beneficial effect on insulin sensitivity in rats and in subjects with type 2 diabetes. It has been reported that these omega‐3 fatty acids are useful in the treatment of hypertriglyceridemia and in the enhancement of high‐density lipoprotein (HDL)‐cholesterol levels in diabetic patients. The present study was therefore aimed to evaluate the antioxidant, antihyperglycemic and antihyperlipidemic effect of L. usitatissimum fixed oil. The antioxidant activity was evaluated in vitro using 1,1‐diphenyl‐2‐picryl hydrazyl (DPPH) and hydrogen peroxide (H₂O₂) assay. The oil exhibited significant in vitro antioxidant activity in the DPPH and H₂O₂ assay. The oil (1, 2, 3 mL/kg) was further investigated against streptozotocin (STZ)‐induced hyperglycemia and hyperlipidemia in albino rats, subjected to 3 weeks of treatment. The oil manifested decrease in blood glucose and glycated hemoglobin levels at higher dose and significant dose dependent negating action on antioxidant enzymes in the heart, liver and kidney tissues. The oil also normalized the various hematological parameters and electrolyte levels in the STZ treated rats. Treatment with oil significantly increased the level of serum HDL and decreased the levels of total cholesterol, triglycerides, and low‐density lipoprotein‐cholesterol in STZ‐diabetic rats in comparison to normal control. The antioxidant, antihyperglycemic and antihyperlipidemic activity of the oil could be attributed to the presence of linolenic acid (ALA, 18:3 n‐3) and its metabolic products, eicosapentanoic acid (EPA, 20:5 n‐3) and docosahexanoic acid (DHA, 22:6 n‐3).     

Dietary Crude Lecithin Increases Systemic Availability of Dietary Docosahexaenoic Acid with Combined Intake in Rats

Crude lecithin, a mixture of mainly phospholipids, potentially helps to increase the systemic availability of dietary omega‐3 polyunsaturated fatty acids (n‐3 PUFA), such as docosahexaenoic acid (DHA). Nevertheless, no clear data exist on the effects of prolonged combined dietary supplementation of DHA and lecithin on RBC and plasma PUFA levels. In the current experiments, levels of DHA and choline, two dietary ingredients that enhance neuronal membrane formation and function, were determined in plasma and red blood cells (RBC) from rats after dietary supplementation of DHA‐containing oils with and without concomitant dietary supplementation of crude lecithin for 2–3 weeks. The aim was to provide experimental evidence for the hypothesized additive effects of dietary lecithin (not containing any DHA) on top of dietary DHA on PUFA levels in plasma and RBC. Dietary supplementation of DHA‐containing oils, either as vegetable algae oil or as fish oil, increased DHA, eicosapentaenoic acid (EPA), and total n‐3 PUFA, and decreased total omega‐6 PUFA levels in plasma and RBC, while dietary lecithin supplementation alone did not affect these levels. However, combined dietary supplementation of DHA and lecithin increased the changes induced by DHA supplementation alone. Animals receiving a lecithin‐containing diet also had a higher plasma free choline concentration as compared to controls. In conclusion, dietary DHA‐containing oils and crude lecithin have synergistic effects on increasing plasma and RBC n‐3 PUFA levels, including DHA and EPA. By increasing the systemic availability of dietary DHA, dietary lecithin may increase the efficacy of DHA supplementation when their intake is combined.     

Docosahexaenoic Acid and Eicosapentaenoic Acid Did not Alter <Emphasis Type="Italic">trans</Emphasis>-10,<Emphasis Type="Italic">cis</Emphasis>-12 Conjugated Linoleic Acid Incorporation into Mice Brain and Eye Lipids

trans 10,cis 12‐CLA has been reported to alter fatty acid composition in several non‐neurological tissues, but its effects are less known in neurological tissues. Therefore, the purpose of this study was to determine if CLA supplementation would alter brain and eye fatty acid composition and if those changes could be prevented by concomitant supplementation with docosahexaenoic acid (DHA; 22:6n3) or eicosapentaenoic acid (EPA; 20:5n3). Eight‐week‐old, pathogen‐free C57BL/6N female mice (n = 6/group) were fed either the control diet or diets containing 0.5% (w/w) t10,c12‐CLA in the presence or absence of either 1.5% DHA or 1.5% EPA for 8 weeks. CLA concentration was significantly (P < 0.05) greater in the eye but not in the brain lipids of the CLA group when compared with the control group. The sums of saturated, monounsaturated, polyunsaturated fatty acids, and n3:n6 ratio did not differ between these two groups for both tissues. The n3:n6 ratio and concentrations of 20:5n3 and 22:5n3 were significantly greater, and those of 20:4n6, 22:4n6, and 22:5n6 were lesser in the CLA + DHA and CLA + EPA groups than in the control and CLA groups for either tissue. DHA concentration was higher in the CLA + DHA group only but not in the CLA + EPA group when compared with the CLA group for both tissues. The dietary fatty acids generally induced similar changes in brain and eye fatty acid concentration and at the concentrations used both DHA and EPA fed individually with CLA were more potent than CLA alone in altering the tissue fatty acid concentration.     

n‐3 PUFA Induce Microvascular Protective Changes During Ischemia/Reperfusion

Ischemia/reperfusion (I/R) injury can occur in consequence of myocardial infarction, stroke and multiple organ failure, the most prevalent cause of death in critically ill patients. I/R injury encompass impairment of endothelial dependent relaxation, increase in macromolecular permeability and leukocyte‐endothelium interactions. Polyunsaturated fatty acids (n‐3 PUFA), such as eicosapentaenoic acid (EPA, 20:5n‐3) and docosahexaenoic acid (DHA, 22:6n‐3) found in fish oil have several anti‐inflammatory properties and their potential benefits against I/R injury were investigated using the hamster cheek pouch preparation before and after ischemia. Before the experiments, hamsters were treated orally with saline, olive oil, fish oil and triacylglycerol (TAG) and ethyl ester (EE) forms of EPA and DHA at different daily doses for 14 days. Fish oil restored the arteriolar diameter to pre ischemic values during reperfusion. At onset and during reperfusion, Fish oil and DHA TAG significantly reduced the number of rolling leukocytes compared to saline and olive oil treatments. Fish oil, EPA TAG and DHA TAG significantly prevented the rise on leukocyte adhesion compared to saline. Fish oil (44.83 ± 3.02 leaks/cm²), EPA TAG (31.67 ± 2.65 leaks/cm²), DHA TAG (41.14 ± 3.63 leaks/cm²), and EPA EE (30.63 ± 2.25 leaks/cm²), but not DHA EE (73.17 ± 2.82 leaks/cm²) prevented the increase in macromolecular permeability compared to saline and olive oil (134.80 ± 1.49 and 121.00 ± 4.93 leaks/cm², respectively). On the basis of our findings, we may conclude that consumption of n‐3 polyunsaturated fatty acids, especially in the triacylglycerol form, could be a promising therapy to prevent microvascular damage induced by ischemia/reperfusion and its consequent clinical sequelae.     

α‐Linolenic acid metabolism in adult humans: the effects of gender and age on conversion to longer‐chain polyunsaturated fatty acids

This review summarises and evaluates current knowledge of α‐linolenic acid (αLNA) metabolism in adult humans. The principal biological role of αLNA appears to be as a precursor for the synthesis of longer‐chain n‐3 polyunsaturated fatty acids (PUFA). Stable isotope tracer studies indicate that conversion of αLNA to eicosapentaenoic acid (EPA) occurs but is limited in men and that further transformation to docosahexaenoic acid (DHA) is very low. A lower proportion of αLNA is used for β‐oxidation in women compared with men, while the fractional conversion to the longer‐chain n‐3 PUFA is greater, possibly due to the regulatory effects of oestrogen. Increasing αLNA intake for a period of weeks results in an increase in the proportion of EPA in plasma lipids, circulating cells and breast milk, but there is no increase in DHA, which may even decline in some pools at high αLNA intakes. Overall, αLNA appears to be a limited source of longer‐chain n‐3 PUFA in man, and so adequate intakes of preformed long‐chain n‐3 PUFA, in particular DHA, may be important for maintaining optimal tissue function. The capacity to up‐regulate αLNA transformation in women may be important for meeting the demands of the foetus and neonate for DHA.     

Fibroblast Growth Factor-21 and the Beneficial Effects of Long-Chain n-3 Polyunsaturated Fatty Acids

Long‐chain n‐3 polyunsaturated fatty acids (LC n‐3 PUFA) in the diet protect against insulin resistance and obesity. Fibroblast growth factor‐21 (Fgf21) is a hormonal factor released mainly by the liver that has powerful anti‐diabetic effects. Here, we tested whether the beneficial metabolic effects of LC n‐3 PUFA involve the induction of Fgf21. C57BL/6 J mice were exposed to an obesogenic, corn‐oil‐based, high‐fat diet (cHF), or a diet in which corn oil was replaced with a fish‐derived LC n‐3 PUFA concentrate (cHF + F) using two experimental settings: short‐term (3 weeks) and long‐term treatment (8 weeks). CHF + F reduced body weight gain, insulinemia, and triglyceridemia compared to cHF. cHF increased plasma Fgf21 levels and hepatic Fgf21 gene expression compared with controls, but these effects were less pronounced or absent in cHF + F‐fed mice. In contrast, hepatic expression of peroxisome proliferator‐activated receptor (PPAR)‐α target genes were more strongly induced by cHF + F than cHF, especially in the short‐term treatment setting. The expression of genes encoding Fgf21, its receptors, and Fgf21 targets was unaltered by short‐term LC n‐3 PUFA treatment, with the exception of Ucp1 (uncoupling protein 1) and adiponectin genes, which were specifically up‐regulated in white fat. In the long‐term treatment setting, the expression of Fgf21 target genes and receptors was not differentially affected by LC n‐3 PUFA. Collectively, our findings indicate that increased Fgf21 levels do not appear to be a major mechanism through which LC n‐3 PUFA ameliorates high‐fat‐diet‐associated metabolic disorders.     

Fatty fish intake,n‐3 fatty acids and self‐rated health in middle‐aged adults

Background – Since n‐3 fatty acids, abundant in fatty fish, may improve health, we raised the question whether self‐reported intake frequency of fatty fish (FF) might be related to the percentage of n‐3 fatty acids in serum phospholipids (PL‐n‐3), and also to self‐rated health (H). Design – The study followed a cross‐sectional design. Methods – In the cross‐sectional Oslo Health Study, PL‐n‐3 were determined in 121 middle‐aged ethnic Norwegians and 102 immigrants from the Indian subcontinent and correlated with FF and H. Logistic regression was used to study the relationship between PL‐n‐3 and H (dichotomized, i.e. Poor vs. Good health). Results – FF correlated positively with PL20:5n‐3 (PL‐EPA, r = 0.467, p <0.001) and PL22:6n‐3 (PL‐DHA, r = 0.499, p <0.001), and negatively with PL20:4n‐6 (PL‐AA, r = –0.350, p = 0.001). H was positively associated with PL‐EPA (r = 0.321, p <0.001) and PL‐DHA (r = 0.275; p <0.001), but negatively with PL‐AA (r = –0.220, p = 0.001). The odds ratio for reporting Poor vs. Good health was significantly higher in subjects with low levels of PL‐EPA (OR = 1.49; 95% confidence interval = 1.17–1.89, p = 0.001), persisting after adjusting for sex, physical activity, ethnicity and length of education. Conclusion – The intake frequency of fatty fish is related to n‐3 fatty acids in the serum phospholipids, and to self‐rated health.     

Low n-6/n-3 PUFA Ratio Improves Lipid Metabolism,Inflammation, Oxidative Stress and Endothelial Function in Rats Using Plant Oils as n-3 Fatty Acid Source

Lipid metabolism, inflammation, oxidative stress and endothelial function play important roles in the pathogenesis of cardiovascular disease (CVD), which may be affected by an imbalance in the n‐6/n‐3 polyunsaturated fatty acid (PUFA) ratio. This study aimed to investigate the effects of the n‐6/n‐3 PUFA ratio on these cardiovascular risk factors in rats fed a high‐fat diet using plant oils as the main n‐3 PUFA source. The 1:1 and 5:1 ratio groups had significantly decreased serum levels of total cholesterol, low‐density lipoprotein cholesterol, and proinflammatory cytokines compared with the 20:1 group (p < 0.05). Additionally, the 20:1 group had significantly increased serum levels of E‐Selectin, von Willebrand factor (vWF), and numerous markers of oxidative stress compared with the other groups (p < 0.05). The 1:1 group had a significantly decreased lipid peroxide level compared with the other groups (p < 0.05). Serum levels of malondialdehyde, reactive oxygen species and vWF tended to increase with n‐6/n‐3 PUFA ratios increasing from 5:1 to 20:1. We demonstrated that low n‐6/n‐3 PUFA ratio (1:1 and 5:1) had a beneficial effect on cardiovascular risk factors by enhancing favorable lipid profiles, having anti‐inflammatory and anti‐oxidative stress effects, and improving endothelial function. A high n‐6/n‐3 PUFA ratio (20:1) had adverse effects. Our results indicated that low n‐6/n‐3 PUFA ratios exerted beneficial cardiovascular effects, suggesting that plant oils could be used as a source of n‐3 fatty acids to prevent CVD. They also suggested that we should be aware of possible adverse effects from excessive n‐3 PUFA.