Dietary Eicosapentaenoic Acid Research Articles

Gαz-independent and -dependent improvements with EPA supplementation on the early type 1 diabetes phenotype of NOD mice

Abstract Prostaglandin E2 (PGE2) is a key mediator of inflammation and is derived from the omega-6 polyunsaturated fatty acid, arachidonic acid (AA). In the β-cell, the PGE2 receptor, Prostaglandin EP3 receptor (EP3), is coupled to the unique heterotrimeric G protein alpha subunit, Gɑz to reduce the production of cyclic adenosine monophosphate (cAMP), a key signaling molecule that activates β-cell function, proliferation, and survival pathways. Non-obese diabetic (NOD) mice are a strong model of type 1 diabetes, and NOD mice lacking Gɑz are protected from hyperglycemia. Therefore, limiting systemic PGE2 production could potentially improve both the inflammatory and β-cell dysfunction phenotype of type 1 diabetes (T1D). Here, we sought to evaluate the impact of eicosapentaenoic acid (EPA) feeding, which limits PGE2 production, on the early T1D phenotype of NOD mice in the presence and absence of Gαz. Wild-type and Gαz knockout NOD mice were fed a control or EPA-enriched diet for 12 weeks, beginning at 4-5 weeks of age. Oral glucose tolerance, splenic T cell populations, islet cytokine/chemokine gene expression, islet insulitis, measurements of β-cell mass, and measurements of β-cell function were quantified. EPA diet feeding and Gɑz loss independently improved different aspects of the early NOD T1D phenotype and coordinated to alter the expression of certain cytokine/chemokine genes and enhance incretin-potentiated insulin secretion. Our results shed critical light on the Gαz-dependent and -independent effects of dietary EPA enrichment and provide a rationale for future research into novel pharmacological and dietary adjuvant therapies for T1D.

Optimum eicosapentaenoic acid + docosahexaenoic acid levels for farmed Atlantic salmon: closing the gap between science and commercial practice

The shift from fish oil to vegetable oil (VO) sources has lowered eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels in salmon aquafeeds. VOs are high in omega-6 and low in omega-3 essential fatty acids like EPA and DHA, crucial for fish metabolism and immunity. Algal oil (AO), with high EPA + DHA and lower omega-6 levels supports fish health and growth, but transferring lab-controlled conditions to real-world commercial farming remains a challenge. This study explored the benefits of high dietary EPA + DHA levels through a commercial farm (CF) study in Chile and a Big Data (BD) study in Norway. The CF study, involving 625,000 Atlantic salmon, compared standard feed with AO-supplemented feed. The latter resulted in improved health responses and better fillet quality. The BD study analyzed real data from 232.6 million fish, revealing that EPA + DHA levels > 8% reduce mortality variability by 21%, improve economic feed conversion ratio by 11%, and increase the likelihood of superior harvests by 27%, demonstrating productivity benefits. Both studies emphasize the advantages of feeds with EPA + DHA levels above typical industry practices, enhancing growth, health, and nutritional quality. Importantly, the BD study complements the CF study, bridging the gap between science and aquafarms, and providing evidence that diets with EPA + DHA > 8% offer biological performance benefits for farmers, regardless of farming environments.

Effect of Dietary Eicosapentaenoic and Docosahexaenoic Fatty Acid Supplementation during the Last Month of Gestation on Fatty Acid Metabolism and Oxidative Status in Charolais Cows and Calves.

Fatty acids (FAs) are of utmost importance in the peripartal period for the development of the central nervous and immune systems of the newborn. The transport of polyunsaturated fatty acids (PUFAs) through the placenta is considered to be minimal in ruminants. Nevertheless, the cow's FAs are the main source of FAs for the calf during gestation. This research aimed to investigate the influence of low-dose eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation during late gestation on the FA metabolism of cows and their calves. A total of 20 Charolais cows during the last month of their gestation were included in the feeding trial and were divided into a control group (CON) and an experimental group (EPA + DHA). The latter received a supplement in the amount of 100 g/day (9.1 and 7.8 g/cow/day of EPA and DHA, respectively). Supplementation of low-dose EPA and DHA alters colostrum and milk fatty acid composition through the elevation of n-3 long-chain polyunsaturated fatty acids (LC-PUFAs) without affecting milk fat and protein concentrations and oxidative status. Plasma composition in cows was significantly altered, while the same effect was not detected in calf plasma. No significant change in mRNA expression was detected for the genes fatty acid synthase (FASN) and acetyl-CoA carboxylase alpha (ACACA).

Eicosapentaenoic acid (EPA) improves grass carp (Ctenopharyngodon idellus) muscle development and nutritive value by activating the mTOR signaling pathway.

Skeletal muscle is the mainly edible part of fish. Eicosapentaenoic acid (EPA) is a crucial nutrient for fish. This study investigated the effect of EPA on the muscle development of grass carp along with the potential molecular mechanisms in vivo and in vitro. Muscle cells treated with 50 μM EPA in vitro showed the elevated proliferation, and the expression of mammalian target of rapamycin (mTOR) signaling pathway-related genes was upregulated (P < 0.05). In vivo experiments, 270 grass carp (27.92 g) were fed with one of the three experimental diets for 56 days: control diet (CN), 0.3% EPA-supplement diet (EPA), and the diet supplemented with 0.3% EPA and 30 mg/kg rapamycin (EPA + Rap). Fish weight gain rate (WGR) was improved in EPA group (P < 0.05). There was no difference in the viscerosomatic index (VSI) and body height (BH) among all groups (P > 0.05), whereas the carcass ratio (CR) and body length in the EPA group were obviously higher than those of other groups (P < 0.05), indicating that the increase of WGR was due to muscle growth. In addition, both muscle fiber density and muscle crude protein also increased in EPA group (P < 0.05). The principal component analysis showed that total weight of muscle amino acid in EPA group ranked first. Dietary EPA also increased protein levels of the total mTOR, S6k1, Myhc, Myog, and Myod in muscle (P < 0.05). In conclusion, EPA promoted the muscle development and nutritive value via activating the mTOR signaling pathway.

Long-term supplementation with EPA and DHA changes the fatty acid profile of rat tissues, upregulates NRF2 expression and downregulates TGFβ expression

We studied the influence of long-term treatment with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the liver, and kidney lipogenesis, inflammation and antioxidative gene expression. Male Wistar rats were divided into three groups on the basis of the different n6/n3 fatty acid ratios achieved by using different dietary oil blends: the control (CON, n6/n3 ratio was ~7), the N6 group (n6/n3 ratio was ~50) and the DHA group (n6/n3 ~1). Treatment significantly influenced the fatty acid profile of the liver and kidney tissues. The most characteristic changes were an increased content of EPA and DHA in the DHA group in both tissues, of the kidney and liver. The expression of transforming growth factor beta (TGF-ß) was downregulated in the liver tissue by long-term EPA/DHA supplementation. This could be attributed to a decrease in the production of arachidonic acid-derived proinflammatory mediators, and an increase in EPA and DHA derived eicosanoids. DHA and EPA supplementation also significantly increased expression of the NRF 2 gene. This finding suggests that n3 PUFA could influence the activation of the NRF 2 pathway, which is important in cell antioxidative defense. In conclusion, we have shown that long-term dietary supplementation with DHA and EPA could influence lipid metabolism, inflammation and antioxidative defense. Therefore, the long-term addition of dietary DHA and EPA could potentially influence the most important pathological processes in aging.

Hexachlorobenzene and omega-3 fatty acid intake from traditional foods in the northern Yukon: A risk and benefit analysis

A human biomonitoring study was conducted in the community of Old Crow, Yukon, in 2019, finding that levels of hexachlorobenzene (HCB) in plasma were elevated in the community relative to the general Canadian population. The aim of this study was to estimate dietary intake of both hexachlorobenzene, and the nutrient omega-3 fatty acids from locally harvested traditional foods in Old Crow, with the aim of identifying possible regional sources of exposure. A stochastic model was constructed to estimate intake of both hexachlorobenzene and the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Average predicted hexachlorobenzene exposure levels from traditional food consumption in Old Crow were below the tolerable daily intake of 1600–1700 ng/kg body weight/day in both average (18 ng/kg body weight/day) and short-term maximum (27 ng/kg body weight/day) exposure models. The primary contributors to average hexachlorobenzene intake were caribou fat, bone marrow, ribs, and kidneys, and Chinook salmon muscle. Average estimated dietary EPA + DHA intake levels from traditional foods were below the recommendation of 2.1 to 3.2 g of EPA + DHA per week in the average (1.6 g/week) exposure model, but above this recommendation in the short-term maximum model (3.3 g/week). The primary contributors to average EPA + DHA intake were the meat of Chinook, coho, and, chum salmon muscle, and whitefish muscle and eggs. The results of this study support the message that traditional foods continue to be an important source of nutrients and other health benefits and that the health benefits of traditional foods generally outweigh contaminant risks.

Association of Eicosapentaenoic and Docosahexaenoic Acid Intake with Low Birth Weight in the Second Trimester: The Japan Pregnancy Eating and Activity Cohort Study.

This study examined the association of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) intake during the second trimester with low birth weight (LBW) in pregnant Japanese women and was conducted in conjunction with the Japan Pregnancy Eating and Activity Cohort (J-PEACH) study. The study included 504 pregnant women from four Japanese sites. During the second trimester (14-27 weeks), the participants filled out a self-administered questionnaire assessing the frequency of DHA and EPA supplement intake in the past month, as well as a brief-type self-administered diet history questionnaire (BDHQ). The analysis involved data from two time points: responses to the BDHQ and infant data at birth. In total, 471 and 33 participants were classified into the normal birth weight and LBW groups, respectively. The participants were divided into high-, medium-, and low-intake groups based on their total dietary and EPA and DHA supplementary intakes. The Cochran-Armitage trend test was used to analyze the data; the prevalence of LBW was higher in the low-intake group (p = 0.04). There was no significant sex-based trend (p = 0.27 and p = 0.35). In Japanese women, low dietary and supplementary EPA and DHA intake until the second trimester were risk factors for LBW.

Effects of dietary eicosapentaenoic acid on the growth performance, fatty acid profile, immunity and heat tolerance of juvenile abalone Haliotis discus hannai Ino

A 93-day growth trial was performed to evaluate the influences of graded dietary EPA levels (0.03% (control group), 0.24%, 0.63%, 1.07%, 1.72% and 2.25%) on the growth performance, immunity and heat tolerance of juvenile abalone Haliotis discus hannai with a mean initial weight of 4.15 ± 0.18 g. After the feeding trial, the findings found that the highest weight gain rate (WGR) belonged to the groups fed with 0.63% ∼ 1.72% of dietary EPA (P < 0.05). The lowest feed conversion ratio was distinguished in the groups with 0.63% ∼ 1.07% of dietary EPA (P < 0.05). Also, EPA supplementation in abalone feed increased the content of crude lipid in the soft body and the activity of lipase in the intestine (P < 0.05). The total antioxidative capacity increased when dietary EPA levels rose from 0.03% to 1.07%, and then decreased (P < 0.05). Furthermore, compared to the control group, the 0.24% and 0.24% ∼ 0.63% of dietary EPA significantly down-regulated the mRNA levels of IκB kinase and kelch-like ECH-associated protein 1, respectively (P < 0.05). However, nuclear factor-κB and interleukin 1 receptor-associated kinase 4 genes expression in the digestive gland were significantly up-regulated by the use of 1.72% and 2.25% of EPA in diet (P < 0.05). The mRNA levels of tumor necrosis factor α and interleukin 16 were significantly up-regulated by the 2.25% of dietary EPA (P < 0.05). The 1.72% of dietary EPA significantly increased the falling rate of abalone after the heat stress compared with the control (P < 0.05). In conclusion, the optimal dietary EPA requirement of juvenile abalone was determined as 1.36% based on quadratic regression analysis against WGR. Moderate dietary EPA content (0.63% ∼ 1.07%) improved the immunity and heat resistance of abalone. Excessive dietary EPA content (1.72% ∼ 2.25%) decreased the growth, meanwhile, increasing the oxidative stress, inflammation and susceptibility of abalone to heat stress.

Dietary Eicosapentaenoic Acid Containing Phosphoethanolamine Plasmalogens Remodels the Lipidome of White Adipose Tissue and Suppresses High-Fat Diet Induced Obesity in Mice.

Dietary supplementation of docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) can alter the lipidome profiles of adipocytes, thereby counteract obesity. DHA/EPA in the form of phospholipids demonstrates higher bioavailability than triglyceride or ethyl ester (EE), but their effects on the lipidome and metabolic changes during obesity are still unknown. High-fat diet-induced obese mice are treated with different molecular forms of EPA, and EPA supplemented as phosphoethanolamine plasmalogens (PlsEtn) has a superior effect on reducing fat mass accumulation than phosphatidylcholine (PC) or EE. The lipidomics analysis indicates that EPA in form of PlsEtn but not PC or EE significantly decreases total PC and sphingomyelin content in white adipose tissue (WAT). Some specific polyunsaturated fatty acid -containing PCs and ether phospholipids are increased in EPA-PlsEtn-fed mice, which may attribute to the upregulation of unsaturated fatty acid biosynthesis and fatty acid elongation reactions in WAT. In addition, the expression of genes related to fatty acid catabolism is also promoted by EPA-PlsEtn supplementation, which may cause the decreased content of saturated and monounsaturated fatty acid-containing PCs. EPA-PlsEtn supplementation is demonstrated to remodel lipidome and regulate the fatty acid metabolic process in WAT, indicating it may serve as a new strategy for obesity treatment in the future.

Oral Administration of Chaetoceros gracilis—A Marine Microalga—Alleviates Hepatic Lipid Accumulation in Rats Fed a High-Sucrose and Cholesterol-Containing Diet

Microalgae are attracting attention as a next-generation alternative source of protein and essential fatty acids that do not consume large amounts of water or land. Chaetoceros gracilis (C. gracilis)-a marine microalga-is rich in proteins, fucoxanthin, and eicosapentaenoic acid (EPA). Growing evidence indicates that dietary fucoxanthin and EPA have beneficial effects in humans. However, none of these studies have shown that dietary C. gracilis has beneficial effects in mammals. In this study, we investigated the effects of dietary C. gracilis on lipid abnormalities in Sprague-Dawley rats fed a high-sucrose cholesterol-containing diet. Dried C. gracilis was added to the control diet at a final dose of 2 or 5% (w/w). After four weeks, the soleus muscle weights were found to be dose-responsive to C. gracilis and showed a tendency to increase. The hepatic triglyceride and total cholesterol levels were significantly reduced by C. gracilis feeding compared to those in the control group. The activities of FAS and G6PDH, which are related to fatty acid de novo synthesis, were found to be dose-responsive to C. gracilis and tended to decrease. The hepatic glycerol content was also significantly decreased by C. gracilis feeding, and the serum HDL cholesterol levels were significantly increased, whereas the serum levels of cholesterol absorption markers (i.e., campesterol and β-sitosterol) and the hepatic mRNA levels of Scarb1 were significantly decreased. Water-soluble metabolite analysis showed that the muscular contents of several amino acids, including leucine, were significantly increased by C. gracilis feeding. The tendency toward an increase in the weight of the soleus muscle as a result of C. gracilis feeding may be due to the enhancement of muscle protein synthesis centered on leucine. Collectively, these results show that the oral administration of C. gracilis alleviates hepatic lipid accumulation in rats fed a high-sucrose and cholesterol-containing diet, indicating the potential use of C. gracilis as a food resource.

Eicosapentaenoic Acid Preserves Mitochondrial Quality and Attenuates Cardiac Remodeling After Myocardial Infarction in Rats.

Eicosapentaenoic acid (EPA) reduces the risk of ischemic heart diseases and is a component of mitochondria. We herein investigated whether dietary EPA mediated mitochondrial fatty acid compositions, dynamics, and functions, resulting in the attenuation of cardiac remodeling after myocardial infarction (MI). The coronary artery of male rats was ligated to induce MI, and they were then treated with or without EPA (1000mg/kg/day) for 12weeks. The EPA treatment improved left ventricular systolic function and increased the mitochondrial content of EPA in the non-infarct region 12weeks after MI. The content of ATP and mitochondrial complex II, III, and IV activities decreased after MI but were maintained by the EPA treatment in association with the preservation of optic atrophy 1, a mitochondrial fusion protein. The present results suggest that dietary EPA increased the mitochondrial content of EPA and preserved the expression of mitochondrial fusion proteins and energy metabolism, which attenuated left ventricular remodeling after MI.

Association between dietary polyunsaturated fatty acids and their concentration in blood plasma, red blood cell, and semen of dogs.

In dogs, dietary omega 3 polyunsaturated fatty acids (n-3 PUFA) affect the fatty acid (FA) profile of blood plasma, erythrocyte membrane (EM), and semen, but their correlation has not yet been investigated. In this study, we evaluated the association between dietary PUFA and their profile in blood plasma, EM, and semen of dogs, with the possibility to predict the semen profile using the values of the three first. Twelve male dogs received the same standard commercial diet for 4 weeks. The FA profile was analyzed by gas chromatography in paired diet, blood (plasma and EM determinations), and semen samples. Data were analyzed with SAS Proc Corr version 9.4. Pearson´s correlation coefficient (significant if p < 0.05) was used to assess the association of dietary FA profiles with those in blood plasma, EM, and semen. There was a positive correlation between dietary eicosapentaenoic acid (EPA) and blood plasma (r = 0.97), EM (r = 0.94) and semen (r = 0.92) EPA, and between dietary docosahexaenoic acid (DHA) and arachidonic acid (ARA) and semen DHA (r = 0.93) and ARA (r = 0.92), respectively. There was a negative correlation between dihomo-gamma-linolenic acid (DGLA) in the diet and EM DGLA (r = -0.94). The dietary EPA is correlated with blood plasma, EM, and semen EPA concentrations, and dietary DHA and ARA are associated with semen DHA and ARA concentrations in dogs. These findings suggest that dietary EPA, DHA, and ARA concentrations could be helpful to predictive markers for such concentrations in the semen of dogs.

Evaluating the Effect of Eicosapentaenoic Acid in Children With Atopic Dermatitis: A Randomized Triple-Blind Clinical Trial.

To evaluate the effects of dietary eicosapentaenoic acid (EPA) in children with atopic dermatitis. Forty-eight children with atopic dermatitis were randomly allocated to receive either 250 mg twice daily EPA (n = 24) or placebo (n = 24) for 4 weeks. The absolute improvement in the SCORing Atopic Dermatitis (SCORAD) index and the necessity to use topical corticosteroids was evaluated. Based on an intention-to-treat analysis, after 2 weeks the scores decreased to 30.50 ± 8.91 and 38.34 ± 10.52 in the EPA and placebo groups, respectively (p = 0.015). Per-protocol analysis showed a decrease in scores to 18.01 ± 10.63 in the EPA group and to 30.11 ± 9.58 in the placebo group (p = 0.001). After 2 weeks, corticosteroid was needed in 11 (50.0%) patients in the EPA group and 14 (58.3%) patients in the placebo group (p = 0.571), and after 4 weeks, it was needed in 7 (33.3%) patients in the EPA group and 14 (63.6%) patients in the placebo group, respectively (p = 0.047). Our results show significant favorable effects of EPA on the SCORAD scale and with regard to the necessity for corticosteroid readministration. Few adverse effects were reported in the 2 groups. We conclude that EPA supplementation is a well-tolerated and effective add-on strategy for reducing the severity of atopic dermatitis in children.

Effects of Omega-3 Fatty Acid Supplementation on Skeletal Muscle Mass and Strength in Adults: A Systematic Review.

Previous studies have suggested that omega-3 polyunsaturated fatty acids, predominantly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have several health benefits. However, their effect on changes in skeletal muscle mass and strength has not been established, owing to differences in study designs. This systematic review aimed to investigate the recent evidence regarding the role of dietary EPA and DHA in muscle mass changes and their association with muscle strength. Databases including PubMed and Google Scholar were searched for randomized controlled trials and single-arm interventions that investigated the effects of omega-3 fatty acids on skeletal muscle mass, strength, and body composition in adults aged 18 years and older. A total of 18,521 studies were retrieved from the databases and manual searches; 21 studies were quality assessed, and the findings were summarized. Studies were categorized into 3 main categories according to the type of omega-3 fatty acid supplementation: pure compounds such as oil tablets, formulated forms with protein, leucine, and vitamin D, and ingredients added to enteral nutrition support products. Overall, the majority of the study results appeared to indicate that omega-3 fatty acids are beneficial for muscle health. However, meta-analysis was not conducted because of the heterogeneity of the study participants, evaluation method of muscle indices, and intervention periods among the studies. High-quality studies are required to validate our conclusions. However, this systematic review of the effects of EPA and DHA on skeletal muscle and body composition provides evidence that can be applied in both clinical and industrial settings.

Dietary EPA+DHA Mitigate Hepatic Toxicity and Modify the Oxylipin Profile in an Animal Model of Colorectal Cancer Treated with Chemotherapy.

Irinotecan (CPT-11) and 5-fluorouracil (5-FU) are commonly used to treat metastatic colorectal cancer, but chemotherapy-associated steatosis/steatohepatitis (CASSH) frequently accompanies their use. The objective of this study was to determine effect of CPT-11+5-FU on liver toxicity, liver oxylipins, and cytokines, and to explore whether these alterations could be modified by dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the form of fish oil (EPA+DHA). Tumor-bearing animals were administered CPT-11+5-FU and maintained on a control diet or a diet containing EPA+DHA (2.3 g/100 g). Livers were collected one week after chemotherapy for the analysis of oxylipins, cytokines, and markers of liver pathology (oxidized glutathione, GSSH; 4-hydroxynonenal, 4-HNE, and type-I collagen fiber). Dietary EPA+DHA prevented the chemotherapy-induced increases in liver GSSH (p &lt; 0.011) and 4-HNE (p &lt; 0.006). Compared with the tumor-bearing animals, ten oxylipins were altered (three/ten n-6 oxylipins were elevated while seven/ten n-3 oxylipins were reduced) following chemotherapy. Reductions in the n-3 fatty-acid-derived oxylipins that were evident following chemotherapy were restored by dietary EPA+DHA. Liver TNF-α, IL-6 and IL-10 were elevated (p &lt; 0.05) following chemotherapy; dietary EPA+DHA reduced IL-6 (p = 0.09) and eotaxin (p = 0.007) levels. Chemotherapy-induced liver injury results in distinct alterations in oxylipins and cytokines, and dietary EPA+DHA attenuates these pathophysiological effects.

α-linolenic acid interconversion is sufficient as a source of longer chain ω-3 polyunsaturated fatty acids in humans: An opinion.

α-linolenic acid (αLNA) conversion into the functionally important ω-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), has been regarded as inadequate for meeting nutritional requirements for these PUFA. This view is based on findings of small αLNA supplementation trials and stable isotope tracer studies that have been interpreted as indicating human capacity for EPA and, in particular, DHA synthesis is limited. The purpose of this review is to re-evaluate this interpretation. Markedly differing study designs, inconsistent findings and lack of trial replication preclude robust consensus regarding the nutritional adequacy of αLNA as a source of EPC and DHA. The conclusion that αLNA conversion in humans is constrained is inaccurate because it presupposes the existence of an unspecified, higher level of metabolic activity. Since capacity for EPA and DHA synthesis is the product of evolution it may be argued that the levels of EPA and DHA it maintains are nutritionally appropriate. Dietary and supra-dietary EPA plus DHA intakes confer health benefits. Paradoxically, such health benefits are also found amongst vegetarians who do not consume EPA and DHA, and for whom αLNA conversion is the primary source of ω-3 PUFA. Since there are no reported adverse effects on health or cognitive development of diets that exclude EPA and DHA, their synthesis from αLNA appears to be nutritionally adequate. This is consistent with the dietary essentiality of αLNA and has implications for developing sustainable nutritional recommendations for ω-3 PUFA.

Effect of dietary eicosapentaenoic acid (20:5n-3) on growth performance, fatty acid profile and lipid metabolism in coho salmon (Oncorhynchus kisutch) alevins

A 12-week feeding trial was conducted to investigate the effects of dietary eicosapentaenoic acid (EPA, 20:5n-3) on the growth performance, fatty acid profile and lipid metabolism in coho salmon (Oncorhynchus kisutch) alevins. Six diets (47% crude protein and 13.5% crude lipid) were formulated to contain graded levels of EPA (0.04%, 0.47%, 0.94%, 1.40%, 1.85% and 2.27%). Nine hundred alevins (0.395 ± 0.02 g) were randomly assigned to 18 white plastic tanks (50 fish in each tank, 0.8 × 0.6 × 0.6 m, and 240-L/tank). Fish were reared in a freshwater flow-through rearing system and fed to apparent satiation 4 times daily. Feed conversion ratio (FCR) in the 1.40% and 1.85% EPA groups was significantly lower than that in the 0.04% EPA group (P < .05). The lowest whole-body lipid content was observed in the 1.85% EPA group, which was significantly lower than those in the 0.04% and 0.47% EPA groups (P < .05). The whole-body EPA, docosahexaenoic acid (DHA, 22:6n-3) and ∑n-3-polyunsaturated fatty acids (∑n-3-PUFAs) contents significantly increased with increasing dietary EPA levels (P < .05). The liver lipoprotein lipase (LPL) and hepatic lipase (HL) reached the lowest value in group of 1.85% EPA, and then no significant differences were observed with increasing dietary EPA levels (P < .05). The liver malate dehydrogenase (MDH) significantly decreased with increasing dietary EPA levels (P < .05), and the lowest value was found in 1.40% EPA group. At the EPA content of 1.85% group, the liver fatty acid synthase (FAS) was significantly lower than those of other groups (P < .05). Fish fed the diet with 1.40% EPA displayed higher specific growth rate (SGR) than that fed the EPA unsupplemented diet. This study revealed that adequate dietary EPA significantly promoted growth performance and lipid metabolism, and based on quadratic regression analysis of SGR indicated that the optimal dietary EPA requirement was 1.41% for coho salmon alevins.

Interactions of dietary eicosapentaenoic acid and vitamin C on growth performance, anti-oxidation and muscle quality of abalone Haliotis discus hannai Ino

A 93-day feeding trial was conducted to investigate the effects of dietary eicosapentaenoic acid (EPA) and vitamin C (VC) on the growth performance, anti-oxidation and muscle quality of abalone Haliotis discus hannai (initial body weight: 26.89 ± 0.26 g; initial shell length: 60.36 ± 0.25 mm). Six experimental diets in a 3 × 2 two-factor design were formulated with graded levels of dietary EPA (0.25%, 0.75% and 1.25%) and dietary VC (0 and 1260 mg/kg). Results showed that the weight gain rate (WGR) of abalone was significantly increased with the increasing dietary EPA levels (P < 0.05), but there was no significant effect of dietary VC on the WGR. The significant highest superoxide dismutase (SOD) activity was observed in the group with 1.25% of dietary EPA and 1260 mg/kg of dietary VC, and there was a significant interaction between dietary EPA and VC (P < 0.05). Dietary EPA supplementation significantly improved muscle hardness and the content of ∑n-3 polyunsaturated fatty acids, volatile compounds, adenosine-5′-monophosphate (AMP) and inosine-5′-monophosphate (IMP) in muscle. Dietary VC supplementation significantly improved the muscle hardness, springiness, chewiness, and the contents of volatile compounds, hydroxyproline and IMP in muscle (P < 0.05). Significant interactions between dietary EPA and VC were observed on volatile compounds, AMP and IMP (P < 0.05). In conclusion, dietary EPA and VC interactively influence the anti-oxidative capability and muscle quality of abalone.

Dietary plant oil supplemented with arachidonic acid and eicosapentaenoic acid affects the fatty acid composition and eicosanoid metabolism of Atlantic salmon (Salmo salar L.) during smoltification

This study sought to investigate whether a “natural diet” (mimicking the fatty acid composition of freshwater aquatic insects eaten by salmon parr) during the freshwater (FW) life stage of pre-smolt Atlantic salmon (Salmo salar L.) affected red blood cells and gill fatty acid composition as well as eicosanoid metabolism in gill during smolting at different temperatures. Before being transferred to seawater (SW), salmon parr were fed with a modified (MO) diet containing vegetable oils (rapeseed, palm, and linseed oils) supplemented with eicosapentaenoic acid (EPA) and arachidonic acid (ARA) to completely replace the fish oil (FO). Fatty acid composition in red blood cells and gill tissues was determined before SW transfer and six weeks after. Additionally, the expression of genes associated with eicosanoid metabolism and Na+/K+-ATPase (NKA) activity in salmon gill was examined at different temperatures before SW transfer and 24 h after. The results showed the changes in fatty acid composition, including sum monounsaturated fatty acids (MUFAs), docosahexaenoic acid (DHA), ARA, EPA, and sum n-6 polyunsaturated fatty acids (n-6 PUFA) in both red blood cells and gill tissues at the FW stage were consistent with the fatty acid profiles of the supplied MO and FO fish diets; however sum EPA and DHA composition exhibited opposite trends to those of the FO diet. The proportion of ARA, EPA, and n-6 PUFA increased, whereas sum MUFAs and DHA decreased in the red blood cells and gill tissues of MO-fed fish compared to those fed with the FO diet at FW stage. Additionally, 5-lipoxygenase-activating protein (Flap) expression was downregulated in MO-fed fish prior to SW transfer. During the process of SW transfer at different temperatures, the MO diet remarkably suppressed NKAα1a expression in MO-fed fish both at 12 and 16 °C. The MO diet also upregulated phospholipase A2 group IV (PLA2g4) expression in gills at 8, 12, and 16 °C, but suppressed phospholipase A2 group VI (PLA2g6) expression in gills at 12 °C compared to FO-fed fish at 12 °C and MO-fed fish at 8 °C. The MO diet also upregulated Cyclooxygenase 2 (Cox-2) expression at 8 °C compared to FO-fed fish and increased Arachidonate 5-lipoxygenase (5-Lox) expression in MO-fed fish at 16 °C compared to both FO-fed fish at 16 °C and MO-fed fish at 8 °C. Our study also determined that both SW transfer water temperatures and diets during the FW period jointly influenced the mRNA expression of PLA2g4, PLA2g6, and Lpl, whereas 5-Lox was more sensitive to dietary changes. In conclusion, the MO diet affected the fatty acid composition in gill and in red blood cells. When transferred to SW, dietary ARA supplementation could promote the bioavailability for eicosanoid synthesis in gill mainly via PLA2g4 activation, and potentially inhibit the stress and inflammatory response caused by different water temperatures through dietary EPA supplementation.

A Piece of the Puzzle-Possible Mechanisms for Why Low Dietary EPA and DHA Cause Hepatic Lipid Accumulation in Atlantic Salmon (Salmo salar).

The present study aimed at elucidating the effects of graded levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the hepatic metabolic health of Atlantic salmon reared in sea cages. Diets containing 10, 13, 16 and 35 g/kg EPA + DHA (designated diets 1.0, 1.3, 1.6 and 3.5, respectively) were fed in triplicate through a full production cycle from an average starting weight of 275 g to slaughter size (~5 kg). Feeding low dietary EPA + DHA altered the hepatic energy metabolism, evidenced by reductions in tricarboxylic acid cycle intermediates originating from β-oxidation, which was compensated by elevated activity in alternative energy pathways (pentose phosphate pathway, branched chain amino acid catabolism and creatine metabolism). Increases in various acylcarnitines in the liver supported this and indicates issues with lipid metabolism (mitochondrial β-oxidation). Problems using lipids for energy in the lower EPA + DHA groups line up well with observed increases in liver lipids in these fish. It also aligns with the growth data, where fish fed the highest EPA + DHA grew better than the other groups. The study showed that diets 1.0 and 1.3 were insufficient for maintaining good liver metabolic health. However, diet 3.5 was significantly better than diet 1.6, indicating that diet 1.6 might also be suboptimal.