Dietary Docosahexaenoic Acid Levels Research Articles

Dietary docosahexaenoic acid (DHA) downregulates liver DHA synthesis by inhibiting eicosapentaenoic acid elongation

DHA is abundant in the brain where it regulates cell survival, neurogenesis, and neuroinflammation. DHA can be obtained from the diet or synthesized from alpha-linolenic acid (ALA; 18:3n-3) via a series of desaturation and elongation reactions occurring in the liver. Tracer studies suggest that dietary DHA can downregulate its own synthesis, but the mechanism remains undetermined and is the primary objective of this manuscript. First, we show by tracing 13C content (δ13C) of DHA via compound-specific isotope analysis, that following low dietary DHA, the brain receives DHA synthesized from ALA. We then show that dietary DHA increases mouse liver and serum EPA, which is dependant on ALA. Furthermore, by compound-specific isotope analysis we demonstrate that the source of increased EPA is slowed EPA metabolism, not increased DHA retroconversion as previously assumed. DHA feeding alone or with ALA lowered liver elongation of very long chain (ELOVL2, EPA elongation) enzyme activity despite no change in protein content. To further evaluate the role of ELOVL2, a liver-specific Elovl2 KO was generated showing that DHA feeding in the presence or absence of a functional liver ELOVL2 yields similar results. An enzyme competition assay for EPA elongation suggests both uncompetitive and noncompetitive inhibition by DHA depending on DHA levels. To translate our findings, we show that DHA supplementation in men and women increases EPA levels in a manner dependent on a SNP (rs953413) in the ELOVL2 gene. In conclusion, we identify a novel feedback inhibition pathway where dietary DHA downregulates its liver synthesis by inhibiting EPA elongation.

Comparative evaluation on the effects of dietary docosahexaenoic acid on growth performance, fatty acid profile and lipid metabolism in two sizes of abalone Haliotis discus hannai Ino

A 93-day feeding trial was conducted to comparatively evaluate the effects of graded levels of dietary docosahexaenoic acid (DHA) (0.06%, 0.46%, 0.99%, 1.57%, 1.95% and 2.25%) on growth performance, fatty acid profile and lipid metabolism in two different sizes of abalone Haliotis discus hannai (initial body weight: 2.83 ± 0.03 g and 26.81 ± 0.17 g, respectively). Results showed that 0.99%–1.95% of dietary DHA contents significantly increased the weight gain rate (WGR) in large size of abalone (P < 0.05), while the WGR in small size of abalone was significantly increased by the 0.46%–0.99% of dietary DHA contents (P < 0.05). There was no significant difference in the survival of abalone among all the six groups (P > 0.05). Based on the WGR, the optimal dietary DHA content for large and small size abalone were estimated to be 1.32% and 0.88%, respectively. Dietary DHA supplementation significantly increased the activities of trypsin and lipase in the intestine, the content of ∑n-3 polyunsaturated fatty acids (PUFA) and ∑n-3/n-6 PUFA ratio in digestive gland in both sizes of abalone (P < 0.05). The total glyceride concentration in the cell-free hemolymph in two sizes of abalone was decreased. In large size of abalone, 1.95%–2.25% of dietary DHA reduced the lipid content in digestive gland. Lipogenic genes in the digestive gland, including sterol regulatory element binding protein-1 (srebp-1) and diacylglycerol acyltransferase, were up-regulated in the 0.46%–1.57% DHA group (P > 0.05). The mRNA expression levels of hormone sensitive lipase (hsl) and carnitine palmitoyl transferase-1 (cpt-1) of lipolytic genes in the digestive gland were significantly increased in the 0.46% and 0.99% DHA groups, respectively (P < 0.05). In the small size of abalone, the lipid content in digestive gland and soft body decreased significantly in the 1.95% and 2.25% DHA groups, respectively (P < 0.05). Lipogenic genes in the digestive gland, including srebp-1 and acetyl-CoA carboxylase, were significantly down-regulated in the 0.99%–1.95% DHA group (P < 0.05). Lipolytic genes in the digestive gland, including hsl and cpt-1, were not significantly different from the control group (P > 0.05). In conclusion, based on the WGR, the dietary DHA requirements for large and small size of abalone were estimated to be 1.32% and 0.88%, respectively. Dietary DHA reduced lipid deposition in both sizes of abalone by promoting lipid decomposition and inhibiting lipid synthesis.

Dietary DHA Enhanced the Textural Firmness of Common Carp (Cyprinus carpio L.) Fed Plant-Derived Diets through Restraining FoxO1 Pathways.

Omega-3 fatty acids have a positive effect on the muscle textural firmness of fish, while the intrinsic mechanism is poorly understood. To investigate the potential mechanism of textural modification caused by dietary docosahexaenoic acid ( DHA) in common carp (Cyprinus carpio L.), three plant-derived diets with varying DHA levels (0%, 0.5%, 1%, D1-D3) were prepared to feed juveniles (initial weight 15.27 ± 0.77 g) for 8 weeks, and the muscular texture, fibers density, and transcriptome were analyzed. The results showed that the growth performance, muscular DHA content, fibers density, and texture of the fish fed diets D2 and D3 were significantly ameliorated compared with the fish fed diet D1. The muscular transcriptome profiles indicated that the up-regulated genes of fish fed dietary DHA mainly in response to muscle proliferation, as well as the FoxO pathway, were significantly enriched in the D2 and D3 groups. Consistent with this, the Quantitative Real-Time PCR (qRT-PCR ) assays indicated that the expression of myogenic regulatory factors (myog, myod, mrf4, mrf5) was up-regulated in the high-DHA groups. Additionally, the expression of foxo1 (inhibitor of myofiber development) mRNA was down-regulated, while its negative regulatory pathway (MAPK and PI3K) was activated in the D2 and D3 groups. The results suggested that the DHA supplementation is beneficial to modifying the muscular textural firmness of common carp fed plant-derived diets, which could be attributed to the inhibition of FoxO1 pathways.

A dose-response study with omega-3 rich canola oil as a novel source of docosahexaenoic acid (DHA) in feed for Atlantic salmon (Salmo salar) in seawater; effects on performance, tissue fatty acid composition, and fillet quality

Long-chain omega-3 rich oils from crops genetically modified with algal genes are a promising new source of the omega-3 fatty acid DHA (docosahexaenoic acid; 22:6n-3) in Atlantic salmon diets. In this study, the fish oil and fish meal content were held constant across diets, and conventional canola oil was replaced with DHA canola (DHA-CA) oil in a step-wise manner at 0%, 25%, 50%, and 100% replacement, respectively. Growth of salmon, reared in seawater, from approximately 465 g to 1.5 kg was equal across all dietary treatments. Survival was >98% in all cases, with no difference between the dietary groups. Digestibility of lipids was high, approximately 93% in all dietary groups. Fatty acid retention in whole body was also high, with greater retention of α-linolenic acid (ALA, 18:3n-3) and eicosapentaenoic acid (EPA; 20:5n-3) in groups containing higher proportions of DHA-CA oil. Fillet, liver, and intestinal fatty acid compositions were influenced by the different fatty acid contents of the diets, with progressively higher inclusion of ALA, EPA, and DHA and a higher n-3:n-6 ratio in fish fed the 25%, 50%, and 100% DHA-CA diets. Increased dietary inclusion levels of DHA reduced the conversion to 1-14C labelled ALA to 1-14C EPA in liver cells, but some conversion of ALA to 1-14C EPA was maintained even at high dietary DHA levels. There was also a significant increase in anti-inflammatory pro-resolving lipid mediators, resolvins, with increased dietary DHA-CA. The visual colour impression of both muscle and skin was improved at higher DHA-CA inclusion levels in diets.Overall, our findings demonstrates that DHA-CA oil is an effective ingredient in Atlantic salmon diets in seawater, and that fatty acids (FA) from this oil are incorporated into the fish tissues in a manner equivalent to FA from conventional sources, with positive effects on fillet quality.

Improved fillet quality in harvest-size Atlantic salmon fed high n-3 canola oil as a DHA-source

New sources of the very long-chain n-3 polyunsaturated fatty acids (n-3 VLC-PUFA) are needed for sustainable growth of salmon farming. In recent research high n-3 VLC-PUFA canola oil has shown promise as a safe and effective source of docosahexaenoic acid (DHA) and other n-3 PUFA in small Atlantic salmon. To study its long-term effects on performance and fillet quality under realistic farming conditions, a 12-month feeding experiment was carried out with Atlantic salmon growing to harvest weight (4.7 kg) in triplicate sea water cages. The fish were fed three diets containing graded inclusion levels of high n-3 canola oil resulting in levels of dietary DHA (22:6 n-3) of 4.0% (Standard; STD), 6.6% (Medium; MED) and 8.3% of total fatty acids (HIGH) and total EPA + DHA of 6.4, 9.1 and 11.0% of total fatty acids, respectively. The STD diet was considered to represent current commercial practice. There were no significant differences between the dietary groups in overall fish growth and weight at harvest, and no differences were seen in feed conversion ratio. Tissue FA-profiles mirrored the diets, giving increased DHA, EPA (20:5 n-3) and ALA (18:3 n-3) with increasing inclusion level of high n-3 LC-PUFA canola oil. Dietary inclusion of n-3 canola oil had no effect on muscle astaxanthin concentration, but instrumentally measured redness, yellowness and chroma increased with n-3 canola oil inclusion, suggesting a positive effect on colour via effects on muscle structure or composition. The prevalence and severity of dark melanin spots in the fillet was significantly reduced by increased inclusion level of n-3 canola oil. The prevalence of severe spots (score ≥ 2), average score and number of affected muscle segments were all lower in MED and HIGH, compared to STD.In conclusion, high n-3 canola oil is an efficient source of DHA and other n-3 fatty acids for harvest-size Atlantic salmon. Increased dietary supply of DHA and other n-3 PUFA, above minimum requirement levels for DHA, improved fillet pigmentation and reduced fillet melanin spots, without compromising fish growth.

Fatty Acid Composition and Digestive Enzyme Activities of Rainbow Trout in Response to Dietary Docosahexaenoic Acid (DHA) and Eicosapentaenoic Acid (EPA) During Salinity Acclimation

This physiological study aimed to evaluate the effects of dietary docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on the fatty acid composition and digestive enzyme activities of rainbow trout (Oncorhynchus mykiss) during salinity acclimation. Rainbow trout with an average initial weight of 90.61 g ±9.25 g were fed diets with the quantities of DHA and EPA equaling to 0.54%, 0.95%, 1.40% and 1.79% (abbreviated as DE-0.54, DE-0.95, DE-1.40, and DE-1.79, respectively) for eight weeks, after which the gastric and intestinal fatty acids composition were analyzed. Subsequently, the fish underwent salinity acclimation. On days 1, 4, 7, and 14 after the freshwater was replaced by seawater and at the end of the 8-week period, gastric and intestinal digestive enzyme activities were determined. The results showed that the gastric and intestinal DHA and EPA contents of the fish were positively correlated to their dietary DHA and EPA levels. Low dietary DHA and EPA levels inhibited the protease activity of rainbow trout. Fish in the DE-0.54 group increased the lipase activity to enhance the utilization of lipids maybe due to the inadequate essential fatty acids for fish in this group. Hence, rainbow trout in the DE-0.54 group failed to maintain suitable activities of digestive enzymes after salinity acclimation. Therefore, a diet with minimum 0.95% DHA and EPA levels is necessary for rainbow trout during salinity acclimation.

Characterization, mRNA expression and nutritional regulation of a Δ6 fatty acyl desaturase-like gene by dietary DHA levels of Perinereis aibuhitensis (Gube, 1878)

The Δ6 fatty acyl desaturase (Δ6 Fad) enzyme plays an important role in the pathways for the biosynthesis of the highly unsaturated fatty acids (HUFA) by converting linoleic (LA, 18:2n-6) and α-linolenic (LNA, 18:3n-3) acids to 18:3n-6 and 18:4n-3, respectively. In the present study, a Δ6 Fad-like gene was cloned and its characterisation, tissue expression and nutritional regulation by dietary DHA (docosahexaenoic acid) levels were analysed in the clamworm Perinereis aibuhitensis. The full-length cDNA was 1535 bp including a 1335 bp open reading frame (ORF) encoding a polypeptide of 444 amino acids, a 113 bp 50’-UTR and an 87 bp 3’-UTR with a poly (A) tail. Sequence comparison revealed that the predicted protein shared higher homologies with Δ6 Fad from Apostichopus japonicus with 56% identify. The tissue distribution of P. aibuhitensis Δ6 Fad-like mRNA was found predominantly in intestine, followed by head, esophagus, stomach and other tissues. Quantitative real-time PCR showed that the Δ6 Fad-like transcriptional levels in intestine gradually decreased with increased content of dietary DHA.

Liver Transcriptome Profiling Reveals That Dietary DHA and EPA Levels Influence Suites of Genes Involved in Metabolism, Redox Homeostasis, and Immune Function in Atlantic Salmon (Salmo salar).

The optimal dietary requirement of omega-3 long-chain polyunsaturated fatty acids (ω3 LC-PUFA), namely docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), for Atlantic salmon that promotes growth and health warrants careful investigation. We used 44K microarrays to study the influence of increasing levels of dietary DHA + EPA (0, 1.0, and 1.4% of the diet, as formulated) in the presence of high linoleic acid (LA) on Atlantic salmon growth and liver transcriptome. After a 14-week feeding trial, Atlantic salmon fed diet ω3LC0 (i.e. 0% of DHA + EPA) showed significantly lower final weight and weight gain, and higher feed conversion ratio compared with ω3LC1.0 and ω3LC1.4 diet groups. The microarray experiment identified 55 and 77 differentially expressed probes (Rank Products analyses; PFP < 10%) in salmon fed diets ω3LC1.4 and ω3LC1.0 compared with those fed diet ω3LC0, respectively. The comparison between ω3LC1.4 and ω3LC1.0 revealed 134 differentially expressed probes. The microarray results were confirmed by qPCR analyses of 22 microarray-identified transcripts. Several key genes involved in fatty acid metabolism including LC-PUFA synthesis were upregulated in fish fed ω3LC0 compared with both other groups. Hierarchical clustering and linear regression analyses of liver qPCR and fatty acid composition data demonstrated significant correlations. In the current study, 1.0% ω3 LC-PUFA seemed to be the minimum requirement for Atlantic salmon based on growth performance; however, multivariate statistical analyses (PERMANOVA and SIMPER) showed that fish fed ω3LC1.0 and ω3LC1.4 diets had similar hepatic fatty acid profiles but marked differences in the transcript expression of biomarker genes involved in redox homeostasis (mgst1), immune responses (mxb, igmb, irf3, lect2a, srk2, and lyz2), and LC-PUFA synthesis (srebp1, fadsd5, and elovl2). This research has provided new insights into dietary requirement of DHA and EPA and their impact on physiologically important pathways in addition to lipid metabolism in Atlantic salmon.

Re-evaluating the dietary requirement of EPA and DHA for Atlantic salmon in freshwater

The requirement for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is recommended at 0.50–1.0% of the dry diet for juvenile Atlantic salmon (Salmo salar). Current commercial aquafeed formulations for Atlantic salmon tend to contain a physiological excess of these fatty acids. The aim of this study was to re-evaluate the EPA and DHA requirement by Atlantic salmon parr in freshwater since it was determined 20 years ago, and feed formulations and salmon production have changed. This study evaluated the effect of different dietary levels of EPA and DHA (0.25 to 2.0%) on growth performance, overall health, and whole-body EPA and DHA content. Salmon (initial weight 22.6 g ± 1.2) were fed four levels (0.25, 0.5, 0.75 and 2%) of EPA + DHA diets for 6 weeks in freshwater at 12 °C. Diets were fed to triplicate tanks, with 20 fish per tank. There were no mortalities throughout the trial and fish nearly doubled their weight after 6 weeks. Categorically, there were no discrete significant differences in growth performance among treatments after 6 weeks. However, weight gain was exponentially related to diet EPA + DHA levels (p < .0001; r2 = 28.3%), and the feed conversion ratio was inversely related. In both cases, these relationships suggested that the asymptote is reached between 0.25% and 0.5% dietary EPA + DHA. Whole body DHA and EPA showed positive linear relationships with diet DHA (p < .001; r2 = 88.7%) and EPA (p < .001; r2 = 92.9%). Based on growth performance and whole-body fatty acid content, salmon fed a diet containing 0.50% EPA + DHA diet exhibited similar growth performance and haematocrit with control diet (2%). Therefore, 0.5% is considered the lowest required EPA + DHA level for Atlantic salmon parr in freshwater in this study.

Dietary Docosahexaenoic Acid (DHA) and Eicosapentaenoic Acid (EPA) Operate by Different Mechanisms to Modulate Hepatic Steatosis and Hyperinsulemia in fa/fa Zucker Rats.

Hepatic steatosis, an early stage of non-alcoholic fatty liver disease, is commonly present in obesity and type 2 diabetes, and is associated with reduced hepatic omega-3 polyunsaturated fatty acid (n3-PUFA) status that impacts on the anti-inflammatory and insulin sensitizing functions of n3-PUFA. Our objective was to directly compare plant- and marine-based n3-PUFA (α-linoleic acid (ALA)), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA)) for their effects on hepatic steatosis, markers of hepatic inflammation and fibrosis, and insulinemia in obese rats. Fa/fa Zucker rats were provided diets containing ALA, EPA, DHA, or linoleic acid (LA, n6-PUFA) for eight weeks and compared to baseline fa/fa rats and lean Zucker rats fed LA-rich diet for eight weeks. Both DHA and EPA groups had liver lipid similar to baseline, however, DHA was more effective than EPA for reducing hepatic fatty acid synthase (FAS), increasing the proportion of smaller lipid droplets, reversing early fibrotic damage, and reducing fasting hyperinsulinemia. EPA was more effective for reducing FoxO1. Dietary ALA did not attenuate hepatic steatosis, most inflammatory markers or FAS. In summary, amongst the n3-PUFA, DHA was the most effective for elevating hepatic DHA levels, and preventing progression of hepatic steatosis via reductions in FAS and a marker of fibrosis.

Effect of increasing docosahexaenoic acid content in weaning diets on survival, growth and skeletal anomalies of longfin yellowtail (Seriola rivoliana,Valenciennes 1833)

Five isoproteic (54.8%) and isolipidic (24.1%) microdiets, which varied in their docosahexaenoic acid (DHA) content (0.25%, 0.75%, 1.64%, 1.99% and 3.17%; dw), were manufactured to determine its effects on longfin yellowtail Seriola rivoliana larvae in terms of fish biological performance, whole body fatty acid profile and incidence of skeletal anomalies from 30 dah (11.31 ± 1.79 Total Length, TL) to 50 dah (19.80 ± 0.58 mm TL). The inclusion of dietary DHA up to 3.17% (dw) improved larval resistance to air exposure, although DHA did not significantly affect fish final growth or final survival. Indeed, high levels of dietary DHA (1.99% and 3.17%, dw) tended to increase the incidence of skeletal anomalies in S. rivoliana larvae, albeit no significant differences were observed. Furthermore, the occurrence of severe anomalies such as kyphosis and lordosis, was mainly associated to the larvae fed the highest levels of dietary DHA. In terms of survival, increasing dietary DHA levels did not significantly affect longfin yellowtail survival rate, despite a tendency for enhanced survival. The results of the present study proved that the inclusion of dietary DHA in inert diets up to a 3.17% (dw) and a DHA/EPA ratio above 3.1 increased the final survival and stress resistance in S. rivoliana larvae.

Docosahexaenoic acid (C22:6n-3) alters cortisol response after air exposure inProchilodus lineatus(Valenciennes) larvae fed on enrichedArtemia

This study investigated the effect of different proportions of dietary docosahexaenoic acid (DHA) and arachidonic acid (ARA) on the growth, survival and stress response of curimba (Prochilodus lineatus Valenciennes) larvae, an omnivorous freshwater species, fed on enriched Artemia. Six different experimental emulsions were formulated to have two levels of ARA (A-0.5 and A-1.0), two levels of DHA (D-0.5 and D-1.0) two combinations of ARA and DHA (AD-3:1 and AD-1:3). There were no significant effects of treatments on curimba standard length and survival at the end of the experiment. The results showed a negative correlation between dietary DHA and whole-body cortisol after 60 s of air exposure. The resting concentration of cortisol was not affected by the diets (p = .424). After air exposure, all treatments except for D-1.0 (p = .137) and D-0.5 (p = .545) exhibited a marked cortisol rise. These results showed that DHA supplementation can have an attenuating effect on cortisol response after air exposure.

The optimum dietary docosahexaenoic acid level based on growth and non-specific immune responses in juvenile rock bream,Oplegnathus fasciatus

A feeding trial was conducted to determine the optimum level and effect of incremental dietary levels of docosahexaenoic acid (DHA, 22:6n-3) on growth and non-specific immune responses in juvenile rock bream, Oplegnathus fasciatus. A basal diet without DHA supplementation was used as a control, and six other diets were prepared by supplementing with 4, 8, 12, 16, 20 or 40 g kg−1 DHA. These diets included no eicosapentaenoic acid and/or arachidonic acid contents. The actual DHA concentrations of the diets were 1, 4.8, 8.9, 13.1, 17.6, 21.2 and 41.4 g kg−1 diet (DHA1.0, DHA4.8, DHA8.9, DHA13.1, DHA17.6, DHA21.2 and DHA41.4 respectively). At the end of feeding trial, final body weight, weight gain, specific growth rate and feed efficiency of fish fed the DHA13.1, DHA17.6, DHA21.2 and DHA41.4 diets were significantly higher than those fed the other diets (P < 0.05). The broken-line analysis of weight gain indicates that the optimum dietary DHA level is 11.9 g kg−1. Fish fed DHA1.0 had the highest hepatosomatic index, an increase in plasma cholesterol, triglyceride, low-density lipoprotein and aspartate aminotransferase levels, as well as a decrease in high-density lipoprotein. Superoxide dismutase activity of fish fed DHA13.1 and DHA17.6 diets was significantly higher than that of fish fed DHA1.0, DHA4.8 and DHA8.9 diets. Fish fed the DHA17.6, DHA21.2 and DHA41.4 diets showed significantly higher lysozyme activity than those fish fed DHA1.0, DHA4.8 and DHA8.9 diets. Therefore, the optimum dietary DHA level could be greater than 11.9 g kg−1 but less than 13.1 g kg−1 in diet.

Omega-3 Fatty Acid Formulations in Cardiovascular Disease: Dietary Supplements are Not Substitutes for Prescription Products.

Omega-3 fatty acid products are available as prescription formulations (icosapent ethyl, omega-3-acid ethyl esters, omega-3-acid ethyl esters A, omega-3-carboxylic acids) and dietary supplements (predominantly fish oils). Most dietary supplements and all but one prescription formulation contain mixtures of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Products containing both EPA and DHA may raise low-density lipoprotein cholesterol (LDL-C). In clinical trials, the EPA-only prescription product, icosapent ethyl, did not raise LDL-C compared with placebo. To correct a common misconception, it is important to note that omega-3 fatty acid dietary supplements are not US FDA–approved over-the-counter drugs and are not required to demonstrate safety and efficacy prior to marketing. Conversely, prescription products are supported by extensive clinical safety and efficacy investigations required for FDA approval and have active and ongoing safety monitoring programs. While omega-3 fatty acid dietary supplements may have a place in the supplementation of diet, they generally contain lower levels of EPA and DHA than prescription products and are not approved or intended to treat disease. Perhaps due to the lack of regulation of dietary supplements, EPA and DHA levels may vary widely within and between brands, and products may also contain unwanted cholesterol or fats or potentially harmful components, including toxins and oxidized fatty acids. Accordingly, omega-3 fatty acid dietary supplements should not be substituted for prescription products. Similarly, prescription products containing DHA and EPA should not be substituted for the EPA-only prescription product, as DHA may raise LDL-C and thereby complicate the management of patients with dyslipidemia.

A possible role for ghrelin, leptin, brain-derived neurotrophic factor and docosahexaenoic acid in reducing the quality of life of coeliac disease patients following a gluten-free diet.

A gluten-free diet (GFD) has been reported to negatively impact the quality of life (QoL) of coeliac disease (CD) patients. The gut-brain axis hormones ghrelin and leptin, with the brain-derived neurotrophic factor (BDNF), may affect QoL of CD patients undergoing GFD. Our aims were to evaluate whether: (a) the circulating concentrations of leptin, ghrelin and BDNF in CD patients were different from those in healthy subjects; (b) GFD might induce changes in their levels; (c) BDNF Val66Met polymorphism variability might affect BDNF levels; and (d) serum BDNF levels were related to dietary docosahexaenoic acid (DHA) as a neurotrophin modulator. Nineteen adult coeliac patients and 21 healthy controls were included. A QoL questionnaire was administered, and serum concentrations of ghrelin, leptin, BDNF and red blood cell membrane DHA levels were determined at the enrolment and after 1year of GFD. BDNF Val66Met polymorphism was analysed. Results from the questionnaire indicated a decline in QoL after GFD. Ghrelin and leptin levels were not significantly different between groups. BDNF levels were significantly (p=0.0213) lower in patients after GFD (22.0±2.4ng/ml) compared to controls (31.2±2.2ng/ml) and patients at diagnosis (25.0±2.5ng/ml). BDNF levels correlated with DHA levels (p=0.008, r=0.341) and the questionnaire total score (p=0.041, r=0.334). Ghrelin and leptin seem to not be associated with changes in QoL of patients undergoing dietetic treatment. In contrast, a link between BDNF reduction and the vulnerability of CD patients to psychological distress could be proposed, with DHA representing a possible intermediate.

Dietary docosahexaenoic acid alleviates autistic-like behaviors resulting from maternal immune activation in mice

The prevalence of autism spectrum disorders over the last several decades has risen at an alarming rate. Factors such as broadened clinical definitions and increased parental age only partially account for this precipitous increase, suggesting that recent changes in environmental factors may also be responsible. One such factor could be the dramatic decrease in consumption of anti-inflammatory dietary omega-3 (n-3) polyunsaturated fatty acids (PUFAs) relative to the amount of pro-inflammatory omega-6 (n-6) PUFAs and saturated fats in the Western diet. Docosahexaenoic acid (DHA) is the principle n-3 PUFA found in neural tissue and is important for optimal brain development, especially during late gestation when DHA rapidly and preferentially accumulates in the brain. In this study, we tested whether supplementation of a low n-3 PUFA diet with DHA throughout development could improve measures related to autism in a mouse model of maternal immune activation. We found that dietary DHA protected offspring from the deleterious effects of gestational exposure to the viral mimetic polyriboinosinic–polyribocytidilic acid on behavioral measures of autism and subsequent adulthood immune system reactivity. These data suggest that elevated dietary levels of DHA, especially during pregnancy and nursing, may help protect normal neurodevelopment from the potentially adverse consequences of environmental insults like maternal infection.

A Comparison of Growth, Survival, and Fatty Acid Composition of the Lined Seahorse, Hippocampus erectus , Juveniles Fed Enriched Artemia and a Calanoid Copepod, Schmackeria dubia

The purpose of this study was to evaluate the effect of varying dietary levels of highly unsaturated fatty acids (HUFAs) in live prey (Artemia nauplii and a calanoid copepod, Schmackeria dubia) on the growth performance, survival, and fatty acid composition of the lined seahorse, Hippocampus erectus, juveniles. Artemia nauplii were enriched with a commercial product (SS™ 50DE-microcapsule as HUFA source, 2/3 DHA, 1/3 EPA. Shengsuo Fishery Feed Research Center of Shandong Province, Qingdao, China) at four concentrations of 0.0, 14.0, 28.0, and 56.0. Newly hatched juveniles were cultured for 35 days. The content of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and n-3 HUFAs in the Artemia nauplii was positively related to the enrichment concentration. At the end of the trials, growth performance of the juveniles was positively related to the enrichment concentration as well. However, the juveniles fed prey enriched with the highest concentration of enrichment (56.0 μL/L) had the significantly lower (P < 0.05) survival rate. The juveniles fed the copepod had the best growth performance and the highest survival rate, suggesting that the copepod, S. dubia, is suitable for feeding the seahorse juveniles. The comparisons between the growth, survival, and fatty acid profiles of the juveniles fed Artemia and copepods indicate that the seahorse juveniles require dietary levels of DHA beyond those achieved by enriching prey with the HUFA enrichment. Surplus EPA resulted from an imbalance between DHA and EPA in the enriched Artemia nauplii probably caused an adverse effect on the seahorse juveniles. This study suggests that DHA and EPA requirement of the lined seahorse juveniles is roughly 32% of total fatty acid, and the optimal DHA/EPA ratio for the species is circa 4:1. To avoid an adverse effect resulting from excessive EPA, maximum proportion of EPA in enriched Artemia nauplii should not exceed 13% of total fatty acid, and a recommended minimum DHA/EPA ratio in the enriched Artemia nauplii is 1.46. Arachidonic acid (20:4n-6) might not be an essential fatty acid for the seahorse juveniles.

Long-Term Effect of Docosahexaenoic Acid Feeding on Lipid Composition and Brain Fatty Acid-Binding Protein Expression in Rats.

Arachidonic (AA) and docosahexaenoic acid (DHA) brain accretion is essential for brain development. The impact of DHA-rich maternal diets on offspring brain fatty acid composition has previously been studied up to the weanling stage; however, there has been no follow-up at later stages. Here, we examine the impact of DHA-rich maternal and weaning diets on brain fatty acid composition at weaning and three weeks post-weaning. We report that DHA supplementation during lactation maintains high DHA levels in the brains of pups even when they are fed a DHA-deficient diet for three weeks after weaning. We show that boosting dietary DHA levels for three weeks after weaning compensates for a maternal DHA-deficient diet during lactation. Finally, our data indicate that brain fatty acid binding protein (FABP7), a marker of neural stem cells, is down-regulated in the brains of six-week pups with a high DHA:AA ratio. We propose that elevated levels of DHA in developing brain accelerate brain maturation relative to DHA-deficient brains.

A comparative analysis of the response of the hepatic transcriptome to dietary docosahexaenoic acid in Atlantic salmon (Salmo salar) post-smolts.

BackgroundThe present study aimed to explore the impact of dietary docosahexaenoic acid (DHA) on aspects of the metabolism of Atlantic salmon (Salmo salar). The effects of diets containing increasing levels of DHA (1 g kg−1, 3 g kg−1, 6 g kg−1, 10 g kg−1 and 13 g kg−1) on the liver transcriptome of post-smolt salmon was examined to elucidate patterns of gene expression and responses of specific metabolic pathways. Total RNA was isolated from the liver of individual fish and analyzed using a custom gene expression 44K feature Atlantic salmon oligo-microarray.ResultsThe expression of up to 911 unique annotated genes was significantly affected by dietary DHA inclusion relative to a low DHA reference diet. Analysis of a total of 797 unique genes were found with a significant linear correlation between expression level and dietary DHA. Gene-Set Enrichment Analysis (GSEA) identified a range of pathways that were significantly affected by dietary DHA content.ConclusionsPathways that showed a significant response to dietary DHA level included those for long-chain polyunsaturated fatty acid biosynthesis, fatty acid elongation, steroid biosynthesis, glycan biosynthesis, protein export and protein processing in the endoplasmic reticulum. These findings suggest that in addition to clear roles in influencing lipid metabolic pathways, DHA might also have key functional roles in other pathways distinct from lipid metabolism.

Growth performance and gene expression in gilthead sea bream (Sparus aurata) fed microdiets with high docosahexaenoic acid and antioxidant levels

This study aimed to determine the effects of increasing docosahexaenoic acid (DHA) levels in Sparus aurata diets supplemented with antioxidants vitamins (vitamins C and E). Six isoproteic and isolipidic formulated diets, which varied in the DHA content (38–78 g kg−1 TFA), were fed to 19 dph S. aurata larvae. No significant differences were found in survival rates or growth, which indicates that all the diets covered the minimum essential fatty acid requirements of this species. Stress resistance was not negatively affected by dietary DHA contents. In agreement, two biomarkers of the oxidative stress of the fish and the gene expression of superoxide dismutase and glutathione peroxidase were not affected by the elevation of dietary DHA, denoting that fish were sufficiently protected from oxidative damage even at high dietary DHA contents. The elevation of dietary DHA did affect neither the occurrence of skeletal malformations nor the expression of osteological markers such as run-related transcription factor 2 or alkaline phosphatase. The results of this study have confirmed that increase of the dietary DHA levels in gilthead sea bream diets does not negatively affect larval performance if the larvae are protected from peroxidation risks. Despite not being harmful, increase of DHA over the recommended requirements does not have any significant improvement in larval performance.