Source Of Long-chain Polyunsaturated Fatty Acids Research Articles

Diets that do not let benthivorous salmonid fish, Thymallus baicalensis, realize their potential for accumulating large content of omega-3 PUFAs in muscle tissue

Salmoniformes are valuable commercial fish that are high in physiologically important omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs), namely eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic (DHA; 22:6n-3) ones. The content of EPA and DHA and, as a result, the quality of fish for consumers depend on the fish diet. We studied the fatty acid (FA) content and composition of grayling, Thymallus baicalensis, inhabiting six rivers, which differed in food supply for fish. The diet of fish was studied using fatty acid markers in adipose tissue and stomach content. In two rivers, grayling's diet was of aquatic origin, while in four rivers, terrestrial invertebrates constituted a high proportion of the fish diet. The study was conducted to test the following question: How do diets with varying amounts of terrestrial-based food influence the content of EPA and DHA, as well as the fatty acid composition, in various tissues of grayling? Grayling inhabiting shaded rivers had lower nutritional value as a source of LC-PUFAs for consumers compared to those in unshaded rivers. This was reflected in the diets of grayling in shaded rivers, which included more prey relying on terrestrial sources of FAs compared to unshaded rivers, where dietary items relied on autochthonous production. Furthermore, these different diets greatly affected the content of EPA and DHA in muscle and adipose tissue but demonstrated a less significant impact on PUFA content in the brain. These findings are of interest because they suggest that the nutritional value of grayling tissues, consumed by predators, including humans, depends on source material within a river and adjacent terrestrial habitat.

A new omega-3 rich euglenoid Eutreptiella sp. from the Korean coastal waters

Euglenoids, the primary producers of fatty acids (FAs), are used in functional foods, feeds, and biofuels. Long-chain polyunsaturated FAs (LC-PUFAs) such as eicosapentaenoic acid and docosahexaenoic acid (DHA) are crucial for human health. The primary commercial source of LC-PUFA is fish; however, its heavy metal bioconcentration is concerning. Globally declining wild-harvested fish stocks is another recently recognized serious problem. Herein, the morphology, molecular phylogeny, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectroscopy, and FA compositions of an unspecified euglenoid strain KCTC 19016P isolated from the Korean coastal waters were examined. The vegetative cells were longitudinally spindle-shaped with a truncated apex and a tail-like extension at the anterior and posterior ends, respectively and had two unequal flagella. They had distinct red eyespots, numerous chloroplasts, and paramylon granules. Pellicular cell striations were easily observed using a scanning electron microscope. Phylogenetic analyses based on nuclear and chloroplast small-subunit ribosomal RNA sequences revealed that Eutreptiella sp. KCTC 19016P was nested within the Eutreptiella clade and was closely related to Eutreptiella marina (AY703209). Using the MALDI-TOF spectrum analysis, we differentiated between Eutreptiella sp. KCTC 19016P and the related NIES strains, thereby confirming their taxonomic similarities. Eutreptiella sp. KCTC 19016P growth was observed for 30 days; the maximum growth rate and doubling time was 0.50 ± 0.05 day−1 and 1.40 ± 0.15 day, respectively. Eutreptiella sp. KCTC 19016P had a relatively high monounsaturated FA percentage compared to the other species. The omega-3 FA content in Eutreptiella sp. KCTC 19016P was significantly higher than that of the other strains, as determined using ordinary one-way analysis of variance (P < 0.0001). Among the four euglenoids, Eutreptiella sp. KCTC 19016P had the highest α-linolenic acid and DHA contents. Thus, this new isolate could potentially be used in aquaculture and nutraceuticals without the risks associated with consuming fish.

Trends in dietary intake and food sources of long-chain polyunsaturated fatty acids among Korean adults between 2007 and 2018.

This study examined trends in the dietary intake and food sources of long-chain polyunsaturated fatty acids (LC-PUFAs) in Korean adults from 2007 to 2018. In total, 46,307 adults (aged 19-64 years) were selected from the 2007-2018 Korea National Health and Nutrition Examination Surveys. Dietary data were obtained using 24-hour dietary recall. Intake levels and food sources of LC-PUFAs, including alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and linoleic acid (LA), were evaluated across the survey years and assessed based on compliance with dietary recommendations over the 2007-2018 period. Linear trends in LC-PUFAs intake levels over time were examined through multiple linear regression analysis. From 2007 to 2018, ALA and LA consumption increased from 1.1 g (0.5% of energy) to 1.4 g (0.6% of energy) and from 8.6 g (3.9% of energy) to 10.0 g (4.5% of energy), respectively. EPA intake decreased from 0.14 g to 0.12 g, and EPA+DHA intake showed a decreasing trend. The proportion of individuals who did not meet the recommended intake of EPA+DHA (250 mg/day) increased (64.4 to 68.4%). Regarding changes in food sources of ALA and LA, the contributions from mayonnaise, eggs, and bread increased, while those from plant food sources decreased. Among food sources of EPA and DHA, anchovy, saury, and Atka mackerel showed lower contributions over time. Our findings suggest that strategies to encourage the consumption of EPA and DHA from healthy food sources are necessary to improve cardiovascular health in the Korean population.

The importance of essential fatty acids and their ratios in aquafeeds to enhance salmonid production, welfare, and human health

Long chain polyunsaturated fatty acids (LC-PUFA), namely those from omega-3 (n-3) and omega-6 (n-6) families, are paramount for both fish and human nutrition. Some of these biomolecules cannot be synthesized de novo and must be acquired through the diet, being termed dietary essential fatty acids (EFA). Fish requirements for EFA have traditionally been met through the incorporation of fish oil (FO) in the formulation of aquafeeds. However, with limited supply of FO the aquaculture industry is searching for additional sustainable sources of LC-PUFA. This has significantly shifted the type of ingredients used in aquafeed formulation, namely vegetable oils (VO) deficient in long-chain omega-3, often resulting in imbalanced levels and ratios of fatty acid classes. Such imbalances can negatively affect fish performance and welfare, as well as the levels of health promoting omega-3 LC-PUFA present in fish fillets. Given the relevance that salmonid aquaculture plays in global fish production (principally Atlantic salmon, Salmo salar), as well as its growing role as a source of dietary health promoting omega-3 LC-PUFA for humans, the present review summarizes the scientific knowledge available to date on the dietary requirements for LC-PUFA by salmonids and humans. We discuss the implications of using imbalanced aquafeed formulations upon fish performance and welfare, as well as the subsequent consequences for human nutrition, along with current efforts to replace FO by alternative ingredients such as algal oil (AO) that can safeguard high-quality salmonid products for human consumption.

Regulation of gene expression associated with LC‐PUFA metabolism in juvenile tambaqui ( Colossoma macropomum ) fed different dietary oil sources

Given the ecological unsustainability of using fish oil (FO) as the main source of long-chain polyunsaturated fatty acids (LC-PUFA), the investigation of alternative dietary LC-PUFA sources is crucial for aquaculture. Tambaqui (Colossoma macropomum) is a valuable economic aquaculture resource in Brazil, capable of endogenously elongating and desaturating linoleic (LA; 18:2n-6) and α-linolenic (ALA; 18:3n-3) acids to longer and physiologically vital LC-PUFA. Yet, it is unclear how this pathway is regulated by different oil sources in tambaqui. Thus, we designed an experiment with 2 different oil diets (fish oil—FO and vegetable oil—VO) at 2 different concentrations (5% or 10%) to investigate the molecular regulation of fatty acid biosynthesis in this species. We observed no differences in survival, body weight gain (BWG) and feed conversion ratio between the treatments. Gene expression analysis shows that fads2 and elovl5 are up-regulated in liver, while fads2 and elovl2 are up-regulated in brain of tambaqui fed with VO. The transcription factors pparβb and pparγ are also up-regulated in the brain by VO diet, when compared to FO diet. The VO diet also contributed to the biosynthesis of LC-PUFA in liver and specifically DHA in the brain. Overall, our approach shows that lipid metabolism-relevant genes are regulated by different dietary lipid sources.

Marine species as safe source of LC-PUFA and micronutrients: Insights in new promising marine food in Peru

Seafood could be a promising way to supplement healthy fatty acids and trace elements to the Peruvian diet. Seafood from northern Peru was characterized with the highest relative concentrations of long-chain polyunsaturated fatty acids (LC-PUFAs), while in the center region marine species had the lowest As and Pb contents. Peruvian marine species are rich in LC-PUFAs and micro-nutrients (Cu, Fe, Mn, Zn), including species considered as potentially edible (e.g. Cycloxanthops sexdecimdentatus), but also non-edible species (e.g. Caulerpa filiformis). Nevertheless, it is crucial to consider toxic metals, e.g. As and Cd, which could pose a risk for consumers. High levels of beneficial LC-PUFAs and micro-nutrients would be taken up (up to 80% of the recommended values) when the Peruvian population would consume the estimated safe amount of seafood. Scoring species for fatty acid and metal content resulted in gastropods (e.g. Bursa ventricosa) as being the least beneficial species.

Harnessing the Lipogenic Potential of Δ6-Desaturase for Simultaneous Hyperaccumulation of Lipids and Polyunsaturated Fatty Acids in Nannochloropsis oceanica

Abstract Burgeoning demand for long-chain polyunsaturated fatty acids (LC-PUFA) due to their established pharmacological and economic significances along with the declining sources of fish urge to explore the sustainable sources of LC-PUFA. Being the predominant LC-PUFA source for marine fishes at the base of the aquatic food web, microalgae has been hailed as a promising natural source for LC-PUFA. However, the potential of algal systems to overproduce LC-PUFA via metabolic engineering is warranted to meet the ever-increasing demand. In this study, we identified and overexpressed Δ6-desaturase, the key enzyme involved in fatty acid desaturation and exemplified its potential on elevating PUFA and lipid content in Nannochloropsis oceanica. Δ6-desaturase overexpression enhanced growth and photosynthetic efficiency. Transgenic cells exhibited a remarkable increase in EPA content and reached up to 652.35 mg/g DW, , the highest EPA production in transgenic N. oceanica by expressing a single key enzyme without impeding growthin a transgenic heterokontgreen alga. Total lipid content was significantly increased by 1.7-fold in the transgenic cell than WT. Together, these findings exemplify a potential candidate for LC-PUFA overproduction and also open a new avenue for sustainable production of microalgal PUFAs.

Eelgrass pathogen Labyrinthula zosterae synthesizes essential fatty acids

Negative consequences of parasites and disease on hosts are usually better understood than their multifaceted ecosystem effects. The pathogen Labyrinthula zosterae (Lz) causes eelgrass wasting disease but has relatives that produce large quantities of nutritionally valuable long-chain polyunsaturated fatty acids (LCPUFA) such as docosahexaenoic acid (DHA). Here we quantify the fatty acids (FA) of Lz cultured on artificial media, eelgrass-based media, and eelgrass segments to investigate whether Lz may similarly produce LCPUFA. We also assess whether field-collected lesions show similar FA patterns to laboratory-inoculated eelgrass. We find that Lz produces DHA as its dominant FA along with other essential FA on both artificial and eelgrass-based media. DHA content was greater in both laboratory-inoculated and field-collected diseased eelgrass relative to their respective controls. If Lz's production scales in situ, it may present an unrecognized source of LCPUFA in eelgrass ecosystems.

Effect of 1 Year Krill Oil Supplementation on Cognitive Achievement of Dutch Adolescents: A Double-Blind Randomized Controlled Trial.

Long-chain polyunsaturated fatty acids (LCPUFA) are important for brain development and function, maybe especially during adolescence. Observational studies have demonstrated an association between fish consumption (a source of LCPUFA) and cognition in adolescents, but intervention trials are lacking. The goal of the current study was to investigate the effect of one year of krill oil (a source of LCPUFA) supplementation on the cognitive performance of adolescents with a low Omega-3 Index (O3I ≤ 5%). A double-blind, randomized, and placebo-controlled supplementation trial with repeated measurements (baseline (T0), three months (T1), six months (T2), and 12 months (T3)) in adolescents (267 randomized) was executed. Participants were randomized to 400 mg eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) per day in Cohort I or placebo and 800 mg EPA + DHA per day in Cohort II or placebo. O3I was monitored by a finger prick at all time points. At T0, T2, and T3, participants executed a neurocognitive test battery. Covariate corrected mixed models were run with either condition (krill or placebo) or O3I as predictors. Krill oil supplementation led to a small but significant increase in mean O3I, but few participants increased to the intended O3I range (8–11%). There was no significant effect of supplementation on the neurocognitive tests, nor a relationship between O3I and neurocognitive test scores. The increase in O3I was small in most participants, probably due to non-compliance. Possibly the increase in O3I was too small to demonstrate an effect. More research on the influence of LCPUFAs on cognition in adolescents is needed.

Omega-3 Uzun Zincirli Çoklu Doymamış Yağ Asitleri ve Fenilketonüri

Beyin, retina ve diğer sinir dokuları uzun zincirli çoklu doymamış yağ asitlerinden (UZÇDYA) zengindir. Birçok klinik ve epidemiyolojik çalışma ile omega-3 UZÇDYA’ların çocukluk çağındaki nöral gelişim üzerine olumlu etkileri olduğu kanıtlanmıştır. Uzun zincirli ÇDYA’lar, diyetle alımları yeterli olduğu sürece temel elzem yağ asitlerinden endojen olarak sentezlenebilirler. Aynı zamanda, et, balık, yumurta, karaciğer ve süt ürünleri gibi proteinden zengin besinler eikosapentaenoik asit (EPA) ve dokosaheksaenoik asit (DHA) gibi UZÇDYA’ların en belirgin diyetsel kaynaklarıdır. Bununla birlikte, klasik fenilketonürili (FKÜ) hastalar yüksek plazma fenilalanin konsantrasyonları ve nörolojik hasarı önlemek için diyet protein alımında sıkı ve ömür boyu süren bir sınırlamaya ihtiyaç duyarlar. Bu katı metabolik kontrol sadece düşük miktarda vitamin ve mineral sağlamakla kalmaz, genellikle doymuş yağ asitleri ve ÇDYA’ların da düşük miktarda alınmasına neden olur. Bu nedenle, FKÜ’lü hastalar sağlıklı kontrollerle karşılaştırıldığında UZÇDYA alımları daha az olmakta ve daha düşük plazma ve eritrosit UZÇDYA konsantrasyonlarına sahip olmaktadırlar. Bebeklik ve çocukluk döneminde, UZÇDYA’lar normal nörogelişim için önemlidir. Yetersizliği, okul öncesi ve okul çağındaki FKÜ’lü çocuklarda erken dönemde saptanabilen merkezi sinir sistemi işlev bozukluklarına katkıda bulunabilir. Ayrıca, UZÇDYA yetersizliğinin kronik nörolojik, inflamatuvar ve metabolik bozukluklara neden olabileceği de ileri sürülmektedir. Diğer taraftan, randomize kontrollü çalışmalardan elde edilen veriler, FKÜ’lü hastalardaki UZÇDYA durumunun diyet takviyesi ile iyileştirilebileceğini önermektedir. Bu derleme yazıda, fenilalaninden kısıtlı diyetler ile UZÇDYA arasındaki ilişki incelenmiş ve FKÜ’lü hastalar için UZÇDYA’ların önemi ele alınmıştır.

Composition and Content of Fatty Acids in the Tissues of Males and Females of Eurasian Perch Perca fluviatilis at the Late Stages of Reproductive Cycle

We have studied the composition and content of fatty acids (FAs) in the muscle, liver, and reproductive tissues of male and female of Eurasian perch from the Krasnoyarsk water reservoir at the late stages of reproductive cycle. The dynamics of FA composition of the muscle tissue correlates with seasonal changes in food-source composition, while the FA composition of the liver and gonad is influenced by the reproductive cycle and differs between males and females. Multivariate analysis shows that the redistribution of FAs at different stages of the reproductive cycle involves mainly the gonads and liver tissue. The nutritive value of the muscle tissue of perch, as a source of long-chain polyunsaturated FAs, does not depend on the reproductive stage.

Substrate specificity and membrane topologies of the iron-containing ω3 and ω6 desaturases from Mortierella alpina.

Polyunsaturated fatty acids (PUFAs) are essential lipids for cell function, normal growth, and development, serving as key structural components of biological membranes and modulating critical signal transduction events. Omega-3 (n-3) long chain PUFAs (LC-PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been shown to protect against inflammatory diseases and enhance brain development and function. This had led to a marked increase in demand for fish and fish oils in human diets, supplements, and aquaculture and created a need for new, sustainable n-3 LC-PUFA sources. We have studied for the first time homogenous preparations of the membrane-type ω6 and ω3 fatty acid desaturases from the fungus Mortierella alpina, as a model system to produce PUFAs. These desaturases possess a di-iron metal center and are selective for 18:1 n-9 and 18:2 n-6 acyl-CoA substrates, respectively. Sequence alignments and membrane topology predictions support that these enzymes have unique cap regions that may include the rearrangement and repositioning of the active site, especially when compared to the mammalian stearoyl-coenzyme A desaturase-1 (SCD1) and the related sphingolipid α-hydroxylase (Scs7p) that act upon different substrates.

Erratum to: Replacement of Marine Fish Oil with de novo Omega-3 Oils from Transgenic Camelina sativa in Feeds for Gilthead Sea Bream (Sparus aurata L.).

Omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA) are essential components of the diet of all vertebrates. The major dietary source of n-3 LC-PUFA for humans has been fish and seafood but, paradoxically, farmed fish are also reliant on marine fisheries for fish meal and fish oil (FO), traditionally major ingredients of aquafeeds. Currently, the only sustainable alternatives to FO are vegetable oils, which are rich in C18 PUFA, but devoid of the eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) abundant in FO. Two new n-3 LC-PUFA sources obtained from genetically modified (GM) Camelina sativa containing either EPA alone (ECO) or EPA and DHA (DCO) were compared to FO and wild-type camelina oil (WCO) in juvenile sea bream. Neither ECO nor DCO had any detrimental effects on fish performance, although final weight of ECO-fed fish (117 g) was slightly lower than that of FO- and DCO-fed fish (130 and 127 g, respectively). Inclusion of the GM-derived oils enhanced the n-3 LC-PUFA content in fish tissues compared to WCO, although limited biosynthesis was observed indicating accumulation of dietary fatty acids. The expression of genes involved in several lipid metabolic processes, as well as fish health and immune response, in both liver and anterior intestine were altered in fish fed the GM-derived oils. This showed a similar pattern to that observed in WCO-fed fish reflecting the hybrid fatty acid profile of the new oils. Overall the data indicated that the GM-derived oils could be suitable alternatives to dietary FO in sea bream.

The enrichment of chicken meat with omega-3 fatty acids by dietary fish oil or its mixture with rapeseed or flaxseed—Effect of feeding duration: Dietary fish oil, flaxseed, and rapeseed and n-3 enriched broiler meat

The consumption of chicken meat has steadily increased in recent decades, thereby making meat enriched with long-chain polyunsaturated fatty acids (LC-PUFA) an important delivery route of this nutrient to humans. This study aimed to evaluate how feeding duration of a diet with fish oil and flaxseed or rapeseed can enhance broiler meat with n-3 fatty acids (FA). One hundred and twenty-three 15-day-old female broilers Ross 308 were housed individually and randomly allocated to four groups: control (15 birds), and three experimental groups (36 birds each) that were each divided into three subgroups of 12 birds. Four diets differing in fat composition were prepared. Lard was the source of supplementary fat in diet L; in the experimental diets, fat was derived from fish oil (FO, 10gkg−1 diet) and either lard (LFO), flaxseed (FFO), or rapeseed (RFO) in amounts appropriate to produce fat levels similar to those in the control diet. Diets were cold-pelleted and fed until slaughter at 36days of age. The control group was fed the L diet throughout the study, whereas birds in the experimental groups were fed the L diet until it was substituted by the experimental diets for one, two, or three weeks preceding slaughter. The performance of all groups did not differ from the control, but within the experimental groups, LFO birds had a higher body weight gain because of higher feed intake. RFO birds had a higher thyroid weight (P<0.02). The levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in breast and thigh meat lipids increased in groups fed the experimental diets as compared to the control. There were substantial increases in α-linolenic acid levels and a lower PUFAn-6/n-3 ratio in birds fed the FFO diet as compared to the RFO and LFO diets (P<0.001). Results indicated that one week of feeding the experimental diets was sufficient to enrich breast meat with LC-PUFA, whereas two weeks were needed to effectively enrich thigh meat with these FA. Thus, the meat of broilers fed diets with fish oil and either flaxseed or rapeseed over a period of two weeks before slaughter can be labeled as “high in omega-3 fatty acids.” A 100g portion of such breast or thigh meat would provide on average 33% and 15.5%, respectively, of the recommended daily intake of EPA and DHA for humans, and therefore make enriched chicken meat a superior source of LC-PUFA than lean fish meat.

Hybrid striped bass feeds based on fish oil, beef tallow, and eicosapentaenoic acid/docosahexaenoic acid supplements: Insight regarding fish oil sparing and demand for -3 long-chain polyunsaturated fatty acids.

Previous research suggests that saturated (SFA) and monounsaturated fatty acid (MUFA) rich lipids, including beef tallow, can make utilization or diet-to-tissue transfer of long-chain polyunsaturated fatty acids (LC-PUFA) more efficient. We hypothesized that using beef tallow as an alternative to fish oil may effectively reduce the LC-PUFA demand of hybrid striped bass × and allow for greater fish oil sparing. Accordingly, we evaluated growth performance and tissue fatty acid profiles of juvenile fish (23.7 ± 0.3 g) fed diets containing menhaden fish oil (considered an ideal source of LC-PUFA for this taxon), beef tallow (BEEF ONLY), or beef tallow amended with purified sources of eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA) to achieve levels corresponding to 50 or 100% of those observed in the FISH ONLY feed. Diets were randomly assigned to quadruplicate tanks of fish ( = 4; 10 fish/tank), and fish were fed assigned diets to apparent satiation once daily for 10 wk. Survival (98-100%) was equivalent among treatments, but weight gain (117-180%), specific growth rate (1.1-1.5% BW/d), feed intake (1.4-1.8% BW/d), thermal growth coefficient (0.50-0.70), and feed conversion ratio (FCR; 1.1-1.4, DM basis) varied. Except for FCR, no differences were observed between the FISH ONLY and BEEF ONLY treatments, but performance was generally numerically superior among fish fed the diets containing beef tallow supplemented with DHA at the 100% or both EPA and DHA at the 50% or 100% level. Tissue fatty acid composition was significantly distorted in favor among fish fed the beef tallow-based feeds; however, profile distortion was most overt in peripheral tissues. Results suggest that beef tallow may be used as a primary lipid source in practical diets for hybrid striped bass, but performance may be improved by supplementation with LC-PUFA, particularly DHA. Furthermore, our results suggest that -3 LC-PUFA requirements reported for hybrid striped bass may not be fully accurate and that DHA may be more critical than EPA as a limiting nutrient in feed formulation.

Production of polyunsaturated fatty acids in recombinant Lipomyces starkeyi through submerged fermentation.

Long chain polyunsaturated fatty acids (LCPUFA) are known to play an important role in human health and nutrition. Considering the limitation of LCPUFA sources, it is necessary to search new avenues for their production. Oleaginous yeasts are an attractive target for harvesting single cell oil, mainly because of the ease of cultivation with cheaper raw material. Lipomyces starkeyi is one such oleaginous yeast, which can accumulate oil to the extent of 60% of its biomass and where genetic transformation can be achieved. In our earlier work, Δ15 desaturase gene (AEP37840) from flax was transformed into L. starkeyi. In the present work, we report optimization of medium for the production of ω-3 enriched oil from this transformed yeast. A basic medium containing 20 g/l glucose as a carbon source and 10 g/l yeast extract as a nitrogen source was used during fermentation. At regular time intervals, glucose was fed to maintain high C:N ratio (65:10) during fermentation. Under the most favorable conditions, dry biomass and total lipid content were 18 and 7.29 g/l, respectively. Prior to genetic transformation, L. starkeyi contained 56.03 mg/l DHA along with 71.4 mg/l EPA and 42.2 mg/l ALA. Genetic engineering of this yeast resulted in a strain that produced 1080 mg/l DHA (17.4%) along with 74.28 mg/l EPA and 126.72 mg/l ALA possibly through modification of PUFA biosynthetic pathway. To the best of our knowledge, this is a first report of DHA enrichment and opens up avenues for LCPUFA production through L. starkeyi.

Detailed distribution of lipids in Greenshell™ mussel (Perna canaliculus).

Greenshell™ mussels (GSM–Perna canaliculus) are a source of omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFA). Farmed GSM are considered to be a sustainable source of LC-PUFA as they require no dietary inputs, gaining all of their oil by filter-feeding microorganisms from sea water. GSM oil is a high-value product, with a value as much as 1000 times that of fish oils. GSM oil has important health benefits, for example, anti-inflammatory activity. It also contains several minor lipid components that are not present in most fish oil products, and that have their own beneficial effects on human health. We have shown the lipid content of the female GSM (1.9 g/100 g ww) was significantly greater than that of the male (1.4 g/100 g ww). Compared with male GSM, female GSM contained more n-3 LC-PUFA, and stored a greater proportion of total lipid in the gonad and mantle. The higher lipid content in the female than the male GSM is most likely related to gamete production. This information will be useful to optimize extraction of oils from GSM, a local and sustainable source of n-3 LC-PUFA.

Pathways of lipid metabolism in marine algae, co-expression network, bottlenecks and candidate genes for enhanced production of EPA and DHA in species of Chromista.

The importance of n-3 long chain polyunsaturated fatty acids (LC-PUFAs) for human health has received more focus the last decades, and the global consumption of n-3 LC-PUFA has increased. Seafood, the natural n-3 LC-PUFA source, is harvested beyond a sustainable capacity, and it is therefore imperative to develop alternative n-3 LC-PUFA sources for both eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). Genera of algae such as Nannochloropsis, Schizochytrium, Isochrysis and Phaedactylum within the kingdom Chromista have received attention due to their ability to produce n-3 LC-PUFAs. Knowledge of LC-PUFA synthesis and its regulation in algae at the molecular level is fragmentary and represents a bottleneck for attempts to enhance the n-3 LC-PUFA levels for industrial production. In the present review, Phaeodactylum tricornutum has been used to exemplify the synthesis and compartmentalization of n-3 LC-PUFAs. Based on recent transcriptome data a co-expression network of 106 genes involved in lipid metabolism has been created. Together with recent molecular biological and metabolic studies, a model pathway for n-3 LC-PUFA synthesis in P. tricornutum has been proposed, and is compared to industrialized species of Chromista. Limitations of the n-3 LC-PUFA synthesis by enzymes such as thioesterases, elongases, acyl-CoA synthetases and acyltransferases are discussed and metabolic bottlenecks are hypothesized such as the supply of the acetyl-CoA and NADPH. A future industrialization will depend on optimization of chemical compositions and increased biomass production, which can be achieved by exploitation of the physiological potential, by selective breeding and by genetic engineering.

Alternative sources of n-3 long-chain polyunsaturated fatty acids in marine microalgae.

The main source of n-3 long-chain polyunsaturated fatty acids (LC-PUFA) in human nutrition is currently seafood, especially oily fish. Nonetheless, due to cultural or individual preferences, convenience, geographic location, or awareness of risks associated to fatty fish consumption, the intake of fatty fish is far from supplying the recommended dietary levels. The end result observed in most western countries is not only a low supply of n-3 LC-PUFA, but also an unbalance towards the intake of n-6 fatty acids, resulting mostly from the consumption of vegetable oils. Awareness of the benefits of LC-PUFA in human health has led to the use of fish oils as food supplements. However, there is a need to explore alternatives sources of LC-PUFA, especially those of microbial origin. Microalgae species with potential to accumulate lipids in high amounts and to present elevated levels of n-3 LC-PUFA are known in marine phytoplankton. This review focuses on sources of n-3 LC-PUFA, namely eicosapentaenoic and docosahexaenoic acids, in marine microalgae, as alternatives to fish oils. Based on current literature, examples of marketed products and potentially new species for commercial exploitation are presented.

DHA supplementation and pregnancy outcomes

Observational studies associate higher intakes of n-3 (omega-3) long-chain polyunsaturated fatty acids (LCPUFAs) during pregnancy with higher gestation duration and birth size. The results of randomized supplementation trials using various n-3 LCPUFA sources and amounts are mixed. We tested the hypothesis that 600 mg/d of the n-3 LCPUFA docosahexaenoic acid (DHA) can increase maternal and newborn DHA status, gestation duration, birth weight, and length. Safety was assessed. This phase III, double-blind, randomized controlled trial was conducted between January 2006 and October 2011. Women (n = 350) consumed capsules (placebo, DHA) from <20 wk of gestation to birth. Blood (enrollment, birth, and cord) was analyzed for red blood cell (RBC) phospholipid DHA. The statistical analysis was intent-to-treat. Most of the capsules were consumed (76% placebo; 78% DHA); the mean DHA intake for the treated group was 469 mg/d. In comparison with placebo, DHA supplementation resulted in higher maternal and cord RBC-phospholipid-DHA (2.6%; P < 0.001), longer gestation duration (2.9 d; P = 0.041), and greater birth weight (172 g; P = 0.004), length (0.7 cm; P = 0.022), and head circumference (0.5 cm; P = 0.012). In addition, the DHA group had fewer infants born at <34 wk of gestation (P = 0.025) and shorter hospital stays for infants born preterm (40.8 compared with 8.9 d; P = 0.026) than did the placebo group. No safety concerns were identified. A supplement of 600 mg DHA/d in the last half of gestation resulted in overall greater gestation duration and infant size. A reduction in early preterm and very-low birth weight could be important clinical and public health outcomes of DHA supplementation. This trial was registered at clinicaltrials.gov as NCT00266825.