Performance and egg quality of laying hens fed flaxseed: highlights on n-3 fatty acids,cholesterol, lignans and isoflavones

Flaxseed is a rich source of α-linolenic acid and phytoestrogens, mainly lignans, whose metabolites (enterodiol and enterolactone) can affect estrogen functions. The present study evaluated the influence of dietary flaxseed supplementation on reproductive performance and egg characteristics (fatty acids, cholesterol, lignans and isoflavones) of 40 Hy-Line hens (20/group) fed for 23 weeks a control diet or the same diet supplemented with 10% of extruded flaxseed. The flaxseed diet had approximately three times the content of lignans (2608.54 ng/g) as the control diet, mainly secoisolariciresinol diglucoside (1534.24 v. 494.72 ng/g). When compared with the control group, hens fed flaxseed showed a similar deposition rate (72.0% v. 73.9%) and egg yield. Furthermore, there was no effect of flaxseed on the main chemical composition of the egg and on its cholesterol content. Estradiol was higher in the plasma of the control group (1419.00 v. 1077.01 pg/ml) probably due to the effect of flaxseed on phytoestrogen metabolites. The plasma lignans were higher in hens fed flaxseed, whereas isoflavones were lower, mainly due to the lower equol value (50.52 v. 71.01 ng/ml). A similar trend was shown in eggs: the flaxseed group had higher level of enterodiol and enterolactone, whereas the equol was lower (198.31 v. 142.02 ng/g yolk). Secoisolariciresinol was the main lignan in eggs of the flaxseed group and its concentration was three times higher then control eggs. Flaxseed also improved the n-3 long-chain polyunsaturated fatty acids of eggs (3.25 v. 0.92 mg/g egg), mainly DHA, however, its oxidative status (thiobarbituric reactive substances) was negatively affected. In conclusion, 10% dietary flaxseed did not affect the productive performance of hens or the yolk cholesterol concentration, whereas the lignans and n-3 polyunsaturated fatty acid content of eggs improved. Further details on the competition between the different dietary phytoestrogens and their metabolites (estrogen, equol, enterodiol and enterolactone) should be investigated.     

Comparison of phospholipid and fatty acid composition of wild and cultured striped bass eggs

The dominant fatty acids in all neutral lipid fractions of non-water hardened eggs from two wild and one cultured stock of striped bass Morone saxatilis were the monoenes, 18 : 1n9/n7>16 : 1n7>17 : 1. The dominant fatty acids in the phospholipid fraction of all eggs, regardless of origin, were 22 : 6n3>18 : 1n9/n7>20 : 5n3>16 : 1n7>16 : 0>18 : 0. Arachadonic acid (AA, 20 : 4n6) was significantly lower (2·0%) in cultured fish eggs compared to either wild stock (5·8–6·1%). Fatty acids from the liver and eggs of wild Shubenacadie fish were similar to one another with respect to both neutral and phospholipid fractions. However, the AA and eicosapentaenoic acid (EPA, 20 : 5n3) content of the phospholipid fraction varied according to the hypothesized migration behaviour of Shubenacadie fish. The total lipid content of wild fish eggs was significantly greater than that of cultured fish. The total phospholipid content of Shubenacadie eggs was significantly higher than either Roanoke or cultured fish eggs. Phosphotidylinositol (PI) was the dominant phospholipid found ins all egg samples from all origins as opposed to phosphotidylcholine, which is usually the dominant phospholipid. These data indicate that PI and AA may have important and as yet unidentified roles in fertilization and embryonic development in these fish.     

Perspectives on the use of marine and freshwater hydrobiont oils for development of drug delivery systems

Marine foods represent a unique source of poly-unsaturated fatty acids (PUFA) of the omega-3 (n-3) family. Today it is generally accepted that fish oil is important in a healthy and balanced omnivorous human diet. This favorable health perception of fish oil is however troubled by the high level of PUFA oxidation and low absorption in the gastro-intestinal tract. In this work we present and described various types of delivery systems which are used to improve PUFA and fish oil availability and oxidative stability.     

Omega-3 fatty acids in psychiatry

The brain is one of the organs with the highest level of lipids (fats). Brain lipids, formed of fatty acids, participate in the structure of membranes, for instance 50 % fatty acids are polyunsaturated in the gray matter, 1/3 are of the omega-3 family, and are thus of dietary origin. The omega-3 fatty acids (mainly alpha-linolenic acid, ALA) participated in one of the first experimental demonstration of the effect of dietary substances (nutrients) on the structure and function of the brain. Experiments were first of all carried out on ex vivo cultured brain cells, then on in vivo brain cells (neurons, astrocytes and oligodendrocytes) from animals fed ALA deficient diet, finally on physicochemical (membrane fluidity), biochemical, physiological, neurosensory (vision an auditory responses), and behavioural or learning parameters. These findings indicated that the nature of polyunsaturated fatty acids (in particular omega-3) present in formula milks for human infants determines to a certain extend the visual, neurological, and intellectual abilities. Thus, in view of these results and of the high polyunsaturated fatty acid content of the brain, it is normal to consider that they could be involved in psychiatric diseases and in the cognitive decline of ageing. Omega-3 fatty acids appear effective in the prevention of stress, however their role as regulator of mood is a matter for discussion. Indeed, they play a role in the prevention of some disorders including depression (especially post partum), as well as in dementia, particularly Alzheimer's disease. Their role in major depression and bipolar disorder (manic-depressive disease), only poorly documented, is not clearly demonstrated. The intervention of omega-3 in dyslexia, autism, and schizophrenia has been suggested, but it does not necessarily infer a nutritional problems. The respective importance of the vascular system (where the omega-3 are actually active) and the cerebral parenchyma itself, remain to be resolved. However, the insufficient supply of omega-3 fatty acids in today diet in occidental (less than 50 % of the recommended dietary intakes values for ALA) raises the problem of how to correct inadequate dietary habits, by prescribing mainly rapeseed (canola) and walnut oils on the one hand, fatty fish (wild, or farmed, but the nature of fatty acids present in fish flesh is the direct consequence of the nature of fats with which they have been fed), and eggs from laying hens fed omega-3 fatty acids.     

Engineering oilseeds to produce nutritional fatty acids

There is a growing body of evidence suggesting that regular consumption of foods rich in omega-3 long chain polyunsaturated fatty acids has multiple positive health benefits. The fats and oils from marine fish contain high contents of these beneficial fatty acids but increased consumer demand has also increased strain on the ability of the world's fisheries to meet demand from wild capture. Many consumers are choosing fish oil supplements or are eating foods that have been complemented with fish oils instead of consuming fish directly. However, removing undesirable odors, flavors and contaminants is expensive. In contrast, oils derived from land plants such as soybean are inexpensive and contaminant free. Recent strides in plant molecular biology now allow the engineering of oilseeds for the production of novel fats and oils, including those synthesized by complex, multigene biosynthetic pathways such as the omega-3 long chain polyunsaturated fatty acids. Given the potential benefits to the environment with regards to overfishing and the health prospects of increased consumption of these healthy fatty acids, producing these fatty acids in oilseeds is a desirable and worthy goal. In this review, we will describe the recent advances in this field along with some of the technical hurdles encountered thus far.     

Effect of increasing the omega-3 fatty acid in the diets of animals on the animal products consumed by humans

As shown by huge amount of assays in human as well as in animal models, w-3 polyunsaturated fatty acids play important role in the development and maintenance of different organs, primarily the brain, and could be useful in the prevention of different pathologies, mainly the cardiovascular diseases, and, as proposed recently, some psychiatric, dermatological or rheumatological disorders. For ALA, the major and cheapest source for human is rapeseed oil (canola oil), and walnut "noix de Grenoble" oil). The actual goal is first to identify which foods are naturally rich in w-3 fatty acids, and, second, to determine the true impact of the formulations (enriched in w-3 fatty acids) in chows used on farms and breeding centres on the nutritional value of the products and thus their effect on the health of consumers, thanks to quantities of either ALA, or EPA or DHA or both. This concern fish (in proportion of their lipid content, mainly mackerel, salmon, sardine and herring), eggs (wildly naturally rich in w-3 fatty acids, both ALA and DHA, or from laying hen fed ALA from linseed or rapeseed), meat from birds, mammals (from the highest concentration : rabbit, then pig and monogastrics, then polygastrics such as beef, mutton and goat) \; in butter, milk, dairy products, cheese (all naturally poor in w-3 fatty acids)... Indeed, the nature of fatty acids of reserve triglycerides (found in more or less large amounts depending on the anatomical localisation, that is to say the butcher's cuts) can vary mainly as a function of the food received by the animal. EPA and DHA are mainly present in animal's products. The impact (qualitative and quantitative) of alterations in the lipid composition of animal foods on the nutritional value of derived products (in terms of EPA and DHA content) eaten by humans are more important in single-stomach animals than multi-stomach animals (due to their hydrogenating intestinal bacteria). The intestinal physiology of birds results in the relatively good preservation of their dietary w-3 fatty acids. The enrichment in eggs is proportional to the amount of w-3 fatty acids in the hen's diet and can be extremely important. Including ALA in fish feeds is effective only if they are, like carp, vegetarians, as they have the enzymes required to transform ALA into EPA and DHA \; in contrast, it is probably less effective for carnivorous fish (75 % of the fish used for human), which have little of these enzymes : their feed must contain marine animals, mainly fish or fish oil. Analysis of the published results shows that, under the best conditions, feeding animals with extracts of linseed and rapeseed grains, for example, increases the level of ALA acid by 20 to 40-fold in eggs (according to the low or high level of ALA in commercial eggs), 10-fold in chicken, 6-fold in pork and less than 2-fold in beef. By feeding animals with fish extracts or algae (oils), the level of DHA is increased by 20-fold in fish, 7-fold in chicken, 3 to 6-fold in eggs, less than 2-fold in beef. In practise, the effect is considerable for fish and egg, interesting for poultry and rabbit, extremely low for beef, mutton and sheep. The effect on the price paid by the consumer is very low compared to the considerable gain in nutritional value.     

In silico proteolysis and analysis of bioactive peptides from sequences of fatty acid desaturase 3 (FAD3) of flaxseed protein

Flaxseed (Linum usitatissimum), commonly known as linseed is an oilseed crop, emerging as an important and functional ingredient of food and has been paid more attention due to its nutritional value as well as beneficial effects. It is mainly rich in is α-linolenic acid (ALA, omega-3 fatty acid), fibres and lignans that have potential health benefits in reducing cardiovascular diseases, diabetes, osteoporosis, atherosclerosis, cancer, arthritis, neurological and autoimmune disorders. Due to its richness in omega-3 fatty acid, a group of enzymes known as fatty acid desaturases (FADs) mainly introduce double bonds into fatty acids’ (FAs) hydrocarbon chains that produce unsaturated fatty acids. Fatty acid desaturase 3 (FAD3), the commonest microsomal enzyme of omega-3 fatty acid, synthesizes linolenic acid (C18:3) from linoleic acid located in endoplasmic reticulum (ER) facing towards the cytosol. The emerging field of bioinformatics and large number of databases of bioactive peptides, helps in providing time-saving and efficient method for identification of potential bioactivities of any protein. In this study, 10 unique sequences of FAD3 from flaxseed protein have been used for in silico proteolysis and releasing of various bioactive peptides using three plant proteases, namely ficin, papain and stem bromelain, that are evaluated with the help of BIOPEP database. Overall, 20 biological activities were identified from these proteins. The results showed that FAD3 protein is a potential source of peptides with angiotensin-I-converting enzyme (ACE) inhibitory and dipeptidyl peptidase-IV (DPP-IV) activities, and also various parameters such as ∑A, ∑B, A_E, W, B_E, V and DHt were also calculated. Furthermore, PeptideRanker have been used for screening of novel promising bioactive peptides. Various bioinformatics tools also used to study protein’s physicochemical properties, peptide’s score, toxicity, allergenicity aggregation, water solubility, and drug likeliness. The present work suggests that flaxseed protein can be a good source of bioactive peptides for the synthesis of good quality and quantity of oil, and in silico method helps in investigating and production of functional peptides.     

Relief for fish stocks: oceanic fatty acids in transgenic oilseeds

Three recent reports (Baoxiu Qi et al., Amine Abbadi et al. and Anthony J. Kinney et al.) describe the production of very long-chain polyunsaturated fatty acids in transgenic plants. This might lead to a sustainable source of these valuable fatty acids for use in human food and animal feed. At present they are mainly available via consumption of fish, which is a limited and endangered resource.     

The effects of nutritional polyunsaturated fatty acids on locomotor activity in spontaneously hypertensive rats

The present study investigated the effects of nutritional omega-3 polyunsaturated fatty acids on locomotor activity in spontaneously hypertensive rats (SHRs), which are used as an animal model of attention-deficit/hyperactivity disorder (ADHD). For 6 weeks, two groups of randomly assigned SHRs received food either enriched with or deficient in omega-3 fatty acids (based on the American Institute of Nutrition—93 G/AIN93G). Using an open field, locomotor activity was subsequently assessed for 6 days. A marked difference in locomotor activity as assessed by the distance travelled in the open field was found between the two groups of rats. In comparison with rats fed with omega-3 fatty acid-enriched food, the animals on the omega-3 fatty acid-deficient diet showed a significantly higher locomotor activity. The present findings demonstrated that nutritional enrichment with omega-3 fatty acids was associated with reduced motor activity in an established animal model of ADHD and support the notion that omega-3 polyunsaturated fatty acids may play a role in the pathophysiology of ADHD.     

Maternal dietary n-3 fatty acids alter cardiac ventricle fatty acid composition, prostaglandin and thromboxane production in growing chicks

The effects of feeding n-6 and n-3 fatty acids to broiler hens on cardiac ventricle fatty acid composition, and prostaglandin E2 (PGE2) and thromboxane A2 (TXA2) production of hatched chicks were investigated. Fertile eggs obtained from hens fed diets supplemented with 3.5% sunflower oil (Low n-3), 1.75% sunflower+1.75% fish oil (Medium n-3), or 3.5% fish oil (High n-3) were incubated. The hatched chicks were fed a diet containing 18:3 n-3, but devoid of longer chain n-6 and n-3 fatty acids for 42 days. Arachidonic acid content was lower in the cardiac ventricle of High n-3 and Medium n-3 compared to Low n-3 birds for up to 2 weeks (P<0.002). Long chain n-3 fatty acids were higher in the cardiac ventricle of chicks from hens fed High and Medium n-3 diets when compared to chicks from hens fed the Low n-3 diet. Differences in long chain n-3 fatty acids persisted up to four weeks of age (P<0.001). Peripheral blood mononuclear cells (PBMNC) of 7-day-old High n-3 broilers produced significantly lower PGE2 and TXA2 than PBMNC from Low n-3 and Medium n-3 birds. These results indicate that maternal dietary n-3 fatty acids increases cardiac ventricle n-3 fatty acids while reducing arachidonic acid and ex vivo PGE2 and TXA2 production during growth in broiler chickens.     

Flaxseed and dried tomato waste used together in laying hens diet

The aim of this study was to investigate the effects of simultaneous supplementation of laying hens with dietary sources of n-3 polyunsaturated fatty acids (PUFA) and carotenoids on egg quality, fatty acids and carotenoid profile of the egg yolk and on feed and yolk lipid peroxidation. A 6-week experiment was carried out with 53-week old laying hens (96 Tetra SL) assigned to a control and three treatment groups supplemented with 5% flaxseeds and different levels of dried tomato waste (DTW, 2.5%, 5.0% and 10.0%). Hens from the groups supplemented with 5% and 7.5% DTW had a significantly lower average daily feed intake and laying percentage as compared to the control. Increased doses of dietary DTW enhanced yolk Roche colour score in direct correlation with the enrichment of egg yolk in carotenoids but decreased their transfer efficiency from feed to egg. After 4 weeks, egg yolk from hens fed with 5% flaxseeds and 7.5% DTW had increased lutein and zeaxanthin levels (by 29% and 24%, respectively) and the colour score was 3.5 fold higher compared to the control group. As a result of the dietary supplementation with flaxseed, the n-3 fatty acid content was 3.1–3.7-fold higher in egg yolk compared with the control and the n-6/n-3 ratio decreased from 18.3 (control) to 4.1–5.4 in supplemented diets. Dietary supplementation with 5% DTW effectively prevented lipid oxidation of eggs enriched with n-3 PUFA, but the increase in DTW content depressed the absorption and deposition of n-3 PUFA in egg yolk.     

Influence of low cholesterol eggs enriched with vitamin-E and omega-3 fatty acid on blood lipid profile of Wistar rats

In the recent past, low cholesterol eggs enriched with vitamin-E and omega-3 fatty acid have been developed and are marketed under different brands claiming them as heart friendly. The influence of these eggs (smart eggs) on lipid profile of rats was evaluated in comparison to that of the standard eggs. Data of 4 week dietary treatment revealed that total plasma cholesterol, low density lipoprotein (LDL) and very low density lipoprotein (VLDL) cholesterol increased only 22% in rats fed on diet containing 4 smart eggs per kg of semi-synthetic diet in contrast to the increase of more than 100 % when fed on diet containing standard eggs. The results suggest that it is not the low cholesterol content alone but also vitamin E and omega-3 fatty acids present in smart eggs that act synergically to prevent a substantial change in blood lipid profile and impose no serious risk to the health of the consumers.     

Cultural symbolism of fish and the psychotropic properties of omega-3 fatty acids

Fish is a food with unique psychotropic properties. Consumption of long-chain omega-3 fatty acids, rich in seafood, reduces depression, aggression and anger while improving mental well-being. We posit that symbols of fish have become linked to the emotional states induced by long-chain fatty acid by associative pairings, both conscious and unconscious. The limbic and hippocampal activity necessary for memory formation containing emotional content and the labeling of social context by cortical processes appears to be optimized by diets rich in long-chain omega-3 fatty acid. In this critical literature survey, we find that fish have been culturally labeled as symbols of emotional well-being and social healing in religious and medical practices among independent cultures, for at least six millennia. This understanding of the perception of fish as a symbolically healing or purifying food can assist current messages improving public health.     

Ovarian follicular development, lipid peroxidation, antioxidative status and immune response in laying hens fed fish oil-supplemented diets to produce n-3-enriched eggs

The objective of the present study was to research the effect of feeding laying hens fish oil-supplemented diets to produce n-3-enriched eggs on their ovarian follicular development, serum lipid peroxidation, antioxidative status and immune response. A total of 105 white Bovens hens at 24 weeks of age were housed in cages in an open-sided building under a 16 h light : 8 h dark lighting schedule. Birds were randomly divided into five treatments and were fed, ad libitum, diets containing 0% (control), 1.25%, 2.5%, 3.5% or 5.0% fish oil from 24 to 36 weeks of age. Egg production and weight were recorded. By weeks 35 and 36 of age 15 eggs were taken at random from each treatment to determine the yolk lipid profile and cholesterol content. At the end of the experimental period, 10 females from each treatment were randomly chosen, anaesthetised and killed by decapitation. Ovary and oviduct samples were immediately weighted and ovarian follicles were classified. Serum thiobarbituric acid-reactive substance (TBARS), hepatic TBARS and hepatic glutathione peroxidase (GSH-Px) activity were measured. No clear trend was observed concerning egg production and egg yolk cholesterol. As dietary fish oil levels increased, n-3-polyunsaturated fatty acids (n-3 PUFA) increased, whereas n-6 PUFA tended to decrease in yolk lipids. No negative effects were detected in ovary and oviduct weights, expressed in both absolute terms and relative to body weight. The numbers and total weights of large yellow follicles (LYF) in the ovary were not significantly affected by fish oil supplementation. Low levels (1.25% to 2.5%) of fish oil reduced both plasma and hepatic TBARS and enhanced GSH-Px activity. It is also interesting to note that inclusion of 2.5% fish oil in laying hen diets enhanced the antibody titre in laying hens. Therefore, it could be concluded that inclusion of fish oil in laying hen diets at moderate levels increased the n-3 fatty acids content in eggs, improved antioxidative status, enhanced the antibody response and did not have a negative influence on the different reproductive morphology parameters in laying hens.     

Biofortification of safflower: an oil seed crop engineered for ALA-targeting better sustainability and plant based omega-3 fatty acids

Alpha-linolenic acid (ALA) deficiency and a skewed n6:n3 fatty acid ratio in the diet is a major explanation for the prevalence of cardiovascular diseases and inflammatory/autoimmune diseases. There is mounting evidence of the health benefits associated with omega-3 long chain polyunsaturated fatty acids (LC PUFA’s). Although present in abundance in fish, a number of factors limit our consumption of fish based omega-3 PUFA’s. To name a few, overexploitation of wild fish stocks has reduced their sustainability due to increased demand of aquaculture for fish oil and meal; the pollution of marine food webs has raised concerns over the ingestion of toxic substances such as heavy metals and dioxins; vegetarians do not consider fish-based sources for supplemental nutrition. Thus alternative sources are being sought and one approach to the sustainable supply of LC-PUFAs is the metabolic engineering of transgenic plants with the capacity to synthesize n3 LC-PUFAs. The present investigation was carried out with the goal of developing transgenic safflower capable of producing pharmaceutically important alpha-linolenic acid (ALA, C18:3, n3). This crop was selected as the seeds accumulate ~?78% of the total fatty acids as linoleic acid (LA, C18:2, n6), the immediate precursor of ALA. In the present work, ALA production was achieved successfully in safflower seeds by transforming safflower hypocotyls with Arabidopsis specific delta 15 desaturase (FAD3) driven by truncated seed specific promoter. Transgenic safflower fortified with ALA is not only potentially valuable nutritional superior novel oil but also has reduced ratio of LA to ALA which is required for good health.     

Invited Review Free Radicals in Foods

During the last decade increasing attention has been given to the role of free radicals in biological oxidations. The subject has been of increasing interest to both the food scientist and the physiologist. Free radical scavengers in the form of both indigenous and added antioxidants are necessary for the successful preservation of food; free radicals are increasingly being implicated in the onset of, among others, ischaemic heart disease and for protection against these diseases it is suggested that the dietary intake of the antioxidant vitamins should be increased especially for diets high in polyunsaturated fats. ^1,2 Convenience and snack foods which absorb substantial amounts of frying oils are being increasingly consumed. Since poly-unsaturated fatty acids are particularly susceptible to oxidation by free radicals during the storage, cooking and frying of foods, the potential risk of exposure to lipid degradation products' is likely to have increased. In foods the non-enzymic and lipoxygenase catalysed oxidation of polyunsaturated fatty acids, β-carotene and vitamin A can result in the loss of essential nutrients and the development of off-flavours.     

Short-time infusion of fish oil-based lipid emulsions, approved for parenteral nutrition, reduces monocyte proinflammatory cytokine generation and adhesive interaction with endothelium in humans

Potential impact of omega-3 fatty acids, as contained in fish oil, on immunological function has been suggested because observations of reduced inflammatory diseases in Greenland Inuit were published. A fish oil-based lipid emulsion has recently been approved for parenteral nutrition in many countries. We investigated the influence of a short infusion course of fish oil-based (omega-3) vs conventional (omega-6) lipid emulsion on monocyte function. In a randomized design, twelve healthy volunteers received omega-3 or omega-6 lipid infusion for 48 h, with cross-over repetition of the infusion course after 3 mo. Fatty acid profiles, monocyte cytokine release and adhesive monocyte-endothelium interaction were investigated. Resultant omega-6 lipid emulsion increased plasma-free fatty acids including arachidonic acid, whereas the omega-3/omega-6 fatty acid ratio in monocyte membranes remained largely unchanged. It also caused a tendency toward enhanced monocyte proinflammatory cytokine release and adhesive monocyte-endothelium interaction. In contrast, omega-3 lipid emulsion significantly increased the omega-3/omega-6 fatty acid ratio in the plasma-free fatty acid fraction and in monocyte membrane lipid pool, markedly suppressing monocyte generation of TNF-alpha, IL-1, IL-6, and IL-8 in response to endotoxin. In addition, it also significantly inhibited both monocyte-endothelium adhesion and transendothelial monocyte migration, although monocyte surface expression of relevant adhesive molecules (CD11b, CD18, CD49 days, CCR2) was unchanged. Although isocaloric, omega-3 and omega-6 lipid emulsions exert differential impact on immunological processes in humans. In addition to its nutritional value, fish oil-based omega-3 lipid emulsion significantly suppresses monocyte proinflammatory cytokine generation and features of monocyte recruitment.     

Omega-3 fatty acids from fish oils and cardiovascular disease

Fish and fish oils contain the omega-3 fatty acids known as eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA). Epidemiological studies have shown an inverse relation between the dietary consumption of fish containing EPA/DHA and mortality from coronary heart disease. These relationships have been substantiated from blood measures of omega-3 fatty acids including DHA as a physiological biomarker for omega-3 fatty acid status. Controlled intervention trials with fish oil supplements enriched in EPA/DHA have shown their potential to reduce mortality in post-myocardial infarction patients with a substantial reduction in the risk of sudden cardiac death. The cardioprotective effects of EPA/DHA are widespread, appear to act independently of blood cholesterol reduction, and are mediated by diverse mechanisms. Their overall effects include anti-arrhythmic, blood triglyceride-lowering, anti-thrombotic, anti-inflammatory, endothelial relaxation, plus others. Current dietary intakes of EPA/DHA in North America and elsewhere are well below those recommended by the American Heart Association for the management of patients with coronary heart disease. (Mol Cell Biochem 263: 217–225, 2004)     

Dietary Supplementation of Polyunsaturated Fatty Acids in Caenorhabditis elegans

Fatty acids are essential for numerous cellular functions. They serve as efficient energy storage molecules, make up the hydrophobic core of membranes, and participate in various signaling pathways. Caenorhabditis elegans synthesizes all of the enzymes necessary to produce a range of omega-6 and omega-3 fatty acids. This, combined with the simple anatomy and range of available genetic tools, make it an attractive model to study fatty acid function. In order to investigate the genetic pathways that mediate the physiological effects of dietary fatty acids, we have developed a method to supplement the C. elegans diet with unsaturated fatty acids. Supplementation is an effective means to alter the fatty acid composition of worms and can also be used to rescue defects in fatty acid-deficient mutants. Our method uses nematode growth medium agar (NGM) supplemented with fatty acidsodium salts. The fatty acids in the supplemented plates become incorporated into the membranes of the bacterial food source, which is then taken up by the C. elegans that feed on the supplemented bacteria. We also describe a gas chromatography protocol to monitor the changes in fatty acid composition that occur in supplemented worms. This is an efficient way to supplement the diets of both large and small populations of C. elegans, allowing for a range of applications for this method.     

Effects of algal diets and temperature on the growth and fatty acid content of the cichlid fish Oreochromis niloticus L. – A laboratory study

The effects of different algal foods and water temperatures on the growth and fatty acid content of the Nile Tilapia, Oreochromis niloticus L., were studied. Four types of algae, given in the same amounts as the control diet, were used as food: Microcystis aeruginosa, colonial and single-celled forms; Arthrospira fusiformis; and Scenedesmus quadricauda. The control group was fed a commercial diet of cichlid pellets, while another group was left unfed. The feeding experiment was run at 25 °C. The condition factor decreased in all algal fed fish groups, except the one fed on Microcystis colonies, whereas the control group showed no significant change. Both food quantity and quality were responsible for this result. Some short-chained fatty acids in the diets could be traced in the long-chained counter-parts in the fish tissue. Both saturated fatty acids and monounsaturated fatty acids were higher in the control vs. treatment groups, whereas the polyunsaturated fatty acids displayed no significant differences amongst any of the treatment groups studied, including the unfed group. Direct quantitative comparison of individual fatty acid in the diet vs. tissue lipids in the fish proved to be difficult due to the great capacity of these tilapias to elongate and desaturate 18 carbon acids into long-chained homologues. The effect of temperature was studied by growing the fish at 16, 20 and 25 °C. All groups were fed commercial cichlid pellets. The level of saturated and monounsaturated fatty acids increased at 20 °C, whereas polyunsaturated fatty acids showed little variation. Docosahexaenoic acid, belonging to the important omega 3 group where the first double bond starts at carbon number three, was highest at 16 °C, resulting in a markedly elevated omega-3/omega-6 ratio at that temperature.