Dietary Essential Fatty Acids Research Articles

Brain Maturation of Preterm Newborn Babies: New Insights

Preterm birth still results in a high number of neurodevelopmental sequelae, although major forms of brain lesions--such as periventricular leukomalacia and intraventricular hemorrhage--are significantly reduced in this population of babies compared with a few years ago. This paper focuses on the possible reasons for this phenomenon. Some brain lesions, such as those affecting the periventricular white matter and the cerebellum, may be underestimated if magnetic resonance imaging is not used. In addition, a functional neurological consequence is not necessarily due to a recognized brain lesion, but may simply derive from an abnormally or suboptimally developed brain structure. The quality of nutrition given to a preterm baby could play a crucial role in such cases. In fact, nutrition is known to affect brain function; a case in point is the improvement in visual function resulting from dietary essential fatty acids. Finally, research in this area should aim at both reducing potential hazards and improving the quality of perinatal care, including the quality of nutrition.

Human milk: maternal dietary lipids and infant development

Human milk provides all the dietary essential fatty acids, linoleic acid (LA; 18:2n-6) and alpha-linolenic acid (18:3n-3), as well as their longer-chain more-unsaturated metabolites, including arachidonic acid (20:4n-6) and DHA (22:6n-3) to support the growth and development of the breast-fed infant. Human milk levels of LA have increased in Westernized nations from mean levels (g/100 g total fatty acids) of 6 to 12-16 over the last century, paralleling the increase in dietary intake of LA-rich vegetable oils. DHA levels (g/100 g total milk fatty acids) vary from 1% and are lowest in countries in which the intake of DHA from fish and other animal tissue lipids is low. The role of DHA in infant nutrition is of particular importance because DHA is accumulated specifically in the membrane lipids of the brain and retina, where it is important to visual and neural function. An important question is the extent to which many human diets that contain low amounts of n-3 fatty acids may compromise human development. The present paper reviews current knowledge on maternal diet and human milk fatty acids, the implications of maternal diet as the only source of essential fatty acids for infant development both before and after birth, and recent studies addressing the maternal intakes and milk DHA levels associated with risk of low infant neural system maturation.

Nutritional manipulation of the fatty acid composition of sheep meat: a review

SUMMARYSheep meat is characterized as being high in saturated fatty acids and low in polyunsaturated fatty acids (PUFA), attributes that are regarded as being disadvantageous within the human diet. Despite fresh forage being a particularly rich source of 18:3n−3 and vegetable oils being high in 18:2n−6 and 18:3n−3, the process of biohydrogenation in the rumen generally results in proportionally less than 0·1 of these essential dietary fatty acids (FA) reaching the small intestine. Increases in muscle content of 18:3n−3 of 1–2-fold have been achieved by supplementation with oil, or oilseeds, whilst increases of 1–3-fold have been obtained from grazing grass compared with concentrates, but in general the polyunsaturated to saturated FA ratio (P:S) in sheep meat has remained low at approximately 0·2–0·3. Substantial improvements in the P:S ratio of up to 0·57 and increases in muscle and adipose tissue levels of 18:3n−3 of up to 4 g/100 g FA can be obtained, but rely on protecting dietary PUFA from biohydrogenation. Additionally, increasing tissue supply of 18:3n−3 will result in only a small improvement in muscle concentration of the nutritionally beneficial 20:5n−3 and 22:6n−3, with meaningful increases relying on a dietary supply of these very-long-chain PUFA. An alternative strategy to improve the human health attributes of sheep meat is to decrease tissue levels of 18:0 by increasing the activity of stearoyl-CoA desaturase (SCD), although the response is often relatively small. Despite the apparent negative impact of ruminal metabolism on muscle FA content, the process of biohydrogenation is often incomplete and several of the intermediaries can have positive effects on human health. Within these intermediaries, future increases in tissue content ofcis-9,trans-11 conjugated linoleic acid (CLA) may be obtained by increasing tissue supply directly, although a greater response may be obtained by maximizing tissue supply oftrans-11 18:1 and elevating the action of SCD. Production of a FA profile in sheep meat that is higher in PUFA, particularly the advantageous very-long-chain PUFA, and with flavour and eating characteristics that meet specific market preferences, is a suitable area for research.

Dietary n-3 HUFA deficiency induces a reduced visual response in gilthead seabream Sparus aurata larvae

Developmental changes in swimming speed were analysed in the seabream ( Sparus aurata) larvae. Four feeding regimes using live preys (rotifer Brachionus plicatilis) enriched with fish oil, soybean oil, linseed oil and rapeseed oil, differing in fatty acid profile, were tested during the first weeks of larval life. There was an increase in burst swimming speed and cruise swimming speed during the visual stimulus experiment at day 16th of life in the present study in agreement with the better eye development in larvae of this age. Swimming activity before stimulus was significantly reduced when larvae were fed rotifers enriched with vegetable oils. Larvae fed with rotifers enriched with fish oil reacted with a higher burst swimming speed after a visual stimulus than after the sound stimulus (159.5 SL/s vs. 18.30 SL/s) denoting the importance of the vision during this period of development not only for predation but also for the burst. The reduction in dietary essential fatty acid contents, by the enrichment with vegetable oils, delays the appearance of response to visual stimulus, in agreement with the minor DHA content in eyes and brains of these larvae and suggesting a delay in the functional development of brain and vision.

Dietary essential fatty acids and gender-specific behavioral responses in cranially irradiated rats

Specific memory deficits, reduced intellectual processing speed, and a variety of social and behavioral problems have been implicated as long-term effects of cranial radiation therapy (CRT). These deficits are thought to be related to changes in brain cytology and structure associated with microvascular aberrations. N-3 fatty acids may serve as protectants in pediatric patients who receive CRT for brain tumors. Timed-pregnant rat dams were fed one of four diets that were identical in all respects, except for their essential fatty acid content. The dams were placed on these diets at the beginning of the third trimester of gestation and their pups remained on them throughout the study. The rats' behavioral response as judged by acoustic startle response (ASR) and neurocognitive response (performance in a radial maze, RM) were evaluated in relation to diet, gender, and CRT. The following hypotheses were tested: (1) female rats will show greater CRT-induced neurocognitive and behavioral deficits; (2) dietary n-3 fatty acids will diminish CRT-induced neurocognitive and behavioral deficits; (3) gender-specific differences would be dampened by n-3 fatty acids in the diet. All three hypotheses were partially supported. These findings are discussed in light of the potential neuroprotective effects of n-3 fatty acids.

Dr. Jiang Replies

Back to table of contents Previous article Next article Letters to the EditorFull AccessDr. Jiang RepliesWEI JIANG M.D.,WEI JIANG M.D.Search for more papers by this author,Published Online:1 Jun 2006AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InEmail To the Editor: Thanks to Dr. Penland for bringing up these thought-provoking and challenging topics. I appreciate his contemplation and valiancy. The role of lipids in brain function is significant. Thirty years ago, lipids were described in a great textbook of biochemistry as being unlike nucleic acids and proteins—that they “do not have information-carrying function” (1) . With the series of convergent discoveries in the fields of neural development, synaptic physiology, and receptor pharmacology, the roles played by lipids and their receptors in brain function are being addressed in neuroscience. Lipids comprise 50%–60% of the dry weight of the adult brain, of which approximately 35% are in the form of long-chain polyunsaturated fatty acids. These polyunsaturated fatty acids are derived through biosynthesis from their respective dietary essential fatty acid precursors, linoleic acid and α-linolenic acid or directly from dietary sources such as eggs, fish, and meat or from single-cell oils. Dietary fat profoundly affects gene expression through binding directly with transcription factors or through eicosanoid regulation of intracellular signaling cascades, which results in alterations in metabolism, growth, and cell differentiation (2) . Chronic N -3 fatty acid deficiency has been found to reduce dopamine receptor binding and increase serotonin receptor density in the frontal cortex of both young and aged rats as well as to alter dopamine metabolism (3 – 5) . A formula low in linoleic acid and α-linolenic acid has been reported to result in low serotonin and dopamine levels in the frontal cortex of adult pigs (6) . The dynamic function of lipids, lipid signaling, was well described by Piomelli (7) as having four defining features: 1) the generation of informational diversity through permutation of simple structural units; 2) the “pervasive use of serial signaling”—that is, the application of a single biochemical pathway to multiple signaling needs; 3) the adoption of a signaling modality defined by the rapid on-demand response to primary signaling events, such as receptor activation; and 4) the localized nature of lipid-mediated signaling. Piomelli stated that in no other mammalian tissue do such features emerge more clearly than in the brain, where the roles of lipid messengers extend from the development of the neocortex to the processing of behavior. He further emphasized the diversity, the heterogeneity, and the complexity of the roles of lipids in the brain, as reflected by the discussion of the varieties of lipids classes “not only among different cell types, but also among different organelles of the same cell.” In fact, heterogeneities exist even within individual cell membranes between the inner and outer leaflet of the plasma membrane (8) and between “lipid rafts” and their surrounding membrane environment (9) . I have little doubt that disturbed lipids metabolization played a role in the psychiatric manifestation of the patient we presented (10) . However, because of minimal research on human behavior in rapid weight reduction or starvation, it remains speculative. I hope recent research in lipidomics that has been used to assess the brain function of lipids, with greater complexity, will bring definitive answers soon.Durham, N.C.Reprints are not available; however, Letters to the Editor can be downloaded at http://ajp.psychiatryonline.org.

Evaluation of oil composition of some crops suitable for human nutrition

Interest in Canola, Cannabis, Sunflower, Cardoon and Safflower, was focused on the composition of the fat because of their growing importance for nutritional and pharmaceutical purposes. We have therefore begun the analysis and characterization of their fatty acids (FAs) in different oils extracted from those crops to obtain reliable data on their suitability for both human nutrition and industrial or pharmaceutical purposes. The oil content fluctuated from 243 g/kg for Cardoon, 327 g/kg for Cannabis, 358 g/kg for Safflower, 411 g/kg for Sunflower to 488 g/kg for Canola. The ratio of n-6 to n-3 and total unsaturated to total saturated fatty acids ranged from 1.8 to 78.6 and 4.0 to 12.9, respectively. All five crop oils contained a high concentration of unsaturated fatty acids, namely linoleic acid (LA) and linolenic acid (LNA), which are two of the main representative compounds, known as dietary essential fatty acids (EFA) because they prevent deficiency symptoms and cannot be synthesized by humans. They could be considered, per si, functional foods without any biochemical extra additions. Thus, we conclude that whole crop oils do not differ significantly in their FAs composition; consequently, all seem to be suitable for human nutrition after refined procedure.

Neuroprotectin D1 (NPD1): A DHA-Derived Mediator that Protects Brain and Retina Against Cell Injury-Induced Oxidative Stress

The biosynthesis of oxygenated arachidonic acid messengers triggered by cerebral ischemia-reperfusion is preceded by an early and rapid phospholipase A2 activation reflected in free arachidonic and docosahexaenoic acid (DHA) accumulation. These fatty acids are released from membrane phospholipids. Both fatty acids are derived from dietary essential fatty acids; however, only DHA, the omega-3 polyunsaturated fatty acyl chain, is concentrated in phospholipids of various cells of brain and retina. Synaptic membranes and photoreceptors share the highest content of DHA of all cell membranes. DHA is involved in memory formation, excitable membrane function, photoreceptor cell biogenesis and function, and neuronal signaling, and has been implicated in neuroprotection. In addition, this fatty acid is required for retinal pigment epithelium cell (RPE) functional integrity. Here we provide an overview of the recent elucidation of a specific mediator generated from DHA that contributes at least in part to its biological significance. In oxidative stress-challenged human RPE cells and rat brain undergoing ischemia-reperfusion, 10,17S-docosatriene (neuroprotectin D1, NPD1) synthesis evolves. In addition, calcium ionophore A23187, IL-1beta, or the supply of DHA enhances NPD1 synthesis. A time-dependent release of endogenous free DHA followed by NPD1 formation occurs, suggesting that a phospholipase A2 releases the mediator's precursor. When NPD1 is infused during ischemia-reperfusion or added to RPE cells during oxidative stress, apoptotic DNA damage is down-regulated. NPD1 also up-regulates the anti-apoptotic Bcl-2 proteins Bcl-2 and BclxL and decreases pro-apoptotic Bax and Bad expression. Moreover, NPD1 inhibits oxidative stress-induced caspase-3 activation. NPD1 also inhibits IL-1beta-stimulated expression of COX-2. Overall, NPD1 protects cells from oxidative stress-induced apoptosis. Because photoreceptors are progressively impaired after RPE cell damage in retinal degenerative diseases, understanding of how these signals contribute to retinal cell survival may lead to the development of new therapeutic strategies. Moreover, NPD1 bioactivity demonstrates that DHA is not only a target of lipid peroxidation, but rather is the precursor to a neuroprotective signaling response to ischemia-reperfusion, thus opening newer avenues of therapeutic exploration in stroke, neurotrauma, spinal cord injury, and neurodegenerative diseases, such as Alzheimer disease, aiming to up-regulate this novel cell-survival signaling.

Metabolic effects of intravenous LCT or MCT/LCT lipid emulsions in preterm infants

Most lipid emulsions for parenteral feeding of premature infants are based on long-chain triacylglycerols (LCTs), but inclusion of medium-chain triacylglycerols (MCTs) might provide a more readily oxidizable energy source. The influence of these emulsions on fatty acid composition and metabolism was studied in 12 premature neonates, who were randomly assigned to an LCT emulsion (control) or an emulsion with a mixture of MCT and LCT (1:1). On study day 7, all infants received [13C]linoleic (LA) and [13C]alpha-linolenic acid (ALA) tracers orally. Plasma phospholipid (PL) and triacylglycerol (TG) fatty acid composition and 13C enrichments of plasma PL fatty acids were determined on day 8. After 8 days of lipid infusion, plasma TGs in the MCT/LCT group had higher contents of C8:0 (0.50 +/- 0.60% vs. 0.10 +/- 0.12%; means +/- SD) and C10:0 (0.66 +/- 0.51% vs. 0.15 +/- 0.17%) than controls. LA content of plasma PLs was slightly lower in the MCT/LCT group (16.47 +/- 1.16% vs. 18.57 +/- 2.09%), whereas long-chain polyunsaturated derivatives (LC-PUFAs) of LA and ALA tended to be higher. The tracer distributions between precursors and products (LC-PUFAs) were not significantly different between groups. Both lipid emulsions achieve similar plasma essential fatty acid (EFA) contents and similar proportional conversion of EFAs to LC-PUFAs. The MCT/LCT emulsion seems to protect EFAs and LC-PUFAs from beta-oxidation.

Diet-induced differences in the essential fatty acid (EFA) compositions of larval Atlantic cod (Gadus morhua L.) with reference to possible effects of dietary EFAs on larval performance

AbstractWe studied the performance of cod rearing in which live feed was given under three different essential fatty acid (EFA) enrichment regimes, using commercially available live-feed enrichments. We assessed the fatty acid profile [docosahexaenoic (DHA), eicosapentaenoic (EPA), and arachidonic acid (AA)] in larval somatic tissue, relative to its amounts in both rotifers and Artemia as well as to larval performance. Overall, percentage lipid level of each experimental diet for the trial was approximately 50%. Further, there were no significant differences in total fatty acid levels of larvae from each treatment at the end of the trial (mean = 444.76 μg fatty acid per mg lipid). However, during the rotifer phase, larvae from each treatment were able to incorporate comparable levels of %DHA, irrespective of levels in the diet. Despite this, the rotifer diet with more %DHA still promoted better larval growth than other treatments. Conversely, larvae from two of the treatments did not exhibit any accumulation of AA, reflecting levels found in the diet instead. However, between-tank differences in larval %AA showed improved growth during the rotifer period when larval %AA was high. Low ratios of EPA had no effect. During the Artemia phase, percentage levels of larval DHA decreased; there was no accumulation of DHA relative to dietary levels, which in Artemia were significantly lower than in rotifers (6 cf. 20–30%). However, DHA levels in larvae at the end of the experiment correlated positively with survival. Artemia contained lower levels of AA than rotifers (1.5 cf. 3.0%), yet comparable levels of AA were found in rotifer-fed and Artemia-fed larvae. This also differed significantly between treatments, and correlated positively with survival.

Dietary coconut oil increases conjugated linoleic acid-induced body fat loss in mice independent of essential fatty acid deficiency

Conjugated linoleic acid (CLA) induces a body fat loss that is enhanced in mice fed coconut oil (CO), which lacks essential fatty acids (EFA). Our objective was to determine if CO enhancement of CLA-induced body fat loss is due to the lack of EFA. The CLA–EFA interaction was tested by feeding CO and fat free (FF) diets for varying times with and without replenishment of individual EFA. Mice fed CO during only the 2-week CLA-feeding period did not differ from control mice in their adipose EFA content but still tended ( P = 0.06) to be leaner than mice fed soy oil (SO). Mice raised on CO or FF diets and fed CLA were leaner than the SO + CLA-fed mice ( P < 0.01). Mice raised on CO and then replenished with linoleic, linolenic, or arachidonic acid were leaner when fed CLA than mice raised on SO ( P < 0.001). Body fat of CO + CLA-fed mice was not affected by EFA addition. In summary, CO-fed mice not lacking in tissue EFA responded more to CLA than SO-fed mice. Also, EFA addition to CO diets did not alter the enhanced response to CLA. Therefore, the increased response to CLA in mice raised on CO or FF diets appears to be independent of a dietary EFA deficiency.

Les rôles physiologiques majeurs exercés par les acides gras polyinsaturés (AGPI)

Polyunsaturated fatty acids (PUFAs) are essential nutrients for mammals and the human species, and belong to either of two distinct and not interconvertible series, omega 6 and omega 3. The metabolic precursors of these two series, linoleic and α-linolenic acids respectively, are the dietary essential fatty acids. These two fatty acids, once absorbed, lead to the specific synthesis and incorporation in practically all cell membranes of long-chain active PUFA derivatives such as arachidonic acid for the omega 6 series and eicosapentaenoic and docosahexaenoic acids for the omega 3 series. Long-chain PUFA affect many physiological functions because they are essential factors in many cellular functions by regulating physical properties of membranes, eicosanoid signalling and gene expression of encoding enzymes of triglyceride storage and fatty acid oxidation. The consumption of omega 6 and omega 3 fatty acids in equilibrated proportions could be crucial in the regulation of cellular physiology and in the prevention of pathologies such as cardiovascular, autoimmune and inflammatory diseases, diabetes and obesity, certain neuropsychiatric affections, etc. Indeed, the dietary intake of omega 3 fatty acid (α-linolenate and also docosahexaenoate) are crucial parameters in the development of retinal and neural function in the newborn infant. On the other hand, a high ratio of omega6/omega 3 fatty acids in cell membranes due to an excessive consumption of omega 6 fatty acids and a relative omega 3 fatty acid deficiency, may promote the pathogenesis of several diseases, including cardiovascular diseases, metabolic syndrome, inflammatory disorders and obesity.

Dietary n‐3 polyunsaturated fatty acid depletion activates caspases and decreases NMDA receptors in the brain of a transgenic mouse model of Alzheimer's disease

Epidemiological data indicate that low n-3 polyunsaturated fatty acids (PFA) intake is a readily manipulated dietary risk factor for Alzheimer's disease (AD). Studies in animals confirm the deleterious effect of n-3 PFA depletion on cognition and on dendritic scaffold proteins. Here, we show that in transgenic mice overexpressing the human AD gene APPswe (Tg2576), safflower oil-induced n-3 PFA deficiency caused a decrease in N-methyl-D-aspartate (NMDA) receptor subunits, NR2A and NR2B, in the cortex and hippocampus with no loss of the presynaptic markers, synaptophysin and synaptosomal-associated protein 25 (SNAP-25). n-3 PFA depletion also decreased the NR1 subunit in the hippocampus and Ca2+/calmodulin-dependent protein kinase (CaMKII) in the cortex of Tg2576 mice. These effects of dietary n-3 PFA deficiency were greatly amplified in Tg2576 mice compared to nontransgenic mice. Loss of the NR2B receptor subunit was not explained by changes in mRNA expression, but correlated with p85alpha phosphatidylinositol 3-kinase levels. Most interestingly, n-3 PFA deficiency dramatically increased levels of protein fragments, corresponding to caspase/calpain-cleaved fodrin and gelsolin in Tg2576 mice. This effect was minimal in nontransgenic mice suggesting that n-3 PFA depletion potentiated caspase activation in the Tg2576 mouse model of AD. Dietary supplementation with docosahexaenoic acid (DHA; 22 : 6n-3) partly protected from NMDA receptor subunit loss and accumulation of fodrin and gelsolin fragments but fully prevented CaMKII decrease. The marked effect of dietary n-3 PFA on NMDA receptors and caspase/calpain activation in the cortex of an animal model of AD provide new insights into how dietary essential fatty acids may influence cognition and AD risk.

Placental Tissue Levels of Nonesterified Polyunsaturated Fatty Acids in Normal and Preeclamptic Pregnancies

Objective. We previously reported that maternal plasma levels of nonesterified polyunsaturated fatty acids were decreased in women with preeclampsia as compared to women with normal pregnancies. Polyunsaturated fatty acids of the n-6 and n-3 families are essential dietary fatty acids. The n-6 polyunsaturated fatty acids are involved in inflammatory reactions, whereas n-3 polyunsaturated fatty acids protect against inflammation. Methods. In this study, we investigated the composition of nonesterified polyunsaturated fatty acids in placental tissue of normal and preeclamptic pregnancies. Linoleic (18:2) and arachidonic (20:4, AA) acids of the n-6 family and linolenic (18:3), eicosapentaenoic (20:5, EPA) and docosahexaenoic (22:6, DHA) acids of the n-3 family were analyzed. Conclusions. We found that total concentrations of nonesterified polyunsaturated fatty acids were lower in placental tissues from preeclamptic pregnancies than from normal pregnancies. Both n-6 and n-3 polyunsaturated fatty acids were decreased. The decrease in n-6 polyunsaturated fatty acids was due to a decrease in AA. The concentration of linoleic acid was not altered. For n-3 polyunsaturated fatty acids, DHA was decreased, with no change in linolenic acid. The percentage decrease in EPA and DHA was greater than for AA, so the ratio of n-6 to n-3 polyunsaturated fatty acids was two-fold higher in preeclampsia than normal pregnancy. Because the levels of essential fatty acids, linoleic (18:2) and linolenic (18:3), are preserved but levels of metabolites (AA and DHA) are reduced, we speculate that placental oxidative stress and increased conversion of AA to thromboxane are responsible for the decreased concentrations of polyunsaturated fatty acids in preeclampsia.

Development of Alcoholic Fatty Liver and Fibrosis in Rhesus Monkeys Fed a Low n‐3 Fatty Acid Diet

The amount and type of dietary fat seem to be important factors that modulate the development of alcohol-induced liver steatosis and fibrosis. Various alcohol-feeding studies in animals have been used to model some of the symptoms that occur in liver disease in humans. Rhesus monkeys (Macaca mulatta) were maintained on a diet that had a very low concentration of alpha-linolenic acid and were given free access to an artificially sweetened 7% ethanol solution. Control and ethanol-consuming animals were maintained on a diet in which the linoleate content was adequate (1.4% of energy); however, alpha-linoleate represented only 0.08% of energy. Liver specimens were obtained, and the fatty acid composition of the liver phospholipids, cholesterol esters, and triglycerides of the two groups were compared at 5 years and histopathology of tissue samples were compared at 3 and 5 years. The mean consumption of ethanol for this group over a 5-year period was 2.4 g.kg.day. As a consequence of the ethanol-dietary treatment, there were significantly lower concentrations of several polyunsaturated fatty acids in the liver phospholipids of the alcohol-treated group, including arachidonic acid and most of the n-3 fatty acids and particularly docosahexaenoic acid, when compared with dietary controls. Liver specimens from animals in the ethanol group at 5 years showed a marked degree of steatosis, both focal and diffuse cellular necrosis, and an increase in the development of fibrosis compared with specimens obtained at 3 years and with those from dietary controls, in which there was no evidence of fibrotic lesions. These findings suggest that the advancement of ethanol-induced liver disease in rhesus monkeys may be modulated by the amount and type of dietary essential fatty acids and that a marginal intake of n-3 fatty acids may be a permissive factor in the development of liver disease in primates.

Influence of dietary conjugated linoleic Acid and fat source on body fat and apoptosis in mice.

To determine whether altered dietary essential fatty acid (linoleic and arachidonic acid) concentrations alter sensitivity to conjugated linoleic acid (CLA)-induced body fat loss or DNA fragmentation. Mice were fed diets containing soy oil (control), coconut oil [essential fatty acid deficient (EFAD)], or fish oil (FO) for 42 days, and then diets were supplemented with a mixture of CLA isomers (0.5% of the diet) for 14 days. Body fat index, fat pad and liver weights, DNA fragmentation in adipose tissue, and fatty acid profiles of adipose tissue were determined. The EFAD diet decreased (p < 0.05) linoleic and arachidonic acid in mouse adipose tissue but did not affect body fat. Dietary CLA caused a reduction (p < 0.05) in body fat. Mice fed the EFAD diet and then supplemented with CLA exhibited a greater reduction (p < 0.001) in body fat (20.21% vs. 6.94% in EFAD and EFAD + CLA-fed mice, respectively) compared with mice fed soy oil. Dietary FO decreased linoleic acid and increased arachidonic acid in mouse adipose tissue. Mice fed FO or CLA were leaner (p < 0.05) than control mice. FO + CLA-fed mice did not differ in body fat compared with FO-fed mice. Adipose tissue apoptosis was increased (p < 0.001) in CLA-supplemented mice and was not affected by fat source. Reductions in linoleic acid concentration made mice more sensitive to CLA-induced body fat loss only when arachidonic acid concentrations were also reduced. Dietary essential fatty acids did not affect CLA-induced DNA fragmentation.

Hypothalamic superoxide dismutase, xanthine oxidase, nitric oxide, and malondialdehyde in rats fed with fish ω-3 fatty acids

Phospholipids located in the cellular membrane play a critical role in the fluid-mosaic model of membrane structure and membrane function. Evidence is mounting for the role of abnormal phospholipid metabolism in some neuropsychiatric disorders including schizophrenia. As an important essential fatty acid (EFA), omega-3 (ω-3) fatty acid series are found in large amounts in fish oil. The aim of this experimental study was to assess the changes of some of the oxidant and antioxidant parameters in the hypothalamus of rats fed with ω-3 EFA diet (0.4 g/kg/day) for 30 days. Eight control rats and nine rats fed with ω-3 were decapitated under ether anesthesia, and hypothalamus was removed immediately. Malondialdehyde (MDA) and nitric oxide (NO) levels as well as superoxide dismutase (SOD) and xanthine oxidase (XO) enzyme activities in the hypothalamus were measured. SOD activity was significantly decreased in ω-3 EFA treated group compared to control group ( p<0.014). Tissue MDA and NO levels were also decreased in ω-3 EFA treated group compared to control rats ( p<0.0001). Xanthine oxidase activity was found to be increased in ω-3 EFA treated rats when compared to the control group ( p<0.0001). Taken together, this preliminary animal study provides strong support for a therapeutic effect of ω-3 EFA in some neuropsychiatric disorders in which reactive oxygen species (ROS) are recently accused to be an important physiopathogenetic factor.

Fish and shellfish as dietary sources of methylmercury and the ω-3 fatty acids, eicosahexaenoic acid and docosahexaenoic acid: risks and benefits

Fish and shellfish supply the human diet with not only complex nutrients including the ω-3 fatty acids, but also highly toxic chemicals including methylmercury. The dietary essential fatty acids are linoleic and α-linolenic acid. Two ω-3 fatty acids with longer carbon chains, eicosahexaenoic acid (EPA) and docosahexaenoic acid (DHA), can be synthesized in humans from α-linolenic precursors. Though not required in the diet per se, EPA and DHA have important roles in metabolism. The almost exclusive source of preformed dietary DHA is fish and shellfish. These foods are also an important source of EPA. In marked contrast to the benefits of fish and shellfish as sources of preformed ω-3 fatty acids, fish and shellfish are almost exclusively the dietary source of methylmercury. Fortunately, these chemicals are not uniformly distributed across many species of fish and shellfish. The purpose of this article is to provide information on the comparative distribution of these chemicals and nutrients to help groups formulating dietary recommendations.

Effect of varying levels of dietary essential fatty acid during early ontogeny of the sea scallop Placopecten magellanicus

This study investigated the biological effects of various dietary essential fatty acids levels to sea scallop larvae, Placopecten magellanicus. Scallop larvae were fed three diets from D-veliger to settlement. Diet A consisted of Isochrysis sp. and Pavlova lutheri, diet B was a mix of Isochrysis sp. and Chaetoceros muelleri and diet C consisted of the same two species, but C. muelleri was grown under silicate deprivation to alter the fatty acid composition. Pediveligers (28 days old) were sampled prior to settlement for fatty acid analysis, growth measurement and survival assessment. Survival and settlement success were measured at the end of the experiment (day 40). Our results show that feeding regime greatly influenced larval size, settlement and fatty acid composition. Diet A was severely deficient in arachidonic acid (20:4n-6, AA), leading to the poorest larval growth, survival and lipid content. Nevertheless, larvae fed diet A selectively accumulate AA by a factor three compared to the dietary amount. Shell size of 28-day-old larvae was positively correlated with AA content and negatively correlated with eicosapentaenoic acid (20:5n-3, EPA)–AA ratio, thus suggesting that these two variables are of major interest for the optimisation of larval growth in sea scallops. Finally, larvae fed diet C displayed 20% higher shell size at day 28 than larvae fed diet A and B, likely in relation to the dietary amount of saturated fatty acid (SFA). However, the moderate survival and settlement success of these groups of larvae might be associated with a relative deficiency in docosahexaenoic acid (22:6n-3, DHA). This study underlines that the overall balance between polyunsaturated fatty acid (PUFA) needs to be considered to adequately fed sea scallop larvae.

Effect of varying levels of dietary essential fatty acid during early ontogeny of the sea scallop Placopecten magellanicus

This study investigated the biological effects of various dietary essential fatty acids levels to sea scallop larvae, Placopecten magellanicus . Scallop larvae were fed three diets from D-veliger to settlement. Diet A consisted of Isochrysis sp. and Pavlova lutheri , diet B was a mix of Isochrysis sp. and Chaetoceros muelleri and diet C consisted of the same two species, but C. muelleri was grown under silicate deprivation to alter the fatty acid composition. Pediveligers (28 days old) were sampled prior to settlement for fatty acid analysis, growth measurement and survival assessment. Survival and settlement success were measured at the end of the experiment (day 40). Our results show that feeding regime greatly influenced larval size, settlement and fatty acid composition. Diet A was severely deficient in arachidonic acid (20:4n-6, AA), leading to the poorest larval growth, survival and lipid content. Nevertheless, larvae fed diet A selectively accumulate AA by a factor three compared to the dietary amount. Shell size of 28-day-old larvae was positively correlated with AA content and negatively correlated with eicosapentaenoic acid (20:5n-3, EPA)–AA ratio, thus suggesting that these two variables are of major interest for the optimisation of larval growth in sea scallops. Finally, larvae fed diet C displayed 20% higher shell size at day 28 than larvae fed diet A and B, likely in relation to the dietary amount of saturated fatty acid (SFA). However, the moderate survival and settlement success of these groups of larvae might be associated with a relative deficiency in docosahexaenoic acid (22:6n-3, DHA). This study underlines that the overall balance between polyunsaturated fatty acid (PUFA) needs to be considered to adequately fed sea scallop larvae.