Dietary fish oil dose- and time-response effects on cardiac phospholipid fatty acid composition

Fish consumption is associated with reduced cardiovascular mortality, and elevated myocardial long-chain n−3 polyunsaturated FA (PUFA) content is implicated in this cardioprotection. This study examined the dose and time responses for incorporation of n−3 PUFA into cellular membranes in rats fed fish oil (FO)-containing diets. For the time course study, rats were fed a 10% FO diet for periods ranging from 0 to 42 d, after which myocardial and erythrocyte membrane fatty acid composition was determined. For the dose response study, rats (n=3) were fed 0, 1.25, 2.5, 5, or 10% FO for 4 wk, with myocardial, erythrocyte, and skeletal muscle membrane FA determined. Myocardial DHA (22∶6n−3) levels doubled in 2 d, stabilizing at levels ≈200% higher than control after 28 d feeding with 10% FO. By comparison, DHA levels doubled after 4 wk of 1.25% FO feeding. In myocardium and skeletal muscle, EPA (20∶5n−3) levels remained low, but in erythrocytes EPA levels reached 50% of DHA levels. The n−3 PUFA were incorporated at the expense of n−6 PUFA in myocardium and skeletal muscle, whereas erythrocytes maintained arachidonic acid levels, and total n−3 PUFA incorporation was lower. This study shows that low doses of FO produce marked changes in myocardial DHA levels; maximal incorporation takes up to 28 d to occur; and while erythrocytes are a good indicator of tissue n−3 incorporation in stable diets, they vary greatly in their time course and pattern of incorporation.     

Hyperphagia modifies FA profiles of plasma phospholipids,plasma FFA,and adipose tissue TAG

Hyperphagia was achieved by continuous intracerebroventricular infusion of a melanocortin receptor antagonist (HS024; Neosystem, Strasbourg, France) in rats. The effects of hyperphagia on FA composition and concentration of plasma phospholipids (PL), plasma FFA, and adipose tissue TAG were studied in rats for 8 d [short-term hyperphagia (STH); n=8], or 28 d [longterm hyperphagia (LTH); n=9]. The control rats were treated with artificial cerebrospinal fluid for 8 d (n=8) or 28 d (n=10). The rats were fed the same regular diet. In STH rats the plasma PL and fasting plasma FFA contained higher concentrations of saturated FA (SFA) and monounsaturated FA (MUFA), and plasma FFA contained lower n−6 PUFA than in the control rats. In LTH rats the plasma PL contained higher concentrations of SFA, MUFA, and n−3 PUFA and higher proportions of 16∶1n−7 and 18∶1n−9 at the expense of 18∶2n−6 than in the control rats. In LTH rats the abundant dietary intake of 18∶2n−6 did not enrich 18∶2n−6 of the plasma PL or adipose tissue TAG. In LTH rats the fasting plasma FFA contained more than twofold higher concentrations of SFA and MUFA, and higher proportions of 16∶1n−7 and 18∶1n−9 at the expense of 18∶2n−6 than in the control rats. This animal obesity model shows that LTH affects the FA composition and concentration of plasma PL, plasma FFA, and adipose tissue TAG, a result consistent with changes associated with increased risk of various diseases in humans. These results also demonstrate that LTH alters the FA composition of plasma PL and adipose tissue TAG in a way that does not reflect the FA composition of dietary fat.     

Lipid content and fatty acid composition of 11 species of Queensiand (Australia) fish

The fatty acid composition of 11 species of fish caught off the northeast coast of Australia was determined. No fatty acid profiles have been previously published for fish from this area nor for nine of these species. Although the percentage of polyunsaturated fatty acid (PUFA) was the same as the calculated average for Australian fish (42.3%), the percentage of n−3 fatty acids was lower (24.4±5.4% vs. 30.7±10.1%) and the n−6 fatty acids higher (16.5±4.5% vs. 11.2±5.9%), P<0.001 in each case. The major n−3 PUFA were docosahexaenoic (15.6 ±6.3%) and eicosapentaenoic acid (4.3±1.1%) while the major n−6 PUFA were arachidonic (8.3±3.2%) and n−6 docosatetraenoic acid (3.1±1.3%). The second-most abundant class of fatty acid was the saturates (31.6±3.5%) while the monounsaturates accounted for 17.4±4.3% of the total fatty acids. The monounsaturate with the highest concentration was octadecenoic acid (11.8±2.6%). There was a positive correlation between the total lipid content and saturated and monounsaturated fatty acids (r=0.675 and 0.567, respectively) and a negative correlation between the total lipid content and PUFA (r=0.774).     

A significant inverse relationship between concentrations of plasma homocysteine and phospholipid docosahexaenoic acid in healthy male subjects

The aim of this study was to investigate the possibility of a relationship between plasma homocysteine (Hcy) and phospholipid FA (PUFA) in healthy Australian males. One hundred thirty six healthy male subjects aged 20–55 yr were recruited from the Melbourne metropolitan area. Each volunteer completed a semiquantitative food frequency questionnaire and gave a blood sample. Plasma Hcy concentrations were determined by an established HPLC method; the plasma phospholipid FA were determined by standard methods. Plasma Hcy concentration was significantly negatively correlated with plasma phospholipid concentration of the PUFA 20∶5n−3 (r=−0.226, P=0.009), 22∶5n−3 (r=−0.182, P=0.036), 22∶6n−3 (r=−0.286, P=0.001), total n−3 (r=−0.270, P=0.002) and the ratio n−3/n−6 PUFA (r=−0.265, P=0.002), and significantly positively correlated with 20∶4n−6 (r=0.180, P=0.037). In the partial correlation analysis, after controlling for serum vitamin B₁₂ and folate concentration, plasma Hcy was significantly negatively correlated with the plasma phospholipid concentration of 22∶6n−3 (r=−0.205, P=0.019), total n−3 (r=−0.182, P=0.038) and the ratio n−3/n−6 PUFA (r=−0.174, P=0.048). Evidence indicates that an increased concentration of n−3 PUFA in tissues has a beneficial effect on cardiovascular health. Our findings provide further evidence that increased consumption of dietary n−3 PUFA increases the concentration of n−3 PUFA in plasma phospholipid, which is associated with a protective effect on cardiovascular diseases and lower plasma Hcy levels. The mechanism that might explain the association between plasma 22∶6n−3 and Hcy levels is not clear.     

Fatty acid profiles and relative mobilization during fasting in adipose tissue depots of the American marten (Martes americana)

The American marten (Martes americana) is a boreal forest marten with low body adiposity but high metabolic rate. The study describes the FA composition in white adipose tissue depots of the species and the influence of food deprivation on them. American marten (n=8) were fasted for 2 d with 7 control animals. Fasting resulted in a 13.4% weight loss, while the relative fat mass was >25% lower in the fasted animals. The FA composition of the fat depots of the trunk was quite similar to other previously studied mustelids with 14∶0, 16∶0, 18∶0, 16∶1n−7, 18∶1n−9, and 18∶2n−6 as the most abundant FA. In the extremities, there were higher proportions of monounsaturated FA (MUFA) and PUFA. Food deprivation decreased the proportions of 16∶0 and 16∶1n−7, while the proportion of long-chain MUFA increased in the trunk. The mobilization of FA was selective, as 16∶1n−7, 18∶1n−9, and particular n−3 PUFA were preferentially mobilized. Relative mobilization correlated negatively with the carbon chain length in saturated FA (SFA) and n−9 MUFA. The Δ9 desaturation of SFA enhanced the mobilization of the corresponding MUFA, but the positional isomerism of the first double bond did not correlate consistently with relative mobilization in MUFA or PUFA. In the marten, the FA composition of the extremities was highly resistant to fasting, and the tail tip and the paws contained more long-chain PUFA to prevent the solidification of lipids and to maintain cell membrane fluidity during cooling.     

Different kinetic in incorporation and depletion of n−3 fatty acids in erythrocytes and leukocytes of mice

n−3 PUFA are well known for their anti-inflammatory effects. However, there has been only limited study on the kinetics of incorporation and depletion of n−3 PUFA in immune cells. In the present study we investigated the incorporation and depletion of n−3 PUFA in erythrocytes and leukocytes in mice during a 6-wk feeding period. Over the first 3-wk period (the incorporation period) the mice were fed a special diet with a high n−3/n−6 PUFA ratio. In the following 3-wk period (the depletion period) the mice were fed a standard chow diet. A linear incease of the concentration of EPA and DHA in erythrocyte membranes was observed during the incorporation period, whereas a stagnation was observed after the second week for leukocytes. The level of EPA did not fall to the background level after the depletion period, and the level of DHA was kept almost constant during the depletion period in the erythrocyte membranes. In leukocytes the concentration of both EPA and DHA decreased during the depletion period, but did not reach the background level after the 3-wk depletion. In conclusion, the kinetics of EPA and DHA in the different cells are different. The rate of incorporation is faster than that of depletion for n−3 PUFA. More n−3 PUFA can be incorporated into leukocytes in comparison with erythrocytes. The ratio of n−3/n−6 PUFA is more important than the amount of n−3 FA in changing the FA compositions of membrane lipids.     

Trans isomeric octadecenoic acids are related inversely to arachidonic acid and DHA and positively related to mead acid in umbilical vessel wall lipids

Long-chain PUFA play an important role in early human neurodevelopment. Significant inverse correlations were reported between values of trans isomeric and long-chain PUFA in plasma lipids of preterm infants and children aged 1–15 yr as well as in venous cord blood lipids of full-term infants. Here we report FA compositional data of cord blood vessel wall lipids in 308 healthy, full-term infants (gestational age: 39.7±1.2 wk, birth weight: 3528±429 g, mean±SD). The median (interquartile range) of the sum of 18-carbon trans FA was 0.22 (0.13)% w/w in umbilical artery and 0.16 (0.10)% w/w in umbilical vein lipids. Nonparametric correlation analysis showed significant inverse correlations between the sum of 18-carbon trans FA and both arachidonic acid and DHA in artery (r=−0.38, P<0.01, and r=−0.20, P<0.01) and vein (r=−0.36, P<0.01, and −0.17, P<0.01) wall lipids. In addition, the sum of 18-carbon trans FA was significantly positively correlated to Mead acid, a general indicator of EFA deficiency, in both artery (r=+0.35, P<0.01) and vein (r=+0.31, P<0.01) wall lipids. The present results obtained in a large group of full-term infants suggest that maternal trans FA intake is inversely associated with long-chain PUFA status of the infant at birth.     

Preferential effect of lead exposure during lactation on non-essential fatty acids in maternal organs

This study determined the effects of lead exposure during the lactational period on maternal organ FA compositions in rat dams that were fed either an n−3 adequate (n−3 Adq) or deficient (n−3 Def) diet prior to conception. On giving birth, dams were subdivided into four groups in a 2×2 design with n−3 FA supply and Pb exposure as the dependent variables. Pb acetate (0.2 wt%) was administered in the drinking water from the time they gave birth to weaning 3 wk later. Following weaning, the dams were decapitated. and the liver, plasma, kidney, brain, and retina analyzed for FA composition. The n−3 deficient diets markedly decreased the percentages of total n−3 FA, including docosahexaenoic acid (DHA), and increased total n−6 FA including both arachidonic (AA) and n−6 docosapentaenoic acids in all tissues (P<0.05). The principal effects of Pb occurred in the liver and plasma, where 20–32% losses in total FA concentration concurrent with increased relative percentages of AA (P<0.05) were observed. In kidney, the percentages of AA and DHA also increased after Pb exposure (P<0.05) with lesser effects in the nervous system. There was a diet x Pb interaction for liver, plasma, and retinal 20-C n−6 PUFA (P<0.05). Generally, shorter-chain saturated and monounsaturated FA concentrations were decreased after Pb exposure. An analysis of the changes in the tissue concentrations induced by Pb indicated that the increases in the percentages of PUFA likely reflected a preferential loss of non-EFA. The mechanisms by which Pb affects saturated and monounsaturated FA concentration are unknown.     

FA composition of plasma,red blood cell,and liver phospholipids of newborn piglets fed trans isomers of alpha-linolenic acid

The effects of dietary cis and trans α-linolenic acid (18∶3n−3) on the FA composition of plasma, red blood cell, and liver phospholipids were studied in newborn piglets. Animals were fed for 14 d with one of three diets: a control diet (group A) containing cis 18∶3n−3 at a level of 2.0% of total FA, a diet (group B) in which a part of the 18∶3n−3 acid was isomerized (1.3% of cis 18∶3n−3 and 0.7% of trans 18∶3n−3), or a diet (group C) with 2.0% cis 18∶3n−3 and 0.7% trans 18∶3n−3. Feeding animals with diets containing trans 18∶3n−3 resulted in the presence of trans isomers of 18∶3n−3, trans isomers of EPA, and trans isomers of DHA in phospholipids; however, the level of total trans n−3 PUFA in tissues was less than 0.3% of total tissue FA. In group B, the reduction of dietary amounts of cis 18∶3n−3 was associated with a decrease in individual and total cis n−3 PUFA. In contrast, in group C there was no decrease in tissue n−3 PUFA despite the increased dietary level of trans 18∶3n−3. These results suggest that the isomerization of a part of dietary n−3 PUFA, leading to the reduction of their levels in the diet, could induce a decrease in n−3 PUFA in phospholipids. The physiological effects of trans PUFA are not known and should be considered in future studies.     

Composition and seasonal variation of fatty acids of <Emphasis Type="Italic">Diplodus vulgaris</Emphasis> L. from the Adriatic Sea

Muscle tissue from the common two-banded sea bream Diplodus vulgaris L. originating from the Adriatic Sea, Croatia, was analyzed. The FA composition of neutral (TAG) and polar (PE, PC, PI/PS) lipid classes was determined, as well as the lipid and water contents during winter and summer periods. Both the total lipid and water contents were higher in the winter period. We identified 16 different FA. The major constituents of the total FA in both seasons were saturates: palmitic (16∶0) and stearic acids (18∶0); monoenes: oleic (18∶1n−9) and palmitoleic acids (16∶1n−7); and polyunsaturates: arachidonic acid (20∶4n−6), EPA (20∶5n−3), and DHA (22∶6n−3), but their amounts and ratios differed significantly between the two seasons and between lipid fractions. The FA composition showed a noticeable pattern of seasonality that reflected fluctuations mainly in TAG. The diminution of the monounsaturated FA content in the summer was clearly followed by an increase in PUFA content. Diplodus vulgaris is a good source of natural n−3 PUFA and would therefore be suitable for inclusion in highly unsaturated low-fat diets.     

Docosahexaenoic acid-and eicosapentaenoic acid-enriched cardiolipin in the manila clam <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis>

The FA composition of cardiolipin (CL) from the Manila clam Ruditapes philippinarum was investigated in whole body and individual organs. CL was isolated by HPLC and its chemical structure characterized using NMR spectroscopy. Two prominent FA, EPA and DHA, were found in approximately equal proportions, contributing together up to 73 mol% of the total FA. The FA composition of CL is presumed to reflect a specific synthesis pathway independent of diet and of total glycerophospholipid FA composition. To the best of our knowledge, this is the first time that a CL dominated by the two PUFA 22∶6n−3 and 20∶5n−3 has been characterized and described. This EPA+DHA specificity of the CL in the Manila clam is though to reflect a functional and structural modification of mitochondrial membranes of this bivalve species compared with scallops, oysters, and mussels that possess a CL dominated by DHA. The FA composition and levels of CL differed little between separated organs, and the large pool of DHA and EPA was found fairly equally distributed in gills, mantle, foot, siphon, and muscle. However, whereas DHA and PUFA levels were most stable between organs, EPA and arachidonic acid were significantly more variable and seemed to be interrelated.     

Fatty acid composition of the adipose tissue and yolk lipids of a bird with a marine-based diet, the emperor penguin (Aptenodytes forsteri)

The emperor penguin (Aptenodytes forsteri) is an Antarctic seabird feeding mainly on fish and therefore has a high dietary intake of n-3 polyunsaturated fatty acids. The yolk is accumulated in the developing oocyte while the females are fasting, and a large proportion of the fatty acid components of the yolk lipids are derived by mobilization from the female's adipose tissue. The fatty acid composition of the total lipid of the yolk was characterized by high levels of n-3 polyunsaturated fatty acids. However, it differed in several respects from that of the maternal adipose tissue. For example, the proportions of 14∶0, 16∶1n−7, 20∶1n−9, 22∶1n−9, 20∶5n−3, and 22∶6n−3 were significantly greater in adipose tissue than in yolk. Thus adipose tissue lipids contained 7.6±0.3% and 8.0±0.3% (wt% of total fatty acids; mean ±SE; n=5) of 20∶5n−3 and 22∶6n−3, respectively, whereas the yolk total lipid contained 1.6±0.1 and 5.5±0.3% of these respective fatty acids. The proportions of 16∶0, 18∶0, 18∶1n−9, 18∶2n−6, and 20∶4n−6 were significantly lower in the adipose tissue than in the yolk lipids. The proportions of triacylglycerol, phospholipid, free cholesterol, and cholesteryl ester in the yolk lipid were, respectively, 67.0±0.2, 25.4±0.3, 5.3±0.2, and 1.8±0.2% (wt% of total yolk lipid). The proportions of 20∶4n−6, 20∶5n−3, 22∶5n−3, and 22∶6n−3 were, respectively, 5.7±0.3, 2.8±0.2, 1.4±0.1, and 11.7±0.5% in phospholipid and 0.4±0.0, 1.2±0.1, 0.8±0.1 and 3.6±0.3% in triacylglycerol. About 95% of the total vitamin E in the yolks was in the form of α-tocopherol with γ-tocopherol forming the remainder. Two species of carotenoids, one identified as lutein, were present.     

Occurrence of high levels of tetracosahexaenoic acid in the jellyfish <Emphasis Type="Italic">Aurelia</Emphasis> sp.

The FA composition of the pelagic jellyfish Aurelia sp. collected from off-shore Western Australia waters was determined by capillary GC and GC-MS, with confirmation of PUFA structure performed by analysis of 4,4-dimethyloxazoline derivatives. PUFA constituted 47.6% of the total FA, with the essential PUFA eicosapentaenoic acid (FPA), arachidonic acid, and DHA accounting for 34%. Of particular interest, the unusual very long chain PUFA 6,9,12,15,18,21-tetracosahexaenoic acid (THA, 24∶6n−3) was present at 9.3%, and the rarely reported 6,9,12,15,18-tetracosapentaenoic acid (24∶5n−6) also was detected at 0.8%. To our knowledge, this represents the first report of THA as a major PUFA in a pelagic marine organism.     

Mice raised on milk transgenically enriched with n−3 PUFA have increased brain docosahexaenoic acid

The brain contains high levels of the long-chain n−3 FA DHA(22∶6n−3), mainly in the gray matter and synaptosomes. Adequate intake of DHA is crucial for optimal nervous system function, particularly in infants. Supplementation of infant formulas with DHA at levels similar to human breast milk is recommended for biochemical and functional benefits to neonates. We generated transgenic mice that produce elevated levels of n−3 PUFA in their milk by expressing the Caenorhabditis elegans n−3 FA desaturase under the control of a lactation-induced goat beta-casein promoter. To examine the postnatal effects of consuming the n−3-enriched milk, we compared the growth and brain and plasma FA composition of mouse pups raised on milk from transgenic dams with those observed for pups raised on milk from nontransgenic dams. A significant decrease in arachidonic acid (ARA, 20∶4n−6) and concomitant increases in n−3 PUFA were observed in the phospholipid fraction of transgenic mouse milk. The n−6∶n−3 FA ratios were 4.7 and 34.5 for the transgenic and control milk phospholipid fractions, respectively. DHA and DPA (22∶5n−6) comprised 15.1% and 2.8% of brain FA from weanling mice nursed on transgenic dams, as compared with 6.9% and 9.2% for weanling mice nursed on control dams, respectively. This transgenic mouse model offers a unique approach to disassociate the effects and fetal programming resulting from a high n−6∶n−3 FA ratio gestational environment from the postnatal nutritional effects of providing milk with differing n−6∶n−3 FA ratios.     

Fish oil supplementation of lactating mothers affects cytokine production in 2 1/2-year-old children

n−3 PUFA influence immune functioning and may affect the cytokine phenotype during development. To examine whether maternal fish oil supplementation during lactation could modify later immune responses in children, 122 lactating Danish mothers with a fish intake below the population median were randomized to groups supplemented for the first 4 mon of lactation with 4.5 g/d of fish oil (equivalent to 1.5 g/d of n−3 long-chain PUFA) or olive oil. Fifty-three mothers with a fish intake in the highest quartile of the population were also included. The FA composition of erythrocyte membranes was measured at 4 mon and at 2 1/2 yr. Plasma immunoglobulin E (IgE) levels and cytokine production in lipopolysaccharide-stimulated whole-blood cultures were determined at 2 1/2 yr. Erythrocyte n−3 PUFA at 4 mon were higher in infants from the fish oil group compared with the olive oil group (P<0.001) but were no longer different at 2 1/2 yr. The median production of lipopolysaccharide-induced interferon γ(IFN-γ) in the fish oil group was fourfold higher than that in the olive oil group (P=0.034), whereas interleukin-10 (IL-10) production was similar. The IFN-γ/IL-10 ratio was twofold higher in the fish oil group (P=0.019) and was positively correlated with 20∶5n−3/20∶4n−6 in erythrocytes at 4 mon (P=0.050). The percentages of atopic children and plasma IgE were not different in the two groups, but the study was not designed to look at atopy. Cytokine responses and erythrocyte FA composition in children of mothers with a high fish intake were intermediate in comparison with those in the randomized groups. Fish oil supplementation during lactation resulted in increased in vitro IFN-γ production in the children 2 yr after the supplementation was given, which may reflect a faster maturation of the immune system.     

Fish oil fatty acid esters of phytosterols alter plasma lipids but not red blood cell fragility in hamsters

In an attempt to combine the hypocholesterolemic properties of plant sterols with the hypotriglyceridemic action of fish oil FA, plant sterols have recently been esterified to fish oil n−3 PUFA. The objective of this study was to determine the effects of plant sterols esterified to n−3 PUFA on plasma lipid levels and erythrocyte fragility. For 5 wk, male Golden Syrian hamsters were fed diets varying in cholesterol and plant sterol content: (i) Noncholesterol (semipurified diet with no added cholesterol or plant sterols) (ii), Cholesterol (0.25% cholesterol) (iii), Sterols (0.25% cholesterol plus 1% nonesterified plant sterols), or (iv) Fish oil esters of plant sterols (0.25% cholesterol plus 1.76% EPA and DHA sterol esters, providing 1% plant sterols). The addition of fish oil esters of plant sterols to the cholesterol diet decreased (P=0.001) plasma total cholesterol levels by 20%, but nonesterified plant sterols did not have such a beneficial impact. In addition, non-HDL cholesterol concentrations were 29% lower in hamsters fed fish oil esters of plant sterols than in hamsters fed nonesterified plant sterols (P<0.0001). Despite higher (P<0.0001) plant sterol levels in whole erythrocytes of hamsters fed nonesterified plant sterols and fish oil esters of plant sterols compared with hamsters fed no plant sterols, no difference was observed in erythrocyte fragility. The present results show that EPA and DHA esters of plant sterols have a hypocholesterolemic effect in hamsters, and that these new esters of plant sterols exert no detrimental effect on erythrocyte fragility.     

Supplementation and delivery of n−3 fatty acids through spray-dried milk reduce serum and liver lipids in rats

Indian diets comprising staples such as cereals, millets, and pulses provide 4.8 energy % from linoleic acid (18∶2n−6) but fail to deliver adequate amounts of n−3 FA. Consumption of long-chain n−3 PUFA such as EPA (20∶5n−3) and DHA (22∶6n−3) is restricted to those who consume fish. The majority of the Indian population, however, are vegetarians needing additional dietary sources of n−3 PUFA. The present work was designed to use n−3 FA-enriched spray-dired milk powder to provide n−3 FA. Whole milk was supplemented with linseed oil to provide α-linolenic acid (LNA, 18∶3n−3), with fish oil to provide EPA and DHA, or with groundnut oil (GNO), which is devoid of n−3 PUFA, and then spray-dired. Male Wistar rats were fed the spray-dired milk formulations for 60 d. The rats given formulations containing n−3 FA showed significant increases (P<0.001) in the levels of LNA or EPA/DHA in the serum and in tissue as compared with those fed the GNO control formulation. Rats fed formulations containing n−3 FA had 30–35% lower levels of serum total cholesterol and 25–30% lower levels of serum TAG than control animals. Total cholesterol and TAG in the livers of rats fed the formulations containing n−3 FA were lower by 18–30% and 11–18%, respectively, compared with control animals. This study showed that spray-dried milk formulations supplemented with n−3 FA are an effective means of improving dietary n−3 FA intake, which may decrease the risk factors associated with cardiovascular disease.     

Effects of geographic source, rearing system, and season on the nutritional quality of wild and farmed Perca fluviatilis

The effects of season, geographic source (Lake Geneva, Rhine River), and rearing system (extensive, semiextensive, and intensive systems) on the lipid content and FA composition of fillets of Perca fluviatilis were studied. Significant differences in the total lipid content were found between fish coming from the Rhine River and Lake Geneva (1.21 and 1.48%, respectively). Seasonal effects were investigated quarterly for perch sampled in the Rhine River. Intensively reared perch displayed a higher lipid content (1.48%) than the other farmed perch, i.e., 1.26% for a semiextensive system and 1.16% for an extensive system. No significant difference in lipid content was found (i) between lacustrine fish and intensively reared fish or (ii) among fish from the Rhine River and the semiextensive or extensive rearing systems. The main FA were 22∶6n−3 (DHA, 21.3–37.1% of total FA), 16∶0 (17.7–20.2%), 20∶5n−3 (EPA, 9.2–13.2%), 18∶1 (8.0–11.5%), 20∶4n−6 [arachidonic acid (ARA), 1.9–10.7%], 16∶1 (4.3–6.0%), and 18∶2n−6 (2.1–6.0%). In comparison with perch coming from the Rhine River, the lacustrine fish were characterized by higher total n−6 PUFA and a lower proportion of both total monounsaturated FA (MUFA) and total n−3 PUFA. Among rearing systems, extensively farmed fish had higher n−6 PUFA and lower n−3 PUFA contents. Wild fish showed higher ARA and 18∶2n−6 than farmed fish. They also had significantly more EPA (12.5–13.2%) than farmed perch (9.2–10.9%). For DHA no difference existed between (i) the lacustrine fish (31.9% of total FA) and the intensively reared fish (33.0%) and (ii) the Rhine (37.1%) and semiextensively reared fish (36%). Effects of size, diet composition, and environmental conditions on the total lipid contents and FA composition are discussed.     

Dietary fish oil dose-response effects on ileal phospholipid fatty acids and contractility

We have reported that dietary fish oil (FO) leads to the incorporation of long-chain n−3 PUFA into the gut tissue of small animal models, affecting contractility, particularly of rat ileum. This study examined the FO dose response for the incorporation of n−3 PUFA into ileal tissue and how this correlated with in vitro contractility. Groups of ten to twelve 13-wk-old Wistar-Kyoto rats were fed 0, 1, 2.5, and 5% FO-supplemented diets balanced with sunflower seed oil for 4 wk, after which ileal total phospholipid FA were determined and in vitro contractility assessed. For the total phospholipid fraction, increasing the dietary FO levels led to a significant increase first evident at 1% FO, with a stepwise, nonsaturating six-fold increase in n−3 PUFA as EPA (20∶5n−3), DPA (docosapentaenoic acid, 22∶5n−3), and DHA, but mainly as DHA (22∶6n−3), replacing the n−6 PUFA linoleic acid (18∶2n−6) and arachidonic acid (20∶4n−6) over the dosage range. There was no difference in KCl-induced depolarization-driven contractility. However, a significant increase in receptor-dependent maximal contractility occurred at 1% FO for carbachol and at 2.5% FO for prostaglandin E₂, with a concomitant increase in sensitivity for prostaglandin E₂ at 2.5 and 5% FO. These results demonstrate that significant increases in ileal membrane n−3 PUFA occurred at relatively low doses of dietary FO, with differential receptor-dependent increases in contractility observed for muscarinic and prostanoid agonists.     

Blood phospholipid fatty acid analysis of adults with and without attention deficit/hyperactivity disorder

Several psychiatric disorders, including juvenile Attention Deficit/Hyperactivity Disorder (ADHD), have been associated with abnormalities of certain long-chain PUFA (LCPUFA). Despite this reported association, the FA levels of patients with the adult form of ADHD have not previously been evaluated. In this study we measured the total blood phospholipid FA concentrations in 35 control subjects and 37 adults with ADHD symptoms to determine whether adults with ADHD symptoms would show abnormalities of FA relative to control subjects. In the serum phospholipids, adults with ADHD symptoms had significantly lower levels of total saturated, total polyunsaturated, and total omega-6 (n−6) FA, as well as the omega-3 (n−3) LCPUFA DHA (22∶6n−3), and significantly higher levels of total monounsaturated FA and the n−3 LCPUFA docosapentaenoic acid (22∶5n−3). In the erythrocyte membrane phospholipids, adults with ADHD symptoms had significantly lower levels of total PUFA, total n−3 FA, and DHA, and significantly higher levels of total saturated FA. Neither serum nor erythrocyte membrane phospholipid DHA was related to ADHD symptom severity (as assessed by the Amen questionnaire) in ADHD subjects. Although the exact cause of these variations is unknown, both environmental and genetic factors may be involved.