Showing papers in "Lipids in 2005"

n-3 fatty acid enrichment of edible tissue of poultry: a review.

Abstract: There is clear evidence of the nutritional benefits of consuming long-chain n-3 PUFA, which are found predominantly in oily fish. However, oily fish consumption, particularly in the United Kingdom, is declining, as is the consumption of all meats with the exception of poultry, which has increased in consumption by 73% in the last 30 yr. This pattern, if less marked, is reflected throughout Europe, and therefore one means of increasing long-chain n-3 PUFA consumption would be to increase the long-chain n-3 PUFA content in the edible tissues of poultry. This review considers the feasibility of doing this, concentrating particularly on chickens and turkeys. It begins by summarizing the benefits to human health of consuming greater quantities of n-3 FA and the sources of n-3 PUFA in the human diet. The literature on altering the FA composition of poultry meat is then reviewed, and the factors affecting the incorporation of n-3 PUFA into edible tissues of poultry are investigated. The concentration of alpha-linolenic acid (ALA) in the edible tissues of poultry is readily increased by increasing the concentration of ALA in the birds' diet (particularly meat with skin, and dark meat to a greater extent than white meat). The concentration of EPA in both white and dark meat is also increased when the birds' diet is supplemented with EPA, although supplementing the diet with the precursor (ALA) does not result in a noticeable increase in EPA content in the edible tissues. Although supplementing the birds' diets with relatively high concentrations of DHA does result in an increased concentration of DHA in the tissues, the relationship between dietary and tissue concentrations of DHA is much weaker than that observed with ALA and EPA. The impact that altering the FA composition of edible poultry tissue may have on the organoleptic and storage qualities of poultry products is also considered.

A study on the causes for the elevated n−3 fatty acids in cows' milk of alpine origin

Abstract: The influence of grass-only diets either from rye-grass-dominated lowland pastures (400 m above sea level) or botanically diverse alpine pastures (2000 m) on the FA profile of milk was investigated using three groups of six Brown Swiss cows each. Two groups were fed grass-only on pasture (P) or freshly harvested in barn (B), both for two experimental periods in the lowlands and, consecutively, two periods on the alp. Group C served as the control, receiving a silage-concentrate diet and permanently staying in the lowlands. Effects of vegetation stage or pasture vs. barn feeding on milk fat composition were negligible. Compared with the control, α-linoleic acid (18∶3n−3) consumption was elevated in groups P and B (79%, P<0.001) during the lowland periods but decreased on the alp to the level of C owing to feed intake depression and lower 18∶3n−3 concentration in the alpine forage. Average 18∶3n−3 contents of milk fat were higher in groups, P and B than in C by 33% (P<0.01) at low and by 96% (P<0.001) at high altitude, indicating that 18∶3n−3 levels in milk were to some extent independent of 18∶3n−3 consumption. The cis-9,trans-11 CLA content in milk of grass-fed cows was higher compared with C but lower for the alpine vs. lowland periods whereas the trans-11, cis-13 isomer further increased with altitude. Long-chain n−3 FA and phytanic acid increased while arachidonic acid decreased with grass-only feeding, but none of them responded to altitude. Grass-only feeding increased milk α-tocopherol concentration by 86 and 134% at low and high altitude (P<0.001), respectively. Changes in the ruminal ecosystem due to energy shortage or specific secondary plant metabolites are discussed as possible causes for the high 18∶3n−3 concentrations in alpine milk.

Gas chromatographic quantification of fatty acid methyl esters: flame ionization detection vs. electron impact mass spectrometry.

Abstract: The determination of FAME by GC is among the most commonplace analyses in lipid research. Quantification of FAME by GC with FID has been effectively performed for some time, whereas detection with MS has been used chiefly for qualitative analysis of FAME. Nonetheless, the sensitivity and selectivity of MS methods advocate a quantitative role for GC-MS in FAME analysis—an approach that would be particularly advantageous for FAME determination in complex biological samples, where spectrometric confirmation of analytes is advisable. To assess the utility of GC-MS methods for FAME quantification, a comparative study of GC-FID and GC-MS methods has been conducted. FAME in prepared solutions as well as a biological standard reference material were analyzed by GC-FID and GC-MS methods using both ion trap and quadrupole MS systems. Quantification by MS, based on total ion counts and processing of selected ions, was investigated for FAME ionized by electron impact. Instrument precision, detection limits, calibration behavior, and response factors were investigated for each approach, and quantitative results obtained by each technique were compared. Although there were a number of characteristic differences between the MS methods and FID with respect to FAME analysis, the quantitative performance of GC-MS compared satisfactorily with that of GC-FID. The capacity to combine spectrometric examination and quantitative determination advances GC-MS as a powerful alternative to GC-FID for FAME analysis.

Highly unsaturated fatty acid synthesis in vertebrates: New insights with the cloning and characterization of a Δ6 desaturase of Atlantic salmon

Abstract: Fish are an important source of the n−3 highly unsaturated fatty acids (HUFA), eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids that are crucial to the health of higher vertebrates. The synthesis of HUFA involves enzyme-mediated desaturation, and a Δ5 fatty acyl desaturase cDNA has been cloned from Atlantic salmon (Salmo salar) and functionally characterization of a Δ6 fatty acyl desaturase of Atlantic salmon and describe its genomic structure, tissue expression, and nutritional regulation. A salmon genomic library was screened with a salmon Δ5 desaturase cDNA and positive recombinant phage isolated and subcloned. The full-length cDNA for the putative fatty acyl desaturase was shown to comprise 2106 bp containing an open reading frame of 1365 bp specifying a protein of 454 amino acids (GenBank accession no. AY458652). The protein sequence included three histidine boxes, two transmembrane regions, and an N-terminal cytochrome b5 domain containing the heme-binding motif HPGG, all of which are characteristic of microsomal fatty acid desaturases. Functional expression showed that this gene possessed predominantly Δ6 desaturase activity. Screening and sequence analysis of the genomic DNA of a single fish revealed that the Δ6 desaturase gene constituted 13 exons in 7965 bp of genomic DNA. Quantitative real-time PCR assay of gene expression in Atlantic salmon showed that both Δ6 and Δ5 fatty acyl desaturase genes, and a fatty acyl elongase gene, were highly expressed in intestine, liver, and brain, and less so in kidney, heart, gill, adipose tissue, muscle, and spleen. Furthermore, expression of both Δ6 and Δ5 fatty acyl desaturase genes in intestine, liver, red muscle, and adipose tissue was higher in salmon fed a diet containing vegetable oil than in fish fed a diet containing fish oil.

The impact of age, body mass index, and fish intake on the EPA and DHA content of human erythrocytes.

Abstract: n−3 FA are beneficial for cardiovascular health, reducing platelet aggregation, TG levels, and the risk of sudden death from myocardial infarction. The percentage of EPA + DHA in red blood cells (RBC), also known as the Omega-3 Index, has recently been proposed as a risk marker for death from coronary heart disease (CHD). The purpose of this study was to begin to explore the factors that can influence RBC EPA + DHA. We collected information on the number of servings of tuna or nonfried fish consumed per month, as well as on age, gender, ethnicity, smoking status, the presence of diabetes, and body mass index (BMI) in 163 adults in Kansas City who were not taking fish oil supplements. The average RBC EPA + DHA in this population was 4.9±2.1%. On a multivariate analysis, four factors significantly and independently influenced the Omega-3 Index: fish servings, age, BMI, and diabetes. The Index increased by 0.24 units with each additional monthly serving of tuna or nonfried fish (P<0.0001), and by 0.5 units for each additional decade in age (P<0.0001). The Index was 1.13% units lower in subjects with diabetes (P=0.015) and decreased by 0.3% units with each 3-unit increase in BMI (P=0.001). Gender or smoking status had no effect, and the univariate relationship with ethnicity vanished after controlling for deathfrom CHD, further studies are warranted to delineate the nondietary factors that influence RBC EPA + DHA content.

Overview of hemostatic factors involved in atherosclerotic cardiovascular disease.

Abstract: Hemostatic factors associated with the development of cardiovascular disease (CVD) include fibrinogen, von Willebrand factor, tissue plasminogen activator (tPA) antigen, plasminogen activator inhibitor-1 (PAI-1), and factor VII. Each SD increment of these increases the association by 24–30%. Most hemostatic factors are intercorrelated with inflammatory markers [e.g., C-reactive protein (CRP)] and LDL cholesterol. Fibrinogen seems the most fundamental hemostatic risk factor for CVD. The Framingham Study reaffirms the significant linear risk factor trends across fibrinogen tertiles (P<0.001) for age, body mass index, smoking, diabetes mellitus, total cholesterol, HDL cholesterol, and TG in both sexes. Fibrinogen may also directly increase CVD risk because of its role in platelet aggregation, plasma viscosity, and fibrin formation. Fibrinogen is also an acute-phase reactant that is elevated in inflammatory states. Fibrinogen mediates the thrombogenic effect of other risk factors. Fibrinogen levels increase with the number of cigarettes smoked and quickly fall after smoking cessation. This rapid fibrinogen decline may be a mechanism for CVD risk reduction after smoking cessation. Weight loss is accompanied by reduced fibrinogen. The correlation between fibrinogen and LDL cholesterol suggests that lipidimposed CVD risk is mediated partly through fibrinogen. Hyperreactive platelets of diabetics may result in part from their increased fibrinogen. Elevated fibrinogen and CRP of unstable angina suggest an acute-phase reaction. Prevalence, case-control, angiographic, and echocardiogram investigations incriminate hemostatic and inflammatory markers as strong independent risk factors for initial and recurrent CVD. Framingham Study data indicate that each SD increase in fibrinogen imposes a 20% independent increment in risk. It may be concluded that fibrinogen and CRP determination may be useful screening tools to identify individuals at added risk for thrombotic complications of CVD.

Fatty acid composition of wild and farmed Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss).

Abstract: The goal of this study was to examine the FA composition of wild and farmed Atlantic salmon (AS) and rainbow trout (RT). FA profiles were obtained by GC/FID. Results showed that lipid and n-3 highly unsaturated FA contents of farmed and wild AS were similar. Total n-3 and n-6 PUFA were significantly higher in farmed AS than in wild AS. Farmed RT contained more fat and less n-3 PUFA than wild RT. Our results show that farmed salmonids provide high levels of n-3 HUFA to consumers.

Furan fatty acids: occurrence, synthesis, and reactions. Are furan fatty acids responsible for the cardioprotective effects of a fish diet?

Abstract: Furan FA (F-acids) are tri-or tetrasubstituted furan derivatives characterized by either a propyl or pentyl side chain in one of the α-positions; the other is substituted by a straight long-chain saturated acid with a carboxylic group at its end. F-acids are generated in large amounts in algae, but they are also produced by plants and microorganisms. Fish and other marine organisms as well as mammals consume F-acids in their food and incorporate them into phospholipids and cholesterol esters. F-acids are catabolized to dibasic urofuran acids, which are excreted in the urine. The biogenetic precursor of the most abundant F-acid, F6, is linoleic acid. Methyl groups in the β-position are derived from adenosylmethionine. Owing to the different alkyl substituents, synthesis of F-acids requires multistep reactions. F-acids react readily with peroxyl radicals to generate dioxoenes. The radical-scavenging ability of F-acids may contribute to the protective properties of fish and fish oil diets against mortality from heart disease.

Effects of stearic acid on plasma lipid and lipoproteins in humans.

Abstract: More than 40 years ago, saturated FA with 12, 14, and 16 carbon atoms (lauric acid, myristic acid, and palmitic acid) were demonstrated to be "hypercholesterolemic saturated FA". It was further concluded that the serum total cholesterol level would hardly be changed by isocaloric replacement of stearic acid (18:0) by oleic acid (cis-18:1n-9) or carbohydrates. These earlier studies did not address the effects of the various FA on the serum lipoprotein profile. Later studies found that the hypercholesterolemic saturated FA increase serum total cholesterol levels by raising concentrations of both the atherogenic LDL and the antiatherogenic HDL. Consequently, the ratio of total to HDL cholesterol will hardly change when carbohydrates replace these saturated FA. Compared with other saturated FA, stearic acid lowers LDL cholesterol. Studies on the effects on HDL cholesterol are less conclusive. In some, the effects on HDL cholesterol were comparable to those of palmitic acid, oleic acid, and linoleic acid, whereas in others a decrease was observed. This may suggest that in this respect the source of stearic acid is of importance, which needs however further study. From all these studies, however, it can be concluded that stearic acid may decrease the ratio of total to HDL cholesterol slightly when compared with palmitic or myristic acid. Without doubt, the effects of stearic acid are more favorable than those of trans monounsaturated FA.

Dietary phospholipids are more efficient than neutral lipids for long-chain polyunsaturated fatty acid supply in European sea bass Dicentrarchus labrax larval development

Abstract: We evaluated the effects of dietary lipid class (phospholipid vs. neutral lipid) and level of n-3 long-chain PUFA (LC-PUFA) on the growth, digestive enzymatic activity, and histological organization of the intestine and liver in European sea bass larvae. Fish were fed from the onset of exogenous feeding at 7 to 37 d post-hatch with five isoproteic and isolipidic compound diets with different levels of EPA and DHA. Diet names indicated the percentage of EPA and DHA contained in the phospholipids (PL) and neutral lipids (NL), as follows: PL5, PL3, PL1, NL1, and NL3. Histological observations showed different patterns of lipid absorption and accumulation in the intestinal mucosa depending on the level and nature of the dietary lipid fraction. Fish fed high levels of neutral lipids (11%, NL3 diet: 2.6% of EPA + DHA in the NL fraction) showed large intracellular and intercellular lipid deposits in the anterior intestine, but no such lipid accumulation was detected when larvae were fed with low and moderate levels of EPA and DHA in the phospholipid and neutral lipid fractions of the diet (PL and NL1 diets). PL were preferentially absorbed in the postvalvular intestine, and the accumulation of marine PL was inversely correlated to their dietary level. The postvalvular intestinal mucosa and liver showed signs of steatosis; large lipid vacuoles were observed in this region of the intestine and in the liver and were inversely correlated with the level of dietary neutral lipids. The best results in terms of growth, survival, and development (maturation of the digestive system and histological organization of the liver and intestinal mucosa) were obtained in the group fed with 2.3% of EPA and DHA in the PL fraction of the diet (PL3 diet), revealing that European sea bass larvae use the LC-PUFA contained in the PL fraction more efficiently than those from the NL fraction of the diet.

Dietary stearic acid and risk of cardiovascular disease: intake, sources, digestion, and absorption.

Abstract: Individual FA have diverse biological effects, some of which affect the risk of cardiovascular disease (CVD). In the context of food-based dietary guidance designed to reduce CVD risk, fat and FA recommendations focus on reducing saturated FA (SFA) and trans FA (TFA), and ensuring an adequate intake of unsaturated FA. Because stearic acid shares many physical properties with the other long-chain SFA but has different physiological effects, it is being evaluated as a substitute for TFA in food manufacturing. For stearic acid to become the primary replacement for TFA, it is essential that its physical properties and biological effects be well understood.

Recent advances in the biochemistry and clinical relevance of the isoprostane pathway.

Abstract: Isoprostanes (IsoPs), lipid peroxidation products formed via the free radical-mediated oxidation of arachidonic acid, have become the "gold standard" biomarker of oxidative stress in vivo over the past 15 yr. Significant advances have been made in understanding this important pathway of lipid peroxidation. Recent studies from our laboratory are discussed that have provided insights into the mechanism of formation and regioisomeric distribution of these compounds and that have identified novel products of the IsoP pathway such as cyclized dioxolane IsoPs, IsoP-derived racemic prostaglandins, and reactive cyclopentenone IsoP, the latter of which possess potent biological actions. Furthermore, new independent studies have demonstrated that IsoPs are the most reliable available marker of lipid peroxidation in vivo, and recent work examining IsoP formation has provided valuable information about the pathogenesis of numerous human diseases. Thus, the complexity of the IsoP pathway has expanded, providing novel insights into mechanisms of lipid peroxidation in vivo and allowing investigators to explore the role of oxidative stress in human disease.

A rapid method for the quantification of fatty acids in fats and oils with emphasis on trans fatty acids using Fourier Transform near infrared spectroscopy (FT-NIR).

Abstract: A rapid method was developed for classifying and quantifying the FA composition of edible oils and fats using Fourier Transform near infrared spectroscopy (FT-NIR). The FT-NIR spectra showed unique fingerprints for saturated FA, cis and trans monounsaturated FA, and all n-6 and n-3 PUFA within TAG to permit qualitative and quantitative comparisons of fats and oils. The quantitative models were based on incorporating accurate GC data of the different fats and oils and FT-NIR spectral information into the calibration model using chemometric analysis. FT-NIR classification models were developed based on chemometric analyses of 55 fats, oils, and fat/oil mixtures that were used in the identification of similar materials. This database was used to prepare three calibration models-one suitable for the analysis of common fats and oils with low levels of trans FA, and the other two for fats and oils with intermediate and high levels of trans FA. The FT-NIR method showed great potential to provide the complete FA composition of unknown fats and oils in minutes. Compared with the official GC method, the FT-NIR method analyzed fats and oils directly in their neat form and required no derivatization of the fats to volatile FAME, followed by time-consuming GC separations and analyses. The FT-NIR method also compared well with the official FTIR method using an attenuated total reflectance (ATR) cell; the latter provided only quantification of specific functional groups, such as the total trans FA content, whereas FT-NIR provided the complete FA profile. The FT-NIR method has the potential to be used for rapid screening and/or monitoring of fat products, trans FA determinations for regulatory labeling purposes, and detection of contaminants. The quantitative FT-NIR results for various edible oils and fats and their mixtures are presented based on the FT-NIR models developed.

Effect of pasture vs. concentrate diet on CLA isomer distribution in different tissue lipids of beef cattle.

Abstract: This study examined the effects of feeding pasture vs. concentrate on the distribution of CLA isomers in the lipids of longissimus and semitendinosus muscle, liver and heart muscle, and subcutaneous fat in beef bulls. Sixty-four German Holstein and German Simmental bulls were randomly allocated to either an indoor concentrate system or periods of pasture feeding followed by a finishing period on a concentrate containing linseed to enhance their beef content of n-3 PUFA and CLA. The concentrations of CLA isomers in the different tissues were determined by GC and silver ion HPLC. The diet affected the distribution of individual CLA isomers in the lipids of the different tissues. The concentration (mg/100 g fresh tissue) of the most prominent isomer, cis-9,trans-11 18:2, was increased up to 1.5 times in liver and heart tissue of bulls fed on pasture as compared with concentrate. However, no diet effect was observed for cis-9,trans-11 18:2 in the lipids of longissimus muscle and subcutaneous fat. In all tissues, the second-most abundant CLA isomer in concentrate-fed bulls was trans-7,cis-9 18:2. In contrast, trans-11,cis-13 18:2 was the second-most abundant CLA isomer in all investigated tissue lipids of pasture-fed bulls. The concentration of the trans-11,cis-13 18:2 isomer was up to 15 times higher in tissues of pasture-fed bulls as compared with concentrate-fed animals. Furthermore, diet affected the concentrations of the CLA trans,trans 18:2 isomers. Pasture feeding significantly increased the concentrations of some trans,trans 18:2 isomers as compared with concentrate, predominantly trans-12,trans-14 18:2 and trans-11,trans-13 18:2. Overall, pasture feeding resulted in significantly increased concentrations of the sum of CLA isomers in the lipids of longissimus muscle, subcutaneous fat, heart and liver muscle of German Holstein and German Simmental bulls, but not in semitendinosus muscle.

Effects of droplet size on the oxidative stability of oil-in-water emulsions

Abstract: The effects of droplet size and emulsifiers on oxidative stability of polyunsaturated TAG in oil-in-water (o/w) emulsions with droplet sizes of 0.806±0.0690, 3.28±0.0660, or 10.7±0.106 μm (mean ± SD) were investigated. Hydroperoxide contents in the emulsion with a mean droplet size of 0.831 μm were significantly lower than those in the emulsion with a mean droplet size of 12.8 μm for up to 120 h of oxidation time. Residual oxygen contents in the headspace air of the vials containing an o/w emulsion with a mean droplet size of 0.831 μm were lower compared with those of the emulsion with a mean droplet size of 12.8 μm. Hexanal developed from soybean oil TAG o/w emulsions with smaller droplet size showed significantly lower residual oxygen contents than those of the larger droplet size emulsions. Consequently, oxidative stability of TAG in o/w emulsions could be controlled by the size of oil droplet even though the origins of TAG were different. Spin-spin relaxation time of protons of acyl residues on TAG in o/w emulsions measured by 1H NMR suggested that motional frequency of some acyl residues was shorter in o/w emulsions with a smaller droplet size. The effect of the wedge associated with hydrophobic acyl residues of emulsifiers was proposed as a possible mechanism to explain differences in oxidative stability between o/w emulsions with different droplet sizes.

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

Abstract: 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.

β-Oxidation Capacity of Red and White Muscle and Liver in Atlantic Salmon (Salmo salar L.)—Effects of Increasing Dietary Rapeseed Oil and Olive Oil to Replace Capelin Oil

Abstract: Post-smolt Atlantic salmon (Salmo salar) were fed six diets in which capelin oil was replaced with 0, 25, 50, 75, or 100% rapeseed oil (RO; low-erucic acid) or 50% olive oil (OO). The experimental diets were fed to single groups of Atlantic salmon for 42 wk, whereas the 100% capelin oil (0% RO) diet was fed in duplicate. The β-oxidation capacity of palmitoyl-CoA was determined, using a method optimized for salmon tissues, at the start of the experiment, after 21 wk (October), and after 42 wk (March) in red and white muscle and in liver. Red muscle showed the highest specific β-oxidation capacity, but when expressed as total β-oxidation capacity for the whole tissue, white muscle was the most important tissue for the β-oxidation of FA. From the initial to the final sampling, the β-oxidation capacity of white muscle increased significantly, whereas the β-oxidation capacity in liver decreased significantly. After 22 wk, white muscle exhibited an increased β-oxidation capacity when the dietary RO content was raised from 25 to 75%, with similar effects in red muscle and liver after 42 wk of feeding. The present results also show that the β-oxidation capacity increased with an increase in fish size.

Effect of abomasal infusions of geometric isomers of 10,12 conjugated linoleic acid on milk fat synthesis in dairy cows

Abstract: The trans-10,cis-12 isomer of conjugated linoleic acid (CLA) decreases TAG accumulation in 3T3-L1 adipocytes, reduces lipid accretion in growing animals, and inhibits milk fat synthesis in lactating mammals. However, there is evidence to suggest that other FA may also exert antilipogenic effects. In the current experiment, the effects of geometric isomers of 10,12 CLA on milk fat synthesis were examined using four Holstein-British Friesian cows in a 4 x 4 Latin Square experiment with 14-d periods. Treatments consisted of abomasal infusions of skim milk, or skim milk containing trans-10,cis-12 CLA (T1), trans-10,trans-12 CLA (T2), or a mixture of predominantly 10,12 isomers containing (g/l00 g) trans-10,cis-12 (35.0), cis-10,trans-12 (23.2), trans-10,trans-12 (14.9), and cis-10,cis-12 (5.1). CLA supplements were prepared from purified ethyl linoleate and infused as nonesterified FA. Infusions were conducted over a 4-d period with a 10-d interval between treatments and targeted to deliver 4.5 g/d of 10,12 CLA isomers. Compared with the control, trans-10, trans-12 CLA had no effect (P> 0.05) on milk fat yield, whereas treatments T1 and T3 depressed (P < 0.05) milk fat content (19.8 and 22.9%, respectively) and decreased milk fat output (20.8 and 21.3%, respectively). Comparable reductions in milk fat synthesis to 4.14 and 1.80 g trans-10,cis-12/d supplied by treatments T1 and T3 indicate that other 10,12 geometric isomers of CLA have the potential to exert antilipogenic effects. The relative abundance of cis-10,trans-12 CLA in treatment T3 and the low transfer efficiency of this isomer into milk suggest that cis-10,trans-12 CLA was the active component..

The fate and intermediary metabolism of stearic acid.

Abstract: Coming from the Greek for "hard fat," stearic acid represents one of the most abundant FA in the Western diet. Otherwise known as n-octadecanoic acid (18:0), stearate is either obtained in the diet or synthesized by the elongation of palmitate, the principal product of the FA synthase system in animal cells. Stearic acid has been shown to be a very poor substrate for TG synthesis, even as compared with other saturated fats such as myristate and palmitate, and in human studies stearic acid has been shown to generate a lower lipemic response than medium-chain saturated FA. Although it has been proposed that this may be due to less efficient absorption of stearic acid in the gut, such findings have not been consistent. Along with palmitate, stearate is the major substrate for the enzyme stearoyl-CoA desaturase, which catalyzes the conversion of stearate to oleate, the preferred substrate for the synthesis of TG and other complex lipids. In mice, targeted disruption of the stearoyl-CoA desaturase-1 (SCD1) gene results in the generation of a lean mouse that is resistant to diet-induced obesity and insulin resistance. SCD1 also has been shown to be a key target of the anorexigenic hormone leptin, thus underscoring the importance of this enzyme, and consequently the cellular stearate-to-oleate ratio, in lipid metabolism and potentially in the treatment of obesity and related disorders.

Docosahexaenoic acid supplementation in vegetarians effectively increases omega-3 index: a randomized trial.

Abstract: Low red blood cell (RBC) membrane content of FPA+DHA (hereafter called omega-3 index) has recently been described as an indicator for increased risk of death from coronary heart disease. The relationship between plasma and RBC FA, focusing on omega-3 index, and the response to DHA supplementation were investigated in a double-blind, randomized, placebo-controlled, intervention study. Healthy vegetarians (87 f, 17 m) consumed daily a microalgae oil from Ulkenia sp. (0.94 g DHA/d) or olive oil (placebo) for 8 wk. DHA supplementation significantly increased DHA in RBC total lipids (7.9 vs. 4.4 wt%), in RBC PE (12.1 vs. 6.5 wt%), in RBC PC (3.8 vs. 1.4 wt%), and in plasma phospholipids (PL) (7.4 vs. 2.8 wt%), whereas EPA levels rose to a much lesser extent. Microalgae oil supplementation increased the omega-3 index from 4.8 to 8.4 wt%. After intervention, 69% of DHA-supplemented subjects (but no subject of the placebo group) reached an omega-3 index above the desirable value of 8 wt%. Omega-3 index and EPA+DHA levels in RBC PE, RBC PC, and plasma PL were closely correlated (r always >0.9). We conclude that an 8-wk supplementation with 0.94 g DHA/d from microalgae oil achieves a beneficial omega-3 index of ≥8% in most subjects with low basal EPA+DHA status. RBC total FA analyses can be used instead of RBC lipid fraction analyses for assessing essential FA status, e.g., in clinical studies.

Astonishing diversity of natural surfactants: 5. Biologically active glycosides of aromatic metabolites.

Abstract: This review article presents 342 aromatic glycosides, isolated from and identified in plants and microorganisms, that demonstrate different biological activities. They are of great interest, especially for the medicinal and/or pharmaceutical industries. These biologically active natural sufactants are good prospects for the future chemical preparation of compounds useful as antioxidant, anticancer, antimicrobial, and antibacterial agents. These glycosidic compounds have been classified into several groups, including simple aromatic compounds, stilbenes, phenylethanoids, phenylpropanoids, naphthalene derivatives, and anthracene derivatives.

Monitoring the oxidation of docosahexaenoic acid in lipids

Abstract: The oxidation of free DHA, DHA mixed with PC, and DHA incorporated into PC, PE, or TG was evaluated to determine which lipid provided DHA with the best protection against oxidation. DHA was either situated at the sn-1 position, sn-2 position, or both positions of the phospholipid, whereas the TG contained DHA at all positions. All lipids were incubated as bulk lipids, in chloroform, or as an emulsion in contact with air at 25-30 degrees C for 28 d. Since DHA, which is highly sensitive to oxidation, has a great impact on our health and is desired as a food additive, the stability of this FA is of great importance. This study was mainly focused on the primary oxidation products, which were monitored as eight monohydroperoxy-DHA isomer groups, the total amount of polyhydroperoxides, and the PV. However, a measure of secondary oxidation products, the carbonyl value, was also monitored. We found that DHA was most protected against hydroperoxide formation when it was incorporated at one position of either PC or PE. In these lipids, hydroperoxide formation at carbon atoms 4, 7, 8, and 11 was completely prevented. DHA mixed with PC was also protected, although to a lesser extent, and all hydroperoxide isomers were detected. In contrast, PC and TG containing DHA at all positions should be avoided, since they were highly oxidized.

Eicosapentaenoic acid, but not oleic acid, stimulates β-oxidation in adipocytes

Abstract: The beneficial roles of dietary fish oil in lowering serum TAG levels in animals and humans have been attributed in part to the high content of two n−3 polyunsaturated very long-chain FA, EPA, and DHA. Recent studies show that EPA induces mitochondrial β-oxidation in hepatocytes, which might contribute to the systemic lipid-lowering effect. Whether EPA affects FA storage or oxidation in adipocytes is not clear. To investigate this possibility, 3T3-L1 adipocytes incubated with EPA (100 μM) for 24 h were assayed for β-oxidation, carnitine palmitoyl transferase 1 (CPT-1) activity, protein, and mRNA expression of CPT-1. For comparison, cells treated with oleic acid, octanoic acid, and clofibrate, a synthetic ligand for peroxisome proliferator-activated receptor α were also analyzed. Mitochondria were isolated by differential centrifugation, and the mitochondrial membrane acyl chain composition was measured by GLC. EPA increased the oxidation of endogenous FA but did not inhibit lipogenesis. Oleic acid and clofibrate did not affect FA oxidation or lipogenesis, whereas octanoic acid suppressed the oxidation of endogenous FA and inhibited lipogenesis. Increased β-oxidation by EPA was associated with increased CPT-1 activity but without changes in its mRNA and protein expression. EPA treatment increased the percentage of this FA in the mitochondrial membrane lipids. We suggest that EPA increased the activity of CPT-1 and β-oxidation in adipocytes by altering the structure or dynamics of the mitochondrial membranes.

Antioxidant activity of various teas against free radicals and LDL oxidation.

Abstract: Tea is a widely consumed beverage throughout the world. We assessed the antioxidant activity of six teas, including the aqueous extracts of green tea and oolong tea (Camellia sinensis), tochu (Eucommia ulmoides), Gymnema sylvestre, Japanese mugwort (Artemisia princeps), and barley (Hordeum vulgare), against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and LDL oxidation, and examined the association of LDL oxidizability with the plasma catechin levels in 10 healthy volunteers with a single dose of 5 g green tea powder. In vitro, the inhibitory effects of DPPH radicals and LDL oxidation were found to be strongest in the extract of green tea and weakest in that of barley. After the ingestion of green tea powder, the lag time increased from basal 52.2 +/- 4.1 to 60.3 +/- 4.2 min at 1 h and 59.5 +/- 4.1 min at 2 h, and then returned to the baseline lag time (51.9 +/- 1.4 at 4 h and 52.1 +/- 4.7 min at 6 h). Regarding the plasma catechin levels, epigallocatechingallate and epicatechingallate significantly increased from basal 3.7 +/- 1.3 and 0.8 +/- 0.8 ng/mL to 65.7 +/- 11.6 and 54.6 +/- 12.6 ng/mL at 1 h, and 74.4 +/- 18.6 and 49.4 +/- 7.1 ng/mL at 2 h, respectively. Green tea therefore showed the strongest antioxidant activity among the six different teas, and the inhibitory effects of green tea on LDL oxidation depended on the plasma catechin levels.

Comparative effects of palm vitamin E and α-tocopherol on healing and wound tissue antioxidant enzyme levels in diabetic rats

Abstract: The effect of supplementing 200 mg/kg body weight palm vitamin E (PVE) and 200 mg/kg body weight α-tocopherol (α-loc) on the healing of wounds in streptozotocin-induced diabetic rats was evaluated. The antioxidant potencies of these two preparations of vitamin E were also evaluated by determining the antioxidant enzyme activities, namely, glutathione peroxidase (GPx) and superoxide dismutase (SOD), and malondialdehyde (MDA) levels in the healing of dermal wounds. Healing was evaluated by measuring wound contractions and protein contents in the healing wounds. Cellular redistribution and collagen deposition were assessed morphologically using cross-sections of paraffin-embedded day-10 wounds stained according to the Van Gieson method. GPx and SOD activities as well as MDA levels were determined in homogenates of day-10 dermal wounds. Results showed that PVE had a greater potency to enhance wound repair and induce the increase in free radical-scavenging enzyme activities than α-Toc. Both PVE and α-Toc, however, were potent antioxidants and significantly reduced the lipid peroxidation levels in the wounds as measured by the reduction in MDA levels.

Identification and quantification of glycerolipids in cotton fibers: reconciliation with metabolic pathway predictions from DNA databases.

Abstract: The lipid profiles of cotton fiber cells were determined from total lipid extracts of elongating and maturing cotton fiber cells to see whether the membrane lipid composition changed during the phases of rapid cell elongation or secondary cell wall thickening. Total FA content was highest or increased during elongation and was lower or decreased thereafter, likely reflecting the assembly of the expanding cell membranes during elongation and the shift to membrane maintenance (and increase in secondary cell wall content) in maturing fibers. Analysis of lipid extracts by electrospray ionization and tandem MS (ESI-MS/MS) revealed that in elongating fiber cells (7-10 d post-anthesis), the polar lipids-PC, PE, PI, PA, phosphatidylglycerol, monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and phosphatidylglycerol-were most abundant. These same glycerolipids were found in similar proportions in maturing fiber cells (21 dpa). Detailed molecular species profiles were determined by ESI-MS/MS for all glycerolipid classes, and ESI-MS/MS results were consistent with lipid profiles determined by HPLC and ELSD. The predominant molecular species of PC, PE, PI, and PA was 34:3 (16:0, 18:3), but 36:6 (18:3,18:3) also was prevalent. Total FA analysis of cotton lipids confirmed that indeed linolenic (18:3) and palmitic (16:0) acids were the most abundant FA in these cell types. Bioinformatics data were mined from cotton fiber expressed sequence tag databases in an attempt to reconcile expression of lipid metabolic enzymes with lipid metabolite data. Together, these data form a foundation for future studies of the functional contribution of lipid metabolism to the development of this unusual and economically important cell type.

Changes in the milk and cheese fat composition of ewes fed commercial supplements containing linseed with special reference to the CLA content and isomer composition.

Abstract: A study was carried out to increase the CLA contents in ewes’ milk fat under field conditions by dietary means and to investigate the extent of the changes and consequences for milk processing and cheese quality. During a 3-mon period, ewes’ bulk milk samples were collected every week from two different herds. For the first 4 wk the ewes were fed a conventional diet. Then the following 6 wk a supplement enriched in α-linolenate (whole linseed) was incorporated into the ovine diet. Finally, in the last 3 wk the feeding was the same as in the first 4 wk. The FA profile in milk fat was monitored by GC, and the distribution of CLA isomers was thoroughly tested by combining GC-MS of 4,4-dimethyloxazoline derivatives (DMOX) with silver ion-HPLC (Ag+-HPLC) of FAME. Reconstructed mass spectral profiles of CLA characteristic ions from DMOX were used to identify positional isomers, and Ag+-HPLC was used to quantify them. An increase in total CLA in milk fat was observed, and total CLA remained elevated during the weeks of enriched α-linolenate feeding. In our experimental conditions there was a linear relationship between trans-vaccenic acid (trans-11-octadecenoic acid; trans-11 18∶1) and 9-cis, 11-trans CLA in ewes’ milk fat. Concerning the CLA isomer profile, increases in the 11,13- and 12,14–18∶2 positional isomers were considerable when linseed was included in the diet. Organoleptic characteristics of cheeses made with CLA-enriched milk did not substantially differ from those made with nonsupplemented ewes’ milk. CLA total content and isomer profile did not change during ripening.

Application of supercritical fluid chromatography in the quantitative analysis of minor components (carotenes, vitamin E, sterols, and squalene) from palm oil.

Abstract: The application of supercritical fluid chromatography (SFC) coupled with a UV variable-wavelength detector to isolate the minor components (carotenes, vitamin E, sterols, and squalene) in crude palm oil (CPO) and the residual oil from palm-pressed fiber is reported. SFC is a good technique for the isolation and analysis of these compounds from the sources mentioned. The carotenes, vitamin E, sterols, and squalene were isolated in less than 20 min. The individual vitamin E isomers present in palm oil were also isolated into their respective components, alpha-tocopherol, alpha-tocotrienol, gamma-tocopherol, gamma-tocotrienol, and delta-tocotrienol. Calibration of all the minor components of palm as well as the individual components of palm vitamin E was carried out and was found to be comparable to those analyzed by other established analytical methods.

Dietary α-linolenic acid increases brain but not heart and liver docosahexaenoic acid levels

Abstract: Fish oil-enriched diets increase n-3 FA in tissue phospholipids; however, a similar effect by plant-derived n-3 FA is poorly defined. To address this question, we determined mass changes in phospholipid FA, individual phospholipid classes, and cholesterol in the liver, heart, and brain of rats fed diets enriched in flax oil (rich in 18:3n-3), fish oil (rich in 22:6n-3 and 20:5n-3), or safflower oil (rich in 18:2n-6) for 8 wk. In the heart and liver phospholipids, 22:6n-3 levels increased only in the fish oil group, although rats fed flax oil accumulated 20:5n-3 and 22:5n-3. However, in the brain, the flax and fish oil diets increased the phospholipid 22:6n-3 mass. In all tissues, these diets decreased the 20:4n-6 mass, although the effect was more marked in the fish oil than in the flax oil group. Although these data do not provide direct evidence for 18:3n-3 elongation and desaturation by the brain, they demonstrate that 18:3n-3-enriched diets reduced tissue 20:4n-6 levels and increased cellular n-3 levels in a tissue-dependent manner. We hypothesize, based on the lack of increased 22:6n-3 but increased 18:3n-3 in the liver and heart, that the flax oil diet increased circulating 18:3n-3, thereby presenting tissue with this EFA for further elongation and desaturation.

Astonishing diversity of natural surfactants: 3. Carotenoid glycosides and isoprenoid glycolipids

Abstract: Carotenoid glycosides and isoprenoid glycolipids are of great interest, especially for the medicinal, pharmaceutical, food, cosmetic, flavor, and fragrance industries. These biologically active natural surfactants have good prospects for the future chemical preparation of compounds useful as antimicrobial, antibacterial, and antitumor agents, or in industry. More than 300 unusual natural surfactants are described in this review article, including their chemical structures and biological activities.