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PubMed1998

Metabolic routing towards polyhydroxyalkanoic acid synthesis in recombinant Escherichia coli (fadR): inhibition of fatty acid beta-oxidation by acrylic acid.

Heterologous expression of the phaC1 gene from Pseudomonas aeruginosa, which encodes one of the polyhydroxyalkanoic acid synthases, in Escherichia coli impaired in fatty acid beta-oxidation results in polyhydroxyalkanoic acid accumulation when cells were cultivated on fatty acids. We evaluated the application of the fatty acid beta-oxidation inhibitor acrylic acid as a tool to channel intermediates of beta-oxidation to polyhydroxyalkanoic acid synthesis. Various E. coli strains affected in fatty acid metabolism and the wild-type strain harboring plasmid pBHR71 were analyzed with respect to polyhydroxyalkanoic acid accumulation in the presence of acrylic acid. The E. coli fadR mutant RS3097 revealed the strongest polyhydroxyalkanoic acid accumulation. The optimum inhibitory concentration of acrylic acid was 0.24 mg ml-1 and caused efficient channeling of intermediates of beta-oxidation to polyhydroxyalkanoic acid synthesis. Under these conditions and grown on decanoate E. coli RS3097 harboring plasmid pBHR71 revealed a polyhydroxyalkanoic acid accumulation contributing to about 60% of cellular dry weight.

Acrylates↗

PubMed2003

Conjugated linoleic acid and vaccenic acid in rumen, plasma, and milk of cows fed fish oil and fats differing in saturation of 18 carbon fatty acids.

The objective of this study was to examine the effect of feeding fish oil (FO) along with fat sources that varied in saturation of 18 carbon fatty acids (high stearic, high oleic, high linoleic, or high linolenic acids) on rumen, plasma, and milk fatty acid profiles. Four primiparous Holstein cows at 85 d in milk (+/- 40) were assigned to 4 x 4 Latin squares with 4-wk periods. Treatment diets were 1) 1% FO plus 2% commercial fat high in stearic acid (HS); 2) 1% FO plus 2% fat from high oleic acid sunflower seeds (HO); 3) 1% FO plus 2% fat from high linoleic acid sunflower seeds (HLO); and 4) 1% FO plus 2% fat from flax seeds (high linolenic; HLN). Diets were formulated to contain 18% crude protein and were composed of 50% (dry basis) concentrate mix, 25% corn silage, 12.5% alfalfa silage, and 12.5% alfalfa hay. Milk production, milk protein percentages and yields, and dry matter intake were similar across diets. Milk fat concentrations and yields were least for HO and HLO diets. The proportion of milk cis-9, trans-11 conjugated linoleic acid (CLA; 0.71, 0.99, 1.71, and 1.12 g/100 g fatty acids, respectively), and vaccenic acid (TVA; 1.85, 2.60, 4.14, and 2.16 g/100 g fatty acids, respectively) were greatest with the HLO diet. The proportions of ruminal cis-9, trans-11 CLA (0.09, 0.16, 0.18, and 0.16 g/100 g fatty acids, respectively) were similar for the HO, HLO, and HLN diets and all were higher than for the HS diet. The proportions of TVA (2.85, 4.36, 8.69, and 4.64 g/100 g fatty acids, respectively) increased with the HO, HLO, and HLN diets compared with the HS diets, and the increase was greatest with the HLO diet. The effects of fat supplements on ruminal TVA concentrations were also reflected in plasma triglycerides, (2.75, 4.64, 8.77, and 5.42 g/100 g fatty acids, respectively); however, there were no differences in the proportion of cis-9, trans-11 CLA (0.06, 0.07, 0.06, and 0.07 g/100 g fatty acids, respectively). This study further supports the significant role for mammary delta-9 desaturase in milk cis-9, trans-11 CLA production.

Animal Nutritional Physiological Phenomena↗

PubMed1991

Effects of eicosapentaenoic acid and arachidonic acid on incorporation and metabolism of radioactive linoleic acid in cultured human fibroblasts.

Effects of exogenous eicosapentaenoic acid, arachidonic acid and oleic acid on incorporation and metabolism of [14C] linoleic acid were examined in cultured human fibroblasts obtained from three donors of different ages. Eicosapentaenoic acid treatment (40 microM) inhibited incorporation of radioactive linoleic acid and actively reduced radioactivity of desaturation-elongation metabolites in phospholipids, predominantly in the phosphatidylethanolamine fraction. In contrast, radioactivities of the metabolites in triacylglycerols were significantly increased with arachidonic acid treatment (40 microM): eicosapentaenoic acid had a smaller effect or none. Oleic acid had virtually no effect. These effects were consistent in the three cell lines, but responses to treatment with the acids differed considerably among individual cells. The pool of linoleic acid metabolites in triacylglycerols may not be negligible. The exogenous fatty acids may influence both the transfer of lipids between the major lipid pools as well as the activities of the desaturation-elongation system.

Arachidonic Acid↗

PubMed1978

Metabolism of arachidonic acid by platelets: utilization of arachidonic acid by human platelets in presence of linoleic and dihomo-gamma-linolenic acids.

In vitro human platelet prostaglandin synthesis has been studied from added radioactive arachidonic acid (i) as function of substrate concentration, (ii) as function of platelet concentration and (iii) as function of pH. Platelets, as in platelet rich plasma when labelled with arachidonic acid, washed and treated with thrombin, released radioactivity mainly from phosphatidylcholine and phosphatidylinositol. The released radioactivity was mostly accounted for by the formation of the previously identified oxygenation products of arachidonic acid. Platelet utilization or arachidonic acid was also studied in presence of linoleic and dihomo-gamma-linolenic acids, the two essential fatty acids known for antithrombotic effect. At its high concentrations linoleic acid decreased platelet cyclo-oxygenase activity as seen by a decreased formation of endoperoxides from arachidonic acid. Dihomo-gamma-linolenic acid was found to be a mutually competitive substrate with arachidonic acid for the platelet prostaglandin synthetase thus causing reduced utilization of arachidonic acid as shown by measuring the various oxygenation products of arachidonic acid. These two acids were utilized differently by platelet prostaglandin synthetase.

8,11,14-Eicosatrienoic Acid↗

PubMed1996

Eicosapentaenoic acid, but not docosahexaenoic acid, increases mitochondrial fatty acid oxidation and upregulates 2,4-dienoyl-CoA reductase gene expression in rats.

The aim of the present study was to investigate whether eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) was responsible for the triglyceride-lowering effect of fish oil. In rats fed a single dose of EPA as ethyl ester (EPA-EE), the plasma concentration of triglycerides was decreased at 8 h after acute administration. This was accompanied by an increased hepatic fatty acid oxidation and mitochondrial 2,4-dienoyl-CoA reductase activity. The steady-state level of 2,4-dienoyl-CoA reductase mRNA increased in parallel with the enzyme activity. An increased hepatic long-chain acyl-CoA content, but a reduced amount of hepatic malonyl-CoA, was obtained at 8 h after acute EPA-EE treatment. On EPA-EE supplementation, both EPA (20:5n-3) and docosapentaenoic acid (DPA, 22:5n-3) increased in the liver, whereas the hepatic DHA (22:6n-3) concentration was unchanged. On DHA-EE supplementation retroconversion to EPA occurred. No statistically significant differences were found, however, for mitochondrial enzyme activities, malonyl-CoA, long-chain acyl-CoA, plasma lipid levels, and the amount of cellular fatty acids between DHA-EE treated rats and their controls at any time point studied. In cultured rat hepatocytes, the oxidation of [1-14C]palmitic acid was reduced by DHA, whereas it was stimulated by EPA. In the in vivo studies, the activities of phosphatidate phosphohydrolase and acetyl-CoA carboxylase were unaffected after acute EPA-EE and DHA-EE administration, but the fatty acyl-CoA oxidase, the rate-limiting enzyme in peroxisomal fatty acid oxidation, was increased after feeding these n-3 fatty acids. The hypocholesterolemic properties of EPA-EE may be due to decreased 3-hydroxy-3-methylglutaryl-CoA reductase activity. Furthermore, replacement of the ordinary fatty acids, i.e., the monoenes (16:1n-7, 18:1n-7, and 18:1n-9) with EPA and some conversion to DPA concomitant with increased fatty acid oxidation is probably the mechanism leading to changed fatty acid composition. In contrast, DHA does not stimulate fatty acid oxidation and, consequently, no such displacement mechanism operates. In conclusion, we have obtained evidence that EPA, and not DHA, is the fatty acid primarily responsible for the triglyceride-lowering effect of fish oil in rats.

Acyl-CoA Dehydrogenase, Long-Chain↗

PubMed1998

Mouse P450RAI (CYP26) expression and retinoic acid-inducible retinoic acid metabolism in F9 cells are regulated by retinoic acid receptor gamma and retinoid X receptor alpha.

We have cloned a mouse cDNA homolog of P450RAI, a cytochrome P450 belonging to a new family (CYP26), which has previously been isolated from zebrafish and human cDNAs and found to encode a retinoic acid-inducible retinoic acid hydroxylase activity. The cross-species conservation of the amino acid sequence is high, particularly between the mouse and the human enzymes, in which it is over 90%. Like its human and zibrafish counterparts, the mouse P450RAI cDNA catalyzes metabolism of retinoic acid into 4-OH-retinoic acid, 4-oxo-retinoic acid, 18-OH-retinoic acid, and unidentified water-soluble metabolites when transfected into COS-1 cells. Retinoic acid-inducible retinoic acid metabolism has previously been observed in F9 murine embryonal carcinoma cells and some derivatives lacking retinoid receptors. We were interested in determining whether P450RAI could be responsible for retinoic acid metabolism in F9 cells and in studying the effect of retinoid receptor ablation on P450RAI expression. In wild-type F9 cells and derivatives lacking RAR gamma, RAR alpha, and/or RXR alpha, we observed a direct relationship between the level of retinoic acid metabolic activity and retinoic acid-induced P450RAI mRNA. These experiments, as well as others using synthetic receptor subtype-specific retinoids, suggest that the RAR gamma and RXR alpha receptors mediate the effects of retinoic acid on the expression of the P450RAI gene.

Amino Acid Sequence↗

PubMed1998

Effect of formula supplemented with docosahexaenoic acid and gamma-linolenic acid on fatty acid status and visual acuity in term infants.

BACKGROUND: Docosahexaenoic acid is present in high concentration in retina and does not influence visual development in preterm infants. It is still under discussion whether docosahexaenoic acid is important for visual development in term infants. METHODS: Thirty-seven infants fed formula for a median of 14 days were randomized at median age of 25 days to three formulas: a) DHAGF: 0.3 wt% docosahexaenoic acid and 0.5 wt% gamma-linolenic acid; b) DHAF 0.3 wt% docosahexaenoic acid; or c) STF: standard formula without long-chain polyunsaturated fatty acids and 17 breast-fed infants were observed, using blood samples and anthropometric measurements from 1 to 4 months of age. At 4 months, visual acuity was measured by swept steady-state visual evoked potential. A cross-sectional study on 25 breast-fed infants was carried out as a reference group for the analyses. RESULTS: Infants fed the two docosahexaenoic acid-supplemented formula had relative docosahexaenoic acid concentrations in red blood cell phospholipids almost as high as those in breast-fed infants, whereas infants in the standard formula group had significantly lower levels. The addition of gamma-linolenic acid to the formula had a positive effect on red blood cell arachidonic acid levels, compared with levels obtained using fish oil only. Visual acuity was significantly different among all feeding groups (analysis of variance; p = 0.05, means +/- standard deviation: breast-fed, 0.37+/-0.06 logMAR; DHAF and DHAGF combined, 0.40+/-0.07 logMAR; and standard formula 0.44+/-0.07 logMAR. However, there was no statistical difference among the formula groups. In a multiple regression analysis including all formula-fed infants, weight at delivery (p = 0.002), but not type of formula, was significantly associated with visual acuity at 4 months of age. CONCLUSIONS: The addition of docosahexaenoic acid resulted in concentrations in red blood cells at similar levels as those in breast-fed infants, whereas the increase in visual acuity did not reach significance. The addition of gamma-linolenic acid resulted in higher arachidonic acid concentrations in red blood cells.

Anthropometry↗

PubMed1988

Magnesium deprivation or short-term essential fatty acid deficiency in rats: effects on serum lipids, platelet fatty acid composition and arachidonic acid incorporation into platelet phospholipids.

The aim of this study was to evaluate the effect of short-term magnesium or essential fatty acid (EFA) deficiencies on plasma lipids, platelet fatty acid composition and [1-14C] arachidonic acid incorporation into platelet phospholipids. Weanling rats were fed purified diets (casein 20%, sucrose 70.5%, lipid 5%) for two weeks. The control and magnesium-deficient diets included corn oil as lipid source. The EFA-deficient diet included hydrogenated coconut oil. The fatty acid composition of serum lipids confirmed the linoleic acid deprivation in the EFA-deficient group. Significant changes in platelet fatty acid composition occurred in this limited period of time and arachidonic acid incorporation into platelet lipids was markedly increased. Magnesium deficiency induced hyperlipaemia. A significant decrease in the percentage of arachidonic acid in total serum lipids was observed, but fatty acid profile appeared quite different in the two deficiencies. In magnesium-deficient rats, the alteration in fatty acid composition of serum lipids was not associated with similar changes in fatty acid composition of platelet lipids. Arachidonic acid incorporation into platelet lipids was markedly increased in magnesium deficient animals as compared to control group. Relatively more arachidonic acid was incorporated into phosphatidylcholine and phosphatidylinositol when magnesium-deficient or EFA-deficient animals were compared to the control group.

Animals↗

PubMed1989

The effects of alkylthioacetic acids (3-thia fatty acids) on fatty acid metabolism in isolated hepatocytes.

Long-chain alkylthioacetic acids (3-thia fatty acids) inhibit fatty acid synthesis from [1-14C]acetate in isolated hepatocytes, while fatty acid oxidation is nearly unaffected or even stimulated. Desaturation of [1-14C]stearate (delta 9-desaturase) is also unaffected. [1-14C]Dodecylthioacetic acid (a 3-thia fatty acid) is incorporated in triacylglycerol and in phospholipids more efficiently than [1-14C]palmitate in isolated hepatocytes. The metabolism of [1-14C]dodecylthioacetic acid to acid-soluble products (by omega-oxidation) is slow compared to the oxidation of [1-14C]palmitate. In hepatocytes from adapted rats (rats fed tetradecylthioacetic acid for 4 days) the rate of [1-14C]palmitate oxidation is increased and its rate of esterification is decreased. Stearate desaturation is also decreased. The rate of cyanide-insensitive peroxisomal fatty acid beta-oxidation is several-fold increased. The metabolic effects of long-chain 3-thia fatty acids are discussed and it is concluded that they behave essentially like normal fatty acids except for their slow breakdown due to the sulfur atom in the 3 position, which blocks normal beta-oxidation.

Acetates↗

PubMed1988

Primary deuterium isotope effects for the 3-methylaspartase-catalyzed deamination of (2S)-aspartic acid, (2S,3S)-3-methylaspartic acid, and (2S,3S)-3-ethylaspartic acid.

3-Methylaspartate ammonia-lyase catalyzes the deamination of (2S)-aspartic acid 137 times more slowly than the deamination of (2S,3S)-3-methylaspartic acid but catalyzes the amination of fumaric acid 1.8 times faster than the amination of mesaconic acid [Botting, N.P., Akhtar, M., Cohen, M. A., & Gani, D. (1988) Biochemistry (preceding paper in this issue)]. In order to understand the mechanistic basis for these observations, the deamination reaction was examined kinetically with (2S)-aspartic acid, (2S,3S)-3-methylaspartic acid, (2S,3S)-3-ethylaspartic acid, and the corresponding C-3-deuteriated isotopomers. Comparison of the double-reciprocal plots of the initial reaction velocities for each of the three pairs of substrates revealed that the magnitude of the primary isotope effect on both Vmax and V/K varied with the substituent at C-3 of the substrate. 3-Methylaspartic acid showed the largest isotope effect (1.7 on Vmax and V/K), 3-ethylaspartic acid showed a smaller isotope effect (1.2 on Vmax and V/K), and aspartic acid showed no primary isotope effect at all. These results, which are inconsistent with earlier reports that there is no primary isotope effect for 3-methylaspartic acid [Bright, H. J. (1964) J. Biol. Chem. 239, 2307], suggest that for both 3-methylaspartic acid and 3-ethylaspartic acid elimination occurs via a predominantly concerted mechanism whereas for aspartic acid an E1cb mechanism prevails.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia-Lyases↗

PubMed1981

[Dependence of metabolic fecal amino acids on the amino acid content of the feed. 1. Metabolic fecal amino acids of rats fed with maize].

The amount of metabolic fecal amino acids (MFAA) in dependence on the amino acid intake was determined for graded maize rations with 15N-labelled rats and the quota of labelled endogenous amino acids in faeces was calculated according to the isotope dilution method. The excretion of amino acids and MFAA in faeces are described as functions of the amino acid intake for 17 amino acids and regressively calculated. For all 17 amino acids investigated, there was a more or less steep increase of MFAA according to an increasing amino acid intake. In contrast to MFAA in N-free feeding, MFAA in feeding with pure maize (16.5% crude protein) increase to the 2- to 4.5-fold value. The thesis of the constancy of the excretion of MFAA can consequently be no longer maintained. The true digestibility according to the conventional method is, on an average of all amino acids, 7.3 units below the one ascertained according to the 15N-isotope method. For the limiting amino acids lysine and threonine the difference is biggest (23 resp. 17 units). Tryptophane as first limiting amino acid could not be determined. The true digestibility of nearly all amino acids ascertained for maize according to the isotope method is above 90%. For the limiting amino acids the expenditure resp. the loss of endogenous amino acids is biggest.

Amino Acids↗

PubMed1998

Survival of Escherichia coli O157:H7 in synthetic gastric fluid after cold and acid habituation in apple juice or trypticase soy broth acidified with hydrochloric acid or organic acids.

Extreme acid tolerance of Escherichia coli O157:H7 has raised doubts about the safety of acidic foods. This study examined whether prior storage in acidic and/or cold conditions enhanced survival of E. coli O157:H7 in synthetic gastric fluid (SGF). Three E. coli O157:H7 strains were stored in trypticase soy broth (TSB; acidified with HCl, malic acid, citric acid, or lactic acid) or pH 3.5 and 6.5 (nonacidic control) apple juice at 4 and 21 degrees C for < or = 7 days and then were incubated in pH 2.5 SGF at 37 degrees C for 4 h. Cells survived better in apple juice than in TSB containing organic acids, suggesting that juice constituents other than organic acids protect E. coli O157:H7. Refrigeration combined with low pH best protected cells in apple juice and acidified TSB, but, compared to the nonacidic control, only acidified TSB enhanced subsequent survival in pH 2.5 SGF. Equal survival in SGF occurred after storage in pH 3.5 or 6.5 apple juice at 4 degrees C, suggesting that low temperature alone in apple juice enhanced acid tolerance. Two strains stored at 4 degrees C in TSB containing malic or citric acid subsequently survived better in SGF than cells stored in nonacidified TSB but poorer than cells stored in the presence of HCl. These differences reflect the higher pKa of these organic acids. However, subsequent survival of these strains in SGF was poorer after refrigerated storage in apple juice than in TSB containing citric or malic acids. Cells stored in lactic acid were most likely to be completely eliminated upon transfer to SGF. Differences in survival in storage media or SGF related to strain, storage conditions, or acidifier were consistent and often statistically significant (P < 0.05). Although the survival of E. coli O157:H7 in refrigerated acidic beverages may not be affected by the type of acidifier used, the subsequent survival in SGF of this pathogen may be critically dependent on this factor.

Beverages↗

PubMed1997

Effect of linoleic acid, linoleic acid anilide, and arachidonic acid on the expression of adhesion molecules on human neutrophils.

The effects of linoleic acid, linoleic acid anilide, and arachidonic acid on the expression of CD11b/ CD18, CD11c/CD18 integrins and L-selectin on human neutrophils were studied by flow cytometry in a whole blood assay. None of these compounds had any effect on the basal expression of CD11b, CD11c, or L-selectin in the concentration range of 20-100 microM. However, linoleic acid at a concentration of 1000 microM slightly up-regulated CD11b and CD11c by a factor of 2.1 and 1.7, respectively. Linoleic acid, linoleic acid anilide, and arachidonic acid did not affect the formyl-methionyl-leucyl-phenylalanine induced up-regulation of CD11b or CD11c. However, linoleic acid and linoleic acid anilide slightly inhibited the phorbol myristate acetate (PMA)-induced expression of CD11b, which was decreased by 27 and 21% at concentrations of 100 and 1000 microM, respectively. Likewise, arachidonic acid at 40 microM inhibited the PMA-induced expression of CD11b by 19%. Our results suggest that linoleic acid, linoleic acid anilide, and arachidonic acid do not dramatically affect the expression of leukocyte adhesion molecules in a whole blood assay.

Anilides↗

PubMed1999

Stability of cyclopropane and conjugated linoleic acids during fatty acid quantification in lactic acid bacteria.

Seven methods commonly used for fatty acid analysis of microorganisms and foods were compared to establish the best for the analysis of lyophilized lactic acid bacteria. One of these methods involves fat extraction followed by methylation of fatty acids, while the other methods use a direct methylation of the samples, under different operating conditions (e.g., reaction temperature and time, reagents, and pH). Fatty acid methyl esters were identified by gas chromatography-mass spectrometry and quantified by on-column capillary gas chromatography. Two reliable methods for the analysis of fatty acids in bacteria were selected and further improved. They guarantee high recovery of classes of fragile fatty acids, such as cyclopropane and conjugated acids, and a high degree of methylation for all types of fatty acid esters. These two direct methylation methods have already been successfully applied to the analysis of fatty acids in foods. They represent a rapid and highly reliable alternative to classical time- and solvent-consuming methods and they give the fatty acid profile and the amount of each fatty acid. Using these methods, conjugated linoleic acids were identified and quantified in lactic acid bacteria.

Bacteria↗

PubMed2004

Lipoic acid-dependent oxidative catabolism of alpha-keto acids in mitochondria provides evidence for branched-chain amino acid catabolism in Arabidopsis.

Lipoic acid-dependent pathways of alpha-keto acid oxidation by mitochondria were investigated in pea (Pisum sativum), rice (Oryza sativa), and Arabidopsis. Proteins containing covalently bound lipoic acid were identified on isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis separations of mitochondrial proteins by the use of antibodies raised to this cofactor. All these proteins were identified by tandem mass spectrometry. Lipoic acid-containing acyltransferases from pyruvate dehydrogenase complex and alpha-ketoglutarate dehydrogenase complex were identified from all three species. In addition, acyltransferases from the branched-chain dehydrogenase complex were identified in both Arabidopsis and rice mitochondria. The substrate-dependent reduction of NAD(+) was analyzed by spectrophotometry using specific alpha-keto acids. Pyruvate- and alpha-ketoglutarate-dependent reactions were measured in all three species. Activity of the branched-chain dehydrogenase complex was only measurable in Arabidopsis mitochondria using substrates that represented the alpha-keto acids derived by deamination of branched-chain amino acids (Val [valine], leucine, and isoleucine). The rate of branched-chain amino acid- and alpha-keto acid-dependent oxygen consumption by intact Arabidopsis mitochondria was highest with Val and the Val-derived alpha-keto acid, alpha-ketoisovaleric acid. Sequencing of peptides derived from trypsination of Arabidopsis mitochondrial proteins revealed the presence of many of the enzymes required for the oxidation of all three branched-chain amino acids. The potential role of branched-chain amino acid catabolism as an oxidative phosphorylation energy source or as a detoxification pathway during plant stress is discussed.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗

PubMed2005

Effect of diets containing linoleic acid- or oleic acid-rich oils on ruminal fermentation and nutrient digestibility, and performance and fatty acid composition of adipose and muscle tissues of finishing cattle.

Two trials were conducted to determine the effect of linoleic acid- or oleic acid-rich safflower oil on ruminal fermentation, nutrient digestion, feedlot performance, carcass characteristics, and fatty acid composition of adipose and muscle tissues of beef cattle. In both trials, cattle were fed a finishing diet based on barley grain, wheat silage, and alfalfa hay. Oils were fed at 5% of dietary DM. In a metabolism trial, four ruminally and duodenally cannulated Angus crossbred steers were subjected to linoleic acid-rich oil or oleic acid-rich oil in a crossover design with covariate periods (no oil supplementation). In a finishing trial, 16 individually fed Angus crossbred steers and heifers (eight per diet) received linoleic acid- or oleic acid-rich oils during the last 86 d of a 116-d feeding period. Ruminal pH, ammonia concentration, protozoal counts, major VFA concentrations, acetate-to-propionate ratio, polysaccharide-degrading activities, microbial N flow to the duodenum, and the efficiency of microbial N synthesis in the rumen were not affected (P = 0.18 to 0.96) by type of oil. Type of oil had no effect on total-tract apparent digestion of nutrients (P = 0.46 to 0.98). Ruminal true nutrient digestibilities did not differ between oils (P = 0.15 to 0.99), except that the linoleic acid-rich oil decreased (P = 0.05) NDF digestibility. Dry matter intake, ADG, G:F, and carcass characteristics did not differ (P = 0.11 to 0.84) between the two oils. Overall, the difference in dietary fatty acids provided to the cattle produced few changes in tissue fatty acids. Weight percentages of c9t11 CLA were unaltered by the addition of linoleic acid to the diet compared with oleic acid, probably as a result of low vaccenic acid production in the rumen, as the pathway of biohydrogenation was apparently primarily through the t10 pathway.

Adipose Tissue↗

PubMed2006

Influence of three rapeseed oil-rich diets, fortified with alpha-linolenic acid, eicosapentaenoic acid or docosahexaenoic acid on the composition and oxidizability of low-density lipoproteins: results of a controlled study in healthy volunteers.

OBJECTIVE: To compare the individual effects of dietary alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) on low-density lipoprotein (LDL) fatty acid composition, ex vivo LDL oxidizability and tocopherol requirement. DESIGN, SETTING AND SUBJECTS: A randomized strictly controlled dietary study with three dietary groups and a parallel design, consisting of two consecutive periods. Sixty-one healthy young volunteers, students at a nearby college, were included. Forty-eight subjects (13 males, 35 females) completed the study. INTERVENTIONS: Subjects received a 2-week wash-in diet rich in monounsaturated fatty acids (21% energy) followed by experimental diets enriched with about 1% of energy of ALA, EPA or DHA for 3 weeks. The omega-3 (n-3) fatty acids were provided with special rapeseed oils and margarines. The wash-in diet and the experimental diets were identical, apart from the n-3 fatty acid composition and the tocopherol content, which was adjusted to the content of dienoic acid equivalents. RESULTS: Ex vivo oxidative susceptibility of LDL was highest after the DHA diet, indicated by a decrease in lag time (-16%, P<0.001) and an increase in the maximum amount of conjugated dienes (+7%, P<0.001). The EPA diet decreased the lag time (-16%, P<0.001) and the propagation rate (-12%, P<0.01). Tocopherol concentrations in LDL decreased in the ALA group (-13.5%, P<0.05) and DHA group (-7.3%, P<0.05). Plasma contents of tocopherol equivalents significantly decreased in all three experimental groups (ALA group: -5.0%, EPA group: -5.7%, DHA group: -12.8%). The content of the three n-3 polyunsaturated fatty acid differently increased in the LDL: on the ALA diet, the ALA content increased by 89% (P<0.001), on the EPA diet the EPA content increased by 809% (P<0.001) and on the DHA diet, the DHA content increased by 200% (P<0.001). In addition, the EPA content also enhanced (without dietary intake) in the ALA group (+35%, P<0.01) and in the DHA group (+284%, P<0.001). CONCLUSIONS: Dietary intake of ALA, EPA or DHA led to a significant enrichment of the respective fatty acid in the LDL particles, with dietary EPA preferentially incorporated. In the context of a monounsaturated fatty acid-rich diet, ALA enrichment did not enhance LDL oxidizability, whereas the effects of EPA and DHA on ex vivo LDL oxidation were inconsistent, possibly in part due to further changes in LDL fatty acid composition.

Adolescent↗

PubMed1985

Platelet fatty acid composition in relation to fatty acid composition in plasma and to serum lipoprotein lipids in healthy subjects with special reference to the linoleic acid pathway.

The fatty acid composition in platelet phospholipids and in the plasma lipid esters as well as the serum lipoprotein lipid concentrations were determined in 67 healthy male subjects in order to establish the relationships between blood lipids and platelets. A positive correlation was found between the concentrations of the triglyceride rich serum lipoprotein lipids and the relative percentage of saturated and monounsaturated fatty acids in plasma. The correlations were also positive between the serum high density lipoprotein-cholesterol concentration and the relative content of linoleic acid in the plasma cholesterol esters and phospholipids. Negative correlations were found between the relative percentage of saturated and monounsaturated fatty acids in the plasma lipid esters versus linoleic acid in plasma and in the platelets. On the other hand there were positive correlations between linoleic acid in the plasma lipid esters and in the platelet phospholipids. These results indicate a direct dietary influence on the platelet phospholipid fatty acid composition. The correlations between the fatty acids of the n-6 series within plasma and platelets as well as between plasma and platelets indicate that a high linoleic acid content is not associated with an increased arachidonic acid concentration. The results also indicate that the limiting metabolic step in the conversion of linoleic acid into arachidonic acid may be located at different levels in plasma and in the platelets.

Adult↗