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PubMed1988

Fish oil reduces cholesterol and arachidonic acid content more efficiently in rats fed diets containing low linoleic acid to saturated fatty acid ratios.

Rats were fed diets containing a high level of saturated fatty acids (hydrogenated beef tallow) versus a high level of linoleic acid (safflower oil) at both low and high levels of fish oil containing 7.5% (w/w) eicosapentaenoic and 2.5% (w/w) docosahexaenoic acids for a period of 28 days. The effect of feeding these diets on the cholesterol content and fatty acid composition of serum and liver lipids was examined. Feeding diets high in fish oil with safflower oil decreased the cholesterol content of rat serum, whereas feeding fish oil had no significant effect on the cholesterol content of serum when fed in combination with saturated fatty acids. The serum cholesterol level was higher in animals fed safflower oil compared to animals fed saturated fat without fish oil. Consumption of fish oil lowered the cholesterol content of liver tissue regardless of the dietary fat fed. Feeding diets containing fish oil reduced the arachidonic acid content of rat serum and liver lipid fractions, the decrease being more pronounced when fish oil was fed in combination with hydrogenated beef tallow than with safflower oil. These results suggest that dietary n-3 fatty acids of fish oil interact with dietary linoleic acid and saturated fatty acids differently to modulate enzymes of cholesterol and fatty acid metabolism.

Animals↗
PubMed1997

Dietary conjugated linoleic acid reduces plasma lipoproteins and early aortic atherosclerosis in hypercholesterolemic hamsters.

Conjugated linoleic acid is a collective term used to designate a mixture of positional and geometric isomers of linoleic acid in which the double bonds are conjugated. Unlike linoleic acid, there is a paucity of information regarding the effect of dietary conjugated linoleic acid on plasma lipoproteins and aortic atherosclerosis. Therefore, fifty hamsters were divided into five groups of ten and fed 0 (Control), 0.06 (LOW), 0.11 (MEDIUM), and 1.1 (HIGH) en% conjugated linoleic acid or 1.1 en% linoleic acid. Blood samples were taken at 4, 8 and 11 weeks for plasma lipid analyses and for plasma tocopherol assay at sacrifice. Animals fed the conjugated linoleic acid-containing diets collectively had significantly reduced levels of plasma total cholesterol, non-high density lipoprotein cholesterol, (combined very low and low density lipoprotein) and triglycerides with no effect on high density lipoprotein cholesterol, as compared to CONTROLs. Linoleic acid-fed animals relative to CONTROLs also had reduced plasma total cholesterol, non-high density lipoprotein cholesterol and triglycerides, but only the latter was statistically significant. Compared to the CONTROL group, plasma tocopherol/total cholesterol ratios determined from plasma pools for the LOW, MEDIUM and HIGH conjugated linoleic acid and linoleic acid groups were increased by 48%, 48%, 86% and 29%, respectively, suggesting a tocopherol-sparing effect, at least for the conjugated linoleic acid treatment. Morphometric analysis of aortas revealed less early atherosclerosis in the conjugated linoleic acid and linoleic acid-fed hamsters compared to the CONTROL group.

Animals↗
PubMed2005

Antiatherogenic effects of structured lipid containing conjugated linoleic acid in C57BL/6J mice.

Conjugated linoleic acids (CLA) were enzymatically acidolyzed with olive oil to produce structured lipids (SL), and their antiatherosclerotic properties were investigated in C57BL/6J mice. Twenty-eight mice were divided into four groups and fed control diet or atherogenic diets supplemented with high cholesterol and high fat (HCHF) containing 5% of lard, olive oil, or SL based on control diet for 4 weeks. The supplementation of SL diet (0.6% CLA) significantly reduced the levels of serum total cholesterol and total triglyceride and increased high-density lipoprotein cholesterol level as compared to lard and olive oil diet groups (p < 0.05). The activity of liver acyl CoA:cholesterol acyltransferase (ACAT) of mice fed the SL diet was significantly lower than that of mice fed the lard or olive oil diet. A reduced formation of aortic fatty streak was observed in SL group. The extent of CLA incorporation depended on tissues or types of phospholipids. More CLA was incorporated in adipose tissue (1.85 mol %) than in the liver (0.33 mol %). Besides, more CLA was found in phosphatidylethanolamine (PE) (0.47 mol %) than in phosphatidylcholine (PC) (0.05 mol %) of hepatic phospholipids. Hepatic phospholipids (PC and PE) of mice fed the SL diet contained reduced contents of arachidonic and linoleic acid compared with mice fed the olive oil or lard diet. The present study suggests that SL could be considered as a functional oil for preventing risks of atheroscelerosis.

Animals↗
PubMed1979

Fetal to maternal transfer of palmitic and linoleic acids across the sheep placenta.

Maternal and fetal blood samples were obtained at 2.5, 10 and 20 min after the injection of 3H-palmitic acid and 14C-linoleic acid into the fetal circulation of pregnant ewes. 3H-palmitic acid was easily detected in the maternal circulation within 2.5 min after its injection into the fetus resulting in an appreciable accumulation in the maternal plasma by the 20th min after injection. In contrast the presence of 14C-linoleic acid in the maternal circulation was barely detectable over the 20-min sampling period. The concentrations of total lipid and unesterified fatty acids within the fetal plasma were considerably lower than in the maternal plasma thereby providing an adverse concentration gradient for the passage of fatty acids between fetus and mother. The differential permeability of the placenta to the passage of the 3H-palmitic acid and 14C-linoleic acid is discussed in relation to their passage from fetus to mother in non-ruminant species and the adverse essential fatty acid status known to exist in the developing ruminant fetus.

Animals↗
PubMed2004

Photochemical production of conjugated linoleic acid from soybean oil.

Conjugated linoleic acid (CLA), an anticarcinogenic compound with numerous other health benefits, is present mainly in dairy and beef lipids. The main CLA isomer present in dairy and beef lipids is cis 9, trans 11 CLA at a 0.5% concentration. The typical minimum human dietary intake of CLA is 10 times less than the 3 g/d suggested requirement that has been extrapolated from animal and cell-line studies. The objectives of this study were to produce CLA isomers from soybean oil by photoisomerization of soybean oil linoleic acid and to study the oxidation status of the oil. Refined, bleached, and deodorized soybean oil with added iodine concentrations of 0, 0.1, 0.25, and 0.5% was exposed to a 100-W mercury lamp for 0 to 120 h. An SP-2560 fused-silica capillary GC column with FID was used to analyze the esterified CLA isomers in the photoisomerized oil. The CLA content of the individual isomers was optimized by response surface methodology. Attenuated total reflectance (ATR)-FTIR spectra in the 3400 to 3600 cm(-1) range and 1H NMR spectra in the 8 to 12 ppm range of the photoisomerized soybean oil were obtained to follow hydroperoxide formation. The largest amount of cis 9, trans 11 CLA isomer in soybean oil was 0.6%, obtained with 0.25% iodine and 84 h of photoisomerization. Lipid hydroperoxide peaks in the ATR-FTIR spectra and aldehyde peaks in the 1H NMR spectra were not observed in the photoisomerized soybean oil, and the spectra were similar to that of fresh soybean oil. This study shows that CLA isomers can be produced simply and inexpensively from soybean oil by photoisomerization.

Hydrogen Peroxide↗
PubMed1994

Is insulin resistance influenced by dietary linoleic acid and trans fatty acids?

The incidence of obesity, noninsulin-dependent diabetes mellitus (NIDDM), hypertension, and coronary artery disease has increased in the developed world. At the same time, major changes in the type and amount of fatty acid intake have occurred over the past 40-50 years, reflected in increases in saturated fat (from both animal sources and hydrogenated vegetable sources), trans fatty acids, vegetable oils rich in linoleic acid, and an overall decrease in long chain polyunsaturated fatty acids (arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid--C20-C22). Recent findings that C20-C22 in muscle membrane phospholipids are inversely related to insulin resistance, whereas linoleic acid is positively related to insulin resistance, suggest that diet may influence the development of insulin resistance in obesity, insulin-dependent diabetes mellitus (IDDM), hypertension, and coronary artery disease (including asymptomatic atherosclerosis and microvascular angina). These conditions are known to have genetic determinants and have a common abnormality in smooth muscle response and insulin resistance. It is proposed that the current diet influences the expression of insulin resistance in those who are genetically predisposed. Therefore, clinical investigations are needed to evaluate if lowering or preventing insulin resistance through diet by increasing arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid, while lowering linoleic acid and decreasing trans fatty acids from the diet, will modify or prevent the development of these diseases.

Animals↗
PubMed1987

Stimulation of hematopoiesis and bone marrow suppressor cells by the subcutaneous injection of linoleic acid.

The effects of injection of linoleic acid into C57Bl/6 mice on hematopoietic and immunological parameters were examined. Administration of linoleic acid stimulated hematopoiesis as it increased spleen weight and cellularity, increased the number of bone marrow and splenic granulocytic-monocytic progenitor cells, and increased the colony stimulating factor activity in the serum of the treated mice. Associated with the hematopoietic stimulation in linoleic acid-treated mice was a decline in the spleen cell blastogenic responses and the appearance of bone marrow suppressor cells which were inhibitory to normal spleen cell blastogenesis. The linoleic acid-induced bone marrow suppressor cells resembled cells of the monocyte lineage in that they were sensitive to treatment with L-leucine methyl ester, partially sensitive to treatment with anti-Ia antibodies and complement, and their suppressor activity was minimized by indomethacin, a prostaglandin synthesis inhibitor. These results suggest that administration of linoleic acid results in hematopoietic stimulation and, concurrently, in the appearance of suppressor cells in the bone marrow. The bone marrow suppressor cells resemble immature cells of the monocyte lineage and appear to mediate their suppressive effects through the production of prostaglandins.

Animals↗
PubMed2006

Eicosapentaenoic acid and 3,10 dithia stearic acid inhibit the desaturation of trans-vaccenic acid into cis-9, trans-11-conjugated linoleic acid through different pathways in Caco-2 and T84 cells.

Stearoyl-CoA desaturase (SCD) is a key enzyme that determines the composition and metabolic fate of ingested fatty acids, in particular the conversion of trans-vaccenic acid (TVA) to conjugated linoleic acid (CLA). The present study addressed the hypothesis that intestinal TVA absorption and biotransformation into CLA can be modulated by EPA and 3,10-dithia stearic acid (DSA) via altered SCD mRNA levels and desaturation indices (cis-9, trans-11-CLA:TVA and oleic acid:stearic acid ratios) in Caco-2 and T84 cells, two well-established in vitro models of the human intestinal epithelium. The study determined the effect of acute (3 h with 0.3 mm-EPA or 0.3 mm-DSA) and acute-on-chronic (1 week with 0.03 mm-EPA or -DSA, followed by respectively, 0.3 mm-EPA or -DSA for 3 h) treatments. In both cell lines, acute EPA treatment did not alter SCD desaturation indices, whereas the acute-on-chronic treatment affected these surrogate markers of SCD activity. This was associated with reduced sterol regulatory-element binding protein-1c and SCD mRNA levels. In contrast, acute and acute-on-chronic DSA treatments significantly reduced SCD desaturation indices without affecting SCD mRNA levels in Caco-2 cells. The present study on intestinal cells shows that the conversion rate of TVA to c9, t11-CLA is affected by other fatty acids present in the diet such as EPA, confirming previous observations in hepatic and mammary cell models.

Caco-2 Cells↗
PubMed2001

Defining mechanisms of toxicity for linoleic acid monoepoxides and diols in Sf-21 cells.

Linoleic acid monoepoxides have been correlated with many pathological conditions. Studies using insect cells derived from Spodoptera frugiperda (Sf-21 cells) have suggested that conversion of the epoxides to the diols is required for toxicity. However, more recent studies using rabbit renal proximal tubules have suggested that linoleic acid monoepoxides are direct mitochondrial toxins. To better understand these discrepancies, we compared the toxicity of these linoleic acid metabolites in Sf-21 cells using mitochondrial respiration as an end point. Linoleic acid (100 microM) and 12,13-epoxy-9-octadecenoic acid (12,13-EOA, 100 microM) increased the rate of oligomycin-insensitive respiration by approximately 3.5- and 3-fold, respectively, decreased the rate of oligomycin-sensitive respiration by approximately 52 and 68%, respectively, and had no effect on the integrity of the electron transport chain. These effects were concentration-dependent, occurred within 1 min, and recovered to basal levels within 45 min. 12,13-Dihydroxy-9-octadecenoic acid (12,13-DHOA, 100 microM) had no effect on oligomycin-insensitive respiration but decreased the rate of oligomycin-sensitive respiration and uncoupled respiration in a concentration-dependent manner. Approximately 79 and 68% of oligomycin-sensitive respiration and uncoupled respiration was inhibited by 12,13-DHOA (100 microM), respectively. These effects occurred within 1 min and were not reversible in 6 h. Effects similar to those induced by 12,13-DHOA (100 microM) were observed using 12,13-EOA (100 microM) in Sf-21 cells expressing human soluble epoxide hydrolase. These data suggest that in this Sf-21 model linoleic acid and linoleic monoepoxides have transient uncoupling effects, whereas the primary mechanism of toxicity for linoleic acid diols in this model is inhibition of the electron transport chain.

Animals↗
PubMed2005

Factors affecting conjugated linoleic acid content in milk and meat.

Conjugated linoleic acid (CLA) has been recently studied mainly because of its potential in protecting against cancer, atherogenesis, and diabetes. Conjugated linoleic acid (CLA) is a collective term for a series of conjugated dienoic positional and geometrical isomers of linoleic acid, which are found in relative abundance in milk and tissue fat of ruminants compared with other foods. The cis-9, trans-11 isomer is the principle dietary form of CLA found in ruminant products and is produced by partial ruminal biohydrogenation of linoleic acid or by endogenous synthesis in the tissues themselves. The CLA content in milk and meat is affected by several factors, such as animal's breed, age, diet, and management factors related to feed supplements affecting the diet. Conjugated linoleic acid in milk or meat has been shown to be a stable compound under normal cooking and storage conditions. Total CLA content in milk or dairy products ranges from 0.34 to 1.07% of total fat. Total CLA content in raw or processed beef ranges from 0.12 to 0.68% of total fat. It is currently estimated that the average adult consumes only one third to one half of the amount of CLA that has been shown to reduce cancer in animal studies. For this reason, increasing the CLA contents of milk and meat has the potential to raise the nutritive and therapeutic values of dairy products and meat.

Animals↗
PubMed2000

Biotransformation of linoleic acid by Clavibacter sp. ALA2: heterocyclic and heterobicyclic fatty acids.

Clavibacter sp. ALA2 transformed linoleic acid into a variety of oxylipins. In previous work, three novel fatty acids were identified, (9Z)-12, 13, 17-trihydroxy-9-octadecenoic acid and two tetrahydrofuran-(di)hydroxy fatty acids. In this report, we confirm the structures of the tetrahydrofuran-(di)hydroxy fatty acids by nuclear magnetic resonance as (9Z)-12-hydroxy-13,16-epoxy-9-octadecenoic acid and (9Z)-7,12-dihydroxy-13,16-epoxy-9-octadecenoic acid. Three other products of the biotransformation were identified as novel heterobicyclic fatty acids, (9Z)-12,17;13, 17-diepoxy-9-octadecenoic acid, (9Z)-7-hydroxy-12,17;13,17-diepoxy-9-octadecenoic acid, and (9Z)-12,17;13,17-diepoxy-16-hydroxy-9-octadecenoic acid. Thus, Clavibacter ALA2 effectively oxidized linoleic acid at C-7, -12, -13, -16, and/or -17.

Biotransformation↗
PubMedDate not supplied

Utilization of amylose-lipid complexes as molecular nanocapsules for conjugated linoleic Acid.

Amylose-conjugated linoleic acid (CLA) complexes were produced by water/dimethyl sulfoxide (DMSO) and KOH/HCl complexation methods. The formation of amylose V form was confirmed by X-ray diffraction (XRD), and complexes formed at 30, 60, and 90 degrees C exhibit melting temperatures exceeding 88 degrees C. Atomic force microscopy (AFM) images showed distinct difference in complex organization, with complexes formed in water/DMSO showing spherical shape with typical diameter of 150 nm. Complexes formed by KOH/HCl showed elongated structure with typical width of 43-160 nm. Water/DMSO complexes exhibit superior protection to CLA against oxidation. All complexes showed high retention of CLA in simulated stomach conditions, and the digestion of complexes by amylases results in high hydrolysis and CLA release by pancreatin and alpha-amylase. Only moderate release was detected following hydrolysis by amyloglucosidase and beta-amylase. It is therefore suggested that amylose-CLA complexes can serve as molecular nanocapsules for protection and delivery of CLA.

Amylases↗
PubMed2003

Lactobacillus growth and membrane composition in the presence of linoleic or conjugated linoleic acid.

Five Lactobacillus strains of intestinal and food origins were grown in MRS broth or milk containing various concentrations of linoleic acid or conjugated linoleic acid (CLA). The fatty acids had bacteriostatic, bacteriocidal, or no effect depending on bacterial strain, fatty acid concentration, fatty acid type, and growth medium. Both fatty acids displayed dose-dependent inhibition. All strains were inhibited to a greater extent by the fatty acids in broth than in milk. The CLA isomer mixture was less inhibitory than linoleic acid. Lactobacillus reuteri ATCC 55739, a strain capable of isomerizing linoleic acid to CLA, was the most inhibited strain by the presence of linoleic acid in broth or milk. In contrast, a member of the same species, L. reuteri ATCC 23272, was the least inhibited strain by linoleic acid and CLA. All strains increased membrane linoleic acid or CLA levels when grown with exogenous fatty acid. Lactobacillus reuteri ATCC 55739 had substantial CLA in the membrane when the growth medium was supplemented with linoleic acid. No association between level of fatty acid incorporation into the membrane and inhibition by that fatty acid was observed.

Animals↗
PubMed1991

Effect of feeding palmitic, oleic, and linoleic acids to Japanese quail hens (Coturnix coturnix japonica). 1. Reproductive performance and tissue fatty acids.

A study was conducted to evaluate the effects of diets containing 3% of either palmitic acid (Diet PA), oleic acid (Diet OA), or linoleic acid (Diet LA) on reproductive performance, fatty acid composition of egg yolk, plasma, and liver, and total plasma phosphorus of Japanese quail. Each diet was fed to 20 individually caged hens from 5 wk of age. A 24-wk production period started at 8 wk of age. Fertile eggs for incubation were obtained by placing at random a male in the cage with the female for 15 to 20 min twice per week. The males were kept in separate individual cages and fed a turkey grower diet throughout. Feed consumption, egg production, egg output, and the number of chicks per hen were higher (P less than .05) in birds fed Diet PA than in those fed Diet OA or Diet LA. Hatchability was not different (P greater than .05) between Diet PA and Diet OA, but they were higher (P less than .05) than that of Diet LA. Quail weight at hatch from birds fed Diet LA was heavier (P less than .05) than those from Diet OA, but not different (P greater than .05) from those fed Diet PA. Total plasma phosphorus concentration was higher (P less than .05) in birds fed Diet PA than in those fed Diet LA. High levels of oleic and linoleic acids were found in egg yolk, plasma, and liver lipids from birds fed Diet OA and Diet LA, respectively. Feeding Diet PA resulted in elevated levels of palmitoleic acid in all three tissues. The highest overall reproductive performance on Diet PA suggests that palmitic acid has some physiological role in reproduction. The sustained near-maximal levels of egg production and fertility achieved in this trial indicate the superiority of the mating procedure, which would also permit testing the response of male and female birds while minimizing injuries incurred by the females.

Animal Feed↗
PubMed1989

Effect of linoleic acid infusion on blood pressure in normotensive and hypertensive rats.

High dietary intake of linoleic acid lowers arterial pressure, and, in vitro, linoleic acid inhibits the enzymatic activity of renin. The purpose of the present study was 1) to evaluate the effect of intravenous infusion of linoleic acid on blood pressure in normotensive and hypertensive Sprague-Dawley rats and 2) to determine whether the hypotensive response to linoleic acid infusion is caused by inhibition of circulating renin. Blood pressure was decreased (P less than 0.01) by linoleic acid infusion in normotensive sodium chloride-deprived animals and in animals with two-kidney, one-clip hypertension. In contrast, linoleic acid infusion did not affect blood pressure in normotensive rats on a "normal" or high sodium chloride intake, in rats with deoxycorticosterone acetate (DOCA)-salt hypertension, and in anephric rats. In sodium chloride-deprived rats, the reduction of blood pressure by linoleic acid infusion was associated with increased plasma renin activity (P less than 0.05); serum angiotensin-converting enzyme activity was unchanged. The in vitro enzymatic activity of exogenous renin in plasma of anephric rats was not affected by linoleic acid infusion. In two-kidney, one-clip hypertensive animals, pretreatment with indomethacin did not alter the hypotensive response to linoleic acid. Thus, although linoleic acid infusion lowered blood pressure in high renin but not in low renin states, the reduction of blood pressure was not related to inhibition of circulating renin or to alterations of endogenous prostaglandin biosynthesis.

Animals↗
PubMed1997

Biotransformation of linoleic acid with the Candida tropicalis M25 mutant.

Linoleic acid was transformed by mutant Candida tropicalis M25 and transformations were studied in batch and fed-batch cultures. Cofermentations with palmitic acid as inducer of the fatty acid degradation pathway were performed. Besides the (Z),(Z)-octadeca-6,9-dienedioic acid, (Z),(Z)-3-hydroxyoctadeca-9,12-dienedioic acid and (Z),(Z)-3-hydroxytetradeca-5,8-dienedioic acid were obtained as the main fermentation products. The maximum concentrations of (Z),(Z)-octadeca-6,9-dienedioic acid and (Z),(Z)-3-hydroxyoctadeca-9,12-dienedioic acid reached values of 6.4 g/l and 6.9 g/l respectively. The structures of the products were characterized by chemical and spectroscopic methods. The configuration of the double bonds was not changed during bioconversion. As only one regioisomer of the hydroxylated fatty acid was detected, the hydroxylation is site-specific.

Biotransformation↗
PubMed1984

Effects of dietary vitamin E on serum and pulmonary fatty acids and prostaglandins in rats fed excess linoleic acid.

The interrelationships of dietary vitamin E and essential fatty acids and their effects on serum and pulmonary prostaglandin (PG) synthesis and fatty acid precursors were examined. In a preexperimental period, male weanling rats were depleted of essential fatty acids (EFA) by feeding on a hydrogenated coconut oil diet. At the end of 45 days, average serum triene:tetraene ratio for the EFA-deficient rats was 0.76. After a refeeding period with a 20% safflower oil diet and 0, 1 or 50 mg of dl-alpha-tocopheryl acetate daily, serum and pulmonary fatty acid profiles and PG synthesis were determined. A trend to growth depression on the high vitamin E diet was observed. Vitamin E supplementation seemed to have no significant effect on fatty acid composition or synthesis of PGE1, PGE2, PGF2 alpha or PGI2 in lung. This may be due to the small lipid content and presumed inability of lung to accumulate excess vitamin E. Lung may, therefore, be resistant to such dietary manipulations. Serum PG synthesis was not affected by vitamin E dose, although the C20:4 omega 6/C18:2 omega 6 ratio in serum was significantly lowered on the high vitamin E diet.

Animals↗