Serum lipids and lipoproteins from rats fed different dietary oils

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Summary The present study was performed to investigate whether a moderately oxidized dietary oil influences lipid peroxidation processes in low‐density lipoproteins (LDL) which have been demonstrated to play an important role in the development of atherosclerosis. Therefore, growing male rats were fed diets containing either a mixture of coconut oil and soybean oil (19:1, w: w), fresh soybean oil, or heated soybean oil as sources of dietary fats over a period of 40 days. Lipids of those diets were characterized by a peroxide value of 5.1, 9.5, and 74 mEq O2/kg, respectively, on average over the whole feeding period. Additionally, according to a bifactorial design, the vitamin E supply of the animals was varied (11 versus 511 mg α‐tocopherol equivalents per kg of diet). Feeding the diets containing the oxidized oils did not affect feed intake and growth, and, with the exception of reduced triglyceride concentrations, did not cause considerable alterations of plasma and lipoproteins lipids. The resistance of LDL against copper‐induced lipid peroxiation was predominately influenced by dietary fatty acids and dietary vitamin E levels whereas the oxidation status of the oil had only a small effect. Feeding the coconut oil diet markedly increased lag times compared to feeding the soybean oil diets, and feeding the high‐vitamin E diets markedly increased lag times compared to feeding the low‐vitamin E diets. At the low dietary vitamin E level, feeding the oxidized soybean oil slightly reduced the lag time before onset of lipid peroxidation compared with rats fed fresh soybean oil. This effect might be due to reduced tocopherol concentrations in the LDL of those rats; the fatty acid composition of LDL lipids was not different between feeding fresh and oxidized soybean oil. At the high dietary vitamin E level, parameters measured to assess the LDL oxidation were completely indifferent between rats fed fresh and those fed oxidized soybean oil. Hence, the study suggests that a moderately oxidized oil at a nutritionally adequate vitamin E supply has no adverse effects on the resistance of LDL to peroxidation. However, the LDL of rats fed oxidized soybean oil had markedly higher concentrations of thiobarbituric acid‐reactive substances (TBARS) than the LDL of rats fed coconut oil or fresh soybean oil. Vitamin E supplementation reduced the TBARS concentrations in rats fed the oxidized oil; nevertheless, the TBARS concentrations remained higher than in rats fed fresh soybean oil. Probably, the increased concentrations of TBARS in LDL are due to the incorporation of dietary lipid peroxidation products into endogenous lipoproteins. Increased concentrations of peroxidation products in LDL after ingestion of oxidized fats could be of clinical relevance because oxidatively modified LDL are taken up by macrophages leading to the formation of fatty streaks. Zusammenfassung Zum Einfluß eines mäßig oxidierten Sojaöls auf die Lipidperoxiation in den Lipoproteinen geringer Dichte von Ratten bei niedriger und hoher Vitamin E‐Zufuhr In der ...

Section: Discussionsupporting

confidence: 71%

The effect of a moderately oxidized soybean oil on lipid peroxidation in rat low‐density lipoproteins at low and high dietary vitamin E levels

Eder

Kirchgeßner

1997

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“…The present study shows that a diet rich in ( n ‐6) polyunsaturated fatty acids lowers the concentration of cholesterol in plasma relative to diets that are rich in saturated and mono‐unsaturated fatty acids. This effect also has been demonstrated by other investigators in various species (M attson and G rundy 1985; M ensink and K atan 1992; S tangl et al 1994). The plasma cholesterol reducing effect of polyunsaturated fatty acids is beneficial for health because lowering the cholesterol level in plasma lowers the risk of coronary heart disease.…”

Section: Discussionsupporting

confidence: 85%

Effect of dietary fats on susceptibility of low‐density lipoproteins to lipid peroxidation in pigs

Eder¹,

Kirchgeßner²

1997

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Summary The present study investigated the effect of dietary fats rich in polyunsaturated fatty acids (soybean oil), mono‐unsaturated fatty acids (olive oil) and saturated fatty acids (beef tallow) on the susceptibility of low‐density lipoproteins (LDL) to lipid peroxidation in pigs. In a cross‐over design with three periods, nine pigs were fed each of the fats in daily amounts of 250 g for two weeks. The susceptibility of LDL to lipid peroxidation was determined by Cu2+‐catalysed oxidation. The lag phase before onset of oxidation, the rate of diene formation during propagation phase and the maximal amount of dienes produced during oxidation were considered for assessing the oxidative susceptibility. The LDL of pigs fed soybean oil had a higher oxidative susceptibility than the LDL of pigs fed beef tallow or olive oil. Probably, the increased susceptibility of LDL from pigs fed soybean oil to lipid peroxidation is due to an enrichment of LDL with linoleic acid whereas an enrichment of LDL with oleic acid in pigs fed olive oil or beef tallow reduced its oxidative susceptibility. The concentration of total tocopherols in plasma, expressed per mol lipid, was not influenced and that in LDL was only slightly influenced by the dietary fat, indicating that the dietary fat had only a small effect on vitamin E status. Pigs fed soybean oil had increased concentrations (expressed per mol lipid) of thiobarbituric acid reactive substances in plasma, suggesting an enhanced lipid peroxidation relative to pigs fed olive oil or beef tallow. The effect of dietary fats on the susceptibility of LDL to lipid peroxidation might be of physiological relevance because oxidatively modified LDL play an important role in the progress of atherosclerosis. Zusammenfassung Der Einfluß des Fettes auf die Oxidationsanfälligkeit der Lipoproteine geringer Dichte beim Schwein In der vorliegenden Arbeit wurde der Einfluß verschiedener Fette, nämlich von Sojaöl mit einem hohem Anteil mehrfach ungesättigter Fettsäuren, von Olivenöl mit einem hohen Anteil einfach ungesättigter Fettsäuren sowie von Rindertalg mit einem hohen Anteil gesättigter Fettsäuren auf die Oxidationsanfälligkeit der Lipoproteine geringer Dichte (LDL) beim Schwein untersucht. Dazu erhielten neun Schweine entsprechend eines Cross‐over Versuchsplans mit drei Versuchsperioden von jeweils zwei Wochen Dauer jedes der drei Fette in einer Zulage von 250 g pro Tag einmal. Die Oxidationsanfälligkeit der LDL wurde durch das Ausmaß der durch Kupferionen induzierten Oxidation bestimmt. Als Meßparameter wurden hierbei die Zeit bis zum Einsetzen der Oxidation, die Rate der Bildung konjugierter Diene sowie die maximal erreichte Konzentration konjugierter Diene herangezogen. Die Zulage von Sojaöl führte zu einer deutlich erhöhten Oxidationsanfälligkeit der LDL im Vergleich zur Zulage von Rindertalg oder Olivenöl. Diese erhöhte Oxidationsanfälligkeit bei der Sojaölzulage ist vermutlich auf eine Anreicherung von Linolsäure in den LDL zurückzuführen. Bei der Zulage von Olivenöl und Rindertalg zeigte s...

“…Stangl et al. (, ) reported in rats a hypocholesterolaemic effect of a fish oil‐ and salmon oil‐enriched diet, respectively, after switching to this diet from a previously fed hyperlipidemic diet. Therefore, either a different control diet or higher oil percentage in the diet or a different design of an experiment can explain the above‐mentioned differences between studies.…”

Section: Discussionmentioning

confidence: 99%

“…Dietary fish oil decreased both TC and HDLC in the rat plasma in comparison with control safflower oil also in our previous experiment (Komprda et al, 2015), where, however, the diets contained 6% of the particular oil. Stangl et al (1993Stangl et al ( , 1994 reported in rats a hypocholesterolaemic effect of a fish oil-and salmon oilenriched diet, respectively, after switching to this diet from a previously fed hyperlipidemic diet. Therefore, either a different control diet or higher oil percentage in the diet or a different design of an experiment can explain the above-mentioned differences between studies.…”

Section: Plasma Lipidsmentioning

confidence: 99%

Effect of dietary fish oil on fatty acid deposition and expression of cholesterol homeostasis controlling genes in the liver and plasma lipid profile: comparison of two animal models

Komprda

Rozikova

Zamazalová

et al. 2016

The objective of the present study was to compare hepatic fatty acid deposition, plasma lipid level and expression of cholesterol homeostasis controlling genes in the liver of rats (Wistar Albino; n = 32) and pigs (Large White × Landrace; n = 32) randomly assigned into two groups of 16 animals each and fed 10 weeks the diet with either 2.5% of fish oil (F; source of eicosapentaenoic and docosahexaenoic acid, EPA+DHA) or 2.5% of palm oil (P; high content of saturated fatty acids; control). F-rats deposited in the liver three times less EPA, but 1.3 times more DHA than F-pigs (p < 0.05). Dietary fish oil relative to palm oil increased PPARα and SREBP-2 gene expression much strongly (p < 0.01) in the pig liver in comparison with the rat liver, but expression of Insig-1 and Hmgcr genes in the liver of the F-pigs relative to the expression of these genes in the liver of the P-pigs was substantially lower (p < 0.01 and p < 0.05 respectively) as compared to rats. When plasma lipid concentration in the F-animals was expressed as a ratio of the plasma concentration in the P-counterparts, dietary fish oil decreased HDL cholesterol less (p < 0.01), but LDL cholesterol and triacylglycerols more (p < 0.05 and p < 0.001 respectively) in rats than in pigs: more favourable effect of fish oil on rat plasma lipids in comparison with pigs can therefore be concluded. Concentration of total cholesterol and both its fractions in the rat plasma was negatively correlated (p < 0.01) with hepatic DHA, but also with unsaturated myristic and palmitic acid respectively. It has been concluded that regarding the similarity of the plasma lipid levels to humans, porcine model can be considered superior; however, using this model, dietary fish oil at the tested amount (2.5%) was not able to improve plasma lipid markers in comparison with saturated palm oil.