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

Abstract

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...

The effect of fatty acid composition of rapeseed oil on plasma lipids and oxidative stability of low-density lipoproteins in cholesterol-fed hamsters

“…It is well known that dietary PUFA increase the susceptibility of LDL to lipid peroxidation whereas dietary antioxidants, especially tocopherols, protect LDL against lipid peroxidation [12,42]. In disagreement with this study several others demonstrated that the administration of oils rich in PUFA, such as soybean oil, sunflower oil or corn oil, increase the susceptibility of LDL lipids in humans and animals as opposed to administering oils rich in MUFA such as olive oil or rapeseed oil [43][44][45][46]. The disagreement between the present results and those above-mentioned is well explainable by different vitamin E concentrations of the diets.…”

The effect of a moderately thermoxidized dietary fat on the vitamin E status, the fatty acid composition of tissue lipids, and the susceptibility of low-density lipoproteins to lipid peroxidation in rats

“…In contrast to erythrocytes, the fatty acid composition of LDL was neither influenced by the type of fat nor by the vitamin E supply. The fatty acid composition of LDL is of particular physiological significance because it influences the susceptibility of LDL to lipid peroxidation [e. g. [16][17][18] [12,13]. * mg α-tocopherol equivalents per kg; a, b, c -significantly different by Fisher's multiple range test (P < 0.05).…”

“…The last parameter is of particular physiological significance because it has been demonstrated that oxidatively modified LDL plays an important role in the pathogenesis of atherosclerosis [14,15]. It is known that the susceptibility of LDL to lipid peroxidation is influenced by several nutritional factors, particularly by dietary fats and antioxidants [16][17][18][19]. Fats with high levels of polyunsaturated fatty acids have been shown to increase the susceptibility of LDL to lipid peroxidation in various species whereas fats with high levels of saturated or monounsaturated fatty acids reduce it [16,17,20,21].…”

Effects of dietary fish oil and oxidized cholesterol on the concentration of 7β‐hydroxycholesterol in liver, plasma, low density lipoproteins and erythrocytes of rats at various vitamin E supply

“…Increased concentrations of α-tocopherol in plasma and LDL of rats fed the coconut oil diets supplemented with pure or oxidized cholesterol in Experiment 2 relative to rats fed the coconut oil diets without cholesterol in Experiment 1 may be due to their higher lipid concentrations in plasma and LDL. A strong relationship exists between the concentration of tocopherols and the concentration of total lipids in plasma [34]. The finding that an increase of the dietary vitamin E concentration from 40 to 240 mg/kg failed to reduce the concentrations of 7β-OH-Chol in liver, LDL and erythrocytes suggests that a dietary vitamin E concentration of 40 mg/kg provided maximum protection of cholesterol in these samples against oxidation even in the case of fish oil as dietary fat.…”