EFFECT OF DIETARY FATS ON SUSCEPTIBILITY OF LOW-DENSITY LIPOPROTEINS TO LIPID-PEROXIDATION IN PIGS

The present study investigated the effect of dietary fats rich in poly unsaturated fatty acids (soybean oil), mono-unsaturated fatty acids (o live oil) and saturated fatty acids (beef tallow) on the susceptibilit y 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 L DL to lipid peroxidation was determined by Cu2+-catalysed oxidation. T he lag phase before onset of oxidation, the rate of diene formation du ring propagation phase and the maximal amount of dienes produced durin g oxidation were considered for assessing the oxidative susceptibility . The LDL of pigs fed soybean oil had a higher oxidative susceptibilit y than the LDL of pigs fed beef tallow or olive oil. Probably, the inc reased susceptibility of LDL from pigs fed soybean oil to lipid peroxi dation is due to an enrichment of LDL with linoleic acid whereas an en richment of LDL with oleic acid in pigs fed olive oil or beef tallow r educed its oxidative susceptibility. The concentration of total tocoph erols in plasma, expressed per mol lipid, was not influenced and that in LDL was only slightly influenced by the dietary fat, indicating tha t the dietary fat had only a small effect on vitamin E status. Pigs fe d soybean oil had increased concentrations (expressed per mol lipid) o f thiobarbituric acid reactive substances in plasma, suggesting an enh anced lipid peroxidation relative to pigs fed olive oil or beef tallow . The effect of dietary fats on the susceptibility of LDL to lipid per oxidation might be of physiological relevance because oxidatively modi fied LDL play an important role in the progress of atherosclerosis.