The Effect of Dietary Fat Saturation on Plasma and Hepatic Lipoproteins in the Rat

Abstract

Semipurified diets containing 10% kilocalories from either safflower oil (SO), corn oil (CO), olive oil (OO) or palm oil (PO) were fed to weanling male rats for 2 weeks. The effects of dietary fat saturation on plasma lipids and lipoproteins were: 1) Nonfasted plasma cholesterol concentration was higher in rats fed OO (mean +/- SEM = 81.0 +/- 2.9 mg/dl) vs. CO (67.5 +/- 2.9); 2) plasma chylomicron cholesterol concentration was higher in rats fed OO vs. SO and CO, with PO values in between; and 3) the cholesterol concentration of plasma very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density lipoprotein (HDL) did not differ among groups. The effects of dietary fat saturation on hepatic lipoproteins (determined by liver perfusion techniques) were: 1) hepatic higher density lipoprotein (d = 1.006-1.21 g/ml) cholesterol production was greater in rats fed SO and CO vs. PO [19.1 +/- 1.2, 17.2 +/- 0.8 and 13.7 +/- 1.6 micrograms/(g liver X 1.5 hour), respectively]; 2) there was no difference in hepatic VLDL cholesterol production among groups; and 3) the ratio of cholesterol to protein of hepatic VLDL and the higher density lipoprotein fraction was higher in rats fed diets rich in polyunsaturated fatty acids versus saturated fatty acids. Dietary fat saturation had no effect on carcass and liver cholesterol concentrations. Since differences in hepatic lipoprotein production were not reflected in plasma lipoprotein patterns, these results suggest that extrahepatic lipoprotein metabolism differs in rats fed diets containing fatty acids of varying saturation.

Effect of Various Dietary Fatty Acid Ethyl Esters on Plasma Cholesterol and Lipoprotein Metabolism in Rats.

“…This may explain the higher chylomicron plus VLDL cholesterol concentration in rats fed saturated fatty acid and MUFA of oleate in this study. These results conform with data from studies with oleate-rich fat in rats [3,24,25].…”

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“…The total cholesterol to protein ratio (a measure of the capacity for cholesterol transport in a lipoprotein) was not significantly affected by dietary saturation, a finding already obtained by other authors (12), although the total cholesterol/protean ratio of the VLDL and LDL of rats fed palm olein-diet was a 30% higher than that of the olive oil-fed group.…”

Comparison of Dietary Casein and Soybean Protein Effects on Plasma Lipid and Gastrin Levels, Hepatic Δ^6-Desaturase Activity and Coronary Arteriosclerosis in Male Sprague-Dawley Rats

“…Whether oleic acid has a similar plasma cholesterol-lowering effect in rats is unclear. No differences in VLDL, LDL, or HDL cholesterol were observed between rats fed on diets rich in monounsaturated fat ty acids (olive oil or palm oil) and rats fed PUFA-rich diet (soy oil or corn oil) at a 10 energy percent fat level, although the group fed on the diet containing olive oil showed a higher chylomicron-cholesterol value [20], In any case, the replacement of PUFA with oleic acid probably will confer protection against 308 Lindholm/Sjöblom/Nordborg/ Östlund-Lindqvist/Eklund Dictan1 Protein. Plasma Lipids and Arteriosclerosis the oxidative modification of lipoproteins, which is currently believed to be a key initial event in the atherogenic process [21].…”