Increased removal of remnants of triglyceride‐rich lipoproteins on a diet rich in polyunsaturated fatty acids

Abstract

We studied the effect of two diets, one rich in polyunsaturated and the other in saturated fatty acids, on the postprandial processing of exogenous and endogenous triglyceride-rich lipoproteins (chylomicrons, very-low-density lipoproteins, and their remnants). For this purpose, 12 normolipidaemic young volunteers were fed, in a cross-over design of 9 days on each diet, either a diet rich in saturated fat (21% of their daily energy intake from saturated fat, 12% from monounsaturated fat, and 3% from polyunsaturated fat) or a diet rich in polyunsaturated fat (10% saturated fat, 9% monounsaturated fat, and 18% polyunsaturated fat) (P/S ratios 0.14 and 1.8, respectively). On the last day of each dietary period blood samples were drawn six times over a 24-h period for determination, by densitometric scanning of SDS gels, of the diurnal pattern of apoprotein B-48 and B-100 in the d less than 1.019 g ml-1 fractions, as estimates for the processing of chylomicrons and very-low-density lipoproteins. In addition to the usual decrease in the fasting and diurnal concentrations of total serum cholesterol and of cholesterol in the low-density lipoprotein fractions (between 15 and 21%), the diet rich in polyunsaturated fat resulted in 43% lower daily concentrations of chylomicrons and their remnants. This was due to differences in the clearance rate of chylomicrons and their remnants, rather than to differences in the absorption rate of exogenous fat. In addition, the concentrations of very low density lipoproteins and their remnants during the day were 20% lower on the diet rich in polyunsaturated fat.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary fat selection on plasma cholesterol synthesis in older, moderately hypercholesterolemic humans.

“…Similarly, and consistent with findings of animal studies in which LDL clearance was increased with PUFA feeding^o.u,13.3536 increased body elimination of sterol would be expected to result in more rapid clearance of lipoprotein cholesterol, as has been observed in humans consuming PUFA diets. 41 The present results are consistent with the concept that in humans, feeding corn oil causes enhanced cholesterogenesis, either in response to increased whole-body excretion and plasma removal of cholesterol or as a consequence of oil fatty acid profile or content of some nonsaponifiable component.…”

Effects of increasing dietary polyunsaturated fatty acids within the guidelines of the AHA step 1 diet on plasma lipid and lipoprotein levels in normal males.

“…Thus, their study cannot be compared with ours, in which saturated fat was held constant, and monounsaturated and polyunsaturated fat levels were altered modestly. Similarly, the study by Demacker et al, 45 in which lower 24-hour lipid and lipoprotein levels were observed during consumption of a high-polyunsaturated fat diet, differs from ours in both saturated and polyunsaturated fatty acid content. Thus, in contrast to other data in the literature confounded by reciprocal changes in saturated and polyunsaturated fats, our data suggested that neither polyunsaturated nor monounsaturated fatty acids affect the metabolism of postprandial lipoproteins when saturated fat and carbohydrates are held constant.…”

Postprandial lipid metabolism: effects of dietary fatty acids

“…In some instances, investigators have chosen to measure response to a test meal which has the same fatty acid composition as the background diet being fed. This is the case with the study of Demacker et al (1991) who altered the diets of free-living subjects so that either butterfat or safflower oil was the predominant fat used in cooking and in meals prepared at their work place. After 3 weeks on each diet, subjects responses to a breakfast, lunch and dinner were monitored over a 24 h period.…”