Effects of saturated and polyunsaturated fat diets on the chemical composition and metabolism of low density lipoproteins in XXXX .

@entity1 @entity844 @entity3952 @entity2365 @entity1674 @entity134 @entity412 @entity5068 @entity8557 @entity165
This study examined the effects of dietary saturated and polyunsaturated fat on the chemical composition and metabolism of low density lipoproteins (LDL) in eight normal male subjects. The influence of these diets on fecal @entity5068 excretion was also measured in four of the subjects. When compared with the saturated fat diet, the polyunsaturated diet lowered both plasma @entity165 polyunsaturated diet lowered both plasma @entity165 (23%, P less than 0.001) and @entity412 (14%, P less than 0.001) levels. Sixty-seven percent of the reduction in the former lipid resulted from a fall in LDL @entity165 (23%, P less than 0.001), although very low density (VLDL) and high density lipoprotein (HDL) @entity165 levels also fell (by 27% and 20% of their respective control value). These changes were accompanied by significant alterations in LDL composition. Specifically, during polyunsaturated fat feeding, the relative percentage @entity165 in the LDL fraction fell while that of phospholipid rose. There was no change in the percentage protein or @entity412 . The @entity844 components of LDL @entity412 , @entity8557 , and phospholipid were also affected by dietary fat saturation level. Overall, polyunsaturated fat feeding produced an enrichment in linoleate with reciprocal changes in @entity2365 , stearate, and @entity3952 which affected @entity1674 more than @entity8557 and phospholipids. The above changes in LDL composition were associated with alterations in the metabolism of LDL apoprotein (apoLDL). The polyunsaturated deit lowered plasma apoLDL by 13% (P less than 0.05). This resulted from an increase in the fractional catabolic rate of LDL (whether determined by plasma decay curve analysis (P less than 0.05) or urine/plasma radioactivity ratios (P less than 0.001) without significant alteration of its corporeal distribution or synthetic rate. The polyunsaturated fat diet did not cause a consistent change in fecal neutral or acidic @entity134 excretion. We conclude that the hypocholesterolemic action of polyunsaturated fat diets is effected by multiple mechanisms whose expression may vary from @entity1 to @entity1 .
