Cholesterol feeding increases low density lipoprotein synthesis.
This study examines the effects of increased dietary cholesterol (6 eggs/d) on the metabolism of low density lipoproteins in a group of seven healthy volunteers. Egg supplementation raised high density and low density lipoprotein cholesterol levels by 18 and 40%, respectively. The composition of the low density lipoprotein was unaltered and therefore the number of circulating particles must have increased. Kinetic studies indicated that this was due primarily to a 23% rise in the rate of synthesis of the lipoprotein. Catabolism was also affected. The fractional removal rate of native low density lipoprotein fell by 10% (P less than 0.05). However, the clearance of the 1,2 cyclohexanedione-treated lipoprotein remained unchanged (control fractional clearance rate [FCR] = 0.188 pools/d; cholesterol feeding FCR = 0.183 pools/d). Therefore, the reduction in low density lipoprotein catabolism appeared to be due to a fall in receptor activity. Consequently, an increased sterol load (34.2 mumol/kg per d vs. 27.7 mumol/kg per d in the control phase, P less than 0.02) was channelled into the receptor-independent route during egg feeding.
D000328:Adult; D002784:Cholesterol / Q000097:blood; D002791:Cholesterol, Dietary / Q000494:pharmacology*; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D003512:Cyclohexanones / Q000494:pharmacology; D005260:Female; D006801:Humans; D008075:Lipoproteins, HDL / Q000097:blood; D008077:Lipoproteins, LDL / Q000096:biosynthesis* / Q000097:blood; D008297:Male; D008657:Metabolic Clearance Rate; D011956:Receptors, Cell Surface / Q000378:metabolism; D011973:Receptors, LDL
D002791:Cholesterol, Dietary; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D003512:Cyclohexanones; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D011956:Receptors, Cell Surface; D011973:Receptors, LDL; C018031:1,2-cyclohexanedione; D002784:Cholesterol