A B S T R A C T 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 < 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 gmol/kg per d vs. 27.7 umol/kg per d in the control phase, P < 0.02) was channelled into the receptor-independent route during egg feeding.

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I . The early effects of a moderate polyunsaturated fat diet on the composition of circulating lipoprotcinn and adipose tissue fatty acids were measured in five healthy adults.

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