Effect of dietary cholesterol on cholesterol synthesis in breast-fed and formula-fed infants.

The fractional synthesis rate (FSR) of cholesterol was measured in 6 breast-fed and 12 formula-fed infants (ages 4 to 5 months) using the 2H2O method. The breast-fed infants had higher cholesterol intakes (18.2 +/- 4.0 vs. 3.4 +/- 1.8 mg/kg per day, P = 0.001), plasma total cholesterol (183 +/- 47 vs. 112 +/- 22 mg/dl, P = 0.013), and plasma low density lipoprotein (LDL)-cholesterol (83 +/- 26 vs. 48 +/- 16 mg/day, P = 0.023) than the formula-fed infants (6.9 +/- 2.6 vs. 2.1 +/- 0.6%/day, P < 0.001). Among all infants, there was a significant inverse relationship (P = 0.002, r = 0.66) between the FSR of cholesterol and dietary cholesterol intake. Our findings indicate that the greater cholesterol intake of the breast-fed infants was associated with elevated plasma LDL-cholesterol concentrations and that cholesterol synthesis in human infants may be efficiently regulated via HMG-CoA reductase when infants are challenged with high intakes of dietary cholesterol.