Infant diet affects serum lipoprotein concentrations and cholesterol esterifying enzymes in baboons.

We characterized the preweaning differences in cholesterol metabolism between breast-fed and formula-fed baboons and determined if formulas with low and high polyunsaturated:saturated fatty acid (P:S) ratios simulated the effects of breast feeding. At birth, 45 infant baboons from three sires and 44 dams were assigned to breast-fed, low P:S formula or high P:S formula diet groups until weaning at 14 wk. From 4 to 14 wk breast-fed infants had higher serum cholesterol because of much higher HDL1- and HDL2-cholesterol concentrations but had lower HDL3-cholesterol than both formula-fed groups. LDL-cholesterol was higher in infants fed the low P:S fomula. Breast-fed infants had higher serum apolipoprotein E than the formula-fed groups, but diet did not affect apolipoprotein A-I or B concentrations. Breast-fed infants had higher hepatic acyl CoA cholesterol acyltransferase activity and lower plasma lecithin cholesterol acyltransferase activity. These enzyme activities were not different between infants fed low or high P:S formulas. Post-heparinized plasma lipoprotein lipase activity was greater in breast-fed infants than in those fed formula. These findings demonstrate that the P:S ratio of formulas has little effect on cholesterol metabolism during the preweaning period and suggest that factors other than fat composition account for the metabolic differences between breast feeding and commercial infant formula.