DIFFERENCES IN CHOLESTEROL-METABOLISM IN JUVENILE BABOONS ARE PROGRAMMED BY BREAST-FEEDING VERSUS FORMULA-FEEDING

We estimated the effects of breast- and formula-feeding on cholesterol and bile acid metabolism for 1.5 years after weaning in 35 newborn ba boons that were breast-fed (n = 12) or fed one of two formulas with hi gh (n = 11) or low (n = 12) polyunsaturated/saturated (P/S) fatty acid composi tion. Infants were weaned at 15 weeks to a high cholesterol, saturated fat diet. Because formula P/S ratio did not affect any varia ble for 1.5 years after weaning, the data were averaged for the two fo rmula groups. After weaning, serum cholesterol and lipoprotein cholest erol concentrations among the infant diet groups were not different un til after 52 weeks of age. From 70 to 97 weeks of age, serum cholester ol and high density lipoprotein-2 (HDL(2))-cholesterol (KDL(2)-C) conc entrations were lower (P < 0.04) among baboons that were breast-fed as infants compared with those fed formulas. We observed no significant postweaning differences in low density lipoprotein (LDL)-C, KDL(3)-C, or serum apolipoprotein A-I, B, or E concentrations. At 97 weeks of ag e baboons that were breast-fed until 15 weeks compared with those form ula-fed had a 25% lower total bile acid synthetic rate (36.6 vs. 48.6 mu mol/day per kg body weight, P < 0.02) due principally to a 29% lowe r cholic acid synthetic rate (23.2 vs. 32.5 mu mol/day per kg body wei ght, P < 0.004). Baboons breast-fed as infants had a 44% higher hepati c LDL-receptor mRNA concentration formula-fed (1.45 vs. pg mRNA/mu g 1 .01 P < 0.003). These results suggest that breast- versus formula-feed ing in baboons imprints differences in bile acid synthesis, regulation of LDL receptor expression, and HDL-C subfraction concentrations.