Influence of formula versus breast milk on cholesterol synthesis rates in four-month-old infants.

We investigated whether supplementation of regular formula (RF) with cholesterol (Ch) (RF+Ch) influenced circulating Ch levels and de novo synthesis compared with their breast-fed (BF) counterparts in 4-mo-old infants. The incorporation rate of deuterium in body water into erythrocyte membrane-free Ch over 48 h was used as an index of cholesterogenesis. Plasma total-Ch and LDL-Ch concentrations were highest (p < 0.02) in BF infants, compared with infants in the RF-fed groups. Infants in the RF+Ch groups showed an intermediate response; their plasma total-Ch and LDL-Ch concentrations were not significantly different from the BF or the RF-fed groups. Plasma total/HDL-Ch and LDL/HDL-Ch ratios were higher (p < 0.05) in BF, and higher in RF+Ch-fed infants, compared with those fed RF, whereas not different between BF and RF+Ch-fed infants. At 4 mo of age, Ch FSR was 4-fold lower (p < 0.0001) in BF versus other groups, but not significantly different between RF- and RF+Ch-fed infants. Thus, despite addition of Ch to the concentration found in breast milk, FSR remained elevated compared with that of the group fed breast milk, with an intermediate response in circulating Ch levels. It is speculated that factors other than Ch intake account for the differential Ch metabolism between formula-fed and BF infants.