Objective:The aim of the study was to compare plasma carnitine profiles in fortified human milk (HM)-fed preterm infants or formula-fed preterm infants.Methods:Plasma acylcarnitine concentrations were determined in 20 formula-fed and 18 HM-fed preterm infants (birth weights between 1000 and 2200 g) by isotope dilution ESI MS/MS technique on study days 0, 14, and 28.Results:Concentrations of free carnitine (FC) and different acylcarnitines did not change during the 4 weeks of the study in infants fed HM. In contrast, in infants fed formula FC increased markedly (day 0: 29.989 16.646] mol/L, median interquartile range], day 14: 43.972 8.455], P<0.05) along with increases of short-chain esters (C2 day 0: 5.300 3.272], day 14: 6.773 2.127], P<0.05; C3 day 0: 0.070 0.059], day 14: 0.110 0.069], P<0.05). In contrast, some medium-chain (C8:1, C12) and long-chain esters (C14, C16) decreased significantly in infant formula by day 14, whereas FC and C2 and C3 esters increased further by day 28 (FC: 47.672 14.753], C2: 7.430 4.688], C3: 0.107 0.047]).Conclusions:The altered carnitine ester profile likely reflects active involvement of the carnitine molecule in the buffering, metabolism, and elimination of nonphysiological acyl moieties.
