Abstract 148

Aims: In neonates, especially in preterms, the absorption of dietary fat is impaired until the postnatal age of 6 months. We aimed to determine in humans in vivo the role of lipolysis and of uptake of long chain fatty acids (LFA) in neonatal fat absorption in a longitudinal fashion.

Subjects: In 16 preterm and in 8 term neonates, lipolysis and uptake of LFA were determined at 4 (preterms) or 3 consecutive timepoints between birth and 6 months after the term age.

Measurements: Lipolysis was determined by measuring serum concentrations of 1-13C-palmitic acid (PA) after the administration of tri-1-13C palmitoyl-glycerol. Uptake of LFA per se (i.e. independent from lipolysis) was determined by measuring serum concentration of 1-13C-stearic acid (SA) after administration of SA.

Results: The efficacy of fat absorption (%FA) increased linearly in preterm infants from 88.7 ± 5.3% at 32.6 wk postconceptional age (PCA) to 97.3 ± 2.3% at 53.6 wk PCA, and in term infants from 91.7 ± 2.3% (40.4 wk PCA) to 96.5 ± 3.0% (59.4 PCA). The 4h-serum concentration of SA, as well as that of PA, appeared highly correlated with the %FA (R = 0.90, P= 0.006, and R = 0.83, P = 0.02; resp.), indicating impaired uptake of LFA per se.

Conclusion: Neonatal fat malabsorption, both in preterm and in term infants, is mainly due to impaired uptake of LFA. Study was supported by a grant from Numico, The Netherlands.