Functional Development of Fat Absorption in Term and Preterm Neonates Strongly Correlates with Ability to Absorb Long-Chain Fatty Acids from Intestinal Lumen

Abstract

Our goal for this study was to determine whether the maturation of fat absorption in neonatal life is functionally related to an increased ability to hydrolyze dietary fat, to absorb long-chain fatty acids, or to do both. In 16 preterm and in eight term neonates, the intestinal ability to hydrolyze triacylglycerols and the capacity to absorb long-chain fatty acids were determined at several times between birth and 5 mo after the term age. These processes were compared with the percentage of fat absorption (formula-fed infants) or with fecal fat excretion (breast-fed infants). The functional capacity to digest triacylglycerols and to absorb the lipolytic products was evaluated by measuring serum concentrations of the lipolytic product [1-13 C]palmitate after the enteral administration of tri-1-13 C palmitoyl-glycerol. Longchain fatty acids absorption (i.e. independent of lipolysis) was determined by measuring serum concentrations of [1-13 C]stearate after its enteral administration. The efficacy of fat absorption increased in preterm infants (formula-fed) from 91.2 Ϯ 1.1% (mean Ϯ SEM) at 32. Efficient absorption of fat from the diet is important for energy supply, growth, and development, especially during development (1). At the neonatal age, and particularly in the case of prematurity, a considerable part of dietary fat is not absorbed from the intestine, but is excreted via the feces (2-5). Fat absorption involves digestion, requiring lipolysis by lipolytic enzymes, and the subsequent intestinal absorption of the hydrolyzed fatty acids and monoacylglycerols (6). The uptake of lipolytic products encompasses intraluminal solubilization of lipolytic products, their subsequent translocation across the small intestine, and their incorporation into chylomicrons that are subsequently secreted into the lymph (7). The importance and relative contribution of incomplete digestion and a decreased ability for fatty acid absorption to the causes of increased fecal fat loss during (preterm) infancy is only partly understood. Several studies suggest that lipolysis of fats could be the rate-limiting step in (preterm) neonatal dietary fat absorption. In the human gastrointestinal system several lipases are active on dietary triacylglycerols: gastric lipase (8, 9), pancreatic (colipase-dependent) lipase (10, 11), and bile salt-stimulated lipase (12). Several investigators have demonstrated a decreased intraduodenal concentration of both pan-

Variation in [U-13C] α Linolenic Acid Absorption, β-oxidation and Conversion to Docosahexaenoic Acid in the Pre-Term Infant Fed a DHA-Enriched Formula

“…The median stool excretion of labelled ALNA (7%) is comparable to that of previous studies in term and pre-term infants using different methods (10,11). Although as a group, these infants appear to absorb ALNA well, availability varied widely with the poorest absorption in the most premature.…”

“…Fat absorption is believed to be related to the maturity of the gastrointestinal tract in the pre-term neonate. Rings et al demonstrated improving absorption of stearic and palmitic acid between 32 wk and 54 wk postconceptual age (10). As regards long chain polyunsaturated fatty acids, Moya and coworkers reported that the absorption of ALNA was relatively high (Ͼ90%), but the absorption of DHA was considerably less (ϳ62%) and more variable (11).…”

Induction of Uncoupling Protein 3 Gene Expression in Skeletal Muscle of Preterm Newborns

“…They stress the importance of the lipid composition of nutrition for postnatal development (see Refs. [37][38][39].…”

Fat Absorption in Newborns: Commentary on the article by Rings et al. on page 57

“…The observations by Rings et al (2) raise the interesting notion that there are limiting functions in the enterocyte previously assumed to be passive, that impact or limit the postprandial response to dietary fat and are related to a variety of interorgan pathways of lipid transport and major disease associated processes (e.g., Clearance of lipoprotein remnant particles). Thus, it is likely that the observations of Rings et al (2) and further investigation of enterocyte functions responsible for processing of dietary fats will lead to a broad impact on our understanding of the implications of changes in fat absorption during more than just the neonatal period of life.…”

“…Thus, it is likely that the observations of Rings et al (2) and further investigation of enterocyte functions responsible for processing of dietary fats will lead to a broad impact on our understanding of the implications of changes in fat absorption during more than just the neonatal period of life.…”