QUANTITATIVE AND QUALITATIVE STUDY OF GASTRIC LIPOLYSIS IN PREMATURE NEWBORN

Abstract

Aim: To determine the role of milk fatty acid (FA) composition on the intragastric fat digestion in premature newborn and to analyse the lipolysis products released in the stomach. Methods: Premature newborn fed either with fresh human milk (HM) (10% medium chain triglycerides (MCT)) or infant formula (IF) (PréGallia®, 25% MCT) were included. Gastric contents were aspirated twice a day during 5 days, just before a gavage feeding (T0 = T180 min) and at various times after the end of the same gavage (15, 30, 60, 90, 120 min). Human gastric lipase (hGL) activity against tributyrin was measured using a Radiometer pH-stat equipment. Lipids were extracted with chloroform-methanol (2/1 v/v) and separated using thin-layer chromatography coupled to a flame ionization detector (TLC-FID). FA methyl esters were analysed by gas chromatography. Results: Eight infants were included in the study (mean age and weight: 34.3 ± 1.8 wks; 1791 ± 165 g). Two were fed with HM and 6 with IF. hGL concentration increased during digestion, but final levels were 2.5 fold lower than in healthy adults (43.7 ± 28.8 vs 100-120 μg/mL). Total hGL secretory ouputs after 180-min digestion period did not differ in relation to the type of milk (137.5 ± 53 μg for HM vs 113 ± 52 μg for IF). The maximum lipolysis level recorded in the gastric contents (21.4 ± 4.3 %) was similar to that recorded in adults (24.4 ± 5.7%). Mean total intragastric lipolysis in the 8 newborn was 6.15 ± 2.2%, vs 10 ± 1% in healthy adults. The total amount of free FA released upon gastric lipolysis was the same with both types of milk. Free FA mainly released in the stomach were oleic acid (C18:1) and linoleic acid (C18:2), whatever the type of milk Conclusion: Intragastric lipolysis is not quantitatively more important in preterm newborn than in adults and is not affected by the amount of ingested MCT. The preferential release of long chain FA might be linked to the fact that they are essential to optimise the intestinal lipolysis by pancreatic lipase. MCT supplementation has therefore no apparent effects on intragastric fat digestion in the newborn and its use for preterm feeding probably needs to be further investigated.