BILE SALT-STIMULATED LIPASE AND DIGESTION OF NONBREAST MILK-FAT

Background: (13) Carbon (C-13)-lipid breath tests are an effective, no ninvasive way of repeatedly measuring fat digestion. The purpose of th is study was to assess the contribution of bile salt-stimulated lipase (BSSL) in human milk to the digestion of non-breast-milk fat in Gambi an infants. Methods: Twelve Gambian infants (aged 3-8 months) were stu died on 4 days. C-13-Trioctanoin (7.5 mg/kg, digested by BSSL preduode nal and pancreatic lipases) and C-13-cholesteryl octanoate (25 mg/kg, digested by BSSL and pancreatic lipases) were used as substrates. The percentage dose recovery (PDR) of C-13 in breath during 5 hours was co mpared after ingestion of each substrate with fresh, expressed breast milk (FBM) or heated, expressed breast milk (HBM). Gas isotope ratio-m ass spectrometry was used to measure C-13 enrichment, and breast milk samples were analysed for esterase activity. Results: Heating breast m ilk significantly decreased esterase activity (mean +/- SD values: FBM = 12.2 +/- 2.9 IU/ml; HEM = 0.5 +/- 0.3 IU/ml), and there was no diff erence in the volumes of milk ingested on each test day (approximately 50 ml). The PDR of C-13 was comparable to that previously described i n healthy English infants and was not increased by BSSL. The mean +/- SD PDR of C-13 from trioctanoin was 36.3 +/- 8.4% for FBM and 34.6 +/- 6.3% for HEM (NS). From cholesteryl octanoate, the mean +/- SD PDR of C-13 was 24.3 +/- 8.7% for FBM and 27.1 +/- 7.5% for HBM (NS). Conclu sions: Bile salt-stimulated lipase may enhance fat digestion in younge r or malnourished infants who have a greater degree of pancreatic enzy me deficiency. However, this study suggests that it does not increase the digestion of non-breastmilk fat in healthy, well-nourished infants aged 3 to 8 months from an underprivileged background, who typically ingest frequent small quantities of breast milk.