A comprehensive study of duodenal bile salts in newborn infants and their relationship to fat absorption
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Total and individual duodenal bile salt concentrations measured during digestion of an amino acid-based test feed are compared with dietary fat absorption in 50 children. Thirty-six were newborn infants, of whom 21 were fed evaporated milk (group 1), and 15 a modified formula (group 2); 16 were older children who served as ‘controls’ (group 3). Total bile salt levels in resting duodenal contents were similar in all the groups, but in groups 1 and 2 these were significantly lower following the feed (P<0.01) and associated with appreciable fat malabsorption. Very low levels of bile salt were recorded during the first 2 hours with levels often less than the critical micellar concentration (CMC) in association with a 2-fold, or greater, dilution of bowel contents by test feed. Significant negative correlations were present in group 1 between dilution and bile salt levels between 1/2 and 2 hours (P<0.05–P<0.001). In groups 1 and 2 many significant correlations were demonstrable between fat excretion (and absorption) and bile salt concentrations, infant’s gestational age, length and other epidemiological data.
In group 3 fat absorption was normal and although bile salt concentrations per unit body weight were significantly lower than in newborns (P<0.05), the actual levels were usually above the CMC.
Thin layer chromatography separation of individual bile salts revealed a strikingly low proportion (11%) of glycine conjugated dihydroxy salts in newborns; these were much lower than the taurine conjugates (P<0.001). The overall glycine to taurine ratios were widely scattered and no difference was shown between the means (1.7–1.9). In 5 babies aged less than one week at the time of study, however, this was 0.8. Taurolithocholic acid was less frequently isolated in the newborns (P<0.05), and within this overall group there was an interestingnegative correlation between its concentration and infant’s weight (P<0.05).
KeywordsBile Acid Taurine Bile Salt IRISH Journal Critical Micellar Concentration
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