Role of bile salts in fat malabsorption of premature infants.

Eighteen premature infants were studied. 9 were fed with human milk and 9 with a modified cow's milk. Subsequent to a 72-hour fat balance, a duodenal intubation was performed on the 14th day of life. Total bile acids were determined in serial duodenal aspirates before and after a milk feed. Bile acid excretion in the faeces during a 72-hour period was also measured. Infants fed with human milk absorbed fat better (mean fat absorption coefficient, 75%) than those receiving a cow's milk formula (mean fat absorption coefficient, 60%). In both groups the bile acid concentrations after a meal were often less than that required for the formation of micellar solutions and solubilization of fat (i.e. <2 mmol/l.). With human milk, a reasonable fat absorption occurred even with bile acid levels below the critical micellar concentration. In the infants fed with the cow's milk formula, impaired fat absorption was correlated with low bile acid levels. Infants on human milk excreted less bile acids in the stool (mean, 41·9 μmol/kg per 24 hr) than did infants fed with the cow's milk formula (mean, 72·4 μmol/kg per 24 hr). In both groups the faecal loss of bile acids was increased compared with that in older infants and children.