title: Neonatal intestinal lactase activity.
abstract: The sequential changes in intestinal lactase activity of 40 neonates were measured indirectly from the differential uptake and excretion of lactose and the non-metabolisable disaccharide lactulose contained in formula feeds. A daily decline in urinary lactose:lactulose excretion ratios, reflecting a rise in intestinal lactase activity, followed formula feeding. Percentage decline was related directly to gestation: full term infants displayed a fivefold greater decline in lactosuria than infants with a gestation of 28 weeks during the first 10 days of milk feeding. The difference between lactose:lactulose ingestion and excretion ratios suggests that within five days of starting feeds intestinal hydrolysis of lactose exceeds 98% efficiency, even in very preterm infants.
mesh_terms: D000375:Aging; D000818:Animals; D005696:Galactosidases / Q000378:metabolism*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007422:Intestines / Q000201:enzymology*; D007785:Lactose / Q000652:urine; D007792:Lactulose / Q000652:urine; D008892:Milk / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D007792:Lactulose; D005696:Galactosidases; D001616:beta-Galactosidase; D007785:Lactose