title: Influence of changes in lactase activity and small-intestinal mucosal growth on lactose digestion and absorption in preterm infants.
abstract: BACKGROUND
  Feeding intolerance (ie, achieving and maintaining full enteral feedings) is a significant problem in preterm infants. A relation exists between feeding intolerance and incomplete lactose digestion.
  
  
  OBJECTIVE
  We sought to identify the factors relating to lactose digestion and absorption, lactase activity, and small-intestinal mucosal growth.
  
  
  METHODS
  Lactose digestion and absorption, lactase-specific activity, and lumen-to-mucosa water flux as a measure of small-intestinal mucosal surface area were determined by using the triple-lumen perfusion technique on 2 occasions 3 wk apart in 10 preterm infants (x+/-SEM gestational age: 28.0+/-0.2 wk).
  
  
  RESULTS
  Lactose digestion and absorption and lactase activity doubled between studies (P=0.035 and P=0.041, respectively). The change in digestion and absorption was related to lactase activity (P=0.034, R2=0.38). Lactase activity correlated with gestational age at birth (P=0.012, R2=0.51). The number of days of feeding explained 80% of the variability in small-intestinal mucosal surface area (P=0.001).
  
  
  CONCLUSIONS
  To our knowledge, this is the first study to measure directly lactose digestion and absorption, lactase activity, and small-intestinal surface area in preterm infants. Changes in lactose absorption relate primarily to lactase activity rather than to mucosal growth. We showed directly a relation between enteral feeding and small-intestinal mucosal growth.
authors.affiliation: Department of Pediatrics, Baylor College of Medicine, US Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Texas Children's Hospital, Houston, TX 77030, USA. rshulman@bcm.tmc.edu
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Shulman
authors.forename: William W
authors.initials: WW
authors.lastname: Wong
authors.forename: E O'Brian
authors.initials: EO
authors.lastname: Smith
mesh_terms: D004063:Digestion; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000254:growth & development / Q000378:metabolism*; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000201:enzymology* / Q000254:growth & development*; D007421:Intestine, Small / Q000201:enzymology / Q000254:growth & development; D043322:Lactase / Q000172:deficiency / Q000378:metabolism*; D007785:Lactose / Q000493:pharmacokinetics*; D007787:Lactose Intolerance; D010477:Perfusion; D011446:Prospective Studies
chemical_list: D043322:Lactase; D007785:Lactose