title: Cow's milk and intestinal blood loss in late infancy.
abstract: OBJECTIVE
  Young infants commonly show occult intestinal blood loss when fed cow's milk, but in older infants blood loss may be less common. This study examined intestinal blood loss in response to cow's milk feeding in normal 7(1/2)-month-old and 12-month-old infants.
  
  
  METHODS
  Infants (n = 62) were fed formula for 1 month and then pasteurized cow's milk for 2 months. Stools were collected for quantitative determination of hemoglobin. Iron nutritional status was assessed.
  
  
  RESULTS
  Infants fed cow's milk from 7(1/2) months of age showed a significant increase in guaiac-positive stools and in stool hemoglobin concentration. These effects were largely limited to those infants who had been breast fed early in life. Infants fed cow's milk from 12 months of age at baseline had greater stool hemoglobin concentrations than 7(1/2)-month-old infants, but cow's milk produced no significant increase. In neither age group did cow's milk affect iron nutritional status.
  
  
  CONCLUSIONS
  The response to cow's milk is attenuated in infants aged 7(1/2) months compared with younger infants. By 12 months of age, the response has disappeared entirely. We conclude that the gastrointestinal tract of healthy infants gradually loses its responsiveness to cow's milk.
authors.affiliation: Fomon Infant Nutrition Unit, Department of Pediatrics, University of Iowa, Iowa City 52242, USA.
authors.forename: E E
authors.initials: EE
authors.lastname: Ziegler
authors.forename: T
authors.initials: T
authors.lastname: Jiang
authors.forename: E
authors.initials: E
authors.lastname: Romero
authors.forename: A
authors.initials: A
authors.lastname: Vinco
authors.forename: J A
authors.initials: JA
authors.lastname: Frantz
authors.forename: S E
authors.initials: SE
authors.lastname: Nelson
mesh_terms: D000367:Age Factors; D000818:Animals; D005260:Female; D005293:Ferritins / Q000032:analysis; D006471:Gastrointestinal Hemorrhage / Q000209:etiology*; D006138:Guaiac; D006801:Humans; D007223:Infant; D008297:Male; D008892:Milk; D009752:Nutritional Status; D009780:Occult Blood
chemical_list: D006138:Guaiac; D005293:Ferritins