title: Threonine Requirement of the Enterally Fed Term Infant in the First Month of Life.
abstract: OBJECTIVE
  Threonine is one of the essential amino acids. Its major fate is incorporation into intestinal mucosal proteins and synthesis of secretory glycoproteins. Therefore, it has an important function in the neonatal gut barrier integrity. The objective was to quantify the threonine requirement in fully enterally fed term neonates by means of the indicator amino acid oxidation (IAAO) method, using L-[1-C]phenylalanine as indicator.
  
  
  METHODS
  After a 24-hour test diet adaptation, containing randomly assigned amounts of threonine (range 5-182 mg · kg · day), the participating neonates received a primed continuous infusion of [C]bicarbonate and L-[1-C]phenylalanine. At baseline and during the plateau phase of both infusions, breath samples were obtained for CO2. The fractional L-[1-C]phenylalanine oxidation (FCO2) was estimated and plotted against the threonine intakes. Biphasic linear regression crossover analysis was used to calculate the breakpoint of the FCO2, representing the mean threonine requirement. Data are presented as mean ± SD.
  
  
  RESULTS
  Thirty-two term neonates (gestational age 39 ± 1 weeks, birth weight 3.3 ± 0.3 kg, mean postnatal age 10 ± 4 days) were studied. The mean threonine requirement was estimated to be 68 mg · kg · day with an upper and lower 95% confidence interval of 104 and 32 mg · kg · day, respectively (r = 0.37).
  
  
  CONCLUSIONS
  The determined threonine requirement is extremely close to the existing requirement recommendations (∼90% of the present World Health Organization requirement guidelines). Infant formula preparations presently on the market, however, contain up to twice as much threonine as recommended. The threonine intake in formula-fed infants may therefore be reduced considerably.
authors.affiliation: *Department of Pediatrics, Academic Medical Centre, Emma Children's Hospital, Amsterdam †Department of Pediatrics, Division of Neonatology, Erasmus Medical Centre, Sophia Children's Hospital, Rotterdam §Department of Pediatrics, Division of Neonatology, Children's Hospital of Fudan University, Shanghai, PR China ||Hospital Pharmacy, Erasmus Medical Centre, Rotterdam, The Netherlands ¶Department of Pediatrics, Division of Gastroenterology, Children's Hospital of Fudan University, Shanghai, PR China.
authors.forename: Jacomine E
authors.initials: JE
authors.lastname: Hogewind-Schoonenboom
authors.forename: Lisha
authors.initials: L
authors.lastname: Huang
authors.forename: Femke
authors.initials: F
authors.lastname: de Groof
authors.forename: Li
authors.initials: L
authors.lastname: Zhu
authors.forename: Gardi J
authors.initials: GJ
authors.lastname: Voortman
authors.forename: Henk
authors.initials: H
authors.lastname: Schierbeek
authors.forename: Andras
authors.initials: A
authors.lastname: Vermes
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.forename: Johannes B
authors.initials: JB
authors.lastname: van Goudoever
mesh_terms: D001639:Bicarbonates / Q000378:metabolism; D001944:Breath Tests; D004750:Enteral Nutrition; D005260:Female; D006801:Humans; D007227:Infant Nutritional Physiological Phenomena / Q000592:standards*; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D009751:Nutritional Requirements; D010084:Oxidation-Reduction; D010649:Phenylalanine / Q000378:metabolism; D013912:Threonine / Q000008:administration & dosage / Q000032:analysis*
chemical_list: D001639:Bicarbonates; D013912:Threonine; D010649:Phenylalanine