title: Composition of premature breast-milk during lactation: constant digestible protein content (as in full term milk).
abstract: There is much discussion about the protein requirements of (very) preterm infants. The protein content of breast milk plays an important role in this discussion. For this reason, we took a close look at the protein content and its composition in premature breast milk. Complete 24 h expressions-were examined using the Kjedahl method, GPC, SDS-PAGGE and nephelometric detection of sIgA. Colostrum of premature breast milk contains a large amount of undigestible proteins, up to 70% of true protein, which decreases to 20-40% in transitory and mature preterm milk. The NPN fraction of mature preterm breast milk was, dependent on the degree of prematurity 20-25%; increasing during lactation from about 18% to 22-26%. This means that, depending on the lactation period only 30-60% of the total protein content of breast milk is available for body protein synthesis. In absolute amounts, digestible protein is reasonably stable during lactation.
authors.affiliation: Bosch Medicentrum, Department of Paediatrics, Hertogenbosch, Netherlands.
authors.forename: R J
authors.initials: RJ
authors.lastname: Beijers
authors.forename: F V
authors.initials: FV
authors.lastname: Graaf
authors.forename: A
authors.initials: A
authors.lastname: Schaafsma
authors.forename: A D
authors.initials: AD
authors.lastname: Siemensma
mesh_terms: D003124:Colorimetry; D004063:Digestion; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000378:metabolism*; D007774:Lactation; D008894:Milk Proteins / Q000032:analysis*; D008895:Milk, Human / Q000737:chemistry*; D009584:Nitrogen / Q000032:analysis; D009751:Nutritional Requirements
chemical_list: D008894:Milk Proteins; D009584:Nitrogen