title: Distribution of sialic acids in the milk of spanish mothers of full term infants during lactation.
abstract: OBJECTIVE
  The protective effect of human milk against infection is well known. Several non-immunologic components, including complex carbohydrates, have been described. The present study was undertaken to determine the sialic acid distribution in different milk fractions (complex carbohydrates).
  
  
  METHODS
  Milk samples from 12 Spanish women at three different lactational stages (colostrum, transitional milk and mature milk) were analyzed. Total and glycoprotein-bound, oligosaccharide-bound, casein-bound, and lipid-bound sialic acids were determined.
  
  
  RESULTS
  Sialic acids from human milk are mainly bound to oligosaccharides and only a small amount is present bound to glycoproteins or in the free form. All the fractions analyzed showed a similar trend: sialic acids decrease rapidly along lactation. Casein-bound sialic acid does not follow this trend. We detected the presence of an O-acetylated species of N-acetylneuraminic acid.
  
  
  CONCLUSIONS
  In human milk from Spanish women we observed slightly different values than those previously reported. This could be a result of population differences but nutritional or methodological aspects can not be discarded.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Universidad de Salamanca, Salamanca, Spain.
authors.forename: Samuel
authors.initials: S
authors.lastname: Martín-Sosa
authors.forename: María-Jesús
authors.initials: MJ
authors.lastname: Martín
authors.forename: Luis A
authors.initials: LA
authors.lastname: García-Pardo
authors.forename: Pablo
authors.initials: P
authors.lastname: Hueso
mesh_terms: D000328:Adult; D003126:Colostrum / Q000737:chemistry*; D005260:Female; D006023:Glycoproteins / Q000737:chemistry; D006801:Humans; D007223:Infant; D007225:Infant Food / Q000032:analysis*; D007231:Infant, Newborn; D007774:Lactation / Q000378:metabolism*; D008895:Milk, Human / Q000737:chemistry*; D009844:Oligosaccharides / Q000737:chemistry; D012794:Sialic Acids / Q000032:analysis* / Q000493:pharmacokinetics*; D013030:Spain
chemical_list: D006023:Glycoproteins; D009844:Oligosaccharides; D012794:Sialic Acids