title: Calcium, phosphate and citrate in human milk at initiation of lactation.
abstract: The onset of copious milk secretion (lactogenesis II) in women occurs between 1 and 3 d after birth, and during this period the composition of breast milk changes. During the first 5 d of lactation we measured the concentrations of total, diffusible and ionized Ca (Catot, Cad, Ca2+), diffusible phosphate (Pid), diffusible citrate (Citd) and lactose in the breast milk. On day 1 after birth the concentrations (mean +/- SEM) were Catot, 5.71 +/- 0.30 mM; Cad, 2.66 +/- 0.19 mM; Ca2+, 2.90 +/- 0.18 mM; Pid, 0.26 +/- 0.16 mM; Citd, 0.25 +/- 0.03 mM and lactose, 76 +/- 11 mM. Between day 1 and day 4 the concentration of Catot increased 1.7-fold to 9.56 +/- 0.39 mM, Cad increased 1.8-fold to 4.75 +/- 0.26 mM, Ca2+ decreased by 20% to 2.33 +/- 0.13 mM, Pid increased 6.6-fold to 1.69 +/- 0.11 mM, Citd increased 20-fold to 5.06 +/- 0.21 mM, and lactose increased 2.3-fold to 173 +/- 4 mM. A high correlation has been found between [Cad] and [Citd] in the milk of both ruminant and non-ruminant species, which show a wide range in concentrations of [Cad] and [Citd], and the data fit a simple physicochemical model of ion equilibria in the aqueous phase of milk. The results of the present study confirm the relationship between [Cad] and [Citd] in human milk, even during lactogenesis II when the composition of the milk is changing very rapidly.
authors.affiliation: Department of Biochemistry, University of Western Australia, Nedlands.
authors.forename: J C
authors.initials: JC
authors.lastname: Kent
authors.forename: P G
authors.initials: PG
authors.lastname: Arthur
authors.forename: R W
authors.initials: RW
authors.lastname: Retallack
authors.forename: P E
authors.initials: PE
authors.lastname: Hartmann
mesh_terms: D000328:Adult; D002118:Calcium / Q000032:analysis*; D002951:Citrates / Q000032:analysis*; D005260:Female; D006801:Humans; D007774:Lactation / Q000502:physiology*; D008895:Milk, Human / Q000737:chemistry* / Q000378:metabolism; D010710:Phosphates / Q000032:analysis*; D012044:Regression Analysis
chemical_list: D002951:Citrates; D010710:Phosphates; D002118:Calcium