In vivo study of the effect of lactoferrin on iron metabolism and bioavailability from different iron chemical species for formula milk fortification.

Iron fortification in infant formulas is a common practice for providing iron to newborns in order to avoid its deficiency (anemia). Depending on the physicochemical species used, its bioavailability might be insufficient to meet iron requirements. In this vein, the influence of Lactoferrin (Lf) presence on iron bioavailability in 2-week-old wistar rats fed with formula milk fortified with 57 Fe(III)2 -Lf or 57 Fe(II)SO4 (in presence of Lf) using quantitative speciation (by HPLC-ICP-MS) and Isotope Pattern Deconvolution (IPD) is studied here. Results obtained were compared among fortifiers and also with the maternal group. In RBCs, iron was mainly bound to hemoglobin in all the assayed groups in the same extent. Regarding serum samples, several iron-proteins were observed (such as transferrin and albumin). In both samples, iron content in the fractions studied was similar in all groups compared and exogenous 57 Fe incorporation of intaked iron was always above 50%, showing no significative differences between physicochemical forms but related to the dose administered. Regarding iron stores (liver) the group fed with formula milk fortified with the higher dose of 57 FeSO4 in presence of Lf presented the highest values of total iron even superior than those found in the maternal group, and also the highest exogenous (57 Fe) incorporation. In conclusion, it was proved that iron fortification is required to ensure proper iron levels in all body compartments. No significative differences were observed between different physicochemical species when iron is administered at low doses. However, higher iron doses lead to a greater incorporation in all the iron-proteins studied.

Iron bioavailability from supplemented formula milk: effect of lactoferrin addition.

PURPOSE: In this work, the absorption and/or bioavailability of iron from two chemical species, 57Fe-Lf (apo-lactoferrin) complex and 57FeSO4 at low and high dose, and in Lf excess were investigated in lactating wistar rats. METHODS: The methodology used is based on the use of stable isotopes in combination with the approach "isotope pattern deconvolution" and ICP-MS for detection. This approach provides quantitative information about exogenous (57Fe) and endogenous iron (natFe) distribution in fluids and tissues in the iron-supplemented rat groups. RESULTS: The observed results with supplemented rats were compared with those found in rats receiving maternal feeding. Interestingly, differences were found between groups in iron for transport and storage compartments, but not in the functional one, depending upon the dose of iron administered and the chemical species. CONCLUSION: Considering the results obtained, supplementation with iron salts in excess of Lf appears to be the best way of iron supplementation of formula milk.

Total zinc quantification by inductively coupled plasma-mass spectrometry and its speciation by size exclusion chromatography-inductively coupled plasma-mass spectrometry in human milk and commercial formulas: Importance in infant nutrition.

This paper summarises results of zinc content and its speciation in human milk from mothers of preterm and full-term infants at different stages of lactation and from synthetic formula milks. Human milk samples (colostrum, 7th, 14th, and 28th day after delivery) from Spanish and Brazilian mothers of preterm and full-term infants (and also formula milks) were collected. After adequate treatment of the sample, total Zn was determined, while speciation analysis of the Zn was accomplished by size exclusion chromatography coupled online with the ICP-MS. It is observed that total zinc content in human milk decreases continuously during the first month of lactation, both for preterm and full term gestations. All infant formulas analysed for total Zn were within the currently legislated levels. For Zn speciation analysis, there were no differences between preterm and full term human milk samples. Moreover Zn species elute mainly associated with immunoglobulins and citrate in human milk whey. Interestingly the speciation in formula milk whey turned out to be completely different as the observed Zn(2+) was bound almost exclusively to low molecular weight ligands (citrate) and only comparatively very low amounts of the metal appeared to be associated with higher mass biomolecules (e.g. proteins).