Iron content and its speciation in human milk from mothers of preterm and full-term infants at early stages of lactation: A comparison with commercial infant milk formulas

Total and speciation analyses of iron in human milk from mothers of preterm and full-term infants at different stages of lactation and formula milk were performed by ICP-MS and SEC-ICP-MS respectively. Total iron content of preterm human milk samples was 0.5 μg/ml as compared with 0.4 μg/ml of full-term samples. Breast milk iron concentration did not vary significantly during the first month of lactation nor according to preterm or full-term gestations. Pre-term and full-term formulas from different manufacturers showed a media total iron content (9.5 μg/ml and 6.0 μg/ml, respectively) significantly higher than the iron content of human milk samples. Only 3 preterm and 2 full-term formulas had total iron contents higher than the minimum recommended level of fortification. Iron distribution patterns in milk proteins for human and formula milk samples were obtained. Whereas iron was mostly spread over the high molecular mass region of biomolecules in human milk samples, iron was mostly spread over fractions eluting at low molecular mass in formulas and these differences were statistically significant. Thus, speciation of iron is clearly different in formula milk than in natural milk.

► Total analysis of iron in human milk along lactating days.
► Speciation analysis of iron in human and formula milk whey.
► Significant differences were found in iron speciation in human and formula milk.