Reference values for minerals in human milk: the Mothers, Infants and Lactation Quality (MILQ) Study

Authors: Allen, Lindsay; ISLAM, M. MUNIRUL - Icddr,b; KAC, GILBERTO - Universidade Federal Do Rio De Janeiro; MICHAELSEN, KIM - University Of Copenhagen; MOORE, SOPHIE - King'S College; ANDERSSON, MARIA - University Hospital Zurich; PEERSON, JANET - Consultant; Doel, Andrew; Dror, Daphna; Shahab-Ferdows, Setareh; DE BARROS MUCCI, DANIELA - Rio De Janeiro State University; TORRES SILVA, GABRIELA - Universidade Federal Do Rio De Janeiro; HAMPEL, DANIELA - University Of California, Davis

Submitted to: Advances in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2025
Publication Date: 8/26/2025
Citation: Allen, L.H., Islam, M., Kac, G., Michaelsen, K.F., Moore, S.E., Andersson, M., Peerson, J.M., Doel, A.M., Dror, D.K., Shahab-Ferdows, S., De Barros Mucci, D., Torres Silva, G., Hampel, D. 2025. Reference values for minerals in human milk: the Mothers, Infants and Lactation Quality (MILQ) Study. Advances in Nutrition. https://doi.org/10.1016/j.advnut.2025.100431.
DOI: https://doi.org/10.1016/j.advnut.2025.100431

Interpretive Summary: This sixth article in the series on Reference Values (RVs) for nutrients in human milk presents the results for minerals. Development of the RVs was the purpose of the Mothers, Infants and Lactation Quality (MILQ) studies in Bangladesh, Brazil, Denmark, and The Gambia, where breast milk samples were collected throughout the first 8.5 months of lactation from well-nourished but unsupplemented women. Our results were compared with the values used by the Institute of Medicine (IOM) for setting recommendations for infant nutrient requirements. The MILQ results were similar to the IOM values for magnesium, potassium, and calcium. MILQ zinc and selenium values were much lower (30-60% of the IOM), sodium, iron, and copper were somewhat lower (60-90% of the IOM)., and only phosphorus was higher (116%). Milk iodine concentrations varied greatly among sites due to the different national policies for salt iodization, so no RV for iodine was developed. The MILQ mineral concentrations are also presented as percentiles to allow comparison and interpretation of data from other studies, and as total infant nutrient intakes. Our results reveal the dynamic changes in milk mineral concentrations during lactation, and the fact that most are lower than currently assumed.

Technical Abstract: This sixth article in the series presenting Reference Values (RVs) for nutrients in human milk describes the values for minerals. In order to develop the RVs, the Mothers, Infants and Lactation Quality (MILQ) study collected human milk samples throughout the first 8.5 months of lactation, in 1,882 well-nourished but unsupplemented women in Bangladesh, Brazil, Denmark, and The Gambia. All minerals were measured by inductively-coupled plasma mass-spectrometry (ICP-MS). Measured mineral concentrations from the MILQ study were compared with those used by the Institute of Medicine (IOM) for setting recommendations for nutrient requirements of infants. While MILQ estimates are within 5% of the concentration used by the IOM for magnesium, potassium, and calcium, they are much lower (30-60% of the IOM values) for zinc and selenium, somewhat lower (60-90% of the IOM reference) for sodium, iron, and copper, and slightly higher for phosphorus (116%). Milk iodine concentrations varied greatly among sites, reflecting the differing national policies for salt iodization, so no RV was set for iodine. The MILQ mineral RVs are also provided as percentiles to enable comparison and interpretation of data from other studies, and as estimates of total intakes of each nutrient based on the 50th percentile for concentration multiplied by milk volume. Importantly, the MILQ data show marked changes in milk mineral concentrations during the first six months of lactation, an observation often missed due to the cross-sectional nature of much of the previously published data.