Abstract
Objectives: The objectives of this study were to quantify concentrations of calcium (Ca), potassium (K), phosphorus (P), magnesium (Mg), sodium (Na), selenium (Se), zinc (Zn), copper (Cu), and iodine (I) in milk produced by healthy women living in the US Pacific Northwest during the first 6 wk postpartum.
Methods: Complete breast expression human milk samples were collected weekly from lactating women (n=37) from birth through 6 wk postpartum. Concentrations of Ca, K, P, Mg, and Na were quantified in duplicate using inductively coupled plasma optical emission spectrometry (ICP-OES, Agilent 5900) and in Se, Zn, Cu, and I using inductively coupled plasma mass spectrometry (ICP-MS, Agilent 7800). Data reported are the median (Q1, Q3) and ranges over the first 6 wk postpartum.
Results: Median human milk Ca, K, P, Mg, and Na concentrations were 288.3 mg/L (260.2, 303.3; 211.0–366.5), 572.0 mg/L (540.5, 606.3; 480.0–656.7), 168.8 mg/L (161.0, 179.2; 138.3–203.8), 26.60 mg/L (24.70, 30.90; range 19.00–38.10), and 0.1500 g/L (0.1300, 0.1800; 0.1000–0.3400), respectfully. Median Se, Zn, Cu, and I concentrations were 23.20 μg/L (21.70, 25.10; 14.80–29.40), 3.300 mg/L (2.800, 3.800; 1.800–5.000), 463.3 μg/L (424.2, 497.0; 303.0–604.3), and 182.0 μg/L (128.7, 272.0; 41.30–798.3), respectively. The concentrations reported in this study fall within the ranges reported in previous studies of human milk.
Conclusions: These data will be used to evaluate the relationship to dietary intake of these same minerals in future publications. Furthermore, these results can be used to design future research studies and to inform national nutrition recommendations for lactation and infancy.