Case study of temporal changes in maternal dietary intake and the association with breast milk mineral contents

Minerals play important roles in infant growth and development, even though they only make up to 0.2 g% of the mature breast milk contents. Limited studies examined the association between maternal dietary intake and breast milk mineral contents in a temporal manner. Twenty Malaysian Malay postpartum mothers were recruited by either convenience or snow balling sampling from the urban lower middle income residential areas. Dietary intake of the subjects was obtained by 24-hour recall during each breast milk collection. Adequacy of maternal mineral intake was compared with the latest Recommended Nutrient Intake for Malaysia. Each of the subject provided breast milk samples for three times (T1, T2, and T3) at consecutive 2-week intervals. Breast milk concentrations of selected macro- and micro-minerals, including Ca, P, K, Na, Mg, Fe, Zn, Cu, Mn, Se, I, Cr and Mo were determined by inductively coupled plasma mass spectrometry (ICP-MS). Subjects were aged 31.4 +/- 6.1 years with a majority (60 %) having post-secondary school/college education. While maternal intake of macro-minerals, Ca, P, K and Mg, did not display a significant temporal changes from T1 to T3, the intake of micro-minerals, Cu, Mn and I decreased significantly over time from T1 to T3. Breast milk K, Fe, Zn and Cu concentrations showed a significant decreased with the progression of lactation from transitional (2-3 weeks) to established stage (>8-12 weeks). Significant correlations were established between maternal intake of K, Na, Fe and Se and their respective concentrations in breast milk in the present study. This case study revealed an inadequate maternal intake of several key micro-minerals (Cu, Mn, I) among the postpartum Malay mothers and a decreasing concentrations of certain essential minerals (K, Fe, Zn and Cu) in breast milk with lactation stage.