Zinc and copper in breast-milk and home-prepared milk fed to urban infants from low-income families

When prepared in the home, differences in mineral concentrations between human and cow's milk can be further increased due to water supply and utensils. Comparisons were made between the concentrations of zinc and copper and their caloric densities of breast-milk and home-prepared milk. Samples of breast-milk and home-prepared milk representative of the milk feedings of the first 6 months were analyzed for zinc and copper by atomic absorption spectrophotometry. The initial high levels at the first day (8 μg/mL) decrease 47% during the first week, and are decreased by 59% at day 15. By the first, second, and third months, the respective decreases are 67%, 84%, and 85%. At 6 months, the breast-milk zinc concentration is only 12% (0.93 μg/mL) of its initial value. In the analyzed samples of breast-milk, the patterns of changes in zinc and copper concentrations were comparable to values in literature. However, in home-prepared milk consumed by infants who are 1–6 months old, no systematic pattern of change was observed. Relatively higher concentrations of zinc and copper in home-prepared milks resulted in metallocalorie ratios comparable to breast milk. The zinc to copper ratio varied relatively less in human milk. Reconstitution of powdered milk products, which comprise the main food item of babies during early weaning, may result in trace-element nutrition unbalance. J. Trace Elem. Exp. Med. 15:123–129, 2002. © 2002 Wiley-Liss, Inc.