Zinc and copper in infants fed breast-milk or different formula.

In 129 term infants at birth and at the age of 4 months, zinc and copper concentrations of plasma and urine were determined by graphite furnace atomic absorption spectrophotometry and the values correlated to other biochemical parameters and somatic data. Of the infants, 49 were exclusively breast-fed, 44 fed with various commercially available cow's milk formula, 35 fed with a hypoallergenic formula (cows's milk whey hydrolysate, commercially available, supplemented with zinc and copper). Plasma zinc values declined from birth to the age of 4 months in all three groups (P < 0.001). In formula fed children, 4 months old, the values (11.1 +/- 1.7 mumol Zn/l) were significantly lower than in breast-fed (12.2 +/- 1.7 mumol Zn/l; P = 0.004) or babies on hypo-allergenic formula (12.4 +/- 1.6 mumol Zn/l; P = 0.0015). In accordance with the literature plasma copper and caeruloplasmin values increased significantly within the first 4 months of life, the plasma levels were similar in either feeding group, only urinary copper excretion was higher in male infants on hypo-allergenic formula (P < 0.03) at the age of 4 months. There were no correlations between zinc or copper values and alkaline phosphatase. In infants on hypo-allergenic formula there was a negative correlation between plasma zinc and weight or height increments. Despite different zinc and copper supply, presumedly different bioavailability, and different plasma zinc values, all infants thrived and weight and length increments were similar in each group.