[Copper, iron and zinc content of preterm and term human milk and cow's milk]

Sixty-eight samples of preterm human milk and 39 samples of term human milk were obtained during 4 weeks postpartum from 7 mothers delivering prematurely and 9 mothers giving birth at term. Eleven cow's milk samples were obtained at random from 11 healthy cows. Samples were measured by flame method using an atomic absorption spectrophotometer (Type WYX-402). The three trace elements content of PT and FT milks decreased significantly with duration of lactation, and the content of each mineral was higher during the first week than that measured during the fourth week. PT and FT milk did not differ significantly in the content of the three elements during the first month of lactation. Copper content of PT milk at each week, iron content of PT milk at the first week and zinc content of PT milk during the first two weeks of lactation are higher than those of cow's milk respectively. The intake of copper, iron and zinc of the preterm infant fed his own mother's milk or cow's milk was calculated. Comparison of the intake level of copper and zinc of breastfed and cow's milk-fed preterm infant with the recommended intake level of the two minerals was made. The results show PT milk is superior to cow's milk for copper, iron and zinc; may be helpful for promoting breast feeding and feeding the preterm infant with supplemental trace elements.