Longitudinal zinc balances in breast‐fed and formula‐fed infants

Abstract

Longitudinal zinc (Zn) balance studies were performed under domestic conditions in term breast-fed (n = 10), term formula-fed (n = 5; Zn concentration in the formula: 4 mg/l) and preterm formula-fed (n = 3) infants during the first 17 weeks of life. Samples of milk, urine and feces were analyzed by atomic absorption spectrometry. The median daily Zn intake in breast-fed infants decreased from 0.592 (0.457-0.829) mg Zn/kg body weight to 0.151 (0.095-0.304) mg Zn/kg body weight in the first 17 weeks of life; comparable values for bottle-fed term infants were 0.58 (0.511-0.701) and 0.674 (0.529-0.731) mg Zn/kg body weight. The median percent retention of Zn intake was 27 (-60 to 81.4)% in breast-fed infants and 21.5 (-42 to 64)% in formula-fed infants. In view of the urinary and fecal Zn losses measured, a daily intake of 0.3-0.5 mg Zn/kg body weight is considered to be sufficient to ensure a Zn retention equivalent to breast-fed infants. This requires a Zn concentration of 2-3 mg/l of Zn depending on milk volume intake.

Concentrations of iron, copper and zinc in human milk and powdered infant formula

“…Figure 1 shows the evolution of Fe, Cu and Zn mean concentrations in deviation in human milk with the stage of lactation. This behaviour is in agreement with other authors (Arnaud et al, 1991;Bates & Tsuchiya, 1990;Casey et al, 1989;Higashi et al, 1982;Karra et al, 1986Kirksey et al, 1979;Krebs et al, 1985a;Moser & Reynolds, 1983;Rajalakshmi & Srikantia, 1980;Schramel et al, 1988;Sievers et al, 1992;Suzuki et al, 1991;Vaughan et al, 1979;Vuori & Kuitunen, 1979;Vuori et al, 1980). The Cu concentration also decreased progressively from the 2nd week (0.528 ± 0.084 mg Cu/l) until the end of the sampling period (0.117 ± 0.023 mg Cu/l), which agrees with most authors (Benemariya et al, 1995;Casey et al, 1985Casey et al, , 1989Suzuki et al, 1991;Vuori & Kuitunen, 1979).…”

Biochemistry of Human Milk

“…213 Comparable values for the formula-fed infants were 0.58 mg/kg and 0.67 mg/kg. 213 Comparable values for the formula-fed infants were 0.58 mg/kg and 0.67 mg/kg.…”

Feeding Patterns in Breast-Fed and Formula-Fed Infants

“…Any infectious disease during the week prior to or during the assigned study period resulted in exclusion of the infants from the respective period. In parallel to this study, balance trials for different trace elements were performed in the study cohort [12,13]. Only mothers who had already decided to feed an infant formula were asked to participate in the study of group B infants.…”

“…In formula-fed infants, the milk volume was assessed by scales on the feeding bottles. The methods of volume assessment have been previously compared [12]. The coefficient of variation for intra-and inter-individual comparisons of the differences of intake measured by the two methods was !…”