Zinc Balances in Preterm Infants

Abstract

Zinc balances were studied in three groups of preterm babies. The first group received bank human milk of 25% concentration, the second group bank human milk enriched with 1 g/100 ml of lactalbumin hydrolysate, and the third group an industrial formula in which 40% of the fats were replaced with medium chain triglycerides (MCT). Zn intakes (μg/kg/day) were, respectively, 796 ± 136 (group 1), 689 ± 231 (group 2), and 252 ± 67 (group 3). In all 3 groups, fecal Zn excretion was very high: range; 6,862–635 μg/kg/day (group 1), 3,022–194 μg/kg/day (group 2), and 304–27 μg/kg/day (group 3), respectively. Zn retentions were mostly negative for groups 1 and 2 (7/8 and 18/23, respectively), and mostly positive (12/14), for group 3. Zn absorption was found to be related to fecal fat (p < 0.001) in all groups, and in group 1 and 2 to fecal N (p < 0.001) and Zn intake (p < 0.02). Positive zinc balances were obtained when fat and nitrogen absorption exceeded 90%. This was achieved at 280 days of postmenstrual age in preterm babies fed bank human milk, but much sooner in preterm babies fed with MCT.

Zinc and Copper Nutritional Studies in Very Low Birth Weight Infants: Comparison of Stable Isotopic Extrinsic Tag and Chemical Balance Methods1

“…These findings are similar to our previously reported results comparing PF and F-PTHM (12), and are consistent with the data of Mendleson et al (2 1) and Tyrala (22). Our data are also in agreement with the observation by Voyer et al (20) that net zinc balance became positive when net fat and nitrogen absorption exceeded 90%.…”

“…Inasmuch as increments in body wt should be associated with zinc and copper accretion, the significant correlation with average daily wt gain seems appropriate. A significant correlation between net zinc balance and net fat and nitrogen absorption has been described (20). In addition, because most of the measures of zinc and copper availability were related to fat excretion (Table 6), and because pasteurization of human milk significantly decreases fat absorption in VLBW infants (36), the use of pooled pasteurized human milk might contribute to the prolonged period of negative net zinc and copper balance described by some investigators (18,19,22).…”

“…Previous reports (19)(20)(21)(22)(23) have demonstrated marked differences in the ability of VLBW infants to absorb dietary zinc and copper and in the ability of enteral nutrition to achieve the in utero accretion rates. Factors contributing to these reported differences include postnatal age (1 9, 2 1, 22), postconceptional age (23), net fat and nitrogen absorption (20), and diet (formula, pooled pasteurized human milk, PTHM) (21). Our study was designed to compare measurements of dietary zinc and copper absorption obtained with both extrinsic stable isotopic tags and standard nutrient balance methods.…”

Zinc Homeostasis in Premature Infants Does Not Differ Between Those Fed Preterm Formula or Fortified Human Milk

“…The lack of correlation between the amount of absorbed zinc and the endogenous fecal zinc, a relationship observed in both normal adults and infants (19 -21), suggests some inefficiency. For example, fat malabsorption has been associated with excessive excretion of endogenous fecal zinc (12), and with negative zinc balance in preterm infants (22).…”

Zinc and copper requirements in preterm infants: An examination of the current literature

“…A total of fourteen studies on zinc retention were identified [11,[17][18][19][21][22][23][24][25][26][27][28][29][30] with data on forty-five distinctly identifiable groups (Tables 1 and 2). All studies were identified in the primary PubMed search.…”