Effects of zinc and copper content of formulas on growth and on the concentration of zinc and copper in serum and hair.

We studied the effect of dietary zinc (Zn) and copper (Cu) on the levels of these elements in serum (at 1, 3, and 5 months of age) and in hair (at 5 months of age) of breast- and formula-fed infants. Three different formulas were used: (a) Commercially available standard infant formula containing 1.0 mg/L of Zn and 30 micrograms/L of Cu; (b) Zn supplemented formula, containing 3.2 mg/L of Zn and 30 micrograms/L of Cu; and (c) Zn- and Cu-supplemented formula, containing 3.2 mg/L of Zn and 400 micrograms/L of Cu. The median Zn content of breast milk was 4.8 mg/L at 1 week, 2.9 mg/L at 1 month, 1.1 mg/L at 3 months and 1.1 mg/L at 5 months. Breast milk Cu content was 510 micrograms/L at 1 week, 440 micrograms/L at 1 month, 270 micrograms/L at 3 months, and 200 micrograms/L at 5 months after delivery. All infants were healthy and full term, and weight and length velocities were similar in each of the four groups studied. Serum Zn levels were significantly higher both in the infants fed the Zn-supplemented formula and those fed the Zn-and-Cu-supplemented formula compared with the other two groups of infants at 3 and 5 months of age. Zn levels in hair were significantly elevated (invariably greater than 80 micrograms/g) only in infants fed Zn-supplemented formula.(ABSTRACT TRUNCATED AT 250 WORDS)