Serum zinc and copper levels in healthy Japanese infants.

The serum zinc and copper concentrations were measured in 45 healthy Japanese infants with age ranging from 5 days to 12 months. At one month of age there was a significant decrease in serum zinc concentration, and this low level persisted until 6 months of age when a significant increase in serum zinc concentration was observed. Serum zinc concentrations remained relatively stable between 6 and 12 months of age. The concentration of serum copper in newborn infants was significantly lower than in healthy children (age: 6 to 12 years), but had risen by 5 months of age to the same levels. There were no significant differences in serum zinc and copper concentrations between male and female infants. However, there was a tendency for serum zinc levels in exclusively breastfed infants to be higher than those in bottlefed infants at 3 months of age and for serum copper levels in exclusively or partially breastfed infants to be higher than those in bottlefed infants at one month of age.