Zinc homeostasis in 1–4 year olds consuming diets typical of US children

Abstract

Few data have evaluated Zn balance in young children after the first year of life. The objective of the present study was to study the relationships among Zn intake, absorption, endogenous faecal excretion, and retention in a group of healthy children. Thirty children, aged 15-48 months, were studied on a diet representative of their usual daily mineral intake. Zn absorption was assessed using a dual-tracer stable-isotope technique. Endogenous Zn faecal excretion and Cu absorption were determined in a subset of children. We found that Zn intake from the in-patient weighed dietary record (5.0 (SD 2.1) mg/d) was significantly greater than the current estimated average requirement (EAR; 2.5 mg/d; P 0.4, for all). Absolute Zn absorption was significantly related to Zn intake (r2 0.696; P < 0.0001), as was Zn retention (r2 0.506; P < 0.0001). Cu absorption was relatively high (75.1 (sd 10.8) %) despite the high Zn intake. The EAR for Zn based on this dataset would appear to be between 4.2 and 4.7 mg/d to allow for a net average retention of 120 microg/d consistent with growth needs. We concluded that at relatively high Zn intakes there was little evidence of down regulation of absorption or up regulation of urinary or endogenous faecal Zn excretion across the intake range studied. Zn retention was positively correlated with intake. A Zn intake between 4.2 and 4.7 mg/d should meet the requirement for normal growth for this age group.