Intestinal excretion of endogenous zinc in Guatemalan school children.

The intestine is the major route of excretion of endogenous zinc (Zn) and has a key role in maintaining Zn homeostasis. The principal objective of this paper is to provide an interpretative report of quantities of endogenous fecal Zn (EFZ) excreted by rural Guatemalan school children fed either normal or low phytate maize as their principal food staple. EFZ was measured by a Zn stable isotope technique. EFZ did not differ between control and low phytate maize groups. The overall EFZ (n = 53) was (mean +/- SD) 1.56 +/- 0.69 mg Zn/d or 0.07 +/- 0.03 mg Zn x kg body wt(-1) x d(-1). EFZ was not correlated with the quantity of Zn absorbed. The estimated EFZ at the level of absorption that matched the physiologic requirement (EFZ(PR)) did not differ from the above mean value. The EFZ(PR) of 0.07 +/- 0.03 mg Zn/kg body wt is twice the value currently used in the estimation of Dietary Reference Intakes. Supported by other recent childhood data, these results suggest that the current estimates of EFZ(PR) used in the calculation of Zn requirements for children are misleadingly low.