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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #149490
Title: THE EXCHANGEABLE ZINC POOL (EZP) IN CHILDREN IS AFFECTED BY ZINC INTAKE BUT NOT UNDERLYING ZINC STATUS

Author
item GRIFFIN, IAN - BAYLOR COL OF MED
item KIM, SANDRA - BAYLOR COL OF MED
item DAVILA, PENNI - BAYLOR COL OF MED
item Abrams, Steven

Submitted to: Pediatric Research
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/2000
Publication Date: 5/28/2001
Citation: GRIFFIN,I.J., KIM,S.C., DAVILA,P.M., ABRAMS,S.A., THE EXCHANGEABLE ZINC POOL (EZP) IN CHILDREN IS AFFECTED BY ZINC INTAKE BUT NOT UNDERLYING ZINC STATUS, PEDIATRIC RESEARCH, 2001. v. 49(4). p. 450A. Abstract No. 2586.

Interpretive Summary: Abstract only

Technical Abstract: BACKGROUND: We have previously described changes in zinc metabolism in two models of zinc deficiency in children, (1) resulting from short-term zinc restriction in healthy children, and (2) resulting from long-term reductions in zinc absorption and increases in endogenous fecal zinc excretion in children with Crohn's disease (CD, an inflammatory bowel disease). In both models plasma zinc fell and similar metabolic changes were detectable using multi-compartmental modeling techniques. The most severe changes were seen in the CD model. However, multi-compartmental models are difficult and time consuming to carry out. A simpler kinetic assessment of zinc status, the exchangeable zinc pool (EZP), can be measured from a small number of timed urine samples after (iv) administration of a stable isotope, and has been suggested as a useful measure of zinc status. OBJECTIVE: To assess changes in a simplified kinetic analysis, the EZP, in two human models of zinc deficiency; and to assess the effect of zinc intake and zinc deficiency on the EZP. DESIGN/METHODS: EZP was measured by collecting timed urine samples between 48 and 120h after administration of 0.5 mg 70-zinc (iv). Tracer:tracee ratio was measured by thermal ionization magnetic sector mass spectrometry, converted to the natural log, plotted against time and extrapolated back to time 0. EZP was calculated by dividing the dose of zinc-70 by the time 0 intercept, as described by Miller et al. Two populations were studied; (i) 5 healthy girls who were studied twice, after 2 weeks adaptation to diets providing 12 mg/d and 3 mg/d zinc; (ii) 9 children with stable CD were compared to 11 matched controls, after 2 weeks adaptation to 12 mg/d zinc. RESULTS: In the healthy children EZP was variable but was lower after adaptation to 3 mg/d zinc than after adaptation to l2 mg/d in all subjects (3.31 ± 1.04 mg/kg vs. 2.07 ± 0.57 mg/kg; Wilcoxon signed rank test, p = 0.04). There was, however, no difference between CD and age-matched controls (2.77 ± 0.93 mg/kg vs. 2.88 ± 0.60 mg/kg, p = 0.77), where both groups were adapted to 12 mg/d zinc. CONCLUSIONS: EZP fell after 2 weeks dietary zinc restriction, but was similar in CD and control subjects (who were on similar zinc intakes). Changes in EZP, therefore, appear to reflect short-term changes in zinc intake, rather than underlying changes in zinc status.