Zinc Metabolism and Requirement in Chinese Preschool Children Consuming Different Diets

Abstract

Zinc metabolism of children differs due to diet and this can affect zinc requirement. We used the balance method to study zinc metabolism in 11 Chinese preschool children (six males and five females, 5.5–6.5 y old with a mean age of 6 y) of normal zinc status as judged by comprehensive criteria before and after they were fed a balanced diet. Zinc intakes and excretions via feces, urine, whole body surface and hair were determined in each subject. After all subjects consumed a balanced diet for 3 wk, losses of zinc in feces and urine increased from 3.77 ± 0.62 mg/d to 5.28 ± 0.92 mg/d (P < 0.05) and 0.19 ± 0.05 mg/d to 0.23 ± 0.05 mg/d (P < 0.05), respectively, as dietary zinc intakes increased from 5.38 ± 0.71 mg/d to 7.12 ± 0.64 mg/d (P < 0.05). Whole body surface zinc loss did not change (0.25 ± 0.07 mg/d vs 0.27 ± 0.09 mg/d (P = 0.57). Hair zinc loss was 5.26 ± 2.49 μg/d. Post-treatment, zinc excretions via feces, urine and whole body surface positively correlated with dietary zinc intakes (0.68–0.88, P < 0.05). Zinc retention did not change (1.17 ± 0.78 mg/d vs 1.35 ± 0.52 mg/d, P = 0.53) with balanced diet treatment. After treatment zinc metabolism in these children was positive and stable. The absorbed zinc, 1.84 ± 0.47 mg/d, was considered their absolute zinc requirement. Assuming that zinc availability is 20%, the zinc requirement in the daily diet of Chinese preschool children should be 9.23 ± 2.35 mg/d (6.88–11.58 mg/d).