Mild to moderate zinc deficiency in short children: effect of zinc supplementation on linear growth velocity.

Twenty-one prepubertal, short Japanese children (11 boys) without endocrine abnormalities were identified as having mild-to-moderate zinc deficiency by zinc kinetics studies (zinc body clearance > or = 20 ml/kg per hour). Only one child had a serum zinc level < 65 micrograms/dl (cutoff level). A total of 10 children (5 boys) received 5 mg/kg per day of zinc sulfate for 6 months; 11 untreated children (6 boys) served as control subjects. During treatment, calorie intake (p < 0.01), growth velocity (p < 0.01), serum zinc, calcium, and phosphorus concentrations, alkaline phosphatase activity (p < 0.001), percentage of tubular reabsorption of phosphorus (p < 0.05), ratio of maximal tubular reabsorption rate for phosphorus to the glomerular filtration rate (p < 0.05), serum osteocalcin level (p < 0.01), and plasma insulin-like growth factor 1 (p < 0.05) were significantly increased, but urinary excretion of growth hormone was unchanged in the zinc-supplemented group. All these values were unchanged in the untreated children. We conclude that zinc supplementation is effective for inducing growth in short children with zinc deficiency, and that body zinc clearance tests facilitate detection of marginal zinc deficiency.

Zinc balance in premature infants given the minimal dietary zinc requirement.

A zinc balance study was conducted on low birth weight infants (670 to 2420 g) fed unsupplemented human milk (the mother's or pooled) (group 1, n = 17) or human milk with zinc supplementation (group 2, n = 17). The mean zinc concentrations of the diets in groups 1 and 2 were 2.2 +/- 1.1 mg/L and 8.4 +/- 0.8 mg/L, respectively, and the mean copper concentration of the diets in both groups was 0.45 +/- 0.12 mg/L. The studies were performed 7 to 128 days after birth, which corresponded to 29 to 43 weeks postconceptional age. The turning point of zinc balance from negative to positive appeared to be greatly influenced by the postconceptional age, being approximately 36 weeks in both group 1 and group 2, rather than other factors such as the zinc intake and the postnatal age. The calculated minimal requirement of dietary zinc during the period from 36 to 40 weeks postconceptional age, for an adequate amount of zinc retention in infants (250 micrograms/kg/d), was 0.8 mg/kg/d. Zinc supplementation did not appear to interfere with copper retention.