Efficacy of zinc supplementation on growth and IGF-1 in prepubertal children with idiopathic short statures and low serum zinc levels

We investigated the effect of zinc supplementation on growth and serum IGF-1 levels in 10 prepubertal Japanese children with idiopathic short statures, who had serum zinc levels of less than 80 µg/dL. Subjects were started on oral zinc supplementation at a dose of 25 mg once daily. In three children, the doses were increased by 50 mg once daily during the study period of 12 mo. The serum zinc levels rose in all subjects and reached a normal range (beyond 80 µg/dL). However, it was found that zinc supplementation did not promote growth. Although the mean IGF-1 standard deviations significantly increased, the majority did not reach the normal range. There were no significant adverse events other than mild gastrointestinal symptoms in 4 out of 10 subjects during the supplementation period. The most likely reason why growth was not promoted is that the zinc supplementation dosage was not enough to stimulate IGF-1 generation and subsequent growth velocity.