Zinc supplementation of malnourished schoolboys in Iran: increased growth and other effects

Abstract

The effects of zinc, 40 mg daily, given as zinc carbonate, in combination with a supplement of egg-white protein (10 g daily), corn oil, minerals, and vitamins to fulfill many requirements, were evaluated in 13-year-old prepubertal village schoolboys in southern Iran. Thirty-five of the 49 boys participating had subnormal plasma zinc concentrations. The boys continued their usual diets in which unleavened wholemeal wheat bread rich in phytate was the main staple. A similar group serving as controls received the same supplements without zinc. A second control group received only the protein supplement. Observations were continued for 18 months. Significantly increased heights, weights, and bone ages occurred in those receiving the supplementary zinc, despite zinc concentrations in plasma that remained subnormal throughout the study in most of the boys. These gains occurred mainly during the final 12 months of supplementation. Serum total protein and albumin concentrations were moderately decreased initially in approximately 75% of the boys. Concentrations of total protein became normal during the first 3 months of treatment. The results demonstrate a clearly defined stimulus to growth brought about by supplementation with zinc when adequate amounts are given. Contrary to findings in a previous study, no statistically significant stimulation of gonadal development was detected in the zinc-supplemented group compared with the controls. However, a tendency toward accelerated sexual development in the zinc supplemented boys was evident.