Submitted to: National Environmental Health Forum
Publication Type: Monograph
Publication Acceptance Date: 10/1/1997
Publication Date: N/A
Interpretive Summary: The importance of zinc for growth and mental function of humans is discussed and illustrated with initial findings from a multi-year study of young urban and rural Chinese children. These children are at high risk for zinc deficiency because their diets contained few high zinc foods, for example flesh foods such as red meat. Children received a daily treatment t of 20 mg zinc alone, zinc plus micronutrients (a broad supplement based o U.S. RDAs excluding minerals that interfere with zinc absorption), or micronutrients alone for 10 wk. Change in knee height during the study, an index of growth, was greatest for children treated with zinc plus micronutrients, intermediate for children treated with micronutrients alone, and least for children treated with zinc alone. Results were highly significant. Compared to treatment with micronutrients alone, treatments containing zinc were also associated with improved performance on computerized tasks measuring attention, reasoning and psychomotor function. Highly variable performance may have masked other apparent treatment effects. For example, both zinc treatments appeared to result in better accuracy and faster response times than micronutrients alone on a task measuring visual perception. Findings have important practical implications for children worldwide who are at risk for zinc deficiency, and illustrate how essential zinc is for human health and function.
Technical Abstract: The essentiality of zinc for growth and brain function of humans is discussed and illustrated with initial findings from a multi-year study of over 1400 urban and rural Chinese children (aged 6-9 y). These children are at high risk for zinc deficiency because their diets contain few foods rich in bioavailable zinc. In low income areas of Chongqing, Qingdao and Shanghai, classrooms of about 40 students each received a daily treatment of 20 mg zinc alone, zinc plus micronutrients (Zn+M; 50% RDA or mean ESADDI, excluding iron, calcium, magnesium and phosphorus, with folate at 25% RDA), or micronutrients alone (M) in a double-blind manner for 10 wk. Highly significant treatment differences were found for knee height, an index of growth. Greatest growth occurred with Zn + M, intermediate with M, and least with Zn. Cognition and psychomotor function were assessed before and after treatment by a battery of computer-administered tasks designed to emphasize attention, perception, memory and reasoning, and th motor and spatial skills necessary for successful performance. Compared to treatment with M, treatment with Zn + M or Zn was associated with improved attention, reasoning and psychomotor function. High response variability, and perhaps ceiling effects, made it impossible to establish as statistically reliable several other apparent treatment effects. For example, both Zn and Zn + M appeared to result in better accuracy and important practical implications for children worldwide who are at risk for zinc deficiency, and illustrate the essentiality of zinc in humans.