The Expanding Field of Zinc Supplementation in Children

Abstract

The determination of zinc deficiency still remains elusive, as there is no single, sensitive index that will provide an accurate answer. Therefore, as suggested by Aggett (1), consideration of known factors that lead to zinc deficiency, a judicious selection of laboratory tests and the clinical or biochemical response to zinc supplements remain the basis of the diagnosis. In controlled studies during the childhood years, a positive growth response to zinc supplements is considered the correction of a pre-existing deficiency state. Thus simple, careful measurements may confirm an existing deficiency and are sometimes more useful than various biochemical assays which have been measured in the quest of defining zinc deficiency. When the many factors that influence plasma zinc concentrations and the limitations of hair zinc levels became known, a broad spectrum of functional indices were examined to include a host of zinc metalloenzymes in plasma, erythrocytes and leukocytes, apothymulin levels in serum and white blood cell chemotaxis. Variations in taste acuity and adaptation to darkness, and measurements of cutaneous hypersensitivity are additional functional indices which are sometimes used to monitor responses to zinc supplements.