Development and application of a model for zinc metabolism in humans.

A model has been developed to describe zinc metabolism in humans. The model was developed from a series of studies in normal volunteers and patients with various clinical disorders. Zinc metabolism was studied with radiotracers for 9-12 mo before and after a daily oral zinc load of 100 mg. Data were analysed by compartmental analysis and a model was developed that consists of compartments for zinc in the gut, plasma, red blood cells, liver, muscle, bone and other tissues with excretion via urine and feces. Using the model parameters of zinc metabolism including absorption, tissue exchange, secretion and excretion have been determined, together with mass of zinc in tissues and in the whole body. The model has been used to identify five sites of long-term regulation of zinc metabolism in humans. These sites are absorption, excretion, exchange with red blood cells, release of zinc from muscle and secretion of zinc into gut. The model is currently being applied to several areas of nutrition including the effects of dietary fiber on zinc stores, the effects of aging on zinc metabolism and the zinc requirements of neonates.