Zinc Kinetics in Humans

Zinc is required for the activity of over 100 enzymes that are involved in the metabolism of proteins, carbohydrates, and lipids. Zinc also has a structural role in several proteins that regulate gene expression. Zinc metabolism has been studied using radioisotopes, stable isotopes or both. Zinc metabolism changed during zinc loading; plasma zinc increased to a new steady state level after about two weeks, and changes occurred in zinc kinetics in each tissue. Zinc metabolism at several sites of regulation change with age, namely, urine excretion, red blood cell exchange, absorption and secretion into the intestine. Zinc metabolism is often perturbed in patients with taste and smell dysfunction. To determine differences in metabolism in these patients, tracer was administered orally or i.v. and measured in plasma, red blood cells, urine, feces, whole body, and over liver and thigh regions for 7 d.