Journal of the American College of Nutrition, Vol 15, Issue 1 79-83, Copyright © 1996 by American College of Nutrition

CLINICAL TRIAL

Use of zinc tolerance test and 24-hour urinary zinc content to assess oral zinc absorption

L. M. Henderson, G. J. Brewer, J. B. Dressman, S. Z. Swidan, D. J. DuRoss, C. H. Adair, J. L. Barnett and R. R. Berardi
Eli Lilly and Co, Indianapolis, Indiana, USA.

OBJECTIVES: The sensitivity of one plasma and two urinary methods to assess zinc absorption after oral dosing were compared over the dose range of 10 to 100 mg. METHODS: Eleven healthy subjects participated in this four-way crossover design study. After an overnight fast, the subjects received a single oral dose of zinc acetate corresponding to 10, 25, 50, or 100 mg of elemental zinc. Plasma zinc concentrations were measured at baseline (pre-zinc administration) and hourly intervals post-zinc administration for 9 hours. Urine was collected for 24 hours prior to and for 24 hours after zinc administration. During this 48-hour period, subjects consumed an isocaloric, caffeine-free diet containing 18 mg of elemental zinc per day. RESULTS: The area under the plasma zinc concentration versus time curve (PZAUC) increased linearly with doses between 10 and 50 mg, then flattened out. By contrast, urinary zinc excretion was approximately linear with doses in the 25 to 100 mg range, but no differences were observed in urinary zinc excretion after doses of 10 and 25 mg. CONCLUSIONS: Plasma zinc concentration is a useful method of evaluating oral zinc absorption from doses of 10 to 50 mg. Urinary zinc excretion is an alternative method of assessing zinc absorption, particularly when doses of 50 to 100 mg of elemental zinc are administered.