Comparison of the Oral Absorption, Distribution, Excretion, and Bioavailability of Zinc Sulfate, Zinc Gluconate, and Zinc-Enriched Yeast in Rats

Scope The oral absorption, distribution, excretion, and bioavailability of zinc sulfate (ZnS), zinc gluconate (ZnG), and zinc-enriched yeast (ZnY) in rats are fully and systemically compared for the first time. Methods and results After zinc compounds were orally administered to rats at a single dose of 4 mg Zn kg –1 , blood, tissues, urine, and feces at different time points were collected for the quantification of zinc concentration. Blood was also harvested for the zinc assay in the multiple-dose administration. Plasma zinc levels among three zinc compounds showed no difference, and zinc was widely distributed in various tissues with the level sequence of bone > liver > pancreas > testes. The net Zn balance was 2.993, 5.125, and 7.482% for ZnS, ZnG, and ZnY, respectively. Conclusion ZnS, ZnG, and ZnY show equivalent bioavailability based on plasma and tissues zinc levels, although ZnY was statistically more absorbed and retained than ZnS and ZnG based on the excretion amount.