A bioavailability study comparing two oral formulations containing zinc (Zn bis-glycinate vs. Zn gluconate) after a single administration to twelve healthy female volunteers

Int J Vitam Nutr Res. 2007 Jul;77(4):243-8. doi: 10.1024/0300-9831.77.4.243.


As the current nutritional zinc intake frequently falls outside the Dietary Reference Intake (DRI) and as zinc is an essential trace mineral involved in the function of many enzymes, zinc supplementation has been recommended to prevent or treat the adverse effects of zinc deficiency. The aim of the present study was to compare the oral bioavailability of zinc bis-glycinate (a new formulation) with zinc gluconate (reference formulation). A randomized, cross-over study was conducted in 12 female volunteers. The two products were administrated orally at the single dose of 15 mg (7.5 mg x 2), with a 7-day wash-out period between the two tests. Serum concentrations of zinc were assayed by a validated inductively coupled plasma optical emission spectrometry (ICP-OES) method and C(max), T(max), and areas-under-the-curve (AUCs) were determined. The comparison between the two treatments was performed by comparing the C(max), AUC(t), and AUC(inf) using an analysis of variance followed by the calculation of the 90% confidence intervals of the ratio test/reference. Bis-glycinate administration was safe and well tolerated and bis-glycinate significantly increased the oral bioavailability of zinc (+43.4%) compared with the gluconate.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Absorption
  • Administration, Oral
  • Adolescent
  • Adult
  • Area Under Curve
  • Biological Availability
  • Cross-Over Studies
  • Female
  • Gluconates / administration & dosage
  • Gluconates / blood
  • Gluconates / pharmacokinetics*
  • Glycine / administration & dosage
  • Glycine / analogs & derivatives*
  • Glycine / blood
  • Glycine / pharmacokinetics
  • Humans


  • Gluconates
  • zinc glycinate
  • gluconic acid
  • Glycine