Clinical Evaluation of the Bioavailability of Zinc-enriched Yeast and Zinc Gluconate in Healthy Volunteers


Zinc (Zn)-enriched yeast and gluconate are considered two of the more biologically available supplements. However, there have been few reports comparing the bioavailability of these supplements. The objective of this study was to demonstrate whether Zn was absorbed better by healthy male volunteers when given supplements where the mineral is found organically bound in yeast or as a salt gluconate form. The trial used a randomized, two-way crossover design. Urine, blood, and fecal samples were collected and analyzed over a 48-h period after a single dose of supplement. The net Zn balance and the relative bioavailability were calculated. No differences were observed in urine excretion of the two supplements. Zinc gluconate gave higher Zn concentrations in the blood in the first 6 h but also showed greater losses in the feces. Zinc yeast also increased in blood with time but showed significantly less loss in the feces. Thus, the net Zn balance after 48 h for Zn yeast was 9.46 but for Zn gluconate it was −2.00, indicating that Zn gluconate supplementation contributed to a net loss of Zn. It was concluded that organic Zn yeast supplements are more biologically available than Zn gluconate salts.

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The authors wish to gratefully acknowledge the technical support staff from the Medical Corporation LTA (Souseikai Osaki Clinic); B. M. L. Association; and Japan Food Research Laboratories and Sogo Clinical Pharmacology Co., Ltd. In addition, they wish to acknowledge the financial support of Lallemand Inc. (Montreal, Canada) and Space-H Enterprise Ltd. (Tokyo, Japan).

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Correspondence to Thomas A. Tompkins.

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Tompkins, T.A., Renard, N.E. & Kiuchi, A. Clinical Evaluation of the Bioavailability of Zinc-enriched Yeast and Zinc Gluconate in Healthy Volunteers. Biol Trace Elem Res 120, 28–35 (2007).

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  • Zinc gluconate
  • Zinc-enriched yeast
  • Bioavailability
  • Zinc absorption