Comparison of Four Commercially Available Zinc Supplements for Performance in a Zinc Tolerance Test

Abstract

Various zinc complexes have been used for supplements and food fortifications, but direct comparisons of bioavailability in humans are few. In the present study, in 12 young adult women, four zinc complexes (oxide, picolinate, gluconate, and glycinate) were compared for acute uptake using a zinc tolerance test (plasma zinc changes hourly for 4 h after a single zinc dosing), and two related measures (erythrocyte zinc and activity of the zinc enzyme 5′‐nucleotidase over the same 4 h period). Plasma zinc rankings based on area under the curve, as well as by rank results per person, were: glycinate > gluconate > picolinate=oxide. Erythrocyte zinc rankings based on area under the curve, as well as by rank results per person, were: glycinate > picolinate >oxide > gluconate. None of the supplement significantly increased 5′‐nucleotidase activities at any of the time points. In summary, zinc glycinate showed the best acute uptake of the four complexes tested. Disclosure Note: R DiSilvestro has a consultant retainer agreement with Albion Laboratories, who supplied zinc glycinate, but this was not true when the study was done, nor did Albion fund this study.