3.1. Basal Plasma Zn and Isotope Ratios 
Basal plasma Zn of the study population was equal to 12.74 ± 1.39 µM (min = 11.03 µM; max = 14.45 µM). None of the volunteers showed plasma Zn values below/above the reference ranges concerning sex and age [The accuracy of the isotope ratio measurements was verified by the analysis of a Zn nitrate standard (VWR Scientific). The relative accuracy of Since the relative accuracy and precision of the isotope ratios calculated with 