4. Discussion
Milk, ZnSOTo, Zn-Asp, Zn-Glu
This preliminary study aimed at evaluating the most efficient Zn-complex among Zn-Asp, ZnSOAt our knowledge, the data herein presented provide the first experimental evidence that Zn administered in the form of Zn-Asp can enrich Zn human content more efficiently than other forms of Zn supplements, such as Zn-Glu and ZnSOTo date, it has not been possible to provide general statements on the effect of amino acids on Zn bioavailability due to the existence of many contradictory studies [At first, amino acids complexes with Zn can keep the cation in solution, thus increasing its bioavailability in the intestinal lumen [For example, studies on cells or perfused intestines have shown a positive effect of amino acids, such as histidine, on Zn uptake [In this study, the subjects consumed the Zn supplements in the form of capsules ingested with the help of a milk drink. Milk can potentially affect the Zn absorption [Although this manuscript did not investigate the possible mechanisms that underlie Zn absorption, the data herein presented could form the rationale to support intervention trials with Zn-Asp in populations where Zn absorption could be limited, such as older adults. Indeed, there is already evidence that a moderate supplementation of Zn-Asp (10 mg Zn++/day × 30 days) in an elderly population (selected on the basis of plasma Zn deficiency) is safe and can positively modulate immune, lipid, antioxidant, and psychological parameters [The method used to evaluate the FZA was robust and reproducible. Indeed, after 6 months the isotopic Zn %E of ZnSOThe results presented here also suggest that 2 mg of Zn given as Zn-Asp in milk was safe and improved FZA for a limited time period. These data do not take into account a possible effect of the amino acids on the Zn excretion, which could confound the results. However, only Histidine was reported to affect the excretion of Zn in the urine [