Preliminary Comparison of Fractional Absorption of Zinc Sulphate, Zinc Gluconate, and Zinc Aspartate after Oral Supple-Mentation in Healthy Human Volunteers

(1) Background: Zinc is generally used as a nutritional supplement for individuals at nutritional risk, such as older adults. This preliminary study investigated the fractional Zn absorption (FZA) after the supplementation on eight healthy volunteers with three different Zn complexes acquired with milk. (2) Methods: The design was a double-blind, three-period crossover trial. The volunteers were randomly divided into three groups. Each individual consumed 200 mL of bovine milk and rotated through a simultaneous administration of a single oral dose of (70)ZnSO(4), (70)Zn-Gluconate ((70)Zn-Glu), and (70)Zn-Aspartate ((70)Zn-Asp), equivalent to 2.0 mg (70)Zn, followed by 2 weeks of wash-out. An estimation of the FZA for comparative purposes was computed by the isotopic ratio between (66)Zn and (70)Zn in urine collected before and 48 h after administration. (3) Results: The estimated FZA was found to be significantly higher for (70)Zn-Asp when compared to the other forms, while the FZA of (70)Zn-Glu was found to be significantly higher than (70)ZnSO(4). (4) Conclusions: The results of this study suggest that complexing Zn with aspartate in milk could be a useful tool to improve FZA in individuals at risk of Zn deficiency. These results provide a rationale for conducting further studies on Zn-Asp preparations.