Zinc Supplementation in a Randomized Controlled Trial Decreased ZIP4 and ZIP8 mRNA Abundance in Peripheral Blood Mononuclear Cells of Adult Women

Zinc plays an integral role in numerous cellular processes including regulation of gene expression. This randomized placebo-controlled trial in adult women evaluated the effects of 20 mg Zn for 23 days. The mRNA abundance of zinc transporters (ZnT1/ZIP3/ZIP4/ZIP8) and metallothionein (MT1) from peripheral blood mononuclear cells was determined by real-time quantitative polymerase chain reaction. In paired samples (n = 6–9), the ZIP4 (P = 0.036) and ZIP8 (P = 0.038) mRNA abundance decreased following zinc supplementation. ZnT1, ZIP3, and MT1 mRNA abundance did not change significantly. The mean ± standard deviation plasma zinc concentration (by inductively coupled plasma mass spectrometry) at baseline was 680 ± 110 μg/L for the zinc group (n = 24) and 741 ± 92 μg/L for the placebo group (n = 23). At endpoint, plasma zinc in the zinc group increased to 735 ± 80 μg/L (P < 0.01) while in the placebo group (717 ± 100 μg/L) it did not change significantly from baseline. The change in mRNA abundance highlights the importance of further investigating ZIP4 and ZIP8 mRNA abundance as potential zinc status biomarkers.