A Randomized Controlled Zinc Supplementation Trial to Evaluate Biomarkers of Zinc Status of Adult Women in Rural Sidama, Southern Ethiopia

Abstract

Objectives: Effects of 20 mg Zn or placebo for 23 d on zinc transporter and metallothionein (MT) mRNA abundance, plasma zinc and zinc-related biomarkers were evaluated in apparently healthy women. Methods: Participants (n=48) were randomly selected from village lists of non-pregnant, non-lactating women with body mass index (BMI) ranging from18.5 to 24.9 residing in rural southern Ethiopia. Demographic and household dietary diversity data were collected. Women were randomized to placebo or zinc supplementation groups. Morning fasting blood, urine and fecal samples were collected at baseline and after 23 d. RNA was extracted from peripheral blood mononuclear cells, reverse-transcribed, and used for gene expression analyses. The mRNA abundance of zinc transporters (ZnT1/ZIP3/ZIP4/ZIP8) and MT1 was determined by qPCR. Plasma zinc was measured by inductively coupled plasma mass spectrometry and plasma, urine and fecal biomarkers by ELISA. Results: Mean ± SD age of participants was 33±5. Household dietary diversity score was 4.5 with no meat, fish, or egg consumption in the last 24h. ZIP4 (P=0.036) and ZIP8 (P=0.038) mRNA abundance decreased following zinc supplementation. Mean plasma zinc at baseline was 680±105 for zinc and 741±92 μg/L for placebo groups. At endpoint plasma zinc for placebo (717±103 μg/L) did not change significantly from baseline but in the zinc-supplemented group, plasma zinc at 735±80 μg/L was higher than baseline (P< 0.01). Plasma bone-specific alkaline phosphatase increased after zinc supplementation (P=0.015), while other potential biomarkers were not significantly affected. Conclusions: The results show that ZIP4 and ZIP8 transporters respond to zinc supplementation in zinc deficient women.