Zinc supplementation for four months does not affect plasma copper concentration in infants

Aim: The aim of the present study, which was undertaken as a sub-study within a randomized controlled trial of zinc supplementation, was to evaluate the effect of prolonged zinc supplementation on copper status as assessed by hematological markers. Methods: Plasma copper and zinc were estimated at baseline and after 120 d of supplementation in a randomly selected infant subset (115) of the children. Of these, 61 children were in a zinc group (Z) getting 10 mg of elemental zinc, and 54 were in a control group (C) getting supplement without zinc. Results: Baseline plasma zinc was comparable in the two groups; post-supplementation zinc was significantly higher (Z 93.0 ± 3.6 vs C 60.6 ± 8.0) in the zinc supplementation group. There was no significant difference in the mean/median copper levels between the zinc and control groups. The percentage of children with plasma copper <100 μg/dl was also not significantly different between groups (baseline Z 14.8%, C 11.1%; post-supplementation Z 18.0%, C 11.1%). There were no differences between the zinc and control groups after 120 d of supplementation in hemoglobin (Hgb), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), or number of lymphocytes or granulocytes. Conclusion: Zinc supplementation of 10 mg/d for 4 mo in this study did not affect copper status, as assessed by plasma copper concentration and hematological parameters, diagnostics of copper deficiency.