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

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.

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.

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 microg/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.

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.