Iron, copper, and zinc status: response to supplementation with zinc or zinc and iron in adult females

Yadrick MK, Kenney MA, Winterfeldt EA · The American Journal of Clinical Nutrition

Ten weeks of 50 mg/day zinc significantly lowered erythrocyte Cu,Zn-superoxide dismutase (a copper-status enzyme) as well as serum ferritin and hematocrit — direct human evidence that the dose range just above the UL depresses copper status within weeks.

Population

Adult women supplemented for 10 weeks (zinc-only and zinc-plus-iron groups)

Intervention

50 mg/day elemental zinc as zinc gluconate (one group also took 50 mg iron)

Comparator

Pre-supplementation values

Limitations

No placebo arm (pre/post comparison); biochemical endpoints only; 10 weeks — it shows the copper-status mechanism engaging, not clinical harm.