At low intakes, but at amounts well in excess of the Recommended Dietary Allowance (RDA), evidence of induced copper deficiency with attendant symptoms of anaemia and neutropenia, as well as impaired immune function and adverse effects on the ratio of low-density-lipoprotein to high-density-lipoprotein (LDL/HDL) cholesterol have been reported.
Even lower levels of zinc supplementation, closer in amount to the RDA, have been suggested to interfere with the utilisation of copper and iron and to adversely affect HDL cholesterol concentrations.
“Individuals using zinc supplements should be aware of the possible complications attendant to their use,” noted the study.