How much supplemental zinc can be taken before supplemental copper is required? At over 150 mg of supplemental zinc per day is it even possible to absorb supplemental copper? In other words does there come a point above which zinc supplementation negates the usefulness of copper supplementation completely and copper deficiency becomes a problem even with copper supplementation? Does supplemental iron have an effect on the metabolism of these metals?

Are there any vitamins or other nutritional factors that alter the uptake of these metals?