Microminerals : Copper

The trace minerals include copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn). They are required by adults in amounts between 1 and 100 mg/day.

Copper
Cu is a key component of several enzymes that play critical functions in the body (Fig. 1). These include ferroxidases such as the ceruloplasmin and hephaestin involved in the oxidation of ferrous iron (Fe²⁺) to the ferric form (Fe³⁺) that is required for its intracellular storage or transport through blood . Meat, shellfish, nuts, and whole grains are good dietary sources of Cu. Dietary deficiency is uncommon. If a deficiency does develop, anemia may be seen because of the effect on Fe metabolism.
Toxicity from dietary sources is rare (UL = 10 mg/day). Menkes syndrome and Wilson disease are genetic causes of Cu deficiency and Cu overload, respectively.

Figure 1: Examples of enzymes that require copper (Cu). ETC = electron transport chain.
1. Menkes syndrome: In Menkes syndrome (“kinky hair” disease), a rare Xlinked (1:140,000 males) disorder, efflux of dietary Cu out of intestinal enterocytes into the circulation by a Cu-transporting ATPase (ATP7A) is impaired. This results in systemic Cu deficiency. Consequently, urinary and serum free (unbound) Cu are low, as is the concentration of ceruloplasmin, which carries over 90% of the Cu in the circulation (Fig. 2). Progressive neurologic degeneration and connective tissue disorders are seen, as are changes to hair. Parenteral administration of Cu has been used as a treatment with varying success. [Note: The mildest form of Menkes syndrome is called occipital horn syndrome.]
2. Wilson disease: In Wilson disease, an autosomal-recessive (AR) disorder affecting 1:35,000 live births, efflux of excess Cu from the liver by ATP7B is impaired. Cu accumulates in the liver; leaks into the blood; and is deposited in the brain, eyes, kidneys, and skin. In contrast to Menkes syndrome, urinary and serum free Cu are high (see Fig. 2). Hepatic dysfunction and neurologic and psychiatric symptoms are seen.
Kayser-Fleischer rings (corneal deposits of Cu) may be present (Fig. 3). Life-long use of Cu-chelating agents, such as penicillamine, is the treatment.

Figure 2: Comparison of Menkes syndrome and Wilson disease. Cu = copper; AR = autosomal recessive.

Figure 3: Kaiser-Fleischer rings.
The bioavailability (percent of the amount ingested that is able to be absorbed) of a mineral can be influenced by other minerals. For example, excess Zn decreases the absorption of Cu, and Cu is needed for the absorption of Fe.