- RDA – 900 micrograms/day
- UL – 10 mg/day
- Copper deficiency and toxicity are not commonly seen in the U.S.
- Food sources: Seafood, nuts, seeds, legumes, whole grains, dark chocolate
Recommended Dietary Allowance (RDA)
- The RDA for adults is 900 micrograms/day
In the body, copper shifts between the cuprous (Cu+) and cupric (Cu2+) forms. Cu2+is the oxidized form while Cu+ is the reduced form. The majority of the body’s copper is in the oxidized form. Copper is important in redox reactions and in scavenging free radicals. It is incorporated into cuproenuzymes. Two forms of superoxide dismutase, a powerful antioxidant, contain copper. Copper is also important in iron metabolism, energy production, and nervous system function. Without copper, iron can accumulate and is not transported to the site where it is incorporated into red blood cells. Cytochrome c oxidase, an essential component of the electron transport chain, is dependent on copper. Copper is required for proper neurotransmitter synthesis and myelin synthesis as well. Both collagen and melanin synthesis are dependent on copper.
Copper is a component of an iron transport protein. Copper is needed for proper iron metabolism.
Zinc supplements at 50 mg/day for extended periods of time can result in copper deficiency. High, chronic doses of zinc increase metallothionein, a protein which binds to copper and decreases its ability to be absorbed.
Vitamin C supplementation may impair ceruloplasmin activity. Ceruloplasmin is required for proper utilization of iron in the body. 1,500 mg/day of vitamin C taken for two months was shown in one study to cause a significant decline in ceruloplasmin oxidase activity.
Copper deficiency can lead to anemia. This anemia is unresponsive to iron therapy but corrected by copper supplementation. Copper deficiency may also lead to abnormally low numbers of neutrophils.
Toxicity/Excess/Upper Limit (UL)
The upper intake level (UL) is set at 10,000 micrograms (10 mg) per day.
Wilson’s Disease is an autosomal recessive disease leading to accumulation of copper in the brain and liver. This can result in liver damage. A Kayser-Fleischer Ring (brownish-yellow color around the eye) is a clinical indicator of Wilson’s Disease.
- Liver, beef, pan fried – 3 oz – 12.4 mg, 620% DV
- Cashew nuts, dry roasted, w/ salt – 1 oz – 0.6 mg – 30% DV
- Sunflower Seeds, dry roasted, with salt – 1/4 cup – 0.6 mg – 30% DV
- Mushrooms, white, cooked, drained – 1/2 cup – 0.4 mg – 20% DV
- Dark chocolate, 1/2 bar – 0.9 ,g – 44% DV
If copper is supplemented, zinc is typically supplemented as well. The zinc is given in a dose 15 times that of copper. Zn:Cu = 15:1. In supplements it is often seen as 30 mg of zinc to 2 mg of copper.