Copper is an essential trace mineral, meaning the human body requires it in very small quantities to function properly and sustain life. Although the amount needed is minute—measured in micrograms—this mineral is fundamentally important for numerous processes occurring at the cellular level. Like other micronutrients, copper cannot be produced by the body and must be obtained through diet.
Defining Copper’s Essential Roles
Copper acts primarily as a cofactor for several different enzymes that drive important biological reactions. These copper-dependent enzymes are directly involved in the production of adenosine triphosphate (ATP), the primary energy currency of the cell, through cellular respiration. Specifically, the enzyme cytochrome c oxidase, which requires copper, catalyzes the final step in generating this energy within the mitochondria.
The mineral is also indispensable for iron metabolism and transport throughout the body. Copper-containing proteins convert stored iron into a form that can be picked up by the transport protein transferrin, making it available for red blood cell formation. Without sufficient copper, the body cannot properly utilize iron, which can lead to a specific type of anemia.
Furthermore, copper plays a role in antioxidant defense, working with the enzyme superoxide dismutase to neutralize potentially damaging free radicals within cells. It is also necessary for the formation of strong connective tissue, including bones, skin, and blood vessels. The copper-dependent enzyme lysyl oxidase is responsible for cross-linking collagen and elastin fibers, which provides structure and elasticity to these tissues. Copper also supports the nervous system, helping in the synthesis of neurotransmitters and the formation of the protective myelin sheath around nerve cells.
Sources and Recommended Intake
The Recommended Dietary Allowance (RDA) for adult men and women is 900 micrograms (mcg) of copper per day. Pregnant and lactating women have slightly higher requirements to support both their own needs and those of the developing child. Because copper is a trace mineral, the body is highly efficient at regulating its absorption, increasing the rate when intake is low and decreasing it when intake is high.
A wide range of foods contains copper, making it generally achievable to meet the RDA through a balanced diet. The richest sources include:
- Organ meats like beef liver
- Shellfish such as oysters
- Nuts like cashews and almonds
- Seeds
- Whole-grain products, legumes, and dark chocolate
Understanding Copper Deficiency
Copper deficiency, known as hypocupremia, is relatively uncommon in healthy individuals who consume a varied diet. When it does occur, it is often due to underlying conditions that impair absorption, such as gastrointestinal surgery, malabsorption disorders, or excessive intake of zinc supplements, which compete with copper for uptake. Genetic disorders like Menkes disease, which interferes with copper absorption, also result in severe deficiency.
Symptoms often reflect the mineral’s roles in iron transport and immune function. A common manifestation is anemia due to the impaired utilization of iron, leading to fatigue and weakness. A lack of copper can also weaken the immune system, resulting in neutropenia, a reduction in white blood cells that fight infection. Neurological issues may also develop, presenting as numbness, tingling in the extremities, or difficulty with walking and coordination.
Risks of Excessive Copper Intake
While copper is necessary for health, chronic or acute overexposure can lead to toxicity, as the body tightly regulates its levels. The Tolerable Upper Intake Level (UL) for adults is set at 10,000 mcg (10 milligrams) per day, and consistently exceeding this amount can cause adverse effects. Acute poisoning, which may result from consuming high doses of copper salts or from contaminated drinking water, typically causes immediate symptoms.
These acute symptoms include abdominal pain, nausea, vomiting, and diarrhea. Chronic overload is most notably associated with Wilson’s disease, a rare inherited disorder where a genetic mutation prevents the liver from properly excreting excess copper into the bile. This inability causes copper to accumulate over time, primarily damaging the liver and the brain. If left untreated, the buildup can cause severe liver damage, neurological problems like tremors and speech difficulties, and can potentially be life-threatening.