Copper is an important trace mineral. We need it for normal growth, bone strength, immune function, and cardiovascular health. However, too much of it can be toxic. Read this post to learn more about the health benefits of copper, food sources, harmful effects of copper overload, and ways to change copper absorption.
Copper is an integral part (cofactor) of a group of enzymes called cuproenzymes, which are important for :
- Energy production in the cell (cytochrome C oxidase) 
- Formation of strong and flexible connective tissue (lysyl oxidase) 
- Iron metabolism (multiple copper oxidases, ferroxidases) 
- The normal function of the brain and nervous system (dopamine β-hydroxylase, cytochrome C oxidase) 
- Antioxidant activity (superoxide dismutase, ceruloplasmin) 
- Formation of the pigment melanin (tyrosinase) 
Oral or intravenous copper is effective for copper deficiency, which may cause anemia, heart disease, bone deformations, and more. Copper deficiency is rare and usually limited to people receiving parenteral (intravenous) nutrition [12, 13].
Copper-impregnated socks, due to Cu antimicrobial and antifungal properties, were effective against athlete’s foot infections (tinea pedis) in a trial of 56 patients .
Copper-impregnated socks may also be used to prevent skin infection, cuts, and wounds that often lead to hard to treat ulcers in diabetic patients .
A supplement containing copper (1-4 tablets daily for 8 weeks) reduces inflammation and improved skin appearance in 257 patients with inflammatory acne vulgaris. However, this study lacked a control group, which makes the results questionable .
Cooper used in wound dressings can help enhance wound healing by increasing skin regeneration and the formation of new blood vessels. In addition, the copper in wound dressings has potent antimicrobial properties, which can reduce the risk of wound contamination [8, 29].
These copper oxide products are non-irritating and safe to use both on intact and damaged skin .
Copper plays an important role in bone formation .
In 73 menopausal women, 3 mg/day of copper supplementation for two years slowed down the loss of bone mineral density that typically accompanies menopause .
Additionally, a study in 59 postmenopausal women found that taking a combination of supplemental calcium and trace minerals, including copper, might slow down bone loss. However, the contribution of copper to these effects is not clear .
Copper supplementation reverses bone abnormalities in copper-deficient infants .
In 10 copper-deficient elderly patients, supplementation improved the overall copper status and markers of bone resorption and formation .
No valid clinical evidence supports the use of copper supplements for any of the conditions in this section. Below is a summary of up-to-date animal studies, cell-based research, or low-quality clinical trials which should spark further investigation. However, you shouldn’t interpret them as supportive of any health benefit.
Copper is essential for the strength and integrity of the heart and blood vessels. Copper supplementation improves altered heart function and promotes the regression of heart enlargement caused by copper deficiency [16, 17, 18, 19, 20, 21].
In 16 healthy young women, copper supplementation (6mg daily for 4 weeks) led to a 30% reduction in plasminogen activator inhibitor-1 (PAI-1), thus potentially decreasing the risk for atherosclerosis. However, it didn’t have an apparent effect on other risk factors for heart disease [36, 37].
A clinical study confirmed these findings in 73 patients, of which 28 were copper-deficient .
Scientists observed the potential of copper supplementation to prevent atherosclerosis in one study on rabbits .
In a study of 33 volunteers, copper supplementation increased secretion of cytokine IL-2 but only in people with normal-low ceruloplasmin (a major copper-carrying protein). It didn’t impact the inflammation-causing cytokine TNF-alpha .
Interestingly, workers exposed to copper salts did not develop cholera during the cholera epidemics in the 19th century .
Further research should cast more light on the conflicting effects of copper on mental health.
According to a meta-analysis of 27 clinical trials (over 3,500 subjects), Alzheimer’s disease patients have significantly higher copper levels in the blood, compared to healthy controls .
- Inflammation 
- Infection (tuberculosis, leprosy, viral hepatitis, pneumonia, and chickenpox) [52, 53]
- Hematologic diseases (iron deficiency anemia, aplastic and pernicious anemia, sickle cell anemia, and beta-thalassemia) [54, 55]
- Diabetes 
- Heart and blood vessel disease [57, 58]
- Malignant diseases (acute and chronic leukemia, Hodgkin’s disease, multiple myeloma, breast and lung cancer) [59, 60, 61, 62]
- Liver disease (cirrhosis, hepatitis, obstruction to bile flow) [63, 64]
- Contraception (oral contraceptive use, copper intrauterine device) [65, 66]
- Pregnancy 
- Drugs (water pills) 
Copper toxicity occurs with the ingestion of copper compounds usually with suicidal intent, or with accidental consumption of copper-contaminated foods, or water.
Ingestion of more than 1 g of copper can cause copper toxicity. However, this is only a rough threshold for toxicity and depends on individual factors .
Symptoms include stomach ache, nausea, vomiting, diarrhea, dizziness, and muscle pain. More serious signs of copper toxicity include severe liver and kidney damage, hemolytic anemia, massive gut bleeding, and even death [70, 71, 69].
The long-term copper toxicity is not frequent in individuals who do not have inherited disorders of copper metabolism.
Chronic ingestion of copper supplements taken in a dose of 30 – 60 mg/day during 3 years caused severe liver disease .
Copper supplementation should not be used in individuals with genetic disorders affecting copper metabolism:
Copper supplementation in adequate doses is likely safe for healthy individuals, including children and pregnant women. Make sure not to exceed the safe upper limit of 10 mg/day .
Copper levels are a marker of antioxidant status and overall health. Low or high levels don’t necessarily indicate a problem if there are no symptoms or if your doctor tells you not to worry about it.
Copper is thought to contribute to AD since alterations in copper levels tend to precede symptoms of AD in some, but not all patients .
One study has shown that copper is a component of the amyloid-beta plaques which are found in the brains of people with AD .
Free copper has the ability to produce free radicals, and increase Lewy body formation, the hallmark of Parkinson’s disease .
Blood copper levels are significantly increased in some type 1 and 2 diabetic patients .
- Liver (especially calf, lamb, beef)
- Seafood (oysters, squid, lobster, crab)
- Fruit and vegetables (dark leafy vegetables, potatoes, mushrooms, avocados, dried fruit)
- Seeds (sesame, sunflower, pumpkin)
- Nuts (cashew, hazelnuts, Brazil nuts, walnuts),
- Beans (chickpeas, soybeans, adzuki),
- Goat cheese
- Soy products (tofu, tempeh, soy milk, soy powder)
- Chocolate, cocoa
- Wheat bran cereals and whole-grain products
The Recommended Dietary Allowance (RDA) for copper :
- Children 0.3 – 0.9 mg/day (depending on age)
- Adults 0.9 mg/day
- Pregnancy and lactation 1 – 1.3 mg/day
The average intake of copper from food in the United States is approximately 1.0 to 1.6 mg/day for adult men and women.
The Tolerable Upper Intake Level, the highest level of daily nutrient intake that is likely to pose no risk of adverse health effects for almost all individuals, for adults is 10 mg/day .
A number of copper supplements are available in the form of oxide, chloride, gluconate, sulfate, and amino acid chelates .
Although copper is essential to health, supplementation is unnecessary for most healthy individuals .
High dietary protein intake has been shown to increase absorption, although individual amino acids can either increase or decrease absorption .
Zinc supplementation increases metallothioneins, proteins that bind copper and prevent its absorption.
Adequate copper blood levels are necessary for normal iron metabolism and red blood cell formation .
Copper absorption may be influenced by the type of carbohydrate consumed.
Dietary fiber may decrease copper absorption .