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 Roles in the Body
Copper (Cu) is an essential trace mineral in the human body. It is required for growth, bone strength, immune function, as well as heart function, and brain development [1, 2].
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) 
Due to its potent antimicrobial properties, copper is also used as a biocide in agriculture, wood preservation, paints, and in hospitals [8, 9, 10, 11].
1) Copper Deficiency
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 supplementation reverses bone abnormalities and stimulates bone formation in copper-deficient infants and older patients [14, 15].
It improves heart function and may reverse heart enlargement caused by copper deficiency [16, 17, 18, 19, 20, 21].
2) Skin Health
Copper increases the production of collagen (which provides strength and structure) and elastin (which provides skin elasticity and resilience) [22, 23].
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 .
According to two studies of 118 volunteers, sleeping on copper oxide-containing pillowcases can reduce fine wrinkles and cause an overall improvement of skin appearance [26, 27].
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 .
3) Bone Loss
Copper plays an important role in bone formation .
It is a cofactor for enzyme lysyl oxidase required for the formation of strong bones [32, 33].
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.
4) Heart Health
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].
In rats, copper supplementation decreased blood levels of total cholesterol, triglycerides, and “bad” LDL–cholesterol while slightly increasing “good” HDL-cholesterol .
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 .
5) Immune Function
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 .
Adequate copper supplementation rapidly restores the number and function of T lymphocytes in copper-deficient rats .
6) Anxiety and Depression
Copper supplementation during pregnancy (1g/day) significantly reduced the symptoms of depression and anxiety in a study of 238 pregnant women. Further research is warranted .
On the other hand, some patients with depression have higher levels of blood copper [45, 46].
Elevated copper levels are also associated with depression in shift nurses and postpartum depression [47, 48].
Further research should cast more light on the conflicting effects of copper on mental health.
Copper supplementation had no beneficial effects on cognition in a study of 68 patients with Alzheimer’s disease .
Studies showed potential beneficial roles of copper in treating rather than causing Alzheimer’s disease .
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 .
The Bad: Copper Excess and Overload
- 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.
1) Oxidative Damage
Increased copper levels may increase the production of free radicals which results in cell and tissue damage [77, 78].
2) Alzheimer’s Disease
Copper is thought to contribute to AD since alterations in copper levels tend to precede symptoms of AD in some, but not all patients .
Generally, subjects with AD have higher blood and/or brain copper concentrations [80, 81, 82, 83].
Copper seems to be associated with worsening of symptoms and may have a causative role, suggesting that the elderly may benefit from reducing copper intake from food and supplements [84, 85, 86].
One study has shown that copper is a component of the amyloid-beta plaques which are found in the brains of people with AD .
3) Parkinson’s Disease
Occupational studies showed that long-term exposure to copper and manganese increases the risk of Parkinson’s disease .
Free copper has the ability to produce free radicals, and increase Lewy body formation, the hallmark of Parkinson’s disease .
4) Heart Disease
According to preliminary research, excessive copper and ceruloplasmin levels may be associated with an increased risk of heart disease [57, 58].
Copper levels in the blood and in the blood vessel wall are elevated in some individuals with atherosclerosis. In addition, copper levels increase with the severity of atherosclerosis [90, 91].
Blood copper levels are significantly increased in some type 1 and 2 diabetic patients .
Copper is involved in the production of free radicals that play an important role in the development of diabetic complications [93, 94].
Copper Sources and Supplementation
Copper-rich food include [95, 96, 97]:
- 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
Copper may also be obtained from drinking water from copper pipes. The U.S. Environmental Protection Agency allows up to 1.3 mg/L of copper in human drinking water [98, 99].
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 .
Copper supplements are indicated for the prevention and treatment of copper deficiency and copper deficiency anemia .
Ways to Increase Absorption
High dietary protein intake has been shown to increase absorption, although individual amino acids can either increase or decrease absorption .
L-histidine and L-cysteine can reduce copper absorption while glycine, L-tryptophan, and L-methionine increase it [105, 106].
Ways to Decrease Absorption
Zinc supplementation increases metallothioneins, proteins that bind copper and prevent its absorption.
Copper deficiency has been reported in humans using up to 600 mg elemental zinc daily or excessive usage of zinc-based dental adhesives [107, 108, 109].
Copper increases gut absorption and utilization of iron, while iron may inhibit copper absorption [110, 111].
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.
Rats fed a diet containing fructose developed more severe signs of copper deficiency than did rats fed a diet containing either glucose or starch .
Dietary fiber may decrease copper absorption .
Excessive dietary intake of molybdenum may form complexes with copper and can induce deficiency .
Part 2: Negative Effects of Copper Deficiency and Blood Tests for Copper Levels