Copper

Copper is a relatively hard heavy metal that conducts electricity well. It has the atomic number 29 in the periodic table of elements and the chemical symbol Cu. The name "copper" is derived from the island of Cyprus, which in ancient times supplied Rome, Greece and other Mediterranean countries with the red metal. The Romans then called it "ore from Cyprus", in Latin "aes cyprium", later "cuprum". This Latin term is also behind the abbreviation Cu, which stands for copper in the periodic table of elements. Copper is an important trace element.

The human body needs it for normal growth, the development and maintenance of stable bones, immune function and cardiovascular health. However, too much copper can be toxic. 100 mg of copper is found on average in the adult human body , mainly in the skeleton, but also in the muscles, internal organs and brain. As a heavy metal, copper also has a strong germicidal effect, which has long been used successfully in holy water fonts in churches, for example. Furthermore, copper is sometimes contained in intrauterine devices (IUDs) and is said to be responsible for the contraceptive effect.

The different functions of copper in the human body

Copper is an essential trace element that is required for growth, bone stability, immune function, heart function and brain development (1, 2).

Copper is an integral part (cofactor) of a group of enzymes called copper enzymes, which are important for the following processes (3):

Energy production in the cell (cytochrome C oxidase) (4)
Formation of strong and flexible connective tissue (lysyl oxidase) (5)
Iron metabolism (several copper oxidases, ferroxidases) (6)
Normal function of the brain and nervous system (dopamine beta-hydroxylase, cytochrome C oxidase) (7)
Antioxidant activity (superoxide dismutase, ceruloplasmin) (5)
Formation of the pigment melanin (tyrosinase) (6)

Due to its potential antimicrobial properties, copper is also used as a biocide in agriculture, in the preservation of wood and in hospitals (8, 9, 10, 11). It is involved in the formation of red blood cells and plays a role in the function of the central nervous system and in pigment metabolism. The copper content of blood serum is between 70 μg and 150 μg.

Foods containing copper

Foods that are rich in copper (95, 96, 97):

Liver (especially veal, lamb and beef)
Seafood (oysters, squid, lobster, crab)
Fruit and vegetables (dark leafy vegetables, potatoes, mushrooms, avocados, dried fruit)
Seeds (sesame seeds, sunflower seeds, pumpkin seeds)
Nuts (cashews, hazelnuts, pecan nuts, walnuts)
Beans (chickpeas, soybeans, adzuki beans)
Goat cheese
Soy products (tofu, tempeh, soy milk, soy powder)
Chocolate, cocoa
Wheat bran and wholemeal products

Copper can also be ingested via drinking water if it flows through copper pipes. In various countries there are limits for the copper content in tap water (98, 99).

Possible health benefits of copper

Treatment of copper deficiency

Oral or intravenous copper supplementation is an effective treatment for copper deficiency, which can cause health problems such as anemia, heart disease, bone deformities and others. Copper deficiency is rare and usually limited to people who are artificially fed (12, 13). Copper supplementation can reverse bone abnormalities and stimulate bone formation in children and elderly patients suffering from copper deficiency (14, 15). Copper can also improve heart function and reverse enlargement of the heart caused by copper deficiency (16, 17, 18, 19, 20, 21).

Copper can promote skin health

Copper increases the production of collagen (which gives strength and structure) and elastin (which gives elasticity and resilience) (22, 23). Copper-impregnated socks were effective in protecting against athlete's foot infections in a study of 56 patients due to the antimicrobial and antifungal properties of copper (24). Copper-impregnated socks could also be used to prevent skin infections and infections of cuts and injuries in diabetics, which can often lead to difficult-to-treat ulcers (25). According to two studies involving 118 subjects, sleeping in pillowcases containing copper oxide can reduce fine wrinkles and improve the overall appearance of the skin (26, 27).

A copper-containing supplement (1 to 4 tablets per day for 8 weeks) reduced inflammation and improved the appearance of the skin in 257 patients with inflammatory acne vulgaris. However, there was no control group in this study, which makes the results questionable (28). Copper used in wound dressings may help promote wound healing by improving regeneration and the formation of new blood vessels. In addition, the copper in dressings has potent antimicrobial properties, which can reduce the risk of wound contamination (8, 29). These copper oxide products are non-irritating to the skin and can be used on both intact and damaged skin (30).

Copper could counteract bone loss

Copper plays an important role in bone formation (31). It is a cofactor of the enzyme lysyl oxidase, which is required for the formation of strong bones (32, 33). In 73 menopausal women, supplementation of 3 mg copper per day for two years slowed the decline in bone mineral density that typically accompanies menopause (34). In addition, a study of 59 postmenopausal women found that taking a combination of supplemented calcium and trace minerals including copper could slow bone loss.

However, it is unclear what contribution copper made to this (35). Copper supplements have been shown to reverse bone abnormalities in children who were copper deficient (14) and in 10 older people who were copper deficient, copper supplementation improved overall copper status and markers of bone resorption and bone formation (15).

Copper could promote heart health

Copper is essential for the strength and integrity of the heart and blood vessels. Copper supplementation may improve altered heart function and promote the regression of enlargement of the heart caused by copper deficiency (16, 17, 18, 19, 20, 21). In 16 young healthy women, copper supplementation (6 mg for 4 weeks) led to a reduction in PAI-1 (plasminogen activator inhibitor-1), potentially reducing the risk of atherosclerosis. However, copper had no apparent effect on other risk factors for heart disease (36, 37).

In rats, copper supplementation reduced total cholesterol levels, triglyceride levels and levels of "bad" LDL cholesterol, while increasing levels of "good" HDL cholesterol (38). A clinical study confirmed these results in 73 patients, 28 of whom were copper deficient (39). In addition, scientists have observed the potential of copper supplementation to prevent atherosclerosis in a study with rabbits (40). Copper supplements may prevent heart disease in people suffering from copper deficiency. However, larger human studies should investigate whether these positive effects on heart health also occur in healthy individuals.

Copper could improve immune function

In a study of 33 subjects, copper supplementation increased the release of cytokine IL-2, but only in subjects with low levels of ceruplasmin (a primary copper-transporting protein) in the normal range. Copper did not affect the pro-inflammatory cytokine TNF-alpha (41). Interestingly, workers exposed to copper salts did not contract cholera during the cholera epidemics of the 19th century (42). Adequate copper supplementation restored the number and function of T lymphocytes in rats suffering from copper deficiency (43).

Copper could alleviate or worsen anxiety and depression

Copper supplementation during pregnancy significantly reduced symptoms of anxiety and depression in a study of 238 pregnant women. However, further research is needed in this area (44). On the other hand, some patients with depression have higher blood copper levels (45, 46). Elevated copper levels are also associated with depression in nurses working shifts and postpartum depression (47, 48). Further research is needed to shed more light on the contradictory effects of copper on mental health.

The potential effects of copper on Alzheimer's are contradictory

In a study of 68 Alzheimer's patients, copper supplementation had no positive effects on cognition (49). However, other studies showed potential positive roles for copper in the treatment of Alzheimer's disease (49). To make matters even more confusing, a meta-analysis of 27 clinical studies with a total of over 3,500 participants showed that Alzheimer's patients have significantly higher blood copper levels compared to healthy people (50).

Need

According to a publication by the German Nutrition Society, it is assumed that adults need 1 to 1.5 mg of copper per day. As a rule, this copper requirement is covered by a normal diet. It should be mentioned that the intake of larger amounts of vitamin C inhibits copper absorption. The tolerable upper intake level - the highest level of daily intake of a nutrient that is unlikely to pose a risk of unwanted side effects for almost all people - is 10 mg of copper per day for adults (100).

Requirements in sport

Caution is advised when supplementing with copper: Copper is toxic in larger amounts. My recommendation is to take 2-5 mg per day with meals

Symptoms of deficiency

Copper deficiency is relatively rare. It can be caused by a highly unbalanced diet, malabsorption or prolonged artificial nutrition. Long-term use of zinc supplements can also result in a copper deficiency. If children are fed a one-sided diet of cow's milk for a long time, a copper deficiency can also develop and, as a result, copper deficiency anemia.

The typical signs of copper deficiency include

Anemia
Reduction of white blood cells
Dysfunction of the immune system
Pigmentation disorders of the skin
Disorders of the central nervous system
Influence on growth

Supplementation

There is a whole range of copper supplements available on the market that contain copper in the form of copper oxide, copper chloride, copper gluconate, copper sulphate and amino acid chelates (101). However, even though copper is essential for health, supplementation is unnecessary for most healthy people (102). Copper supplements are intended for the prevention and treatment of copper deficiency and copper deficiency anemia (103).

Ways to increase the absorption of copper

High protein intake has been shown to increase copper absorption, although individual amino acids can either increase or decrease copper absorption (104). L-histidine and L-cysteine can reduce copper absorption, while L-glycine, L-tryptophan and L-methionine can increase copper absorption (105, 106).

Factors that can reduce the absorption of copper

Zinc

Zinc supplementation increases levels of metallothionein - proteins that bind copper and prevent its absorption. There are reports of copper deficiency in people who have taken up to 600 mg of elemental zinc per day or used excessive amounts of zinc-based bonding creams for dentures (107, 108, 109).

Iron

Copper increases the absorption and utilization of iron in the digestive tract, while iron may inhibit the absorption of copper (110, 111). Adequate copper blood levels are necessary for normal iron metabolism and red blood cell formation (112).

Carbohydrates

Copper absorption could be influenced by the types of carbohydrates consumed. Rats fed a diet that included fructose developed more severe signs of copper deficiency than rats fed a diet that included glucose or starch (113).

Dietary fiber

Dietary fiber may reduce copper absorption (114).

High molybdenum intake

Excessive intake of molybdenum can lead to the formation of complexes with copper and cause copper deficiency (115).

Safety and side effects

Copper is safe and harmless when used to treat copper deficiency. Copper is not safe and harmless when taken in large amounts. Adults should not take more than 10 mg of copper per day. Kidney failure and death can occur after consuming as little as one gram of copper sulfate. Symptoms of copper overdose include nausea, vomiting, bloody diarrhea, fever, stomach pain, low blood pressure, anemia and heart problems.

Overdose and poisoning

Overdose or poisoning with copper is rare. Ingesting large quantities of copper salts causes nausea and copper salts are poorly absorbed by the body. The lethal dose is therefore relatively high at approx. 10 g of copper sulphate. However, it is suspected that a high copper content in drinking water (over 10 mg/l) can lead to liver damage in young children. The symptoms of poisoning are severe vomiting, diarrhea and blue-green burns to the mucous membranes. Shock may also occur and, 5 to 6 hours after ingestion of the poison, hemolysis, i.e. destruction of the red blood cells.

The treatment of poisoning consists of drinking a quarter of a liter of water or milk and possibly gastric lavage with 0.1% potassium cyanoferrate. In addition, the loss of water and electrolytes must be replaced and pain and any shock that may occur must be treated. Diabetes, taking the contraceptive pill, pregnancy, some liver diseases, kidney stones and rheumatism can lead to increased copper levels in the blood.

Possible causes of excessive copper levels in the body

Inflammations (51)
Infections (tuberculosis, leprosy, viral hepatitis, pneumonia and chickenpox (52, 53)
Hematological diseases (iron deficiency anemia, aplastic or pernicious anemia, beta-thalassemia (54, 55)
Diabetes (56)
Diseases of the heart and blood vessels (57, 58)
Malignant diseases (acute or chronic leukemia, Hodgkin's disease, multiple myeloma, breast and lung cancer (59, 0, 61, 62)
Diseases of the liver (cirrhosis, hepatitis, obstruction of the bile flow) (63, 64)
Contraceptives (oral contraceptives, copper implants in the uterus) (65, 66)
Pregnancy (67)
Medication (diuretics) (68)

Signs of excessive copper levels

Acute toxicity

Acute copper toxicity usually results from consuming large amounts of copper with suicidal intent or inadvertently consuming food or water contaminated with copper. Consuming more than one gram of copper can cause poisoning. However, this is only a rough estimate and may vary due to individual factors (69). Symptoms of copper poisoning include stomach pain, vomiting, diarrhea, drowsiness and muscle aches. More serious signs of copper poisoning include severe liver and kidney damage, hemolytic anemia, massive intestinal bleeding, and even death (70, 71, 69).

Chronic toxicity

Long-term copper toxicity occurs primarily in people who suffer from hereditary disorders of copper metabolism. Chronic use of copper supplements at doses of 30 to 60 mg per day over several years can also lead to serious liver disease (72).

Copper should not be supplemented by people suffering from the following genetic disorders that affect copper metabolism:

Wilson's disease (73)
Idiopathic copper toxicosis (74)
Cirrhosis syndromes in childhood (75, 74)

Copper supplementation in adequate doses is probably safe and harmless for healthy people, including children and pregnant women. The upper safe limit of 10 mg copper per day should not be exceeded (76).

Diseases and problems associated with (too) high copper levels

Oxidative damage

Elevated copper levels can increase the production of free radicals, resulting in cell and tissue damage (77, 78).

Alzheimer's disease

Copper is believed to contribute to Alzheimer's disease, as changes in copper levels precede symptoms of Alzheimer's in some - but not all - Alzheimer's patients (79). In general, Alzheimer's patients have elevated copper levels in the blood and/or brain (80, 81, 82, 83). Copper appears to be associated with a worsening of Alzheimer's symptoms and may play a triggering role, suggesting that older people may benefit from a reduction in dietary and supplemental copper intake (84, 85, 86). One study has shown that copper is a component of the amyloid beta plaques found in the brains of Alzheimer's patients (87).

Parkinson's disease

Workplace studies have shown that people with long-term exposure to copper and manganese have an increased risk of Parkinson's disease (88). Free copper has the ability to produce free radicals and increase the formation of Lewy bodies, which are a hallmark of Parkinson's disease (89).

Heart disease

Preliminary research suggests that excessive copper and ceruloplasmin levels may be associated with an increased risk of heart disease (57, 58). In some people with atherosclerosis, copper levels are elevated in the blood and the walls of blood vessels. In addition, copper levels increase with the severity of atherosclerosis (90, 91).

Diabetes

Blood copper levels are significantly elevated in some type 1 and type 2 diabetes patients (92). Copper is also involved in the production of free radicals, which play an important role in the development of diabetic complications (93, 94).

Precautions and warnings

Pregnancy and breastfeeding: Pregnant and breastfeeding women between the ages of 14 and 18 should not consume more than 8 mg of copper per day and pregnant and breastfeeding women aged 19 and over should not consume more than 10 mg of copper per day. Higher doses can be dangerous.

Children: Children should not consume more than the upper tolerable amount of copper. This amount is 1 mg of copper per day for children between 1 and 3 years, 3 mg of copper per day for children between 4 and 8 years, 5 mg of copper per day for children between 9 and 13 years and 8 mg of copper per day for teenagers aged 14 and over. Higher amounts can cause liver damage and other problems.

Hemodialysis: People who have to undergo hemodialysis due to kidney disease appear to be at higher risk for copper deficiency. This group of people may need copper supplements. This should be clarified with the doctor treating you.

Certain hereditary diseases including idiopathic copper toxicosis and childhood cirrhosis: Taking extra copper could exacerbate these conditions.

Wilson's disease: Taking copper supplements may exacerbate this condition and interfere with treatment.

Interactions

Care should be taken when combining copper with the following medications:

Penicillamine

Penicillamine is used in Wilson's disease and rheumatoid arthritis. Copper may reduce the amount of penicillamine absorbed by the body and reduce the effectiveness of penicillamine.