Copper is an essential trace mineral necessary for survival. Most of the copper in the body is found in the liver, brain, heart, kidneys and skeletal muscle. Copper helps with the formation of collagen, increases the absorption of iron and plays a role in energy production.
The Recommended Daily Allowance (RDA) for copper is 900 micrograms for adolescents and adults. Copper deficiency is rare, and often caused by genetic defects of copper metabolism or excessive intake of zinc or vitamin C supplements.
Copper deficiency has also been seen in infants fed cow's milk instead of formula due to the low copper content of cow's milk. Since copper is stored in the liver, deficiencies develop slowly over time.
Copper deficiency can cause an increased risk of infection, osteoporosis, impaired neurological function and compromised growth. Other physical effects of copper deficiency include depigmentation of the hair and skin.
Metabolic diseases that affect the absorption of vitamins and minerals offer one way of assessing the necessity of these nutrients and their function in human physiology. In the case of copper, Menkes disease (an X-linked recessive disorder) adversely affects brain copper metabolism, resulting in failure to thrive and neurodevelopmental delays in infants from around 6-8 weeks of age.
Typically, children with Menkes disease die before the age of three. Subcutaneous copper injections can help to normalize blood copper levels, but whether these help to normalize brain copper levels depends on the type of genetic mutation in each case.
A recent clinical trial found that early treatment (before symptoms began) helped to improve gross motor, fine motor/adaptive, personal-social, and language neurodevelopment in children, in addition to improved growth.
As we saw above, copper is necessary for proper cognitive function, supporting neurodevelopment and growth. In addition to affecting children, impairments of homeostatic mechanisms in brain copper metabolism have been associated with neurodegeneration in adults.
Both a deficiency in copper and an excess of copper can damage brain tissue, with elevated levels of copper leading to oxidative damage in the brain. In Wilson's disease, dangerous amounts of copper accumulate in the liver, brain and other vital organs, while an excessive accumulation of copper has also been associated with Alzheimer's disease. Other risks of copper excess are discussed below.
Inadequate copper intake can lead to neutropenia, a deficiency of white blood cells (also called neutrophils). The main function of neutrophils in the body is to fight off infection. The fewer neutrophils you have, the more susceptible you are to infectious diseases.2
Severe copper deficiency is associated with lower bone mineral density and an increased risk of osteoporosis. More research is needed on the effects of marginal copper deficiency and on the potential benefits of copper supplementation for prevention and management of osteoporosis.2
Copper also plays an important role in the maintenance of collagen and elastin, major structural components of our bodies. Without sufficient copper, the body cannot replace damaged connective tissue or the collagen that makes up the scaffolding for bone. This can lead to a range of problems, including joint dysfunction, as bodily tissues begin to break down.
Copper is found in a wide variety of foods. Some of the best sources of copper are organ meats, shellfish, nuts, legumes and chocolate:
Most fruits and vegetables are low in copper. Copper is also added to some breakfast cereals and other fortified foods.
Copper supplements are available, but it is best to first try to obtain essential vitamins and minerals through food in order to reduce the risk of other deficiencies arising. Additionally, the nutrients in food have a synergistic effect, i.e. they work together to create an effect larger than that which would be seen from taking individual nutrients in isolation.
Focus on obtaining your daily copper requirement from foods then use supplements as a backup.
High intakes of zinc (150 mg/day or above) and vitamin C (1,500 mg/day) have been shown to induce copper deficiency by induce copper deficiency by competing with copper for absorption in the intestine.