Biology 14-16

Copper: Essential for Human Health

Copper is an essential trace element vital to the health of all living organisms. Although the amount of copper found in the human body (50–120 milligrams ) would fit on the head of a pin, this tiny quantity is essential. Research has revealed that copper is vital for the optimal health of the human body, along with other mineral micronutrients such as iron, calcium and zinc.

This e-source explores copper's essentiality and uses in the human body. Below are different sections, for quick navigation.

The human body contains around 2 mg of copper per kilogram of body mass. While copper is found throughout the body, it is concentrated in organs with high metabolic activity, such as the liver, kidneys, heart and brain. This tiny amount is enough to provide copper ions for billions of protein molecules, in particular enzymes, where the copper ions are essential cofactors. Without cofactors, the enzymes could not work.

Copper is an essential trace mineral that cannot be formed by the human body so must be ingested from dietary sources every day. According to the World Health Organisation, 1–3 milligrams per day of copper are required to prevent any symptoms of deficit. Various health and nutrition organisations around the world have set dietary reference values, highlighting the importance of copper as part of a balanced diet.

Adequate Copper Intakes 
           (mg/day)   
 Age Female  Male 
 7–11 months 0.4  0.4 
 1 – <3 years 0.7 0.7
 3 – <10 years 1.0  1.0 
10 – <18 years
1.1 1.3 
 ≥18 years  1.3 1.6 
 Pregnancy  1.5  
 Lactation  1.5  

Source: European Food Safety Authority.

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Copper is Used Throughout the Body

Virtually every cell in the body utilises copper and – together with iron and zinc – copper is one of the trio of minerals essential to good health. Copper is vital to the health of the body from foetal development through to old age. Quite simply, without copper our brains, nervous systems and cardiovascular systems could not function normally.

Copper is essential for:

  • Brain development during foetal and post-natal growth, and maintenance of brain health throughout life, including effective anti-oxidative defence.
  • Efficient communication between nerve cells.
  • Maintenance of healthy skin and connective tissue.
  • Wound healing.
  • Structural integrity and function of heart and blood vessels.
  • Growth of new blood vessels.
  • Proper structure and function of circulating blood cells.
  • Formation of the cells of our immune system (white blood cells).
  • Maintenance of a healthy and effective immune response.
  • Generation and storage of energy in the ‘power plants’ of our cells, the mitochondria.
Copper as an essential nutrient

Beyond the Brain

The liver

After copper is ingested, it is absorbed from the small intestine into the bloodstream. Here, copper bonds with transport proteins, which carry it to the liver. Once copper is taken up into the liver, it is either stored, distributed around the body in transport proteins or excreted into the bile.
  
Copper plays a central role in the conversion of iron to its useable iron (III) (ferric) form and also helps transport iron around the body. Copper deficiency can lead to anaemia and tissue iron overload.

The brain and nervous system

Copper is crucial for the normal development of the brain and nervous system. It plays a role in the production and maintenance of myelin, which insulates nerve cells, so ensuring the proper transmission of nerve impulses.

Copper is also involved in the synthesis of neurotransmitters, the chemicals that allow communication between nerve cells.  Copper deficiency can lead to degeneration of the nervous system.

Copper for the brain and nervous system

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Cells

The release of cellular energy (ATP) inside the mitochondria depends on the crucial involvement of a copper-containing enzyme. A similarly vital function for copper, as a cofactor, is the neutralisation of free radicals that would otherwise oxidise and destroy healthy cells. Copper deficiency can lead to cancer and heart disease.

The heart

Copper is essential for the synthesis of collagen. This is found in connective tissue, which is the main supporting and binding tissue of the body. Copper is also needed for healthy muscle tone and function and so plays a vital role in the heart. Copper deficiency can lead to heart failure.

Blood vessels

Copper serves as a cofactor for an enzyme involved in the coagulation of blood. The blood vessels are surrounded and protected by connective tissue, and copper helps to sustain their elasticity, particularly for the aorta and smaller arteries. Copper deficiency can lead to circulatory problems and low blood pressure.

Copper is essential for a wide range of biological functions that play an important role in maintaining healthy skin, namely tone, wound healing, and ultraviolet (UV) protection.

Copper is required for the production of collagen and elastin, two components that provide support and elasticity for skin. As a cofactor for the enzyme tyrosinase, copper is involved in the synthesis of the skin pigment melanin, which provides protection from UV radiation. Copper deficiency can lead to skin degeneration and loss of pigmentation.

Bone

Collagen is the main structural material in bone. Cross-linking of collagen molecules affects bone strength. Enzymes with copper cofactors are involved in this process. Copper deficiency can lead to fractures, skeletal abnormalities and osteoporosis.

The immune system

Copper is necessary for the maintenance of a healthy white blood cell count; many of these white cells are phagocytes which engulf and destroy microorganisms. Copper deficiency can lead to a depressed immune system, reduced white cell count and increased incidence of pneumonia.

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Dietary Sources of Copper  

Copper is available from a wide variety of fresh and processed foods. Good sources include grains, nuts (particularly brazil and cashew nuts), meats (liver and kidney), shellfish, legumes (peas and beans) and seeds. Dark chocolate is also a rich source of copper. Eating a well-balanced diet should allow you to meet your daily requirements of copper.

Copper rich foods
Some of the copper rich foods. If you don't like lobster, dark chocolate is also a good source! (Courtesy of ARS.)

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Copper Deficiency

Copper is an essential micronutrient. Deficiency causes serious health problems, but is very rare. Deficiency disorders are more often caused by genetic faults in the transport proteins than by a diet low in copper. The copper is available, but it cannot get into cells.

A healthy balanced diet should provide the copper required each day. There is concern that poor or unbalanced diets may not provide sufficient copper.

Copper Excess   

Copper homeostasis balances uptake and excretion of copper to meet the body's needs on a continuous basis.

Acute copper poisoning is a rare event, largely restricted to the accidental drinking of solutions of copper nitrate or copper sulfate, which should be kept out of easy access in the home. These, and organic copper salts, are powerful emetics and large doses are normally rejected by vomiting.

The capacity for healthy human livers to excrete copper is considerable and chronic copper poisoning is very rare, with the few reports of it restricted to patients with liver disease.

Balancing Trace Elements

The intake of adequate copper is, on its own, not good enough. Minerals interact in the body, working as a team. The advice of research scientists is to regard copper, iron and zinc as an essential trio – too much of one can hamper the body's ability to absorb or process the other two. Deficiency diseases may then result.

Sources of minerals

 Mineral Function in human body
 Deficiency disease
Common food sources
 Iron
  • Oxygen carrier (haem) in haemoglobin    
  • Electron carrier (in respiration)
  • Enzyme cofactor (catalase; peroxidase - breakdown of hydrogen peroxide)
  • Anaemia
  • Liver
  • Red meat
  • Spinach
 Zinc
  • Enzyme cofactor (carbonic anhydrase - carriage of carbon dioxide; carboxypeptidase - protein digestion)
  • Growth retardation
  • Loss of appetite
  • Impaired immune function
  •  Most foods

Deficiencies

For example:

  • Too much zinc can inhibit the absorption of copper. This may result in poor copper status in the body, which over time may lead to bone abnormalities, problems with the heart and circulation and impaired immunity.
  • Iron needs copper: without adequate copper, iron cannot be converted to its most useful iron (III) (ferric) form. Copper is also necessary for the transport of iron to and from the tissues.

Copper is increasingly being recognised as an essential micronutrient. A growing body of research indicates that, as part of a balanced diet, an adequate intake of copper is vital to ensure a wide range of health benefits.

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Questions and Activities

  1. What is a cofactor?

  2. Calculate the fraction by mass of copper in a human body (e.g. body mass = 75 kg, mass of copper = 150 mg).

  3. How many atoms of copper would there be in a single human (given the atomic mass of copper ≈ 63 and Avogadro's number ≈ 6 x 1023)?

  4. How does copper get into the human food chain?

Suggested Activity

  1. Visualise what the amount of copper in a human body may look like.
  2. Use a small length of mains flex and scissors to cut small strands of copper wire about 1mm long.
  3. Add these to a precision balance with a sensitivity of better than 1.0 mg.
  4. Calculate the amount of copper in your own body.
  5. Keep adding strand fragments until you have the equivalent of the mass of copper in your own body.
  6. Tip the copper onto a filter paper.
  7. Use a digital camera to photograph the copper strands and record this in a document.
  8. Show all your calculations.
If you do not have such a sensitive balance, you can use a less sensitive one and a longer length of stripped copper flex. Then calculate by measuring and counting the strands how much your cuttings weigh.

Suggestions for Research

  1. What other metal ions are cofactors?
  2. What are the main medical disorders linked with copper deficiency?
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Did you know?

Natural foods such as cereals, meat and fish generally contain sufficient copper to provide up to 50% of required copper intake. Also, there are some unexpected and delightful sources such as cocoa, providing one valid, scientific reason to eat (dark) chocolate!
Brain and nervous system
Copper is crucial for the development of the brain and nervous system. (Courtesy of Gida.de.)
Nerve cell

Copper enables production and maintenance of myelin, which insulates nerve cells, so ensuring the proper transmission of nerve impulses. The myelin sheath is shown in green in this picture. (Courtesy of Gida.de.)

Copper is essential for the reactions in mitochondria
Copper is essential for the reactions in mitochondria that drive the metabolism of cells. This illustration shows a section through a mitochondrion. (Courtesy of Gida.de.)
Muscle and connective tissue in the heart
Muscle and connective tissue in the heart contain elastin and collagen. Copper is the cofactor in lysyl oxidase, the enzyme involved in cross linking these molecules to form strong tissue. (Courtesy of Gida.de.)

Artwork of white blood cells


Copper is essential for a healthy immune system.


Food Copper
(mg/100g
edible portion)
Comments
Chicken 0.06 Roasted, meat only
Liver 4.51 Beef, braised
Tuna 0.04 White, canned in water, drained solids
Oysters 0.57 Battered or breaded, fried
Potato 0.22 Baked, without salt, flesh only
Potato 0.17 Boiled, no skin, no salt
Mushrooms 0.24 Canned, drained
Green Peas 0.14 Frozen, cooked, drained, no salt
Banana 0.10 Raw
Raisins 0.36 Golden, seedless
Peanuts 0.67 Dry roasted, no salt
Peanuts 1.14 Raw
Brazil Nuts 1.77 Dried, unblanched
Chick Peas 0.17 Canned
Chick Peas 0.85 Raw
Sunflower Seeds 1.75 Kernels, dried
Chocolate (Dark) 0.80 Dark chocolate bar

This table shows typical copper content of various food types.
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