Generality
Generalities on copper
Despite being present in very limited quantities in the body - from 50 to 120 mg - copper is an essential element for the human species.
In the various tissues it acts above all as a protein constituent, that is cofactor of numerous enzymes - for example cytochrome C oxidase and superoxide dismutase - and transporters - for example albumin and coagulation factor V - in turn involved in various physiological functions.
Once introduced with the foods that contain it, the copper is absorbed in the small intestine and from here, thanks to the bond with the albumin, it is conveyed to the liver. The hepatocytes in turn synthesize a complex consisting of copper and its transporter (celuroplasmin), which is then secreted to be distributed to various tissues. Any excesses are eliminated mainly via the bile and minimally excreted in the urine.
Thanks to its ability to pass from the reduced form (Cu +) to the oxidized form (Cu2 +), copper enters numerous metabolic pathways that require an oxidative-reductive intervention. Its action is important for the mineralization of the skeleton and for the formation of new red blood cells and connective tissue. Copper also participates in the respiratory chain, melanin synthesis and protection systems against oxidative stress and excess biogenic amines.
The copper requirement for the Italian adult population has been set at 1.2 mg per day; only for nurses this share rises to 1.5 mg / day. The foods richest in copper are: some offal and fishery products - such as molluscs and crustaceans - but also cocoa, oilseeds or dried fruit, cereal germ and bran.
Since these foods are quite common in the human diet, there is no real danger of incurring syndromes associated with copper deficiency. However, some cases have been recorded in children undergoing severe malnutrition, in premature infants kept on a milky diet and in patients who were only parenterally fed for a long time. The associated symptomatology includes problems of bone mineralization up to osteoporosis, anemias, depigmentation of skin and hair, greater susceptibility to infections, vasal and skin fragility.
In some cases a dose of "only" 30 g of copper sulphate has proved lethal; in any case, the intake of these quantities, by mistake or for suicide, has a powerful emetic effect that favors a rapid elimination of excesses through vomiting. Symptoms associated with severe systemic intoxication include coma, oliguria, hepatic necrosis, collapse and death. The American institutes (Food and nutrition Board 2001) set the toxicity threshold at 10 mg / day; However, cases of intoxication due to diet alone are extremely rare.
For more information, see the article: Copper.
Food
Foods rich in copper
The best food sources of copper include:
- seafood
- shellfish - especially crabs and lobsters
- shellfish - especially oysters
- offal of the fifth quarter - predominantly liver for food and kidney or kidney as food
- cocoa and chocolate
- oilseeds or dried fruits - especially nuts, pecans, peanuts, sunflower seeds
- the germ of cereals and the bran that contains it - especially wheat and rye. Note : whole grains and derivatives of refined grains are richer in copper
- vegetable oils and fats - especially corn oil and margarine that contains it
- legumes - especially beans and lentils.
Other food sources that contain copper are:
- sweet fruits - such as lemons and grapes, especially raisins or raisins, but also coconut, papaya and apples
- tubers - especially potatoes
- other legumes - such as peas
- mushrooms
- brewer's yeast
- meats - especially lamb, duck, pork and beef
- dark green leafy vegetables - for example black cabbage.
Although not particularly rich, if taken in significant quantities, tea, polished rice and chicken meat are also favored.
To avoid copper deficiency it is generally sufficient to respect a balanced diet, or at least vary the range of foods without excluding any of the VII fundamental groups. With a normocaloric diet, even in developing countries - mainly based on millet, tubers or rice, associated with legumes or small quantities of fish or meat, certain fruits and vegetables, and some vegetable oils - it is very likely that the contribution copper is adequate. The supply of copper seems adequate even in countries where the diet consists mainly of red meat.
water
Copper in drinking water
As a natural element in the earth's crust, copper is present in most of the world's surface and underground waters, although the actual concentration varies greatly depending on the geographical area.
In many regions of the world, copper pipes that carry drinking water are a real source of food copper. Copper pipes can release a small amount of metal, particularly in the first two years of service. Subsequently, inside the copper tubes, normally a protective surface is formed which delays the corrosion.
Drinking water can contribute 20-25% to the daily copper intake.
Supplements
Copper supplements
Copper supplements can prevent copper deficiency, but should only be taken under the supervision of a doctor. In fact, the different forms of copper supplementation have equally different absorption rates. For example, the absorption of copper from cupric oxide supplements is lower than that from products based on gluconate, sulphate or copper carbonate.
For healthy adults on a balanced diet that includes a wide range of foods, supplementation is generally not recommended. However, under medical observation, copper supplementation may be necessary for premature infants, for those with low birth weight, for children fed unbalanced formulas during the first year of life and for malnourished children in general.
More generally, doctors can consider the copper supplement in the following cases:
- diseases that reduce digestion - for example children with frequent diarrhea or infections, alcoholics etc.
- insufficient diet - for example elderly, sick with eating disorders or following extraordinary restrictions
- taking drugs that block the metabolic use of copper in the body
- anemia treated with iron supplements
- intake of zinc supplements
- osteoporosis.
Many vitamin supplements contain inorganic copper, such as cupric oxide. These supplements can cause an excess of free copper in the brain because, in an inorganic form, it can directly cross the blood-brain barrier until it reaches the nervous tissue.
Normally instead, the organic copper of food is first absorbed, then processed by the liver and finally conveyed in the blood by transport proteins, phases that allow to keep the circulating free copper levels under control and prevent what happens with inorganic copper.
Bibliography
- Georgopoulos, PG; Roy, A; Yonone-Lioy, MJ; Opiekun, RE; Lioy, PJ (2001). "Environmental copper: its dynamics and human exposure issues". Journal of Toxicology and Environmental Health. Part B, Critical Reviews. 4 (4): 341–94
- Sadhra, Steven S .; Wheatley, Andrew D .; Cross, Hilary J. (2007). "Dietary exposure to copper in the European Union and its assessment for the EU regulatory risk assessment". Science of The Total Environment. 374 (2-3): 223–34
- World Health Organization. 1998. Copper. Environmental Health Criteria 200. Geneva: IPCS, WHO
- Stern, Bonnie Ransom (2007). "U-Shaped Dose-Response Curve for Risk Assessment of Essential Trace Elements: Copper as a Case Study". In Robson, Mark G .; Tuscan, William A. Risk Assessment for Environmental Health. San Francisco: John Wiley and Sons. pp. 555-62.
