copper

What can foods high in copper do for you?

• Help your body utilize iron
• Reduce tissue damage caused by free radicals
• Maintain the health of your bones and connective tissues
• Help your body produce the pigment called melanin
• Keep your thyroid gland functioning normally
• Preserve the myelin sheath that surrounds and protects your nerves

What events can indicate a need for more high-copper foods?

• Iron deficiency anemia
• Blood vessels that rupture easily
• Bone and joint problems
• Elevated LDL cholesterol and reduced HDL cholesterol levels
• Frequent infections
• Loss of hair or skin color
• Fatigue and weakness
• Difficulty breathing and irregular heart beat
• Skin sores

Excellent food sources of copper include asparagus, calf's liver, crimini mushrooms, turnip greens and blackstrap molasses.

For serving size for specific foods, see Nutrient Rating Chart below at the bottom of this page.

Description Function Deficiency Symptoms Toxicity Symptoms Cooking, storage and processing Factors that affect function

Nutrient interaction Health conditions Food Sources Public Health Recommendations References

Description

What is copper?

First recognized in the 1870's as a normal constituent of blood, copper is a trace mineral that plays an important role in our metabolism, largely because it allows many critical enzymes to function properly. Although copper is the third most abundant trace mineral in the body (behind iron and zinc), the total amount of copper in the body is only 75-100 milligrams, less than the amount of copper in a penny. Copper is present in every tissue of the body, but is stored primarily in the liver, so concentrations of the mineral are highest in that organ, with lesser amounts found in the brain, heart, kidney, and muscles.

How it Functions

What is the function of copper?

Copper is an essential component of many enzymes. Each of the copper-containing enzymes discussed below has a distinct function, indicating that copper plays a role in a wide range of physiological processes including iron utilization, elimination of free radicals, development of bone and connective tissue, and the production of the skin and hair pigment called melanin.

Iron Utilization

Approximately 90% of the copper in the blood is incorporated into a compound called ceruloplasmin, which is a transport protein responsible for carrying copper to tissues that need the mineral. In addition to its role as a transport protein, ceruloplasmin also acts as an enzyme, catalyzing the oxidation of minerals, most notably iron.

The oxidation of iron by ceruloplasmin is necessary for iron to be bound to its transport protein (called transferrin) so that it can be carried to tissues where it is needed. Because copper is necessary for the utilization of iron, iron deficiency anemias may be a symptom of copper deficiency.

Elimination of Free Radicals

Superoxide dismutase (SOD) is a copper-dependent enzyme that catalyzes the removal of superoxide radicals from the body. Superoxide radicals are generated during normal metabolism, as well as when white blood cells attack invading bacteria and viruses (a process called phagocytosis). If not eliminated quickly, superoxide radicals cause damage to cell membranes. When copper is not present in sufficient quantities, the activity of superoxide dismutase is diminished, and the damage to cell membranes caused by superoxide radicals is increased. When functioning in this enzyme, copper works together with the mineral zinc, and it is actually the ratio of copper to zinc, rather than the absolute amount of copper or zinc alone, that helps the enzyme function properly.

Development of Bone & Connective Tissue

Copper is also a component of lysyl oxidase, an enzyme that participates in the synthesis of collagen and elastin, two important structural proteins found in bone and connective tissue. Tyrosinase, a copper-containing enzyme, converts tyrosine to melanin, which is the pigment that gives hair and skin its color.

Melanin Production

As a part of the enzymes cytochrome c oxidase, dopamine hydroxylase, and Factor IV, copper plays a role in energy production, the conversion of dopamine to norepinephrine and blood clotting, respectively. Copper is also important for the production of the thyroid hormone called thyroxine and is necessary for the synthesis of phospholipids found in myelin sheaths that cover and protect nerves.

Deficiency Symptoms

What are deficiency symptoms for copper?

Because copper is involved in many functions of the body, copper deficiency produces an extensive range of symptoms. These symptoms include iron deficiency anemia, ruptured blood vessels, osteoporosis, joint problems, brain disturbances, elevated LDL cholesterol and reduced HDL cholesterol levels, increased susceptibility to infections due to poor immune function, loss of pigment in the hair and skin, weakness, fatigue, breathing difficulties, skin sores, poor thyroid function, and irregular heart beat.

Despite the fact that most Americans consume less than recommended amounts of copper in their diet, these symptoms of copper deficiency are relatively rare. However, certain medical conditions including chronic diarrhea, celiac sprue, and Crohn�s disease result in decreased absorption of copper and may increase the risk of developing a copper deficiency. In addition, copper requires sufficient stomach acid for absorption, so if you consume antacids regularly you may increase your risk of developing a copper deficiency. Inadequate copper status is also observed in children with low protein intake and in infants fed only cow�s milk without supplemental copper.

Toxicity Symptoms

What are toxicity symptoms for copper?

In recent years, nutritionists have been more concerned about copper toxicity than copper deficiency. One explanation for this is the increase in the amount of copper found in drinking water due to the switch in most areas of the country from galvanized water pipes to copper water pipes.

Excessive intake of copper can cause abdominal pain and cramps, nausea, diarrhea, vomiting, and liver damage. In addition, some experts believe that elevated copper levels, especially when zinc levels are also low, may be a contributing factor in many medical conditions including schizophrenia, hypertension, stuttering, autism, fatigue, muscle and joint pain, headaches, childhood hyperactivity, depression, insomnia, senility, and premenstrual syndrome.

Postpartum depression has also been linked to high levels of copper. This is because copper concentrations increase throughout pregnancy to approximately twice normal values, and it may take up to three months after delivery for copper concentrations to normalize. Since excess copper is excreted through bile, copper toxicity is most likely to occur in individuals with liver disease or other medical conditions in which the excretion of bile is compromised.

The toxic effects of high tissue levels of copper are seen in patients with Wilson�s disease, a genetic disorder characterized by copper accumulation in various organs due to the inadequate synthesis of ceruloplasmin (the protein that transports copper through the blood) by the liver. Wilson's disease primarily effects the liver, kidneys, and brain causing degenerative physiological changes (including cirrhosis of the liver, muscular rigidty and spastic contraction, and emotional disturbances) that are fatal if untreated. The treatment of Wilson�s disease involves avoidance of foods rich in copper and any supplements containing copper and drug treatment with chelating agents that remove the excess copper from the body.

In 2000, the Institute of Medicine at the National Academy of Sciences established the following Tolerable Upper Intake Levels (ULs) for copper:

• 0-12 months: not possible to establish a TUL, sources of copper must be from food and formula only
• 1-3 years: 1000 micrograms
• 4-8 years: 1000 micrograms
• 9-13 years: 5000 micrograms
• 14-18 years: 8000 micrograms
• 19 years and older: 10,000 micrograms
• Pregnant women 14-18 years: 8000 micrograms
• Pregnant women 19 years and older: 10,000 micrograms
• Lactating women 14-18 years: 8000 micrograms
• Lactating women 19 years and older: 10,000 micrograms

Impact of Cooking, Storage and Processing

How do cooking, storage, or processing affect copper?

The leaching of copper from copper water pipes can increase the copper content of drinking water. Cooking with copper cookware can also increase the copper content of foods.

Foods that require long-term cooking can also have their copper content substantially reduced. The cooking of navy beans, for example, can result in the loss of half their original copper content. The processing of whole grains can also dramatically reduce copper content. In wheat, for example, the conversion of the whole grain into 66% extraction wheat flour (where 34% of the original grain is removed from the flour and discarded) results in a drop of about 70% in the original copper that was present.

Many vegetables and whole grains now appear to be lower in copper than they were during the mid-1900's. The depletion of copper from soils is believed to be responsible for this lowered amount of copper.

Factors that Affect Function

Which factors might contribute to a deficiency of copper?

Unlike most minerals, copper appears to undergo absorption up into the body from the stomach. Proper levels of stomach acid are important for this absorption. For this reason, individuals with compromised stomach acid (hypochlorhydria) may be at increased risk of copper deficiency.

Because zinc can compete with copper in the small intestine and interfere with its absorption, persons who supplement with inappropriately high levels of zinc and lower levels of copper may increase their risk of copper deficiency.

Nutrient Interactions

How do other nutrients interact with copper?

Copper is known to react with a variety of other nutrients, including iron, zinc, molybdenum, sulfur, selenium, and vitamin C. However, with respect to food, we haven't seen research evidence showing that other nutrients�including iron and zinc�interfere with absorption of copper. Similarly, while copper is known to interact with a variety of minerals once it has been absorbed up into the body, we have not seen research showing food-related problems in this regard. The situation is somewhat different, however, when it comes to dietary supplements that often provide minerals (or vitamins) in much higher doses than can be obtained from food. There's some evidence, although not conclusive, that zinc supplements, when taken at 50 milligrams or more on a daily basis over an extended period of time, can lower availability of copper. There's also some evidence (once again not conclusive) that high supplemental doses of vitamin C�in a range approaching 1,000 milligrams or more�may decrease copper availability. While not applicable to adults, there is also some evidence that in the formula feeding of infants, too much iron in a formula can lower absorption of copper from that formula.

Health Conditions

What health conditions require special emphasis on copper?

Copper may play a role in the prevention and/or treatment of the following health conditions:

• Allergies
• Anemia
• Baldness
• Bedsores
• Heart Disease
• HIV/AIDS
• Hypothyroid disease
• Leukemia
• Osteoporosis
• Periodontal disease
• Rheumatoid arthritis
• Stomach ulcers

Food Sources

What foods provide copper?

Excllent sources of copper include asparagus, calf's liver, crimini mushrooms, turnip greens and molasses.

Very good sources of copper include chard, spinach, sesame seeds, mustard greens, kale, shiitake mushrooms, and cashews.

Good sources of copper include eggplant, tomatoes, summer squash, winter squash, green peas, romaine lettuce, garlic, sunflower seeds, green beans, beets, fennel, olives, leeks, sweet potato, quinoa, buckwheat, barley, spelt, tempeh, tofu, soybeans, miso, scallops, shrimp, walnuts, pumpkin seeds, flaxseeds, peanuts, almonds, pineapple, raspberries, lentils, garbanzo beans, lima beans, kidney beans, ginger, and black pepper.

 

Introduction to Nutrient Rating System Chart

In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the World's Healthiest Foods that are either an excellent, very good, or good source of copper. Next to each food name, you'll find the serving size we used to calculate the food's nutrient composition, the calories contained in the serving, the amount of copper contained in one serving size of the food, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling." Read more background information and details of our rating system.

Public Health Recommendations

What are current public health recommendations for copper?

In 2000, the Institute of Medicine at the National Academy of Sciences established new recommendations for copper including Adequate Intake (AI) levels for infants up to one year old and Recommended Dietary Allowances (RDAs)for all people older than 1 year old. The recommendations are as follows:

• 0-6 months: 200 micrograms
• 7-12 months: 220 micrograms
• 1-3 years: 340 micrograms
• 4-8 years: 440 micrograms
• Boys 9-13 years: 700 micrograms
• Girls 9-13 years: 700 micrograms
• Boys 14-18 years: 890 micrograms
• Girls 14-18 years: 890 micrograms
• Men 19-70 years: 900 micrograms
• Women 19-70 years: 900 micrograms
• Men greater than 70 years: 900 micrograms
• Women greater than 70 years: 900 micrograms
• Pregnant women 14-50 years: 1000 micrograms
• Lactating women 14-50 years: 1300 micrograms

In 2000, the Institute of Medicine at the National Academy of Sciences established the following Tolerable Upper Intake Levels (ULs) for copper:

• 0-12 months: not possible to establish a TUL, sources of copper must be from food and formula only
• 1-3 years: 1000 micrograms
• 4-8 years: 1000 micrograms
• 9-13 years: 5000 micrograms
• 14-18 years: 8000 micrograms
• 19 years and older: 10,000 micrograms
• Pregnant women 14-18 years: 8000 micrograms
• Pregnant women 19 years and older: 10,000 micrograms
• Lactating women 14-18 years: 8000 micrograms
• Lactating women 19 years and older: 10,000 micrograms

For more details on this, see the Toxicity Symptoms section above.

References

• Burkitt MJ. A critical overview of the chemistry of copper-dependent low density lipoprotein oxidation: roles of lipid hydroperoxides, alpha-tocopherol, thiols, and ceruloplasmin. Arch Biochem Biophys 2001 Oct 1;394(1):117-35 2001. PMID:15240.
• Davis CD. Low dietary copper increases fecal free radical production, fecal water alkaline phosphatase activity and cytotoxicity in healthy men. J Nutr. 2003 Feb; 133(2):522-7 2003.
• Groff JL, Gropper SS, Hunt SM. Advanced Nutrition and Human Metabolism. West Publishing Company, New York, 1995 1995.
• Harris ED. Copper homeostasis: the role of cellular transporters. Nutr Rev 2001 Sep;59(9):281-5 2001. PMID:15230.
• Harris ED, Qian Y, Tiffany-Castiglioni E, et al. Functional analysis of copper homeostasis in cell culture models: a new perspective on internal copper transport. PMID:7230.
• Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. National Academy Press: Washington DC, 2001 2001.
• Lininger SW, et al. A-Z guide to drug-herb-vitamin interactions. Prima Health, Rocklin, CA, 2000 2000.
• Nath R. Copper deficiency and heart disease: molecular basis, recent advances and current concepts. PMID:7240.
• Roughead ZK, Lukaski HC. Inadequate copper intake reduces serum insulin-like growth factor-I and bone strength in growing rats fed graded amounts of copper and zinc. J Nutr 2003 Feb;133(2):442-8 2003.
• Schaefer M, Gitlin JD. Genetic disorders of membrane transport IV. Wilson's disease and Menkes disease. PMID:7220.
• Strausak D, Mercer JF, Dieter HH, et al. Copper in disorders with neurological symptoms: Alzheimer's, Menkes, and Wilson diseases. Brain Res Bull 2001 May 15;55(2):175-85 2001. PMID:15260.
• Waggoner DJ, Bartnikas TB, Gitlin JD. The role of copper in neurodegenerative disease. PMID:7200.

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