Copper is necessary in trace amounts for red blood cell, collagen and energy production; neuron signaling; immunity; and iron metabolism. However, it is difficult to gauge copper status because of unreliable biomarkers with slow reactivity to changes in copper intake, especially in marginal deficiencies.
Roles in health: A 2016 review of studies since 1990 identified gaps in knowledge and uncertainties that complicate the assessment of copper status, disease prevention and requirements. Small amounts of copper are stored in the body, requiring daily intake to maintain the delicate copper balance.
Copper’s role in the development of Alzheimer’s disease remains unclear, including whether supplementation or restriction may delay its progression. Conflicting results were observed in a recent review: Some studies showed elevated levels of copper lowered disease risk, while others showed elevated levels promoted disease risk. Other studies suggest excessive amounts of copper and iron from supplements may contribute to impaired cognition, but research is limited.
One study suggests copper deficiency may be a contributing factor in the development of ischemic heart disease. Studies have shown copper deficiency can elevate blood lipid levels and blood pressure and could lead to cardiac abnormalities. However, despite the elevation in cardiac markers, studies indicate that supplementation doesn’t change cardiovascular disease risk factors.
|Age||Recommended Dietary Allowance||Tolerable Upper Intake Levels|
|Food Sources||Milligrams (mg) per serving||Rating|
|3 ounces pan-fried beef liver||12.4|
|3 ounces cooked Pacific oysters||2.3||Excellent|
|3 ounces cooked Dungeness crab||0.6||Excellent|
|3 ounces simmered turkey giblets||0.6||Excellent|
|1 ounce dry roasted cashews||0.6||Excellent|
|1 ounce 70% to 85% cacao dark chocolate||0.5||Excellent|
|½ cup raw firm tofu||0.5||Excellent|
|½ cup canned chickpeas||0.3||Excellent|
Sources of copper: Widely available in plant and animal sources, copper content varies based on soil composition. Copper also can leach into tap water through copper pipes if corroded. The Environmental Protection Agency set the safe maximum level of copper in public water systems at 1.3 milligrams per liter.
Typical American diets are rich in copper, providing roughly 1,400 micrograms daily for men and 1,100 micrograms per day for women 19 and older. Less than 1 percent of adults are below the estimated average requirement for copper.
Bioavailability appears to be protective; absorption ranges from 75 percent when the diet contains 400 micrograms per day to only 12 percent when it contains 7.5 milligrams per day.
Copper also is available in supplements containing only copper, copper plus other ingredients and in multivitamins.
Signs of deficiency: Copper deficiency is generally rare, but possible reasons for inadequate intake or deficiency include genetic disorders such as Menkes disease in which copper absorption is faulty, malnutrition, prolonged parenteral nutrition, malabsorption and gastric bypass. High doses of supplemental zinc (50 milligrams or more daily) for prolonged periods of time can alter copper metabolism and result in deficiency. People with celiac disease may be at risk of deficiency, which is correctable with copper supplementation and a gluten-free diet.
Deficiency may lead to anemia, osteoporosis, connective tissue disorders, abnormal lipid metabolism, cardiovascular disease and greater risk of infection.
Toxicity: Copper toxicity is rare from dietary sources, except with Wilson’s disease, a rare genetic condition in which excessive amounts of copper accumulate in the body and can be fatal.
Excess supplementation or exposure to copper pots and pipes can increase intake beyond the Tolerable Upper Intake Level. Chronic elevated levels of copper can result in liver damage. Symptoms of copper toxicity are nausea, vomiting, diarrhea and stomach pain. Toxicity can lead to more serious conditions including liver damage, kidney failure, coma and death.
Bottom line: Most Americans consume adequate copper from food sources. Those considering copper supplementation should consult a health care provider. To better understand the role of copper in health, large-scale studies evaluating the relationship of copper and health with reliable biomarkers are needed.
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