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What is copper?

Copper is a mineral, a metal that is an essential nutrient to human health.

The chemical symbol for copper is Cu.

Copper Functions

Copper is needed for [1]:

  • Energy release from foods (as part of an enzyme cytochrome c oxidase)
  • Recruiting iron from the body stores
  • Integrity of connective tissue in the skin, bones, heart muscle and vessels
  • Synthesis of signaling molecules in the brain (neurotransmitters: dopamine, serotonin, epinephrine)
  • Synthesis of the nerve sheets
  • Synthesis of the pigment melanin, which gives color to the skin, hair and eyes

In the blood, copper is bound to a protein ceruloplasmin that acts a s a body copper store.

How much copper do you need?

According to Institute of Medicine in the U.S., the Recommended Dietary Allowance (RDA) for copper for adults is 900 micrograms (1 mg)/ day [1].

Copper Rich Foods

  • PLANT FOODS: nuts, seeds, legumes, cereal grains, potatoes, tomatoes
  • ANIMAL FOODS: liver, oysters, clams, crabs
  • Municipal water in some areas and some mineral waters may be high in copper.
  • Human breast milk contains about 500 mcg (o.5 mg) copper per liter [2]. The Adequate Intake Level (AI) for copper for infants 0-6 months old is 200 mcg/day and for 7-12 months old infants 220 mcg/day [1].

Chart 1. Foods High in Copper

PLANT FOODS Copper (mcg)
Baking chocolate (1 oz, 28 g) 920
Chestnuts (1 cup, 237 mL) 725
Mushrooms, shiitake (1/2 cup, 120 mL) 650
Cashew nuts (1 oz, 28 g) 630
Sunflower seeds (1 oz, 28 g) 520
Hazelnuts, Brazil nuts, walnuts (1 oz, 28 g) 450-500
Tomato paste (1/2 cup) 500
Artichokes, globe (1 cup, 237 mL) 390
Pumpkin seeds (1 oz, 28 g) 390
Almonds, pecans, pistachios (1 oz, 28 g) 330-380
Turnip and beet greens (1 cup, 237 mL) 360
Sweet potatoes (1 vacuum pack, 250 g) 350
Soybeans (1/2 cup, 120 mL) 350
Spinach (1 cup, 237 mL) 310
Beans, navy, white (1/2 cup, 120 mL) 145-300
Soy milk (1 cup, 237 mL) 295
Chickpeas (1/2 cup, 120 mL) 290
Potatoes without skin (1 cup, 237 mL) 260
Blackberries, raspberries (1 cup, 237 mL) 240-260
Lentils (1/2 cup, 120 mL) 250
Buckwheat groats (1 cup, 237 mL) 245
Cowpeas (1/2 cup, 120 mL) 230
Rice, brown (1 cup, 237 mL) 200
Tofu (1 piece, 80 g) 190
Vegetables: asparagus, kale, kohlrabi, sauerkraut, squash (1 cup, 237 mL) 170-230
Peanut butter (2 tbsp, 32 g) 185
Cornmeal, yellow (1 cup, 237 mL) 180
Mango (1 cup, 237 mL) 180
Dates, deglet noor (1/2 cup, 120 mL) 180
Peas, split (1/2 cup, 120 mL) 180
Shredded wheat cereal (2 biscuits) 170
Cherries, sour, red (1 cup, 237 mL) 170
Barley, pearled (1 cup, 237 mL) 165
Coconut meat (1/2 cup, 120 mL) 155
Prunes (1/2 cup, 120 mL) 150
Pineapple (1 cup, 237 mL) 150
Miso (1/2 cup, 120 mL) 150
Beef liver (3 oz, 85 g) 12,400
Crabs, Alaska king (3 oz, 85 g) 1,000
Oysters, clams (3 oz, 85 g) 580-670
Chicken or turkey giblets (1/2 cup, 120 mL) 200-400
Shrimps, canned (3 oz, 85 g) 255
Duck meat (3 oz, 85 g) 200
Salmon, chinook (3 oz, 85 g) 200
Sardines, canned (3 oz, 85 g) 160
Chocolate milk (1 cup, 237 mL) 160

Chart 1 source: USDA.gov [2]. All listed foods are ready to eat.

Copper Deficiency: Causes, Symptoms

Normal “free serum copper” levels are 10-15 mcg/dL and “total copper” levels are 64-140 mcg/dL [4].

Copper deficiency may occur in preterm infants, infants fed with cow’s milk formula, chronic alcoholics, individuals with cystic fibrosis, Crohn’s or celiac disease or other small intestinal disorder affecting absorption of copper, gastric bypass (bariatric surgery for weight loss) [3], kidney patients on hemodialysis, those who take zinc supplements or a metal binder penicillamine and in individuals with hereditary disorders of copper metabolism [1].

Symptoms of copper deficiency can include anemia that cannot be corrected with iron supplements, low level of white blood cells (leukopenia) resulting in increased susceptibility for infections, bone disorders including osteoporosis in small children, and loss of pigmentation [1].

Copper Supplements

Without prescription (over-the-counter):

  • Oral copper supplements include cupric oxide, copper gluconate, copper sulfate, and copper amino acid chelates.

By prescription:

  • Cupric chloride is intended for use in the solutions for total parenteral nutrition (TNP) and not for direct intravenous or intramuscular injections.

Possible Copper Benefits

Copper supplements are EFFECTIVE in treatment of copper deficiency [1].

There is INSUFFICIENT EVIDENCE about copper effectiveness in prevention or treatment of Alzheimer’s disease, arthritis, cancer, coronary heart disease, dental plaques, osteoporosis, skin conditions, systemic lupus erythematosus (SLE) or wound healing or in improving immunity [1,7].

Copper Safety: Side Effects, Toxicity

The Tolerable Upper Intake Level (UL) for copper–the amount that should not cause side effects–for adults is 10 mg/day [1].

Acute Copper Toxicity (Copper Overdose)

Copper in large amounts may be toxic; intoxication is usually due to drinking beverages from copper containers or contaminated water supplies. In the U.S., the maximal allowed copper concentration in water is 1.3 mg/liter [1]. The main symptoms of acute copper poisoning are abdominal pain, nausea, vomiting and diarrhea, and, in severe cases–after taking as little as 1 g of copper sulfate–liver and kidney failure, coma and death [1,8].

Chronic Copper Toxicity

Chronic intake of copper in high enough amounts may cause liver or kidney damage [1]. Do not take copper supplements without a doctor’s approval, if you have a liver, biliary or kidney disease. Copper may be absorbed from a copper intrauterine device.

Wilson’s Disease

Wilson’s disease is a genetic disorder in which copper cannot be properly secreted from the liver into the bile, so it accumulates in the liver, brain, kidneys and eyes [1,5]. Symptoms usually appear between 5 and 35 years of age and can include enlarged liver or spleen, jaundice, leg swelling, tremor, muscle stiffness, and brownish Kayser-Fleischer rings in the iris and cornea of the eye [1]. Diagnosis is made by checking the blood copper and ceruloplasmin levels (both are usually low, except in acute phase) and liver biopsy. Treatment is by zinc supplements that bind copper in the gut and slow down its absorption, or by trientine hydrochloride and d-penicillamine that bind copper in the body and remove it through the kidneys. Subsequent copper accumulation is prevented by a low-copper diet.

Chart 2. Low-Copper Diet for Wilson’s Disease

Allowed foods (<100 mcg copper/serving) Limit foods containing 100-200 mcg copper to 6 servings/day Avoid foods containing more than 200 mcg copper/serving
Meats and fish Chicken and turkey light meet, beef, cold cuts and frankfurters (without pork) Fish, turkey and chicken dark meat (3 oz), peanut butter (2 tbsp) Lamb, pork, pheasant quail, duck, goose, squid, salmon, shellfish (oysters, scallops, shrimp, lobster, clams, crabs), organ meats (liver, kidneys), meat gelatin
Dairy and eggs Most dairy products, eggs Chocolate milk
Vegetables Most vegetables Beets (1/2 cup), spinach (1/2 cup), tomato juice and other tomato products (1/2 cup), broccoli (1/2 cup), asparagus (1/2 cup), potatoes (1/2 cup), pumpkin (3/4 cup), parsnips (2/3 cup), winter and summer squash (1/2 cup) Vegetable juice cocktail, mushrooms, fresh sweet potatoes, turnip greens, kale, kohlrabi, sauerkraut, globe artichokes
Legumes Bean sprouts (1 cup), green peas (1/2 cup) Dried beans and peas, soybeans, lentils, soy flour, soy grits, tofu, soy protein meat substitutes
Nuts and seeds All nuts and seed
Fruits Most fruits, including fruits dried at home Mango (1/2 cup), papaya (1/4 average), pear (1 medium), pineapple (1/2 cup) Nectarine, avocado, raspberries, blackberries, grapes, commercially dried fruits including raisins, dates, prunes
Cereals White breads & pasta, rice, regular oatmeal, cereals with < 100 mcg copper per serving, all others not listed on the right Whole-wheat bread (1 slice), whole wheat crackers (6), instant oatmeal (1/2 cup), cereals with 100-200 mcg copper per serving Millet, barley, wheat germ, buckwheat, couscous, bran breads, cereals with >200 mcg copper per serving
Fats Butter, cream, margarine, mayonnaise, non-dairy creamer, sour cream, oils, salad dressings (made from allowed ingredients) Olives (2 medium)
Sweets Most sweets, jams, jellies, candies, carob, flavoring extracts Licorice (1 oz), syrups (1 oz) Candy with nuts, chocolate, or cocoa
Beverages, other Coffee, tea, fruit juices, fruit-flavored beverages, lemonade, soups made with allowed ingredients Cereal beverages (1 cup), carbonated beverages (12 oz), ketchup (2 tbsp), dehydrated and canned soups Instant breakfast beverages, mineral water, soy-based beverages, vegetable juice mix, cocoa, alcohol, chocolate, copper-fortified formulas, brewer’s yeast, multivitamin supplements with copper

Chart 2 source: Gicare.com [6]. This is only an informative chart; ask your doctor for a diet appropriate for you personally.

Copper Interactions With Drugs and Nutrients

High doses of zinc supplements and antacids taken for prolonged periods reduce copper absorption, which may lead to copper deficiency [1]. Penicillamine (a metal binder) stimulates copper excretion [1].

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