Copper
Copper is a trace mineral that enzymes need to make energy, move iron into the blood and build connective tissue. Adults need 0.9 mg a day, and a handful of nuts or seeds covers a large part of it.
0.9 mga day for adults, US RDA
1 mg on EU food labels (NRV), the figure behind label percentages
Upper limit · 5 mg (EU) or 10 mg (US) a day
- Most per 100 g 7mg Lamb liver
- Main sources Liver, shellfish, nuts then seeds, cocoa, beans and whole grains
- In the body 50 - 120 mg in a whole adult body
- Works against Zinc high doses block copper absorption
Daily amount: the US RDA for adults aged 19 and over (NIH). Food figures per 100 g from USDA FoodData Central; per portion, only for foods with a Caltide calorie page.
Foods High in Copper
Ranked per 100 g, with what a usual portion gives, limited to 3 foods per category. Foods with a Caltide calorie page link to it.
L
Lamb liver
2 mg in 1 oz
7mg / 100 g
O
Oysters
0.43 mg in 1 oyster
2.9mg / 100 g
C
Calamari
0.35 mg in 1 item
2.3mg / 100 g
C
Cashews
0.62 mg in 1 handful
Nutrition facts
2.2mg / 100 g
S
Sunflower seeds
2.6 mg in 1 cup
1.8mg / 100 g
C
Cashew butter
0.28 mg in 1 tablespoon
1.8mg / 100 g
L
Lobster
3.4 mg in 1 lobster
1.7mg / 100 g
C
Chia seeds
0.19 mg in 1 tablespoon
Nutrition facts
1.6mg / 100 g
S
Sun-dried tomatoes
0.78 mg in 1 cup
1.4mg / 100 g
D
Dark chocolate
0.22 mg in 2 squares
Nutrition facts
1.1mg / 100 g
B
Black-eyed peas
0.94mg / 100 g
W
White sorghum bran
0.84mg / 100 g
What Is Copper?
Copper is an essential trace mineral. A whole adult body holds only 50 to 120 mg of it, mostly in muscle, bone and the liver. It works as a helper inside enzymes called cuproenzymes, which cannot do their job without it.
What Copper Enzymes Do
- Energycytochrome c oxidase, the last step in turning food and oxygen into usable energy
- Ironceruloplasmin and hephaestin, which ready iron to leave the gut and travel in the blood
- Connective tissuelysyl oxidase, which links collagen and elastin fibers in skin, bone and blood vessels
- Pigment and brain chemicalstyrosinase for the skin and hair pigment melanin, and an enzyme that makes the neurotransmitter norepinephrine
- Antioxidant defensesuperoxide dismutase, which disarms a reactive form of oxygen
Because two of those enzymes move iron, a copper shortage can cause anemia that iron tablets do not fix, along with a low white blood cell count and, over time, nerve damage that affects balance and walking.
Copper per Portion in Common Foods
The daily amount is so small that whole milligrams hide the differences, so this table uses two decimals. It lists the richest foods with a Caltide calorie page, a usual portion of each, and the copper in that portion.
| Food | Usual portion | Per 100 g | Per portion |
|---|---|---|---|
| Cashews | 1 handful (28 g) | 2.2mg | 0.62mg |
| Chia seeds | 1 tablespoon (12 g) | 1.6mg | 0.19mg |
| Dark chocolate | 2 squares (20 g) | 1.1mg | 0.22mg |
A Day of Food With Enough Copper
One ordinary day from foods in the Caltide library, in usual portions, with no supplements.
| Meal | Food | Amount | Copper |
|---|---|---|---|
| Breakfast | Oats | 40g | 0.16mg |
| Snack | Cashews | 28g | 0.62mg |
| Lunch | Chickpeas | 180g | 0.63mg |
| Lunch | Bread | 24g | 0.03mg |
| Dinner | Salmon | 125g | 0.08mg |
| Dinner | Potato | 200g | 0.43mg |
| Treat | Dark chocolate | 20g | 0.22mg |
| Total | 2.16mg |
Nuts, beans and potatoes do most of the work. This is why a copper shortage from diet alone is rare in people who eat a varied diet.
Copper Deficiency and Copper Buildup
Copper deficiency usually has a cause other than diet. Celiac disease and weight-loss surgery reduce absorption, Menkes disease is a rare genetic defect in copper transport, and months of high-dose zinc block copper uptake in the gut. The opposite problem, Wilson disease, is a genetic condition in which the liver cannot pass copper into bile, so it builds up in the liver and brain.
Common Copper Mistakes
Taking zinc alone for months. High-dose zinc taken for months is a known cause of copper deficiency. The AREDS eye formula pairs 80 mg of zinc with 2 mg of copper for this reason.
Mixing up micrograms and milligrams. US tables give copper in micrograms (900 µg), EU labels in milligrams (1 mg). They describe nearly the same amount.
Thinking more is better. Too much copper from supplements can damage the liver and cause stomach pain, nausea and diarrhea. Most people need none on top of food.
How Much Copper You Need
In micrograms, the same for men and women, and the signs of too little or too much.
| Age | Men and women |
|---|---|
| 1 - 3 years | 340µg |
| 4 - 8 years | 440µg |
| 9 - 13 years | 700µg |
| 14 - 18 years | 890µg |
| 19+ years | 900µg |
| Pregnancy | 1,000µg |
| Breastfeeding | 1,300µg |
Copper in Supplements
Most multivitamins with minerals contain copper, and some zinc products add it on purpose.
Copper Supplement Forms
Copper is sold as cupric oxide, cupric sulfate, copper gluconate and copper amino acid chelates. Labels list the copper itself, often in micrograms. Most people get enough from food and do not need a separate copper tablet.
Copper and Zinc Supplements
If you take a zinc supplement above the upper limit for weeks, ask whether you need copper with it. Eye supplements based on the AREDS study include 2 mg of copper next to 80 mg of zinc so the zinc does not cause a shortage.
Ask a doctor or pharmacist before combining a supplement with a medicine.
Tracking Copper in Caltide
- Logged automaticallyCaltide adds up the copper in every food you log and shows it against the amount for your age and sex in the Nutrition tab.
- Supplements count tooAdd your multivitamin or zinc and copper tablet once with its copper. Each day you tick it off, it counts toward your total.
Copper Sources and References
The figures and claims on this page are checked against these sources. Food amounts come from USDA FoodData Central.
Questions About Copper
Adults need 900 µg (0.9 mg) a day, rising to 1,000 µg in pregnancy and 1,300 µg when breastfeeding (US RDA). The EU label reference is 1 mg.
Liver and oysters lead. Among the foods in the Caltide library, lamb liver has the most, 7 mg per 100 g, then Oysters (2.9 mg) and Calamari (2.3 mg).
It is part of enzymes that make energy in cells, move iron into the blood, link collagen and elastin in connective tissue, make the skin pigment melanin and some brain chemicals, and protect cells from oxidative damage.
No. It is rare and usually has a cause: celiac disease, weight-loss surgery, the genetic condition Menkes disease, or months of high-dose zinc, which blocks copper absorption.
To prevent copper deficiency. High-dose zinc lowers copper absorption, so the AREDS eye supplement, which has 80 mg of zinc, also contains 2 mg of copper.
Yes, but rarely from food. The upper limit for adults is 5 mg a day in the EU and 10 mg in the US. In Wilson disease, a genetic condition, copper builds up in the liver and brain even on a normal diet.
Yes. In the Caltide food library dark chocolate has 1.1 mg per 100 g, so two squares give about a fifth of the daily reference.
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