Copper: the mineral most people only hear about when zinc goes wrong

Copper deficiency is rare from diet alone and common enough from one specific habit: taking high-dose zinc supplements for months. That is the practical story of copper, and it is the reason this page exists.

What it does in the body

• Copper is a cofactor for several enzymes involved in energy production, iron metabolism, neuropeptide activation, connective tissue synthesis and neurotransmitter synthesis. — general adults Evidence E source

How much you need

• The RDA for copper is 900 mcg a day for adults aged 19 and over. — general adults Evidence E source
• The Tolerable Upper Intake Level for copper is 10,000 mcg a day for adults aged 19 and over. — general adults Evidence E source
• The word liver hides a fortyfold range of copper between animals, and two national tables disagree almost sixfold about beef liver alone. — not applicable, reference datasets Evidence E source
• The middle of the American copper distribution sits just above the recommended intake and nowhere near the ceiling. — United States, all ages Evidence E source

How well your body absorbs it

• Four weeks of zinc cut the amount of copper reaching the liver almost by half in healthy people. — healthy adults, Denmark Evidence B source
• Iron supplements cut zinc absorption nearly in half and left copper absorption untouched, even at four hundred milligrams of iron. — adults with an ileostomy, mean age 55 years Evidence B source
• Copper mostly survives cooking, and where it is lost the liquid is what carries it away. — not applicable, reference dataset applied to raw foods Evidence E source

What too little does

• Copper deficiency causes anaemia, loss of skin pigment, bone defects, unsteady movement and more infections. — people with copper deficiency Evidence E source
• In a review of 198 published cases of spinal cord damage from copper deficiency, the two commonest causes were stomach surgery and swallowing too much zinc. — 198 reported cases of copper deficiency myelopathy, mean age 53.6 years Evidence C source
• In the same 198 cases, copper treatment brought neurological improvement in about a quarter of people, and only one in twenty recovered fully. — 198 reported cases of copper deficiency myelopathy Evidence C source
• Copper deficiency can damage the spinal cord, and in the pooled case reports only a quarter of patients improved even after they were treated. — adults with copper deficiency myelopathy reported in the literature, mean age 53.6 years, 63.8% female Evidence D source

What the evidence does and does not show

• The evidence is insufficient to say whether copper levels or copper supplements affect cardiovascular risk. — general adults Evidence E source
• Five randomised trials in 176 people found that copper supplements left total cholesterol, LDL and HDL where they were. — adults in 5 randomised trials Evidence A source
• The same measurement wobbled by a fifth from one day to the next in the same person, which sets a floor on how small an effect anyone can detect. — healthy adults with repeated baseline measurements Evidence B source
• Pooling twenty-one trials in nearly four thousand children, zinc supplements did not lower haemoglobin the way the copper theory predicted. — apparently healthy children aged 0 to 15 years Evidence A source
• A high dose of zinc pushed blood copper down three days after heart surgery, and by three weeks the difference had gone. — adults undergoing coronary artery bypass graft surgery, Iran Evidence B source
• Across eighteen pregnancy cohorts, higher maternal blood copper tracked with shorter pregnancy, most likely because it marks inflammation. — pregnant women with singleton live births across 18 cohorts, including a Malawi cohort analysed for acute-phase reactants and infection Evidence C source
• Europe allows copper to be advertised for normal hair pigmentation, which is the kind of claim that surprises people. — general population, EU food labelling Evidence E source
• Europe refused to let copper be sold for cholesterol and blood sugar, and the United States authorises no copper claim at all. — general population, EU and US food labelling Evidence E source

What too much does

• Regular high doses of zinc from supplements, or excessive use of zinc-containing denture creams, can cause copper deficiency because zinc inhibits copper absorption. — general adults Evidence E source
• One slice of beef liver carries more copper than the daily ceiling for adults and about thirteen times the recommended intake. — United States food supply, portion sizes as eaten Evidence E source
• Europe treats about five milligrams of copper a day as the point where the body starts retaining it, which is half the American ceiling. — European population, adults Evidence E source

Medicines it interacts with

• The NIH states copper has no known clinically relevant interactions with medications. Evidence E source

What to do with this

If you do not take supplements, copper needs nothing from you. It is in shellfish, organ meat, nuts, seeds, whole grains and chocolate, and the amounts add up without anyone trying.

The one situation worth acting on is zinc. A high-dose zinc supplement taken for months, or a zinc-heavy denture cream used generously, blocks copper absorption well enough to produce a real deficiency. If you are taking zinc through the winter and feel tired or notice odd nerve symptoms, copper is one of the things to raise with a doctor rather than to treat yourself.

If you want the reason to take that seriously, look at what happens next. In a review of 198 published cases of spinal cord damage from copper deficiency, the two commonest causes were stomach surgery and swallowing too much zinc. After copper was replaced only a quarter of those people improved at all, and one in twenty got back to where they started.

Copper itself has no known clinically relevant interactions with medicines, which makes this one of the shorter cautions on this site.

Where copper is, and why one word covers a fortyfold range

Liver is the answer everybody gives, and liver is not one food. Within the British table raw liver runs from 0.50 mg per 100 g in chicken through 1.13 in pig and 2.50 in ox to 9.67 in lamb and 20.48 in calf. Across national tables the disagreement is worse: American data put beef liver at 14.5 mg per 100 g where the British table puts ox liver at 2.50 mg. One 85 gram slice comes to 12.3 mg by the American figure, above the American ceiling of 10 mg and about thirteen times the 0.9 mg recommendation. Chicken liver at 0.57 mg per 100 g is a different food.

None of that is a reason to fear liver. It is a reason to eat the strong ones occasionally and to stop treating the word as a single number. For everyone else the arithmetic is dull in a good way. The median American copper intake is 0.94 mg a day and 1.00 mg among adults, against a recommendation of 0.9 mg and a ceiling of 10. Most people land within a rounding error of the target without trying. Cooking does not take it away either: the retention factor is 100 per cent for 173 of 269 methods, and the lowest anywhere is 55 per cent, in wet methods where the liquid is thrown out.

Two ceilings, two different questions

Europe treats about 5 mg a day as the point where copper starts accumulating in the body and set a safe level of 0.07 mg per kilogram of body weight, roughly 4.9 mg for a 70 kilogram adult. The American ceiling is 10 mg and it was built on liver injury. Those are different questions with different answers and they should not be printed as one number. EFSA also concluded that total exposure from all sources poses no concern for the European population, which is about habitual intake across a population rather than about one slice of liver.

What copper supplements do

Unsettled. This is the weakest part of the copper page and the honest thing is to say so. The only pooled randomised evidence on copper supplements covers blood lipids: five trials, 176 people, and total cholesterol, LDL and HDL all stayed where they were. Beyond that, whether copper intake or copper supplements change cardiovascular risk cannot be answered from the evidence that exists. When this page was last researched, no meta-analysis of randomised trials on copper supplementation turned up in our corpus or on the web. That is a gap in what has been done rather than a verdict on copper, and anybody selling a copper supplement is working in the same empty space.

One number that is easy to read backwards

Across 18 pregnancy cohorts, higher copper in the mother's blood went with a higher chance of preterm birth, an odds ratio of 1.30, and with pregnancies shorter by about a day and a half. Do not read that as copper doing harm. In one of those cohorts copper tracked with the standard markers of inflammation and with malaria and HIV infection, which is what blood copper does: it rises when the body is inflamed. The likeliest reading is that copper was marking illness.

Where to get it from food

The bottom line

Ordinary food covers copper without anyone thinking about it, and the upper limit of 10,000 micrograms sits more than ten times above the daily requirement. The realistic risk is not what you eat but what you take. High-dose zinc supplements and zinc-heavy denture creams block copper absorption, and the deficiency that follows shows up as anaemia and nerve problems that are easy to blame on something else. Copper itself has no known clinically relevant interactions with medicines. Newer work sharpens the zinc story and leaves a hole where the benefit evidence should be. Four weeks of zinc at the standard Wilson disease dose cut the copper in the livers of healthy people to about half of where it started, which is the mechanism behind every warning on this page. The same study measured how unreliable that reading is: the same person's liver copper moved by about a fifth from one day to the next, and five of 37 participants showed no response to any zinc regimen at all. Against that, pooling 21 trials in nearly 4,000 children found zinc supplements left haemoglobin where it was. Both things are true. Zinc moves copper, and ordinary supplemental doses in children have not produced the anaemia the mechanism predicts. Iron, by contrast, leaves copper absorption untouched even at 400 mg, while cutting zinc absorption nearly in half in the same people. On what copper supplements do for anybody, the evidence is close to absent, and this page says so below rather than filling the space.

Sources

1. cu-01 · Position of an expert body · expert body statement
   It is a cofactor for several enzymes (known as cuproenzymes) involved in energy production, iron metabolism, neuropeptide activation, connective tissue synthesis, and neurotransmitter synthesis
   NIH Office of Dietary Supplements, Copper - Health Professional Fact Sheet · checked 2026-09-16 · extracted
2. cu-02 · Position of an expert body · expert body statement
   19+ years 900 mcg (value from the source's table, not a sentence)
   NIH Office of Dietary Supplements, Copper - Health Professional Fact Sheet · checked 2026-09-16 · extracted
3. cu-03 · Position of an expert body · expert body statement
   19+ years 10,000 mcg (value from the source's table, not a sentence)
   NIH Office of Dietary Supplements, Copper - Health Professional Fact Sheet · checked 2026-09-16 · extracted
4. cu-d-09 · Position of an expert body · reference dataset
   CoFID 18-409 Liver, calf, raw — Copper (mg) 20.48 · 18-413 Liver, lamb, raw 9.67 · 18-415 Liver, ox, raw 2.50 · 18-417 Liver, pig, raw 1.13 · 18-411 Liver, chicken, raw 0.50 · FNDDS 2706153 Liver, beef — Copper, Cu 14.472 MG на 100 г (value from the source's table, not a sentence)
   CoFID 2021 (Public Health England, OGL v3.0) and USDA FNDDS 2021-2023 · checked 2026-09-21 · independently re-checked
5. cu-d-14 · Position of an expert body · national dietary survey
   copper_mg (мг) · NHANES 2021-2023, зважено · усі усі n=6694 медіана 0.94 p5 0.38 p95 2.25 · усі 19+ n=4886 медіана 1.00 p5 0.41 p95 2.37 (value from the source's table, not a sentence)
   NHANES 2021-2023, dietary recall, CDC National Center for Health Statistics · checked 2026-09-21 · independently re-checked
6. cu-d-01 · Randomised controlled trial(s) · randomised intervention study with radiotracer imaging
   Zinc acetate × 3 daily (standard of care treatment) reduced the hepatic copper content to 56% (95% CI 29–82) of the baseline value, zinc acetate × 1 daily to 56% (95% CI 31–81) and zinc gluconate × 3 daily to 49% (95% CI 33–65)
   Scientific Reports, 2022 · checked 2026-09-21 · independently re-checked
7. cu-d-04 · Randomised controlled trial(s) · randomised crossover isotopic absorption study
   Oral iron therapy may impair zinc absorption and thus zinc status in a dose-independent fashion but does not affect copper absorption.
   American Journal of Clinical Nutrition, 2003 · checked 2026-09-21 · independently re-checked
8. cu-d-08 · Position of an expert body · reference dataset
   copper_mg · 269 методів · 100% (втрат немає): 173 методів із 269 · найнижчий фактор: 55% · медіана: 100% (value from the source's table, not a sentence)
   USDA Table of Nutrient Retention Factors, Release 6 (2007), Agricultural Research Service · checked 2026-09-21 · independently re-checked
9. cu-05 · Position of an expert body · expert body statement
   effects of copper deficiency include anemia, hypopigmentation, hypercholesterolemia, connective tissue disorders, osteoporosis and other bone defects, abnormal lipid metabolism, ataxia, and increased risk of infection
   NIH Office of Dietary Supplements, Copper - Health Professional Fact Sheet · checked 2026-09-16 · extracted
10. cu-t2 · Observational data · systematic review of case reports
    The most common etiology was prior gastric surgery (n=55, 36.2 %) followed by excessive zinc consumption from the use of zinc denture cream (n=39, 19.9%).
    Elsamadicy et al., The Spine Journal, 2024 · checked 2026-09-16 · independently re-checked
11. cu-t3 · Observational data · systematic review of case reports
    In spite of appropriate treatment with copper supplementation, only 47 cases (24%) reported improvement in neurological status, and only 10 (5.1%) recovered to baseline.
    Elsamadicy et al., The Spine Journal, 2024 · checked 2026-09-16 · independently re-checked
12. cu-d-06 · Mechanistic or laboratory data · systematic review of case reports
    In spite of appropriate treatment with copper supplementation, only 47 cases (24%) reported improvement in neurological status, and only 10 (5.1%) recovered to baseline.
    The Spine Journal, 2024 · checked 2026-09-21 · independently re-checked
13. cu-07 · Position of an expert body · expert body statement
    Overall, the evidence to date is insufficient to support any conclusions about the association between copper concentrations and CVD risk or the impact of copper supplementation on CVD.
    NIH Office of Dietary Supplements, Copper - Health Professional Fact Sheet · checked 2026-09-16 · extracted
14. cu-t1 · Meta-analysis or systematic review · meta-analysis of randomised controlled trials
    Pooled mean net change in total cholesterol (TC) (standard mean difference(SMD) [95% CI] = - 0.05 [- 0.52, 0.43]), low density lipoprotein cholesterol (LDL-C) (SMD [95% CI] = 0.22 [- 0.46, 0.89]), and high density lipoprotein cholesterol (HDL-C) (SMD [95% CI] = 0.18 [- 0.14, 0.49]) for those treated with Cu supplementation had no significant difference when compared with control.
    Li et al., Biological Trace Element Research, 2021 · checked 2026-09-16 · independently re-checked
15. cu-d-02 · Randomised controlled trial(s) · randomised intervention study with radiotracer imaging
    In 10 participants with repeated baseline measurements (Fig. 5), the coefficient of variation (CV%) of the repeatedly measured hepatic copper content was 19.6% (95% CI 10.9–25.5).
    Scientific Reports, 2022 · checked 2026-09-21 · independently re-checked
16. cu-d-03 · Meta-analysis or systematic review · meta-analysis of randomised controlled trials
    Zinc supplementation did not affect changes in hemoglobin concentrations (pooled WMD: 0.8 g/L; 95% CI: -0.6, 2.2; P = 0.27).
    Journal of Nutrition, 2010 · checked 2026-09-21 · independently re-checked
17. cu-d-05 · Randomised controlled trial(s) · randomised controlled trial
    Although the plasma copper level was transiently decreased early after surgery in the zinc-vitamin E group, considering the lack of change in other copper biomarkers, it seems that the use of zinc supplements at the dose used in the present study does not have a significant negative effect on the role of intracellular copper.
    Biological Trace Element Research, 2025 · checked 2026-09-21 · independently re-checked
18. cu-d-07 · Observational data · meta-analysis of observational cohorts
    The random-effect meta-analysis across 18 cohorts revealed that 1 μg/mL increase in maternal Cu concentration was associated with higher risk of PTB with odds ratio of 1.30 (95% confidence interval [CI]: 1.08, 1.57) and shorter gestational duration of 1.64 d (95% CI: 0.56, 2.73).
    American Journal of Clinical Nutrition, 2024 · checked 2026-09-21 · independently re-checked
19. cu-d-11 · Position of an expert body · regulatory register entry
    POL-HC-6360 Copper Copper contributes to normal hair pigmentation Authorised (value from the source's table, not a sentence)
    EU Register on nutrition and health claims (European Commission) · checked 2026-09-21 · independently re-checked
20. cu-d-12 · Position of an expert body · regulatory register entry
    POL-HC-6975 Copper Copper contributes to the cholesterol and glucose Non-authorised (value from the source's table, not a sentence)
    EU Register on nutrition and health claims (European Commission) · checked 2026-09-21 · independently re-checked
21. cu-04 · Position of an expert body · expert body statement
    People who regularly consume high doses of zinc from supplements or use excessive amounts of zinc-containing denture creams can develop copper deficiency because zinc can inhibit copper absorption.
    NIH Office of Dietary Supplements, Copper - Health Professional Fact Sheet · checked 2026-09-16 · extracted
22. cu-d-10 · Position of an expert body · reference dataset
    Liver, beef — Copper, Cu 14.472 MG на 100 г [fdc_id 2706153] · 1 slice, any size 85 г 12.3 MG · 1 cup 125 г 18.1 MG · Liver, chicken — Copper, Cu 0.57 MG на 100 г [fdc_id 2706154] · 1 liver 22 г 0.1 MG (value from the source's table, not a sentence)
    USDA FNDDS 2021-2023 (Food and Nutrient Database for Dietary Studies) · checked 2026-09-21 · independently re-checked
23. cu-d-13 · Position of an expert body · regulatory safety assessment
    Combined exposure to copper from all sources does not pose health concerns for the EU population
    EFSA, Total copper intakes below new safe level, news release · checked 2026-09-21 · independently re-checked
24. cu-06 · Position of an expert body · expert body statement
    Copper is not known to have any clinically relevant interactions with medications.
    NIH Office of Dietary Supplements, Copper - Health Professional Fact Sheet · checked 2026-09-16 · extracted