- 01A zinc problem, not a copper problem
In people who take supplements, low copper is most often caused by too much zinc, not too little copper in food, so the first fix is finding and cutting the zinc; copper is added under a doctor's care.
Copper is a trace mineral your body needs only in milligrams, and a normal diet covers it. Most people who end up low on copper are not short of it in their food: they are taking too much zinc, which blocks copper from being absorbed. In that case the first fix is finding and cutting the zinc, with copper added only under a doctor's care.
What copper does in your body
Copper is a helper that several enzymes cannot work without. Its best-known job is in the blood: ceruloplasmin, the main copper-carrying protein, helps load iron onto transferrin (the protein that carries iron in blood) so iron can reach the bone marrow and be made into red cells. This is why low copper causes anemia even when you eat enough iron 1.
| What copper is part of | What it does |
|---|---|
| Ceruloplasmin | Moves iron out of storage and into red cell production |
| Superoxide dismutase | Neutralizes reactive oxygen inside cells |
| Cytochrome c oxidase | Runs the last step of turning food into energy |
| Lysyl oxidase | Cross-links collagen and elastin in skin, blood vessels and bone |
| Pigment and nerve coating | Needed to make melanin (hair and skin pigment) and myelin, the fatty layer that insulates nerves |
How much copper do you need a day?
The Institute of Medicine set the recommended dietary allowance (RDA, the intake that covers about 97% of healthy people) at 900 mcg a day for adults, with higher needs in pregnancy and breastfeeding 6. The US tolerable upper intake level (UL, the most you can take daily long term without expected harm, counting food and supplements together) is 10 mg, set to protect the liver 6. In 2023 the European Food Safety Authority's scientific committee concluded that copper does not build up in the body at 5 mg a day, and set an acceptable daily intake of 0.07 mg per kg of body weight, about 5 mg a day for an average adult 2.
| Group | Daily need (RDA) | US upper limit |
|---|---|---|
| Adults 19+ | 900 mcg | 10 mg |
| Pregnancy | 1,000 mcg | 10 mg |
| Breastfeeding | 1,300 mcg | 10 mg |
<a href="/compounds/multivitamin">Many multivitamins</a> already contain copper, often close to the RDA. Before adding a standalone copper capsule, check the label of anything else you take so you are not stacking two sources toward the upper limit.
Signs you might be low on copper
Copper deficiency is uncommon, and when it happens it tends to show up on a blood count before anything else. A review of patients at Mayo Clinic found that copper deficiency causes anemia and neutropenia (a low count of neutrophils, the white cells that fight bacteria) that can be mistaken for myelodysplastic syndrome, a bone marrow cancer; the blood counts recovered with copper replacement 5.
Copper deficiency can also damage the spinal cord. This nerve damage, called copper deficiency myelopathy, closely mimics vitamin B12 deficiency: numbness and tingling in the feet, poor balance, and an unsteady, wide-based walk 4. Neurologist Neeraj Kumar, in his Mayo Clinic review, has called it "human swayback", after the same disease in copper-deficient sheep. The nerve damage may only partly reverse once copper is restored, so an early diagnosis matters 4.
The people at real risk of copper deficiency are a short list:
- Anyone taking high-dose zinc (above the 40 mg a day upper limit) for weeks to months 6.
- People who have had gastric bypass or other bariatric surgery 1.
- People with malabsorption from celiac disease, Crohn's disease or a gut resection 1.
- Heavy users of zinc-containing denture adhesive cream; case reports have linked overuse to copper deficiency with nerve damage 1.
- People on long-term tube or IV feeding without copper added 1.
Markers to read beside a possible copper deficiency
If anemia is the flag, the <a href="/conditions/anemia">anemia</a> page walks through how blood tests find the cause, and the <a href="/compounds/iron">iron</a> guide explains when iron is the right fix. If your neutrophil count is the number that flagged, <a href="/biomarkers/neutrophils-absolute/low">low absolute neutrophils</a> lists the other common causes, and <a href="/conditions/b12-deficiency">B12 deficiency</a> covers the condition copper deficiency is most often confused with.
Why copper and zinc go together
Zinc and copper compete in the gut, and zinc wins. High zinc intake makes gut lining cells produce a protein called metallothionein, which binds copper more tightly than zinc. The trapped copper is shed with the gut cells instead of reaching the blood. This is why the US upper limit for zinc is 40 mg a day: it was set specifically to avoid zinc-induced copper deficiency 6.
How too much zinc drains copper
So when a zinc user turns out to be low on copper, the problem is the zinc, not a shortage of copper in food. Stopping or cutting the zinc comes first; a doctor decides whether copper is needed on top and checks the blood count again afterwards.
The best-known example of pairing the two is the AREDS eye study formula, which combines 80 mg of zinc with 2 mg of copper, a ratio of 40 to 1. The copper was added to prevent zinc-induced copper deficiency over years of use 1. AREDS used cupric oxide, the poorly absorbed form discussed below; the aim was to offset the zinc, not to treat a deficiency. There is no agreed ideal zinc-to-copper ratio for everyday supplements. A zinc supplement within the 40 mg upper limit does not usually need copper alongside it; the concern scales with the zinc dose and how long you take it. The <a href="/compounds/zinc">zinc guide</a> covers zinc dosing, and <a href="/conditions/zinc-deficiency">zinc deficiency</a> covers who is genuinely low on zinc.
Supplements that bear on copper
Which form is best? Bisglycinate, gluconate, sulfate or oxide
The form matters most at the cheap end. Cupric oxide, common in budget multivitamins, dissolves poorly and is barely absorbed. Animal nutritionist David Baker reviewed the data and titled his paper bluntly:
Cupric oxide should not be used as a copper supplement for either animals or humans.Baker DH, Journal of Nutrition, 1999 3
| Form | Absorption | Notes |
|---|---|---|
| Copper bisglycinate (chelate) | Generally well absorbed (limited comparative human data) | Copper bound to the amino acid glycine. |
| Copper gluconate | Generally well absorbed (limited comparative human data) | Common standalone form. |
| Copper sulfate | Generally well absorbed (limited comparative human data) | Soluble salt; more likely to cause nausea on an empty stomach. |
| Cupric oxide | Poor | Cheapest and common in multivitamins; little copper reaches the blood 3. |
So the best copper supplement is any form other than cupric oxide. Among bisglycinate, gluconate and sulfate there is no good human trial showing one corrects deficiency better than the others.
How to take a copper supplement
Copper supplements and multivitamins commonly provide 1 to 2 mg a day, under both the EU safe level of about 5 mg and the 10 mg US limit. Most people do not need that on top of food. Where a deficiency is diagnosed, the dose, the route and how long to take it are set by a doctor, because they depend on the cause and how low you are.
When and how copper is usually taken
Side effects and when copper is risky
The common side effects of copper supplements are nausea, stomach pain and a metallic taste. Copper is stored and cleared by the liver, so long-term intakes above the upper limit can damage the liver; the 10 mg US limit exists for that reason 6. If you already have liver results, <a href="/learn/liver-enzymes-explained">liver enzymes explained</a> shows how to read them.
Copper bracelets are not a proven way to raise body copper, and a copper IUD is not a recognised cause of deficiency or a way to treat one.
Does copper help hair, skin, joints or the heart if you are not low?
The evidence for copper supplements is evidence for correcting deficiency. Copper is needed for melanin, so severe deficiency can lighten hair and skin, but trials have not shown that extra copper reverses gray hair or helps <a href="/symptoms/hair-loss">hair loss</a> in people with normal copper. For the heart, the studies the NIH reviews are mixed and do not show that extra copper helps people who are not low 1, and there is no good trial evidence for joints. Copper peptides in skin serums are a topical product and have nothing to do with oral supplements.
Foods high in copper
Food covers copper for most people. Organ meat is the richest source by far: 3 ounces of pan-fried beef liver holds about 12,400 mcg, over 13 times the RDA 1. That single serving is above both the US upper limit of 10 mg and the EU safe level of about 5 mg, so liver is a food to eat occasionally, not daily 16. The <a href="/compounds/beef-liver">beef liver</a> guide covers its vitamin A trade-off too.
- Beef liver: about 12.4 mg per 3 oz
- Oysters and crab
- Cashews, sunflower seeds and sesame seeds
- Dark chocolate and cocoa
- Lentils, chickpeas and other legumes
- Shiitake mushrooms and potatoes with skin
Testing your copper: serum copper and ceruloplasmin
A copper blood test usually means <a href="/biomarkers/copper">serum copper</a>, read together with <a href="/biomarkers/ceruloplasmin">ceruloplasmin</a>. About 65 to 90% of copper in blood rides on ceruloplasmin. Ceruloplasmin rises whenever the body is inflamed or fighting infection (doctors call it an acute-phase protein), and also in pregnancy and with estrogen, including the contraceptive pill 1. Those rises push serum copper up too. A normal serum copper during inflammation can hide low stores, and a high result is far more often inflammation or estrogen than copper overload.
Low serum copper with low ceruloplasmin, alongside low neutrophils or anemia, is the pattern that points to true deficiency 5. Low copper with low ceruloplasmin is also the typical finding in Wilson disease, where copper is in fact building up in the liver and brain. Take a low result to a doctor before taking any copper; they may check urine copper or other tests to tell the two apart 1.
Read these together
Zinc has its own reading trap. As our <a href="/conditions/zinc-deficiency">zinc deficiency</a> page puts it: "A serum zinc test supports the diagnosis but cannot rule it out, because only about 0.1% of the body's zinc is in the blood and the level drops with inflammation, meals and afternoon draws." A high zinc next to a low copper, though, is a strong pointer. The guide to <a href="/learn/how-to-read-any-lab-result">reading any lab result</a> explains why a value inside the reference range can still need context.
Free, no accountRead your blood testGot a copper result next to a blood count? Read every line of the report, free.Read my results
Citations
- NIH Office of Dietary Supplements. Copper: Fact Sheet for Health Professionals (2022)
- EFSA Scientific Committee. Re-evaluation of the existing health-based guidance values for copper and exposure assessment from all sources. EFSA Journal 2023;21(1):7728
- Baker DH. Cupric oxide should not be used as a copper supplement for either animals or humans. J Nutr 1999;129(12):2278-9
- Kumar N. Copper deficiency myelopathy (human swayback). Mayo Clin Proc 2006;81(10):1371-84
- Halfdanarson TR et al. Hematological manifestations of copper deficiency: a retrospective review. Eur J Haematol 2008;80(6):523-31
- Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (2001)
Educational context only, not medical advice or a diagnosis. Always discuss your results with a clinician.
