≈0.9 mg/day (requirements). Diet is usually enough.
⚠️ NOT a treatment: copper is high in depression (biomarker) — observational association, do not supplement
See the study (meta-analysis (observational)) →Review: copper deficiency is more common than was believed and can have serious consequences (blood, nerves). The requirement is ~0.9 mg/day. Note: excess zinc in supplements can cause copper deficiency.
View the study (study) →⏱ 3 min read
Copper is an essential trace mineral whose biological functions are carried out through its incorporation into a select group of enzymes (cuproenzymes): ceruloplasmin (plasma iron transport), cytochrome c oxidase (mitochondrial respiratory chain), Cu-Zn superoxide dismutase (antioxidant defense), lysyl oxidase (cross-linking of collagen and elastin in connective and vascular tissue), dopamine beta-hydroxylase (catecholamine synthesis), and tyrosinase (skin and hair pigmentation); this multiplicity of functions explains why clinical deficiency produces a complex picture with microcytic anemia (through interference with iron metabolism), neutropenia, connective tissue abnormalities, skin depigmentation, and, in severe cases, myelopathy with serious neurological manifestations.
The most concentrated dietary sources are organ meats (especially liver), shellfish (especially oysters), seeds (sunflower, sesame, pumpkin), nuts, legumes, dark chocolate, and whole grains; typical Western diets provide adequate amounts for most people, and clinical copper deficiency is relatively rare except in specific situations: severe intestinal malabsorption, gastric bariatric surgery, excessive chronic zinc supplementation (zinc competes with copper for intestinal absorption, and chronic zinc excess can precipitate clinically relevant copper deficiency), and prolonged parenteral nutrition without adequate supply.
The clearest indication is the treatment of documented clinical copper deficiency, an uncommon but clinically important situation when it occurs: copper-deficiency anemia (which mimics iron-deficiency anemia but does not respond to iron because the problem is the utilization of iron, not its availability) and the associated hematological and neurological complications are corrected with specific oral or parenteral copper supplementation depending on severity.
In people on chronic high-dose zinc supplementation (more than 50–100 mg/day for months), secondary copper deficiency is a recognized and well-documented complication that justifies adding proportional copper supplementation to prevent it; combined formulations (zinc + copper in an approximate 10–15:1 ratio) are standard practice in chronic zinc supplementation.
At the extreme of copper-related pathologies are two specific genetic diseases: Menkes syndrome (a defect in copper absorption and distribution with severe clinical deficiency from infancy, devastating neurological manifestations, and a need for parenteral copper) and Wilson disease (pathological copper accumulation with liver and neurological involvement, treated with chelators and strict dietary copper restriction); both are rare but illustrate the importance of proper copper regulation.
The recommended dietary allowances are 900 micrograms daily in adults, achievable with varied diets; complete multivitamins typically contain 0.5–2 mg of copper; specific oral copper products usually contain 1–3 mg of elemental copper (as copper gluconate, sulfate, or citrate); the tolerable upper limit is 10 mg/day in adults, a prudent figure to avoid toxicity from excess intake.
Generally well tolerated at usual nutritional and supplemental doses; the most frequent adverse effects with high doses or excess intake are digestive discomfort (nausea, vomiting, abdominal pain, diarrhea), an unpleasant metallic taste and, in extreme cases of acute toxicity, hepatotoxicity and systemic manifestations; people with Wilson disease have an absolute contraindication to copper supplementation; those taking chronic high-dose zinc need proportional copper supplementation to prevent secondary deficiency; those taking penicillamine (a copper chelator used in Wilson disease) should avoid supplements; in pregnancy and breastfeeding, adequate dietary intake is important and specific supplementation is indicated only with documented deficiency; copper-only supplements without clear clinical justification provide no benefit in people with a normal diet and may needlessly contribute to excess intake; old domestic copper plumbing is an additional source of intake worth keeping in mind in some specific situations.
Information, not medical advice. Scientific evidence reflects the quality of the studies.