Interaction fact sheet · Synergy
Zinc and copper
A logical combination when zinc is taken at high doses over a long period.
High-dose zinc taken long term can deplete copper, causing anemia or neurological problems. With short-term, moderate doses, this is not an issue.
Documented cases
In 1978, Prasad and colleagues described an adult with sickle cell disease who had been treated with zinc for two years and whose blood copper levels had plummeted. The patient had abnormally small red blood cells and a relative decrease in white blood cells. Copper supplementation corrected both abnormalities. The team subsequently found a decrease in ceruloplasmin, the protein that carries copper, in several other patients taking zinc.
In 2005, Willis and colleagues reported three cases identified through bone marrow aspiration. A 47-year-old man had disabling neuropathy that had been worsening for 18 months, with mild anemia and a severe reduction in white blood cells. A 21-year-old man taking zinc for a genetic skin condition had anemia and a reduced white blood cell count. A 42-year-old man had anemia, severe neutropenia and neuropathy. In all three cases, copper deficiency was due to excess zinc.
Why AREDS added copper
The AREDS trial followed 3,640 people aged 55 to 80 with macular degeneration for an average of 6.3 years. The zinc arm received 80 mg of zinc per day with 2 mg of copper, added to prevent zinc-induced deficiency. No statistically significant serious adverse effects were associated with the formulations tested. The mechanism usually described involves an intestinal protein, metallothionein, which zinc increases and which retains copper.
Cautious approach
Add up the zinc from all your products and stay below 25 mg per day without medical advice. For a long course or a higher dose, get professional supervision: tests can check copper and ceruloplasmin. Unusual fatigue, tingling, walking difficulties or repeated infections while taking zinc warrant a consultation. Don't add copper at random: it has its own limit of 5 mg per day. See also the fact sheet magnesium and zinc and our article on forms of zinc .
Limits
Evidence of deficiency is based on clinical cases: they show that the risk exists, not how often it occurs. The doses and durations involved are often high or poorly known. AREDS involved older people with an eye disease and did not compare zinc with and without copper: it therefore does not directly measure copper's protective effect.
Main sources
- 01Prasad AS et al. Hypocupremia induced by zinc therapy in adults. JAMA, 1978. PubMed 359844
- 02Willis MS et al. Zinc-induced copper deficiency: a report of three cases initially recognized on bone marrow examination. American Journal of Clinical Pathology, 2005. PubMed 15762288
- 03Age-Related Eye Disease Study Research Group. A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no. 8. Archives of Ophthalmology, 2001. PubMed 11594942
Frequently Asked Questions (FAQ)
At what dose does zinc start lowering copper?
Published cases involve high, prolonged intakes over months or years. The upper limit set in Europe is 25 mg of zinc per day for adults. Above that, or for a long course, have a doctor supervise it.
Faut-il toujours ajouter du cuivre au zinc ?
Not at usual doses over a short period. Adding copper makes sense with prolonged high doses, as in the AREDS trial (80 mg of zinc for 2 mg of copper). Copper also has an upper limit, set at 5 mg per day in Europe.