What Copper Does
Copper is a trace mineral the body needs in small amounts. Per the NIH Office of Dietary Supplements, it acts as 'a cofactor for several enzymes... involved in energy production, iron metabolism, neuropeptide activation, connective tissue synthesis, and neurotransmitter synthesis,' and supports immune function and antioxidant defenses [1].
How Much Adults Need
The RDA is 900 mcg/day for adults, and the Tolerable Upper Intake Level is 10,000 mcg (10 mg)/day [1]. The gap between requirement and ceiling is wide, so copper toxicity from food or normal supplements is rare.
The Most Common Cause of Deficiency: Too Much Zinc
Copper and zinc compete for absorption. NIH notes that 'high dietary intakes of zinc can interfere with copper absorption,' and 'people who regularly consume high doses of zinc from supplements... can develop copper deficiency' [1]. This is the single most common reason healthy people end up low in copper — which is why prolonged high-dose zinc deserves caution (see Zinc Intake and Copper Balance).
Other Causes
- Malabsorption — celiac disease and other gut conditions reduce copper uptake [1].
- Bariatric / GI surgery — can lower absorption over time.
- Menkes disease — a rare inherited disorder of copper handling [1].
Low copper can cause anemia and, when severe, neurological problems — the same picture seen with zinc-induced copper deficiency.
Food Sources and Practical Guidance
Copper is found in shellfish, organ meats, nuts, seeds, whole grains, and dark chocolate. Most people meet their needs from food and don't need a copper supplement. The main thing to watch is not *adding* copper but *avoiding* prolonged high-dose zinc that depletes it.