The estimated safe and adequate intake for copper in adults is 1.5-3 mg/day and ranges from 0.4-0.7 mg/day for infants and 0.7-2.5 mg/day for children.
The richest dietary sources of copper, containing greater than 0.2 mg per portion, includeshellfish, nuts, seeds, legumes, whole grain, liver, and other organ meats. Moderate sources, containing 0.1-0.2 mg per portion, are grain products, chocolate, dried fruits, mushrooms, tomatoes, bananas, and potatoes. Eggs, dairy products, white grains, green beans, broccoli, and cabbage contain lower amounts of copper.
Dosage recommendations are usually based on zinc intake. The recommended ratio of zinc to copper is 10:1. It has been suggested that supplementation should not exceed 3 mg of copper.
Excessive copper intake results in gastrointestinal pain, nausea, vomiting, and diarrhea. More serious effects include coma, oliguria, hepatic necrosis, and death. There is no well-established level of copper intake that causes toxicity, although gastrointestinal effects have been seen with intakes as low as 0.07 mg/kg of body weight.