Which foods contain a high level of copper? Dietary copper is found in a wide variety of foods including animal liver, seafood, nuts and seeds, soy products, avocados and dark chocolate. get more out of your top foods. [Read More] Copper is an essential mineral found throughout all body tissues. It is a critical component of many enzymes. Symptoms of copper deficiency include neutropenia, hypochromic anemia, impaired immune function, bone abnormalities and altered cardiovascular and pulmonary function.