Copper

Manufactures red blood cells, bones and collagen; stimulates the immune system; promotes healing, absorption of iron; metabolism of fatty acids and the formation of RNA.

It is found in wheat, cereals, peanuts, nuts, legumes, potatoes, yeast, oysters, shellfish, liver, cocoa, and black pepper.

Deficiency is rare, however, symptoms may include anemia, nervous disorders, infertility, and Menke's Disease (kinky hair syndrome).