Copper is a trace element important for:

• The formation of red blood cells
• The maintainance of bones, blood vessels, nerve endings, and the immune system
• The creation of many enzymes

Copper deficiency, although rare, can cause anemia, improper development of bones and nervous tissue, loss of elasticity in tendons and blood vessels, and abnormal color and consistancy of hair. Too much copper, usually resulting from unlined copper pots, can cause violent vomiting and diarrhea.

References:

• Brody, Jane. Jane Brody's Nutrition Book. Bantam Books. 1987.