Copper is a chemical element with symbol Cu (from Latin: cuprum). Copper in the blood and blood stream exists in two forms: bound to ceruloplasmin (85-95%), and the rest "free", loosely bound to albumin and small molecules. Free copper normally reduces oxidative stress, as it is involved in the metabolic elimination of reactive oxygen species, such as with the superoxide radical through Cu-Zn dependent superoxide dismutase. Excessive free copper impairs zinc homeostasis, and vice versa, which in turn impairs antioxidant enzyme function, increasing oxidative stress. Chronically elevated levels of copper intake produces zinc deficiency.