Copper (Cu) is a mineral perhaps more familiar to us for its use in cookware, wire, and even jewelry than as a nutrient. However, copper functions as a co-factor in oxygen-dependent enzymes in the body. Though there are only about a dozen copper-containing human enzymes, they participate in a variety of critical physiological processes, including but not limited to, energy metabolism, formation of connective tissue, regulation of iron storage and transport, and antioxidant functions. Copper may play a role in slowing the progression of age-related macular degeneration, which is responsible for causing severe vision loss in the elderly.

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Deficiencies of copper from low dietary intakes are rare in the United States as most of the population meets or exceeds the RDA for copper. However, deficiencies that are secondary to other factors are more common. Copper deficiencies are somewhat common in people who have gastric bypass surgery to treat obesity, as well as in those with other conditions that cause nutrient malabsorption. Excessive zinc intake decreases copper absorption and is another cause of copper deficiency. One of the most common copper deficiency symptoms highlights another important mineral-mineral interaction (in addition to that of copper and zinc): A copper deficiency often results in anemia because copper-containing enzymes are required to release iron from stores and for its incorporation into its heme form. Symptoms of copper deficiency include impaired immune response and osteoporosis.

The RDA for copper is 900 micrograms per day in adults. Approximately 55% to 75% of dietary copper is absorbed, which is much more efficient than other trace minerals. Although copper is found in a wide variety of foods, it is highest in organ meats, shellfish, nuts, seeds, mushrooms, chocolate, and legumes. (INFOGRAPHIC 14.10)

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