If you are considering a zinc supplement, it's important to maintain a good zinc-to-copper ratio. Not doing so can lead to health consequences including anemia, a low white blood cell count, abnormal cholesterol metabolism and raised risk for heart disease. Always consult a health care provider before altering your diet or consuming new supplements.
Nutritional Status
When you consume too much zinc, your body makes more of an intestinal cell protein called metallothionein. This protein binds certain metals, trapping them in your intestinal cells and preventing absorption. It has a stronger affinity for copper than zinc, so high levels of this enzyme due to excess zinc lead to decreased copper absorption. This does not appear to work the other way around -- high copper intakes do not affect your zinc nutritional status, according to the Oregon State University Linus Pauling Institute.
Acceptable Ratio
A ratio of 15-to-1 is the general industry standard for supplements, according to "Nutrition in Kidney and Disease," by Laura D. Byham-Gray, et al. If the ratio of zinc becomes higher, your copper absorption may become impaired. Many enzymes in your body depend on copper, including those involved in energy production, connective tissue formation, central nervous system function, antioxidant functions, melanin formation, gene expression and iron metabolism. For example, anemia related to poor iron metabolism is the most common sign of copper deficiency.
Average Intakes
The average dietary zinc intake in the United States is 9 mg per day for women and 13 mg a day for men. The average intake of copper in the United States is 1 mg to 1.1 mg daily for women and 1.2 to 1.6 mg daily for men. That puts the zinc to copper ratio at 9 to 1 to 1.1 for women and 13 to 1.2 to 1.6 for men. The recommended daily amount for zinc is set at 11 mg if you are male and 8 mg if you are female. The RDA calls for 900 mcg copper daily if you are of either sex.
Upper Limits
A total intake of 60 mg zinc daily may trigger a copper deficiency, according to the Linus Pauling Institute. That's why the U.S. Food and Nutrition Board sets the tolerable upper level of intake for zinc, or UL, at 40 mg daily for adults. This includes both dietary and supplemental zinc. Gaining adequate zinc is important, however, because it plays critical roles in neurological function, immune response, growth and development, and reproduction. The tolerable upper intake for copper is 10 mg daily.
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