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Zinc
What is the health risk of too much zinc?
Zinc toxicity has been seen in both acute and chronic forms. Intakes of 150 to 450 mg of zinc per day have been associated with low copper status, altered iron function, reduced immune function, and reduced levels of high-density lipoproteins (the good cholesterol) (34). One case report cited severe nausea and vomiting within 30 minutes after the person ingested four grams of zinc gluconate (570 mg elemental zinc) (35). In 2001 the National Academy of Sciences established tolerable upper levels (UL), the highest intake associated with no adverse health effects, for zinc for infants, children, and adults (2). The ULs do not apply to individuals who are receiving zinc for medical treatment, but it is important for such individuals to be under the care of a medical doctor who will monitor for adverse health effects. The 2001 Upper Levels for infants, children and adults are (2):
Table 2: Upper Levels for Zinc for Infants, Children, and Adults
Age |
Infants and Children |
Males and Females |
Pregnancy and Lactation |
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0 to 6 months |
4 mg |
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7 to 12 months |
5 mg |
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1 to 3 years |
7 mg |
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4 to 8 years |
12 mg |
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9 to 13 years |
23 mg |
||||
14 to 18 years |
34 mg |
34 mg |
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Ages 19+ |
40 mg |
40 mg |
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Selected Food Sources of Zinc
The 2000 Dietary Guidelines for Americans state, “Different foods contain different nutrients and other healthful substances. No single food can supply all the nutrients in the amounts you need” (36). The following table suggests a variety of dietary sources of zinc and lists the milligrams (mg) and percent Daily Value (%DV*) per portion. As the table indicates, red meat, poultry, fortified breakfast cereal, some seafood, whole grains, dry beans, and nuts provide zinc. Fortified foods including breakfast cereals make it easier to consume the RDA for zinc, however they also make it easier to consume too much zinc, especially if supplemental zinc is being taken. Anyone considering taking a zinc supplement should first consider whether their needs could be met by dietary zinc sources and from fortified foods.
If you want more information about building a healthful diet, refer to:
Dietary Guidelines for Americans
