Because zinc is an element, it's a nutrient that must be provided by your diet, making it an essential dietary mineral. You need only small amounts of zinc, so it's sometimes referred to as a trace element. Zinc performs a number of functions in immune, reproductive, cellular and neurological processes. Taking in too much zinc can cause a number of short-term and long-term side effects.
Definition
The normal daily requirement for zinc is 11 mg for males over age 14 and 8 mg per day for women over age 19. Pregnant women over age 19 require 11 mg per day and pregnant teens 13 mg per day. Children up to age 3 require 3 mg per day and those between the ages of 4 and 8 need 5 mg. Males and females aged 9 through 13 need 8 mg. The tolerable upper level dose for adults over age 19 is 40 mg per day, according to the Office of Dietary Supplements.
Causes
Zinc overdose can occur because of excessive supplementation, accidental ingestion or from food or drinks contaminated by zinc released from galvanized containers, the Linus Pauling Institute at Oregon State University warns. Inhaling zinc oxide fumes causes metal fume fever.
Side Effects
Many of the side effects associated with zinc overdose are gastrointestinal. These typically include abdominal pain and cramping, nausea, vomiting, diarrhea, headaches and loss of appetite. Mild gastrointestinal symptoms can occur at doses of 50 to 150 mg per day, the Linus Pauling Institute notes. Zinc lozenges can cause a strange taste in the mouth and mouth irritation and are associated with a loss of the sense of smell. Metal fume fever causes weakness, sweating and fast breathing, known as tachypnea, that starts within eight hours and may continue up to 12 to 24 hours after exposure.
Long-Term Effects
Long-term zinc overdoses of as little as 60 mg per day for 10 weeks can cause copper deficiency, which can lead to anemia, the Office of Dietary Supplements explains. To avoid copper deficiency, supplements containing high levels of zinc often include additional copper as well, such as the AREDS formula used to prevent macular degeneration, which contains 80 mg of zinc.
Considerations
Avoid zinc nasal sprays and gels, which have caused a permanent loss of smell in some people, the Linus Pauling Institute warns. If you take over-the-counter preparations high in zinc, such as the AREDS formula devised for preventing macular degeneration, discuss the potential side effects with your medical practitioner. In the AREDS study, an increased number of genitourinary problems occurred, indicating that excess zinc may cause urinary problems.
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