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Zinc Deficiency and Toxicity

by Larry E. Johnson, MD, PhD

Zinc is widely distributed in the body—in bones, teeth, hair, skin, liver, muscle, white blood cells, and testes. It is a component of more than 100 enzymes, including those involved in the formation of RNA (ribonucleic acid) and DNA (deoxyribonucleic acid).

The level of zinc in the body depends on the amount of zinc consumed in the diet. Zinc is necessary for healthy skin, healing of wounds, and growth.

Much of the zinc consumed in the diet is not absorbed. A diet high in fiber and phytate (present in whole-grain bread, bran, beans, soybeans, other legumes, and nuts) reduces zinc absorption.

Zinc Deficiency

  • Zinc deficiency has many causes, including various disorders, alcoholism, and use of diuretics.

  • People lose their appetite and hair and may feel sluggish and lose their sense of taste.

  • Doctors can measure the zinc level in blood, but this test is not a reliable way to determine zinc status.

  • Zinc supplements taken by mouth can cure the deficiency.

Many conditions can increase the risk of developing zinc deficiency. Deficiency due to a diet low in zinc is uncommon in developed countries. Zinc deficiency is more common among older people who live in institutions and people who are homebound.

Did You Know...

  • Lack of zinc can weaken the immune system and make wounds heal more slowly.


What Can Cause Zinc Deficiency?



Diet (an uncommon cause in developed countries)

Insufficient consumption of meat and other proteins

Consumption of foods that contain phytates (which inhibit absorption), such as whole grains, cereals, corn, rice, beans, soybeans, other legumes, and nuts



Bloodstream infection (sepsis)

Chronic kidney disease

Diabetes mellitus

Disorders that impair absorption (malabsorption)

Liver disorders

Pancreatic disorders

Sickle cell disease



Intravenous feedings for a long time

In acrodermatitis enteropathica, a rare hereditary disorder, zinc cannot be absorbed.


Early symptoms include a loss of appetite and, in infants and children, slowed growth and development. People may lose their hair in patches. They may feel sluggish and irritable. Taste and smell may be impaired. Rashes may develop. In men, sperm production may be reduced. The body’s immune system may be impaired, and wounds may heal more slowly and less completely.

If pregnant women have zinc deficiency, the baby may have birth defects and may weigh less than expected at birth.

In acrodermatitis enteropathica, symptoms usually appear when an affected infant is weaned. This disorder may result in diarrhea and hair loss. A rash develops around the eyes, nose, and mouth and on the buttocks. The immune system may be impaired, resulting in many infections. Infants may not grow as expected.


  • A doctor's evaluation

  • Response to zinc supplements

Doctors suspect zinc deficiency based on the person’s circumstances, symptoms, and response to zinc supplements. Blood and urine tests do not accurately measure zinc status.


  • Zinc supplements

Zinc supplements are taken by mouth until symptoms disappear. Zinc supplements are effective for acrodermatitis enteropathica.

Zinc Toxicity

People rarely consume too much zinc. Usually, zinc excess results from consuming acidic foods or beverages packaged in a zinc-coated (galvanized) container. In certain industries, inhaling zinc oxide fumes can result in zinc excess.

People may have nausea, vomiting, and diarrhea. Inhaling zinc oxide fumes can cause rapid breathing, sweating, fever, and a metallic taste in the mouth—a disorder called metal fume fever. Consuming too much zinc for a long time can reduce the absorption of copper, cause anemia, and impair the immune system.


  • A doctor's evaluation

Doctors suspect the diagnosis based on the person’s circumstances and symptoms.


  • Dietary changes

Treatment involves reducing zinc consumption.

People with metal fume fever usually recover after being in a zinc-free environment for 12 to 24 hours.

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