Zinc

Other name(s):

zinc gluconate, zinc sulfate

General description

Zinc is an essential trace element. It’s almost as plentiful in the human body as iron. It’s found in the eyes, brain, pancreas, kidneys, liver, and adrenal glands. In 1963, it was recognized as an essential nutrient in humans.

Zinc is needed for insulin to work well. It’s also involved in protein and DNA synthesis. Bone and teeth need zinc for good mineralization. Zinc is also needed to prevent birth defects.

Zinc works in the exchange of carbon dioxide between the lungs and the bloodstream. It's also part of enzyme functions in the liver and intestine.

Medically valid uses

Zinc is not widely used to treat any health condition. It’s only used to treat deficiencies from malnutrition or malabsorption issues.

Unsubstantiated claims

Please note that this section reports on claims that have not yet been backed up by studies.

Zinc may aid in wound healing. It may also help maintain normal levels of vitamin A. It may also improve how your immune system works. It’s also claimed to keep normal oil gland function. It may also improve sex drive and slow the aging process.

Zinc is also claimed to shorten the length of the common cold. But not all studies have found this to be true. Using nasal gels or sprays that contain zinc has been linked to long-lasting (permanent) loss of the sense of smell.

Recommended intake

Zinc is measured in milligrams (mg). The RDA is the recommended dietary allowance.

* Adequate Intake (AI)

You need to eat foods that contain zinc every day because your body doesn't store zinc. Zinc supplements come in a range of doses. Zinc supplements come in several forms. Two of the main forms are zinc sulfate and zinc gluconate. Zinc sulfate contains higher concentrations of zinc (23% per 100 mg) than zinc gluconate (14.3% per 100 mg). You should take zinc with food. This can help prevent an upset stomach.

Vegetarian diets are lower in zinc than nonvegetarian diets. Legumes and whole grains contain substances that bind to zinc and interfere with how the body absorbs zinc. Vegetarians might need as much as 50% more of the RDA than nonvegetarians.

Certain conditions increase the need for zinc. They include Down syndrome and some forms of anemia, including sickle cell and thalassemia. They also include acrodermatitis enteropathica, an inherited condition that affects the skin, hair, and intestinal tract. Other reasons for increased need include extensive burns, diabetes, prolonged stress or trauma, and using water pills (diuretics) for a long time.

Malabsorption syndromes may also increase the need for zinc. These may include Crohn's disease, tropical and nontropical sprue, celiac disease, cystic fibrosis, and ulcerative colitis. They may also include problems that lead to a surgical removal of all or part of the pancreas. Intestinal parasites can also increase the need for zinc supplements.

Alcoholism and cirrhosis of the liver can also increase the need for zinc. So can eating disorders, such as anorexia or bulimia.

Women who are pregnant or breastfeeding may need to take supplements. Always talk with your healthcare provider before doing so.

Studies have shown that as many as 1 in 4 older adults may not get enough zinc.

Acrodermatitis enteropathica is a disease in babies that is a rare, inherited problem. It appears when the baby is weaned and zinc can't be absorbed. It’s marked by hair loss, rash, diarrhea, frequent infections, and delayed growth. This condition is treated by giving zinc supplements as directed by your child's healthcare provider.

Zinc deficiency in adults can lead to iron-deficiency anemia. It can also lead to pigment changes in the skin. It may also lead to loss of sense of smell, changes in how foods taste, anorexia, hair loss, and a weak immune system. Moderate zinc deficiencies may lead to decreased testicular function in men.

Other symptoms include enlarged liver, impaired thinking, rashes, skin sores, and mouth sores. They also include swelling of the eyelids, infection of the skin around the fingernails, and slowed healing.

Side effects, toxicity, and interactions

Eating zinc from normal dietary sources doesn’t cause side effects. Foods cooked in galvanized (zinc-plated) cookware can cause stomach upset. Two or more grams of zinc will cause zinc toxicity. Symptoms can include drowsiness, poor memory, problems with motor skills, nausea, vomiting, and diarrhea.

Zinc supplements may cause an unpleasant metallic taste in your mouth.

People with a copper deficiency should use zinc with caution. This is because it can make copper deficiency worse.

Eating large amounts of zinc over the long-term can cause a copper deficiency. This is because zinc competes with copper for absorption. Some foods may decrease zinc absorption. These include bran products, protein, and phytates found in plants and seeds.

Red wine and lactose in milk aid in zinc absorption.

Additional information

Babies absorb zinc from breastmilk well. Breastmilk has a zinc-binding enzyme that helps babies absorb zinc through the intestine. Breastmilk provides enough zinc (2 mg per day) for the first 4 to 6 months. But it doesn't provide enough for babies 7 to 12 months old, who need 3 mg a day. Babies of this age should eat age-appropriate foods that contain zinc.