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The human body needs both macronutrients (proteins, carbohydrates, and fats) and micronutrients (vitamins and minerals) to function correctly. Zinc is an essential nutrient found mainly in animal-based foods. It is a micronutrient and trace mineral, meaning the body needs it in very small quantities. However, zinc is vital for hundreds of body processes.

The Role of Zinc in the Human Body

Some of the bodily functions for which zinc is necessary include:

• Enzymatic processes, chemical reactions, and metabolic functions

• Formation of DNA

• Protein formation

• Cell growth

• Cell and tissue repair

• Healthy immune function

• Sense of taste and smell

Health Benefits of Zinc

Growth and Development

Zinc is necessary for cell growth and multiplication. For this reason, it is required in larger quantities during periods of rapid growth and development, such as childhood, adolescence, and pregnancy. 

For example, a consequence of zinc deficiency is stunted growth in children. In pregnant women, a zinc deficiency can lead to growth retardation, congenital malformations, and spontaneous abortion.

Immunity

Getting adequate zinc is essential to support the functioning of immune cells, thus,   improve immune function in the body. Research also shows that a zinc deficiency can put you at risk of infectious conditions such as diarrhea and pneumonia. Older adults with reduced zinc intake due to poor appetite are at risk of skin problems, infections, and pneumonia.

Low levels of zinc in the blood have been found in people with autoimmune conditions such as rheumatoid arthritis. 

A systematic review found that, compared to a placebo, prophylactic use (prevention of an infection or illness) of zinc-containing nasal sprays and lozenges can reduce the risk of contracting illness caused by viral respiratory tract infections (such as the common cold).  However, these zinc-containing products have no effects on those who are already infected with the human rhinovirus (HRV). 

Notably, the review points out that all participants are generally healthy individuals unlikely to have zinc deficiency. Overall, the data quality is low, and the effects are modest. The review also points out the small sample sizes of the primary studies and the risk of bias in the review. 

While participants of the studies in this review did not report anosmia (permanent or long-lasting loss of smell) associated with zinc-containing nasal sprays, this is a common side effect.

In fact, in 2009, the U.S. Food and Drug Administration (FDA) ordered the maker of Zicam Cold Remedy Nasal Gel and Zicam Cold Remedy Gel Swabs to withdraw these products from the market due to reported cases of anosmia associated with them. 

There are mixed results regarding the role of zinc in respiratory tract infections, such as the common colds, so you should talk to your doctor if you are interested in using zinc supplements. There is no data to support the fact that zinc will help you get rid of an illness faster. There are also no recommendations for the types of zinc or the best dosage to avoid side effects. 

If you are concerned about getting enough zinc, remember that many plant- and animal-based foods are naturally rich in zinc. 

Skin Health and Wound Healing

The body needs zinc for normal cell growth and the repair of damaged tissues. In addition, zinc supports the immune system in controlling inflammation in healing wounds. 

Zinc also has applications on the skin. Topical zinc oxide is a common and effective treatment for diaper rash. Zinc has also been studied for use in people with acne vulgaris. Creams containing zinc may benefit people with severe skin burns, diabetic ulcers, and slow- or non-healing wounds. 

Learn more: What is Zinc Oxide Ointment Used For?

Research has shown that taking oral zinc supplements may benefit people with severe skin conditions with a zinc deficiency. 

Eye Health

Zinc is present in high concentrations in ocular tissues such as the retina. It is essential for normal eye function and helps to protect eye structures from damage by free radicals. 

Research suggests that taking zinc supplements and other nutrients can lower the risk by 25% of an eye condition called age-related macular degeneration, which causes vision loss in older adults.

Blood Sugar and Blood Cholesterol

People with high blood glucose and high blood cholesterol levels frequently have a zinc deficiency. High blood sugar and cholesterol are also risk factors for heart disease. Studies suggest that taking zinc supplements may lower blood sugar and cholesterol levels in people with type 2 diabetes and gestational diabetes.

Fertility

Studies have found that a zinc supplement may improve sperm quality in men experiencing infertility. However, it is unclear whether supplemental zinc can improve sperm quality without other vitamins with antioxidant properties, such as vitamin C and vitamin E. More research is needed on this topic to make any recommendations.

Recommended Daily Intakes: How Much Zinc Do You Need? 

Zinc Requirements for Different Age Groups

The recommended daily amount of zinc for different age groups is as follows:

• Birth to 6 months: 2 milligrams (mg) of zinc every day

• 7-36 months: 3 mg of zinc every day

• 4-8 years: 5 mg of zinc every day

• 9-13 years: 8 mg of zinc every day

• Teens (aged 14-18 years)

  • Boys: 11 mg of zinc every day

  • Girls years: 9 mg of zinc every day

  • Pregnant: 12 mg of zinc every day

  • Lactating: 13 mg of zinc every day

• Adults (19+ years)

  • Men: 11 mg of zinc every day

  • Women (age 19+): 8 mg of zinc every day

  • Pregnant: 11 mg of zinc every day

  • Lactating: 12 mg of zinc every day

Food Sources of Zinc 

Foods rich in zinc include:

• Seafood, especially shellfish (crab, oysters, lobster)

  • Oysters are the richest source of zinc and contain 28-32 mg in 3 ounces

• Meats such as beef and pork

• Poultry

• Eggs

• Dairy products

• Legumes

• Whole grains

• Nuts and seeds

• Fortified foods such as breakfast cereals

Note: Zinc is not absorbed well from plant-based foods because plant-based foods also contain phytates, which prevent zinc absorption in the human gut.

Considerations When Taking Zinc Supplements

The Importance of Balancing Zinc Levels

Most people get enough zinc from dietary sources and do not need to take a zinc supplement in the form of pills or lozenges. 

If you are considering taking oral zinc supplements, talk to your healthcare provider first because too much zinc can be harmful. It can interfere with other essential minerals' absorption and lead to iron and copper deficiency. High doses of zinc can also cause side effects like nausea and vomiting. 

Your doctor may recommend taking a zinc supplement if your diet is low in zinc-rich foods (for example, if you are on a restricted diet, such as a vegan diet). They may also prescribe zinc supplements if laboratory testing confirms a zinc deficiency. 

Note: Zinc levels in the body are difficult to measure accurately. If you have symptoms of zinc deficiency, your doctor may recommend taking zinc supplementation to see if your symptoms improve.

Risk Factors for Zinc Deficiency

A zinc deficiency is rare in the United States, although it can occur in developing countries where malnourishment is rampant. However, a zinc deficiency may be present in people with certain conditions, such as: 

• Malabsorptive syndromes (poor absorption of zinc and other nutrients from the digestive tract)

• Other digestive disorders, such as inflammatory bowel disease (ulcerative colitis and Crohn’s disease)

• After gastrointestinal surgery

• Chronic liver disease or kidney disease 

• Sickle cell disease

• Burns and sepsis 

• Severe or prolonged diarrhea 

• Pregnancy

• Vegetarians and vegans

Signs and Symptoms of Zinc Deficiency

• Loss of taste and smell

• Loss of appetite

• Diarrhea

• Depression

• Falling sick frequently due to decreased immunity

• Slowed wound healing

• Hair loss

Potential Side Effects of Zinc Supplements

Taking zinc supplements in the form of lozenges can cause nausea and a metallic taste in the mouth. Using nasal sprays and throat sprays containing zinc can cause a loss of smell in some people.

Additionally, taking zinc supplements can interfere with your other medications and make them less effective. For example, zinc can decrease the absorption of tetracycline antibiotics.

Zinc Toxicity: Signs of Excessive Zinc Intake

Toxicity from excessive intake of zinc through food sources is very rare. It almost always occurs because of high doses of zinc supplements. Too much zinc in the body can cause signs and symptoms such as:

• Nausea

• Vomiting

• Abdominal discomfort or cramping

• Loss of appetite

• Diarrhea

• Headache

Common Myths About Zinc Supplementation

Does Zinc Really Prevent Colds?

Zinc cannot prevent colds or reduce symptoms in terms of severity. However, randomized controlled trials have found that supplemental zinc may reduce the duration of respiratory tract infections such as the common cold by 1-2 days. 

Zinc nasal sprays and throat sprays are generally not preferred because they can cause a loss of smell. However, zinc lozenges are a common over-the-counter supplement for the common cold. Lozenges slowly dissolve and coat the mouth and throat. If taken within a day of symptom onset, zinc may also reduce inflammation and shorten the illness's duration. 

Note: Some of the trials that have shown zinc is beneficial for the common cold were funded by pharmaceutical companies that make zinc lozenges.

Does Zinc Help in COVID-19?

There isn’t enough evidence to support the use of zinc supplementation in people with COVID-19. Experts do not recommend taking more than the recommended dietary allowance (11 mg of zinc daily for adult men and 8 mg of zinc daily for adult women) to prevent or treat COVID-19.

Frequently Asked Questions About Zinc

What Happens if I Take Zinc Every Day?

Taking zinc daily can lead to more zinc than your body needs, which can be harmful. It can cause side effects such as nausea, vomiting, upset stomach, loss of appetite, dizziness, and headache. Prolonged intake of too much zinc can lead to copper deficiency. 

Excessive use of zinc creams (more than recommended on the label) can cause neurological symptoms, including numbness, weakness, and poor coordination.

How Does Zinc Heal the Body?

Zinc heals the body because it is essential for functions such as cell repair, growth and development, and immune system function. 

Can You Overdose on Zinc Supplements? 

Yes, you can overdose on zinc supplements. The National Institutes of Health considers dietary intake of 40 mg of zinc per day from all sources (foods, beverages, supplements) to be the upper dose limit for adults. Infants under six months should not take more than 4 mg of zinc daily. 

Which is the best zinc supplement?

Zinc gluconate, zinc sulfate, zinc acetate, zinc oxide, zinc orotate, and zinc picolinate are different forms (salts) of zinc. They are used in oral zinc supplements (tablets, lozenges, syrups) and topical zinc products (creams and sprays). 

Because there are many different forms of zinc, researchers have designed trials to test the various properties of each one. One randomized controlled trial found that the absorption of elemental zinc from zinc citrate and zinc gluconate is comparable, but absorption from zinc oxide is considerably lower. However, the body absorbs zinc salts differently in different formulations. Therefore, you may see a zinc oxide diaper cream, zinc orotate lozenges, and a zinc gluconate nasal spray.