Zinc Deficiency Symptoms, Treatment, and Prevention

What is zinc deficiency? Who is susceptible to zinc deficiency? How common is it? Are there zinc deficiency symptoms or signs?

Over the last few years, more and more people are asking questions like these. Many have turned to zinc to support healthy immune function.* If you haven’t taken a zinc supplement yourself, then chances are you know someone who has. 

Let’s start with some basics. Zinc, a mineral found in the earth, is present in many foods and is an essential nutrient – meaning your body can’t make zinc, you must consume it. 

Zinc acts as an antioxidant in the human body and plays an important role in immune function.* Structurally, zinc is also an important component of the body’s connective tissues, and it aids in wound healing.* More than 50 different enzymes in the body use zinc as a cofactor in their chemical reactions. Zinc also plays a role in gene expression, influences hormones, and impacts the action of nerve cells.*

As you can see, zinc has important physiological action throughout the body.

What is a zinc deficiency?

Zinc deficiency – low zinc levels – occurs when there isn’t enough zinc available to meet the body’s demands. 

There are two main types of zinc deficiency – inherited and acquired. 

An inherited zinc deficiency is a genetic disorder that causes impaired absorption of zinc in the digestive tract. Individuals with an inherited zinc deficiency most likely need to take a zinc nutritional supplement during their life.

An acquired zinc deficiency is related to a lack of nutritional zinc intake, chronic illness, or both.  Nutritional causes can include eating a diet low in animal protein sources or high in phytates or oxalates – plant chemicals that limit how zinc is absorbed in the intestines. An increased demand for zinc occurs during pregnancy, lactation, and certain illnesses.

Chronic illnesses can affect the body’s ability to absorb zinc and other nutrients. Some medications can also limit absorption. 

Another way illness can cause a zinc deficiency is through excess loss of zinc. This can occur with severe burns, diarrhea, use of alcohol or diuretic medications, in certain blood disorders, and in individuals undergoing hemodialysis.

Is zinc deficiency common?

Severe zinc deficiency is rare is in the United States; however, it is estimated that 12 percent of the population is at risk of developing a mild zinc deficiency from low dietary intake or decreased absorption due to chronic illness. 

Most healthy adults are not at risk for zinc deficiency. Infants, children, teenagers, those who are pregnant or lactating, the elderly, and those who eat a vegetarian or vegan diet have an increased risk.

Zinc deficiency symptoms and signs

There are both symptoms of zinc deficiency and signs of zinc deficiency. Although the terms “symptoms” and “signs” are often used interchangeably, there are differences. 

A symptom is something you can feel or notice within yourself that you might not be able to measure (for example, nausea, fatigue). A sign is objective, meaning your doctor can observe it about you and can measure it in some way (for example, fever or blood pressure).

Zinc deficiency symptoms include fatigue, irritability, loss of appetite, a change in sense of taste or smell, sensitivity to light, diarrhea, and glossitis (tongue burning/pain). Common zinc deficiency symptoms in men are the same as in women, although men might also experience the low zinc symptom of erectile dysfunction.

Some of the signs of low zinc include hair loss, facial rash, impaired immune function resulting in increased infections or slow wound healing, and deformed, thickened, or discolored fingernails or toenails. Signs of zinc deficiency in females and males can also include decreased function of reproductive organs, including delayed puberty in children, altered menstrual cycles in women of childbearing age, and low sperm production in men.

Many of the zinc deficiency signs and symptoms are similar to those of other nutrient deficiencies. 

If you think you might have low zinc levels, or a zinc deficiency, then it is important to consult with your health-care practitioner who can determine which nutrient deficiency might be at the root of your signs and symptoms.

How to ensure proper zinc intake

The daily dietary zinc intake needed to prevent a zinc deficiency varies by age, sex, and life stage. The recommended zinc intakes for each life stage are as follows:

• Infants: 2-3 mg per day
• Toddlers: 3 mg per day
• Children: 5-8 mg per day
• Adolescents: 9-11 mg per day
• Adults: 8-11 mg per day
• Pregnant and lactating women: 11-13 mg per day

In addition, those who eat a vegetarian or vegan diet have a higher daily requirement for dietary zinc intake and should aim to consume about 50-percent more zinc from food than the recommended daily intake for their life stage. This is because the main plant sources of zinc are high in phytates, which reduce zinc absorption. 

It is possible to consume too much zinc, and a copper deficiency is the major risk of doing so. One study found that 60 mg of zinc (10 mg from diet and 50 mg from a zinc supplement) consumed daily for 10 weeks resulted in signs of a copper deficiency.¹ For this reason, the tolerable upper intake level for zinc in adults is 40 mg per day from all sources combined (food, supplements, and medications).

The best way to ensure proper zinc intake is to eat foods that are rich in zinc each day. Some individuals, particularly those with increased need or difficulty with absorption, might require a zinc supplement to meet their daily needs.

Food sources of zinc

The most bioavailable food sources of zinc are seafood, meat, poultry, and eggs. These foods have sulfur-containing amino acids that enhance zinc absorption while lacking the absorption-inhibiting phytates found in plant-based foods. 

A single serving of oysters contains up to 32 mg of zinc, above and beyond any other single food source. If you eat primarily plant-based foods, then keep in mind you might need to aim for 50-percent more of the zinc-based foods per day, compared to those who eat meat, to absorb sufficient zinc to prevent a deficiency.

Common food sources of zinc² include:

What to do if you suspect a zinc deficiency

Talk to your health-care practitioner if you think you might have a zinc deficiency. Unlike many other nutrient deficiencies, a zinc deficiency is a clinical diagnosis rather than a lab diagnosis. This is because blood zinc levels are not a reliable indication of zinc stores. Instead, your health-care practitioner will assess your low zinc symptoms and signs, deficiency risk factors, and overall nutritional state.

Zinc and copper: A final note

Zinc and copper have an interactive relationship in the body, and too much zinc intake could lead to a deficiency in copper. Before beginning a zinc supplement, it’s important to determine all sources of zinc in your diet and supplement regimen. Many nutritional supplements contain zinc, including multi-vitamin/mineral supplements, those that are marketed for supporting immune function, reproductive health products, and stress-reducing supplements. Many weight management, beauty, healthy aging, or blood-sugar support products might also contain zinc.

When all sources of zinc combined – both food and supplements – total 40 mg or less of total zinc intake daily (the tolerable upper intake for adults), then the risk of a copper deficiency is low. Another goal for zinc and copper intake is to aim for a ratio of 15 mg of zinc to 1 mg of copper (15:1), similar to the intake amount you would achieve by remaining within the RDA guidelines for daily intake of each nutrient.

Thorne offers two well-absorbed forms of zinc – Zinc Bisglycinate and Zinc Picolinate – each available in 15 mg and 30 mg capsules. In addition, Zinc Picolinate 30 mg capsules are available in an NSF Certified for Sport® option. 

If you supplement with higher doses of zinc, then consider adding Thorne’s Copper Bisglycinate.

References

1. Yadrick M, Kenney W, Winterfeldt E. Iron, copper, and zinc status: response to supplementation with zinc or zinc and iron in adult females. Am J Clin Nutr 1989;49(1):145-150.
2. Zinc Fact Sheet for Health Professionals. NIH.gov. https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/ [Accessed December, 5, 2023]