Zinc is a mineral that plays numerous roles in cells throughout the body, especially the immune system.¹ For instance, individuals with lower blood levels of zinc tend to have poor immune function and increased susceptibility to infection.^2,3 Additionally, research suggests that supplementation with zinc can help raise zinc blood levels and attenuate common respiratory ailments.⁴ Before we discuss zinc’s specific immune benefits, let’s review its various roles in human health, the different sources of zinc, and some of the most common health factors known to increase the risk of zinc deficiency. 

What is zinc?

Zinc is an essential mineral, meaning that it must be consumed daily, as the body is unable to make its own supply. In addition to its immune and respiratory-supportive properties, zinc is involved in over 2,000 biological reactions affecting hormone levels, muscle and liver function, skin repair, and bone growth.^5,6 As the second most abundant mineral in the body after iron, zinc is vital for maintaining healthy cell structures, DNA and RNA synthesis, and regulating the proper growth of cells.⁵ Although zinc is naturally present in many foods, the amount of zinc in specific foods varies greatly. 

Examples of foods naturally high in zinc include:⁷

Although most people achieve the recommended daily intake of zinc (11 mg/day for men and 8 mg/day for women) through diet alone, some may require additional amounts. This can be achieved by either increasing your consumption of zinc-rich foods or taking a zinc supplement.

What are the different types of zinc supplements?

The main goal of taking a zinc supplement is to increase blood levels of zinc, which depends heavily on how well the body absorbs this mineral. To help promote zinc absorption, most zinc supplements are “chelated,” meaning that zinc is bound to an organic molecule, typically an amino acid.  

Common types of zinc supplements include:

• Zinc glycinate 
• Zinc gluconate
• Zinc picolinate
• Zinc citrate
• Zinc orotate
• Zinc acetate

Some research suggests that zinc bound to glycine or picolinate is better absorbed than certain other zinc forms.^8,9 For example, in a comparative study evaluating the effects of a single dose of zinc bisglycnate vs. zinc gluconate on blood zinc levels in healthy subjects, researchers found that supplementation with zinc bisglycinate resulted in 43% higher blood zinc levels than zinc gluconate.⁸

In another comparison study, participants were given single doses of zinc glycinate, zinc picolinate, zinc gluconate, and zinc oxide. After 4 hours, participants’ red blood cell levels indicated that the zinc chelated with glycine resulted in the highest zinc levels, followed by zinc picolinate, zinc oxide, and zinc gluconate.¹⁰

How efficiently the body is able to absorb different forms and types of zinc supplements is especially important for individuals at high risk of zinc deficiency. Not sure if you are one of them? Here is a list of some of the most common reasons and risk factors for zinc insufficiency.  

Health factors that may increase the need for zinc:

Vegetarian diets:

Vegetarians consume greater amounts of foods that contain high levels of phytates (plant compounds that inhibit zinc absorption) such as grains and legumes. As a result, vegetarians may require up to 50% more zinc than the daily recommended intake.¹¹

Advanced age:

Research suggests that zinc deficiency increases with age, such that about one in three individuals over the age of 50 is deficient in zinc.¹² It’s also estimated that 50% of people over the age of 65 fail to consume the daily recommended amounts of zinc.¹³ This, in addition to other health factors leave older adults particularly vulnerable to becoming zinc deficient. 

Other reasons for low zinc levels among older adults include: ^12,14

• Use of acid-lowering medications such as proton pump inhibitors 
• Decreased appetite due to lower activity levels
• Decreased intestinal absorption 
• Increased likelihood of having a medical condition that leads to lower zinc levels (e.g., blood pressure and blood sugar problems).

Pregnancy and lactation (breastfeeding):

Due to increased zinc demands during pregnancy and lactation, pregnant or nursing women are more likely to be deficient in zinc.¹⁵ Furthermore, because iron inhibits zinc absorption, women who take iron supplements during pregnancy may further exacerbate any underlying zinc deficiency.¹⁶

High blood sugar levels:

Increased urinary losses of zinc (i.e., peeing zinc out) can result from some of the kidney function changes that often occur in people with blood sugar problems.¹⁷

Gastrointestinal problems:

When the gastrointestinal system doesn’t function properly, this can affect the absorption of all nutrients, including zinc.¹⁸ Additionally, inadequate zinc intake can lead to compromised gut health, which may, in turn, exacerbate zinc deficiency further.¹⁷

Excessive alcohol intake: 

Due to its ill effects on gut and liver health, excess alcohol intake may lead to lower zinc levels.¹⁹

Chronic kidney problems:

Those who need dialysis (a procedure used to filter the blood in those with chronic kidney problems) tend to have low zinc status.²⁰

Problems with red blood cells:

Those with genetic abnormalities that affect the body’s red blood cells tend to have low zinc levels.²¹

Poor diet or disordered eating:

Those that consume a nutrient-poor diet, such as people with disordered eating habits, is a common reason for zinc deficiency.²²

Now that we’ve identified some of the most common health factors affecting zinc status, let’s discuss why zinc levels are important, and how they can affect the immune system.

Zinc’s effects on immune health  

Supports a healthy immune response

The body’s immune system eliminates unwanted bacteria and viruses by activating specialized white blood cells called macrophages. These cells are skilled at seeking out and destroying unwanted invaders, but they require assistance from other important immune cells known as Helper T cells. A specific type of Helper T cells named “Th1” produces a chemical that helps activate the body’s macrophages. 

In a study analyzing the effects of a zinc-deficient diet on Th1 immune responses, participants consumed a low-zinc diet for up to 24 weeks and then had their immune activity analyzed.²³ Results showed that the zinc-deficient diet led to decreased Th1 immune activity, and compromised immune function in all participants. This research suggests that adequate zinc levels are necessary for a healthy immune system. 

Provides immune support during infection 

During the course of an infection, zinc blood levels may decrease as zinc gets transported into the body’s tissues to help resist the spread of infection.²⁴ Importantly, rapid depletion of zinc can lead to “hyperactive” immune responses—resulting in the excessive production of certain cytokines—which may impair the recovery process.¹³ Evidence supporting this connection comes from the studies showing that older adults often have lower blood levels of zinc, elevated levels of certain cytokines, and poorer recovery from infection.²⁵

In a study analyzing the effects of zinc on immune health (i.e., the production of various cytokines, frequency of infection, and markers of unhealthy cell stress known as oxidative stress), a group of older adults was randomly assigned to receive zinc supplements or a placebo pill for six months.² After completion, those who supplemented with zinc had higher blood levels of zinc, fewer infections, lesser amounts of unhealthy cytokines, and lower oxidative stress levels than subjects receiving the placebo. These results show that having a sufficient zinc intake may help promote healthier immune responses and attenuate infection frequency.

Supports the production of T lymphocytes

T lymphocytes are important immune cells that help the body eliminate infected cells.²⁶ In a study evaluating zinc’s effects on the production of T-lymphocytes, immune-related skin reactions, and immune response to a tetanus vaccine, a group of older adults were randomly assigned to receive zinc supplements for one month, or placed in a control group without zinc.²⁷ At the trial end, T-lymphocytes increased significantly in the zinc group, whereas they remained the same in the control group. In the skin challenge test, favorable immune cell activity changes were reported in the zinc group, but not in the control group. 

In the immune test evaluating responses to a tetanus vaccine, scientists measured the ability of the participants to produce antibodies—a vital immune response that helps the body recognize and remove harmful bacteria and viruses. The test results showed that zinc users experienced a much greater antibody response than those not taking zinc.²⁷ Collectively, this study found that supplementing with zinc increased the activity and production of various immune cells. 

May shorten the duration of common respiratory ailments 

Because blood zinc levels rapidly decline during an infection, many believe that supplementing with zinc during this time is advantageous for the immune system.²⁴ Evidence to support this comes from a recent meta-analysis, which found that taking zinc within the first few days of a cold shortened the cold’s duration by 33% (roughly 2 to 3 days quicker than the placebo group).⁴

Conclusion

While most healthy adults achieve the recommended daily intake of zinc through diet alone, individuals such as older adults, vegetarians, pregnant and lactating women, and people with certain health problems may need higher amounts to maintain healthy zinc levels. Adequate zinc intake is necessary for a healthy immune system—especially during times of infection when blood zinc levels may be reduced. We recommend speaking to your health care provider about incorporating a zinc supplement into your healthcare regimen if you have concerns about your zinc status.