We know that zinc supports immune defense, but can it also help with the COVID-19 outbreak? Early studies suggest that zinc may block the ability of viruses to multiply, potentially rendering them dormant. But just how much do we know about its effects on the new coronavirus in humans?
A Potential Role of Zinc in the COVID-19 Pandemic
The COVID-19 outbreak has turned our world upside down. Among many preventive measures, people are turning to zinc for additional immune support. Zinc lozenges seem to be especially popular and stocks in pharmacies and health stores are running low.
So what should you do? Stock up on zinc supplements or not?
Zinc for Prevention and Supportive Care
Evidence Overview
For starters, there’s no evidence that zinc can directly prevent or treat the new coronavirus.
The 2019 coronavirus is extremely recent, and we are still lacking robust studies specifically related to it. No effective or FDA-approved products are yet available to treat or prevent it.
That shouldn’t take away the importance of general supportive and preventive measures, though.
Zinc is considered a general supportive treatment for measles and SARS‐CoV. But there’s no evidence that it can do the same for patients infected with the new coronavirus [1].
To avoid confusion, the Severe Acute Respiratory Syndrome coronavirus (SARS‐CoV) was first identified in 2003. What we are dealing with right now is a pandemic of a very similar, but distinct virus that scientists have named SARS-CoV-2 or 2019-nCoV [1].
The best preventive measures you can take against 2019-nCoV are those of standard care: social distancing, hand washing, and avoiding touching your face.
Why Your Immune System Needs Zinc
Zinc is a dietary trace mineral that helps immune cells develop and stay healthy. It’s important for preventing an array of infections and problems that can arise from poor immune function [1].
People typically take zinc supplements because they want to maintain strong immune defense but are not getting enough of this mineral from their diet.
Yet, most people are not at risk of zinc deficiency. If you eat a fairly balanced diet and have no serious gut issues, you probably don’t need supplements.
Groups vulnerable to zinc deficiency include those with sickle cell anemia, Crohn’s disease, ulcerative colitis, liver disease, and other chronic diseases that reduce zinc absorption in the gut [2].
Zinc deficiency results in a widespread loss of immunity. People with weakened immune systems are at an increased risk of infectious diseases, and coronavirus is no exception [1].
For Immunity & Infections
Zinc is essential for the normal development and function of many immune cells [3].
Because of the critical role it plays in the immune system, even a mild deficiency can impair immune function and increase the risk of bacterial, viral, and parasitic infection [4].
In clinical states associated with immunodeficiency (e.g., sickle cell disease, human immunodeficiency virus (HIV) infection) and in the elderly, zinc supplementation can restore natural killer cell activity, lymphocyte production, and resistance to infections [5, 6, 7, 8].
Studies in HIV patients with low blood zinc levels reveal that chronic supplementation is associated with lower opportunistic infections and a reduced risk of immunological failure [9, 10]. However, supplementation must be exercised with caution as excessive zinc may worsen disease symptoms [11, 12].
In malnourished infants and children in developing countries, zinc administration reduced the duration, severity, and incidence of diarrhea, respiratory infections, and malaria [13, 14, 15, 16, 17].
Similar beneficial effects were reported for other infectious diseases in humans including shigellosis, leprosy, tuberculosis, leishmaniasis, hepatitis C, and the common cold [18, 19, 20].
On the other hand, excessive levels may suppress immunity. A study in healthy young men revealed that high doses of zinc reduced several immune functions, including activation of lymphocytes and phagocytosis of neutrophils [21].
Speeds Up Recovery from the Common Cold
Owing to its immune-boosting properties, zinc is among the most popular supplements for a common cold.
However, the research is less convincing when it comes to using zinc for common cold prevention [22, 23].
Taken within the first 24 hours of experiencing symptoms, zinc (at least 75 mg/day) can speed up recovery and reduce symptoms of the common cold. It probably doesn’t help prevent the common cold, though, according to a large scientific review [24].
Indeed, most clinical trials and reviews show a significant decrease in the duration of symptoms in adults. Zinc gluconate or zinc acetate supplements with 9-24 mg of elemental zinc per dose have shown the best results, when initiated within the first 24 hours [25, 26, 27].
Remember that colds can be caused by many different viruses, including other types of coronaviruses. These are not the same as the 2019 coronavirus [28].
Zinc Inhibits RNA Viruses in Cells
The new coronavirus belongs to a big family of RNA viruses. In lab experiments, increasing zinc levels in the cells of RNA viruses stopped the viruses from multiplying [1, 29].
Viruses need some zinc to survive, but they maintain relatively low internal zinc levels. In fact, high zinc levels are a big red alarm for viruses — one that can lead them to commit suicide (apoptosis) [30].
According to other cell-based studies, ionic zinc may also block two vital proteins that SARS-CoV requires to multiply (papain-like protease-2 and 3CL protease). While it’s theoretically possible that zinc may target the same proteins in SARS-CoV-2, this has yet to be tested [31, 32].
In mice infected with the coronavirus mouse hepatitis virus (MHV), high doses of zinc also somewhat hindered the virus from producing important proteins. However, this virus is different from the 2019 coronavirus [30].
Effects on Respiratory Symptoms from Measles
Measles is a highly contagious viral infection with fever, respiratory problems, a rash, and various complications. The new coronavirus is not as contagious but it can cause a fever and similar respiratory complications in some patients [33, 34].
Zinc is sometimes used as a supportive treatment for measles. According to the research, zinc supplements reduce measles‐related health problems and deaths caused by lower respiratory tract infections in zinc-deficient children [1].
We have yet to see whether zinc can reduce respiratory complications in zinc-deficient people with COVID-2019.
Viruses, in general, work by invading the body’s own cells and using the components inside to help replicate and spread.
The SARS-CoV-2 virus, in particular, appears to enter human cells by attaching to the ACE2 receptor, which serves as an entry point for the virus [35].
Evidence is currently lacking to claim that zinc can block the ACE2 receptor. Cell studies suggest that it may have a weak blocking effect, but this hasn’t been confirmed in animals or humans [36].
Normally, the ACE2 receptor plays an important role in balancing the body’s fluids and blood pressure [37].
ACE2 receptors can be found in the body’s airways, making them a target for several types of viruses. Recent research suggests that SARS-CoV-2 mainly causes serious respiratory complications by infecting the lungs via ACE2 [37, 38].
Other authors have suggested that the way the new coronavirus multiplies when it first infects patients may be similar to the flu (influenza, not to be confused with the common cold). But both symptomatic and symptom-free patients who did throat swabs tested positive for coronavirus [39].
Therefore, the new coronavirus likely has to pass through the mouth and throat to get to the lungs–but it likely doesn’t cause major harm as it passes through these initial barriers. Research is revealing new aspects of SARS-CoV-2 by the hour, so new data may paint a different picture.
Since zinc likely doesn’t block ACE2, it may have a more important role in prevention. By supporting immune health, zinc may help reduce one of the biggest risk factors for severe COVID-19: waning innate immunity in the elderly. This is still just an unproven hypothesis, though [40].
What About Zinc Lozenges?
The fact that the new coronavirus needs to get deep into the lungs to cause serious harm also means that zinc lozenges are probably not the best choice.
Zinc lozenges will get high amounts of zinc to the mouth and throat mucus. They are a good option when you catch a cold because it tends to stay in the upper respiratory tract. In this scenario, zinc speeds up recovery [41].
Viruses that cause the common cold will usually use the cells that line your mouth and throat to get in to the mucous layer, causing symptoms like throat pain and difficulty swallowing. Different mechanisms are implicated in COVID-19 [41].
Therefore, maintaining normal zinc levels through diet may to be more effective than zinc lozenges, based on the extremely limited data we have for SARS-CoV-2 prevention. That means getting zinc from food (like oysters and beef) or taking supplements by mouth if you can’t meet your daily zinc needs through diet alone.
Effects on Allergy and Asthma
Allergy and asthma can be liable to create some complications for COVID-19 sufferers as a result of its effects on the respiratory system.
A study showed that zinc supplementation improved symptoms (e.g., cough, wheezing, and shortness of breath) in 284 children with asthma [42].
Low blood zinc levels may be linked to more severe asthma symptoms in some children [43].
Zinc was also able to reduce airway inflammation and over-sensitivity in mouse models of allergic inflammation and asthma [44, 45, 46].
In response to grass pollen, zinc increased regulatory T-cells and decreased proliferation in peripheral blood mononuclear cells (PBMCs) isolated from allergic subjects [47].
More research is needed before proclaiming zinc a safe and effective supplement for asthma and allergies.
Dosage
15-30mg is a good dosage for zinc in the form of picolinate to support the immune system. See this page for buy links.
Takeaway
There is no evidence to claim that zinc can prevent or treat the new coronavirus. Zinc is important for immune health, but most people can get enough of this mineral from a balanced diet.
People who are at risk of deficiency, including those with gut disorders or other chronic health problems, might need to supplement to maintain adequate zinc levels in the body.
Based on what we know, the best way to help prevent the new coronavirus from spreading any further is to follow standard precautions, including social distancing and careful handwashing.
