COVID-19: Is it linked to Zinc deficiency?

September 29, 2021

Many patients and their health care providers are constantly on the lookout for ways to reduce or prevent the common cold. Medical researchers discovered zinc supplementation through serendipity as a potential treatment for common cold symptoms. Researchers have now investigated if zinc deficiency may have a link to COVID-19.

Zinc’s effect on the common cold

It all began 40 years ago when a paediatrician was performing a clinical observation on a child undergoing chemotherapy. The patient also had frequent severe colds. The initial treatment was to stimulate immune response and treat zinc deficiency. However, the doctor later discovered that it helped with cold symptoms.

Two intrepid investigators from Austin (Texas) joined forces with the physician to ask to cough, sniffling people to participate in a clinical trial that tested the effects of oral zinc on the duration and severity of the common cold. Participants took dissolvable zinc tablets for 2 hours every day until their symptoms subsided. 7 days later, 86% of 37 subjects who were zinc-treated became symptomatic. This was compared to 46% in the placebo-treated group.

Numerous clinical trials have been performed since then with different results. These differences could be due to differences between the study population, duration of symptoms prior to supplementation, or the dosage and frequency of zinc intake. A meta-analysis of six clinical trials comparing zinc supplementation with placebo has been published. The average length of cold symptoms was 2.25 days.

Zinc and immune health

Basic science research has shown that zinc is crucial for both the maintenance and development critical components of our adaptive and innate immune systems. The innate immune system’s response to disease-causing agents or pathogens is fairly generic, but it is very fast. Our adaptive immune response to a pathogen is more targeted. This includes direct attacks by T cells or T lymphocytes and the production specific antibodies from B lymphocytes that target the pathogen.

It is no surprise that there has been a lot of interest in finding out if zinc can reduce the severity of COVID-19. There are currently a variety of clinical trials that evaluate the effects of zinc supplementation on COVID-19 prevention and treatment.

Preventing zinc deficiency

Zinc deficiency can cause bone marrow dysfunction, which decreases the number of immune precursor cells that become these beneficial B and T lymphocytes. Zinc deficiency can also increase pro-inflammatory cytokine levels. Inflammatory cytokines excessive production has been linked with tissue damage in acute illnesses. But, chronic diseases such as cancer and atherosclerosis can be caused by prolonged production of inflammatory chemicals.

Zinc, which is second in trace minerals in the human body after iron, is vital for many cellular processes. The human body does not have a zinc store, unlike iron. Zinc levels can be difficult to determine accurately. This is because of its distribution throughout many cellular components. It is important to examine your diet to determine if you are getting enough zinc. The table below shows the recommended daily allowances (RDAs), for zinc.

Oysters have more zinc per serving than other foods, but red meat and poultry are the main sources of zinc in American diets. You can also get zinc from these other foods:

  • Beans
  • Nuts
  • Seafoods such as lobster and crab
  • Whole grains
  • Fortified cereal

Zinc Deficiency For Elderly People

There is evidence that older adults may not get enough zinc. NHANES III data analysis revealed that between 35 and 45 percent of older adults were below the required zinc intake of 6.8 mg/day to elderly females and 9.4 mg/day to elderly men.

Some people may be more at risk for having low zinc levels, such as:

  • Women who are pregnant or lactating
  • People with gastrointestinal disorders like Crohn’s or ulcerative colitis
  • Vegetarians
  • People suffering from chronic liver or kidney disease
  • People with cancer, sickle cell disease, or diabetes
  • Alcoholics who drink too much
  • Certain diuretic medications applicable for some people who are taking them.

Supplemental zinc can be helpful in cases of inadequate dietary intake, or in certain stages of the disease.

Too much of a good thing

Consuming too much zinc can pose health risks. Zinc intake above 150 mg per day can cause nausea, vomiting and diarrhea. Moreover, High levels of zinc might cause copper deficiency. The zinc intake exceeding 150 mg daily. Low blood counts and irreversible damage can result from copper deficiency.

Zinc supplements can interact with different drugs, including antibiotics like quinolones and tetracyclines. Zinc supplements could also interact differently with penicillamine (a drug used in the treatment of rheumatoid arthritis). The use of zinc nasal sprays also has a linkage to permanent loss of smell.

Although it is not clear if zinc plays any significant role in COVID-19 prevention or treatment, we do know that zinc plays an important part in immune function. It is a good time to examine your diet and make sure you aren’t at risk of zinc deficiency. Cooper Complete(r), OptiZinc supplements contain 30 mg zinc in OptiZinc (r) form. This has been shown to be more absorbable. All Cooper Complete multivitamins contain 15 mg zinc.

Reminder: Your physician is the best person to understand your health. It’s important that you talk with your doctor about which supplements might be best for your needs.

Nina B. Radford MD, Cooper Clinic Cardiologist, and Director of Clinical Research, contributed this article.