Published on December 27, 2021

Education on basic health and nutritional strategies to help improve immunity are still lacking from the majority of public health measures taken to end the COVID-19 pandemic

Key Points

  • Key components to maintaining good health, including a robust immune system, have been missing from the mainstream and public health message about how to end the COVID-19 pandemic
  • Diet, exercise, and getting enough of certain nutrients, such as vitamins A, C, D, selenium and zinc are essential to immune health
  • Other immune-relevant nutrients include amino acids (such as glutathione and glutamine), antioxidants (such as vitamin E), phytochemicals (such as quercetin), omega-3 fatty acids, and iron

The news these days remains filled with talk about how to deal with “the next wave” or the “newest or next variant,” with repeat lock-downs in parts of the world, masking, reminders of maintaining hygiene, social distancing, vaccinations and other measures being implemented to help stop or slow the spread of COVID-19, again…

What is still missing, however, are ways we can boost the integrity of our immune systems, to help shield us from infection if we are exposed and additionally improve our immune response to minimize the risk of severe outcomes if we are infected.

More Should Follow in the Foot Steps of Florida Health!

One health authority that has begun to educate about ways to boost immune health and help prevent COVID-19 is Florida Health, which has included getting outside, staying active, eating healthy, and getting plenty of zinc, vitamins D and C, and quercetin as part of their state-wide COVID-19 prevention strategy.

Diet, lifestyle (e.g. sleep and exercise patterns), intrinsic factors (e.g. genetics) and environmental factors (e.g. toxins) all play a central role in maintaining individual health. Unhealthy eating patterns with lack of physical activity, over time, can have a cumulative effect on health and chronic disease with numerous harmful effects, including nutrient deficiencies, excess weight and obesity, heart disease and stroke, type 2 diabetes, cancer, deficits in brain function and many other chronic diseases – as well as a sub-par immune response.

Nutrient Deficiencies Compromise Immune Function and Increase Infection Risk

Getting enough of certain nutrients is especially important, as both the innate and adaptive immune responses rely on these nutrients in order to function properly – of note, vitamins D, A, C and minerals such as selenium and zinc. Unfortunately, there is an alarmingly high rate of insufficiency of these nutrients in the American population.

Examples of how several of these nutrients are important to immune function are included in the infographic below.

Click to Enlarge & Print

Many studies have linked nutrient deficiencies to an increased susceptibility to disease and worse disease outcomes, specifically those related to COVID-19. A new review by Uwe Grober and Michael Holick discusses several of these immune-relevant nutrients that “may help to increase the physiological resilience against COVID-19.” In other words, these nutrients play key roles in the body’s response to viral respiratory tract infections, including COVID-19, and may help protect against severe disease symptoms and outcomes.

Vitamin D

Much has been discussed about vitamin D and how it is involved in the immune response, along with evidence connecting higher vitamin D levels and intake with lower risk of COVID-19 infection, severe symptoms, and death. A summary of posts on vitamin D and COVID-19 can be found here.

Specific anti-SARS-CoV-2 properties of vitamin D include:

  • Supports the innate and acquired immune system
  • Increases the synthesis of antimicrobial and antiviral peptides (AMPs) that help lower the infectivity of respiratory viruses
  • Down regulates ACE-2 that SARS-CoV-2 binds to during the infection phase
  • Regulates the balance of T-cells
  • Increases lymphocytes, which are essential to the adaptive immune response
  • Has anti-inflammatory effects and helps prevent the cytokine storm
  • Increases the expression of antioxidant defenses
  • Increases the biodiversity of the gut microbiome, which has been shown to have protective effects against inflammation and respiratory tract infections
  • Produces vaso-protective effects (improves blood vessel integrity and function)

A panel of vitamin D researchers and scientists recommend a vitamin D level of 40-60 ng/ml (100-150 nmol/L) and over 200 doctors and scientists have openly advocated for vitamin D levels of 40-60 ng/ml to help fight COVID-19. Supplementation to reach these levels can vary greatly between individuals due to several factors, therefore testing is essential in order to calculate the appropriate supplement amount.

Vitamin A (Retinol)

Vitamin A is such an important nutrient to immune function that it has earned the name “the anti-infective vitamin.” Like vitamin D, vitamin A is a fat soluble vitamin that is converted within the body into a hormone-like molecule called retinoic acid (RA). Both work closely to influence immune cell function, especially within the adaptive immune response.

Specific anti-SARS-CoV-2 properties of vitamin A include:

  • Supports the innate and acquired immune system
  • Regulates T-cells
  • Increases lymphocytopoiesis, or the generation of new lymphocytes (T cells and B cells), that are essential to adaptive immunity
  • Has anti-oxidant and anti-inflammatory effects
  • Regulates surfactant protein gene expression, which may then reduce the impact of SARS-CoV-2 infection on the ability to breathe
  • Plays a crucial role in the formation of epithelial cells and improves the integrity of epithelial tissues (those of the respiratory, gastrointestinal and urogenital tracts)

An estimated 75% of adults in the United States do not meet the recommended intakes for vitamin A. The authors suggest 2,000 to 4,000 IU of vitamin A (as retinol) per day for all elderly, adults and adolescents in order to help prevent viral respiratory tract infections.

Vitamin C

Vitamin C is a popular immune-boosting nutrient that has been used for decades to help fight infections such as the flu and the common cold. One of the major roles of vitamin C is as an antioxidant, protecting cells of the immune system from damage due to oxidative stress that results from the response to infection.

Specific anti-SARS-CoV-2 properties of vitamin C include:

  • Supports the innate and acquired immune system
  • Has antiviral, antibacterial, antimicrobial and immunomodulatory properties
  • Decreases damage due to reactive oxygen species (ROS), necessary products of the immune response that fight infection, within the endothelium and alveolar membranes
  • Decreases the cytokine storm
  • Improves treatment to Acute Respiratory Distress Syndrome (ARDS)
  • Decreases the risk of multi-organ dysfunction
  • Increases immune cells such as lymphocytes, T-, B- and natural killer cells
  • Has anti-oxidant and anti-inflammatory effects
  • Enhances the integrity of epithelial tissues, especially within the alveolar system

For prevention, the authors suggest 1,000 to 3,000 mg of vitamin C per day, in divided doses, along with a quercetin supplement.


The element selenium has antioxidant, anti-inflammatory, immunomodulatory, anti-carcinogenic and antiviral properties. Selenium deficiency has been linked to increased risk of cancer, cardiovascular, thyroid, neurodegenerative and infectious diseases, as well as inflammation and immunodeficiency.

Specific anti-SARS-CoV-2 properties of selenium include:

  • Increasing GSH-peroxidases to decrease damage due to oxidative stress due to reactive oxygen species (ROS) that are necessary products of the immune response
  • Increases the synthesis of anti-viral proteins
  • Decreases inflammation
  • Supports the innate and acquired immune system
  • Regulates T-cell function
  • Increases the proliferation of T-lymphocytes
  • Has pronounced vaso-protective effects (improves blood vessel integrity and function)

The authors suggest 100-200 ug of selenium per day for elderly, adult, and adolescent individuals to help prevent viral respiratory tract infections, with a suggested serum level of 130-150 ug/L.


Zinc is a nutrient known to benefit the immune system, and deficiency of zinc impairs the capacity of many different immune cells to carry out their functions. Zinc has been shown to significantly reduce the duration and severity of the common cold, and to help prevent viral respiratory tract infections. Deficiency of zinc is common in the elderly, and subclinical zinc deficiency may be responsible for higher rates of infections and degenerative pathologies that are related to age.

Specific anti-SARS-CoV-2 properties of zinc include:

  • Supports the innate and acquired immune system
  • Regulates T-cell function and increases T-cell counts
  • Inhibits ACE-2 expression which SARS-CoV-2 binds to during the infection phase
  • Inhibits RNA-dependent RNA polymerase of viruses such as SARS-CoV-2; this impairs the ability of the virus to replicate and helps to reduce the risk, duration, and severity of infection
  • Has anti-inflammatory effects and decreases the risk of cytokine storm
  • Increases antioxidant defenses
  • Enhances mucosal barrier function (such as in the airway epithelium)
  • Has pronounced vaso-protective effects (improves blood vessel integrity and function)

The authors suggest 10-20 mg of zinc per day to help reduce the risk of viral respiratory tract infections.

Other Key Nutrients worth Noting

Nutrients work synergistically with each other, and the authors of this paper felt that several other immune-relevant nutrients deserved mention. These include amino acids (such as glutathione and glutamine), antioxidants (such as vitamin E), phytochemicals (such as quercetin), omega-3 fatty acids, and iron.

Are You Getting Enough Vitamin D & Other Immune Boosting Nutrients?

Having and maintaining healthy vitamin D levels and other nutrient levels can help improve your health now and for your future. Choose which to measure, such as your vitamin D, omega-3s, and essential minerals including magnesium and zinc, by creating your custom home test kit today. Take steps to improve the status of each of these measurements to benefit your overall health. You can also track your own intakes, symptoms and results to see what works best for YOU.

Enroll and test your levels today, learn what steps to take to improve your status of vitamin D (see below) and other nutrients and blood markers, and take action! By enrolling in the GrassrootsHealth projects, you are not only contributing valuable information to everyone, you are also gaining knowledge about how you could improve your own health through measuring and tracking your nutrient status, and educating yourself on how to improve it.

What Does it Take YOU to Get Your D to 40 ng/ml (100 nmol/L)?

Did you know your health could be greatly affected by making sure you have a vitamin D level of at least 40 ng/ml (100 nmol/L)? Help us help you.

STEP 1 - Do you know what your vitamin D level is? If not, be sure to test today to find out.

STEP 2 – Determine your target level. Are you at your target level? Experts recommend a level of at least 40-60 ng/ml (100-150 nmol/L).

STEP 3 – Need to boost your level? Use the D*calculator to see how much vitamin D it may take to reach your target. Opt for the Loading Dose for a quicker boost.

STEP 4 – Optimize how your body absorbs and utilizes vitamin D with co-nutrients and these simple steps.

STEP 5 – Re-Test! This is an important step to make sure you have reached your target level, and to ensure you are not taking too much! Re-testing after 3-4 months is recommended.

STEP 6 – Adjust, Repeat…

Give your immune system the nutrients it needs to support a healthy you and protect yourself from unnecessary diseases, especially COVID-19.


The first Randomized Controlled Trial on vitamin D and COVID-19 has shown a 96% lower risk of ICU admission for those receiving vitamin D (as 25(OH)D to quickly boost vitamin D blood levels) along with the standard treatment, compared to those receiving standard treatment alone.

These results support many previous observational studies showing a relationship between vitamin D levels and intake and COVID-19 severity.

Review the Latest Nutrient Research for COVID-19

GrassrootsHealth Nutrient Research Institute has launched the new Immune Boost project with the use of our myData-myAnswers nutrient health system that nearly 15,000 people are already using for their health. Specific markers that influence immune health are suggested for testing as part of this project including:

  • Vitamin D
  • Omega-3 Index
  • Essential elements magnesium, selenium, and zinc
  • hsCRP

Our goal is to demonstrate how one can use the Nutrient Research Model established by Dr. Robert Heaney to show the effect of vitamin D serum levels of at least 40 ng/ml (100 nmol/L) on risk reduction for all ethnicities in the population. Status and intake of other nutrients will also be analyzed for any type of relationship to immune status and symptom severity. Join the project today!

Please let us know if you're interested in helping sponsor this project.

CLICK HERE for updates and new information about the project.

Through GrassrootsHealth Nutrient Research Institute, you can also test your essential elements magnesium, copper, zinc and selenium, toxins such as lead, mercury and cadmium, as well as your omega-3 levels, inflammation levels and thyroid stimulating hormone (TSH) level. Find out your levels today! Log on to the test selection page (click the link below) to get your tests and see for yourself if your levels can be improved.

Make sure you track your results before and after, about every 6 months!

Click Here to Access the Test Page

How can I track my nutrient intake and levels over time?

To help you track your supplement use and nutrient levels, GrassrootsHealth has created the Personal Health Nutrient Decision System called

For each specific supplement, you can track what days you take it, how much, and many other details.  This will help you know your true supplemental intake and what patterns of use work for you to reach and maintain optimum nutrient levels. Check it out today!