We have shared a wealth of information on vitamin D and other nutrients and their influence on immune system function and incidence of colds, flu and COVID-19. Here, we present that information in a summarized, easy-to-access format.

Vitamin D & COVID-19

Dr. Manson of Harvard Medical School and lead researcher: “Vitamin D may be more important now than ever”

“Vitamin D may be even more important now than ever,” says Dr. JoAnn Manson, MD, DrPH, of Harvard Medical School and Brigham and Women’s Hospital. Dr. Manson was the lead researcher and author of the VITAL trial and its resulting publications, which focused on the effects of supplemental vitamin D and omega-3s on specific health outcomes, mainly cancer and cardiovascular health. Now, with the current coronavirus epidemic, she is urging everyone to do what they can to avoid vitamin D deficiency, through sun exposure and supplements, due to emerging and growing evidence that vitamin D status may be related to the risk of developing COVID-19 disease and to its severity.


Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths

This paper is a review of the current research around the role of vitamin D in immune function, specifically in response to viral infections of the respiratory system. It outlines the relationship between vitamin D serum levels and the incidence of seasonal flu, as well as past epidemics such as those caused by the SARS and MERS coronaviruses. High risk conditions, the progression of illness, and mechanisms and proposed actions of vitamin D during the immune response are also reviewed.


COVID Outcomes among Patients Receiving Vitamin D, Magnesium, and B12

This study found that those receiving the DMB combination were significantly less likely to require subsequent oxygen therapy or intensive care support, meaning that simply taking vitamin D, magnesium and vitamin B12 supported immune and lung function. Only 3 out of the 17 patients (18%) in the DMB group required subsequent oxygen therapy, two of which required the therapy within 24 hours after their first supplement dose. For the patients who did not receive supplementation, 16 of the 26 (62%) required subsequent oxygen therapy. There was a significant protective effect against clinical deterioration with the need for oxygen therapy for DMB supplementation, after adjusting for age (P=0.039) or hypertension (P=0.044) separately.



Protective Role of Vitamin D against Coronavirus: Scientific Review and Dose for Immunity

This video by Dr. Renu Mahtani is clear, concise, and beautifully explains how vitamin D directly affects lung health, inflammation, and helps prevent viral attack.


Vitamin D and Immunity, Lots of Evidence

Vitamin D is essential to a healthy, fully functional, immune response. Simply put – if the body does not have enough vitamin D (as well as several other nutrients), immune function will be hindered.  This video, produced by Dr. John Campbell, explains this further and dives deeper into some of the evidence more specific to COVID-19 infection. Keep in mind that several papers referred to in the video suggest vitamin D doses that are too low for most people – a topic that is very clearly addressed in the recent post titled Current Recommendations are Too Low.


Positive Control Effects of Sunlight and Vitamin D on Influenza and Coronavirus

The results of this study showed an inverse relationship between simulated sunlight intensity and transmission of the influenza virus over long distances regardless of humidity. In darkness, the half-life (the time it takes for half of the virus to decay) was 31.6 minutes. In simulated sunlight, the half-life was reduced to approximately 2.4 minutes, with nearly 100% viral decay after only 8 minutes, suggesting that it would be unlikely for long-range outdoor transmission of influenza to occur during the daytime sun. Transmission would be more likely over short distances and at lower light intensities.

Dr. Reinhold Vieth Presents Evidence of the Biology of Evolution to Demonstrate How a Person’s Skin Color Impacts Vitamin D Levels and Health Outcomes

For what reason could skin color have such a large effect on our health, to the extent that the mortality rate of COVID-19 is so much greater among dark skinned populations? In the video below, Dr. Reinhold Vieth clearly explains the history of the human species, our ability as a species to adapt and evolve to new environments, and how lighter skin is an example of such an adaptation in order to maintain our ability to survive and produce offspring.

Vitamin D & Immune Function

Your Immune Cells Rely on Vitamin D


  • Vitamin D Activates the T-cells for Immune Response
  • How Does Your Immune System Work?
  • The Innate vs Adaptive Immune Response
  • The Role of T Cells in Destroying Viruses
  • Is your immune system strong enough to help you stay healthy?

Vitamin D: An Orchestrator of Immune Responses

Actions of vitamin D:

  • With immune and epithelial cells (such as those in the lungs and gastrointestinal tract)
  • With white blood cells and pathogen destruction
  • Immune modulating effects within the microbiota

Vitamin D and Immunity: Tying it All Together

More Complex Vitamin D Dependent Functions in the Adaptive Immune Response

  • Vitamin D is needed to activate T cells, turning naïve T cells into primed T cells that are better able to respond to a pathogen
  • Vitamin D influences T cell differentiation to induce lower levels of inflammatory cytokines and higher levels of anti-inflammatory cytokines
  • Vitamin D regulates the maturation of the dendritic cells, another type of white blood cells, to then modulate helper T cell (Th) function
  • T cells respond directly to active vitamin D by developing regulatory T cells

Vitamin D3 Itself Creates Profound Anti-Inflammatory Effects

These authors discovered that vitamin D3 itself needed and taken in by the cells, and it is also actively used by the cells as a “potent and general mediator of endothelial stability at physiologically relevant levels.” Of particular note in the results was that vitamin D3, which was previously thought to be inactive, had the most potent effect – more than 10 times more potent than 1,25(OH)2D and more than 1,000 times more potent than 25(OH)D.

The ‘Other’ Pandemic

The Ignored Pandemic: Vitamin D Deficiency, by Dr. Eric Berg, DC, is a great, simple video to watch and share with others who may not have much education or background on vitamin D. The video quickly discusses:

  • Overview of vitamin D’s importance
  • Vitamin D’s various roles in the immune system
  • Regulation of the inflammatory response (cytokine storm)
  • How different immune cells rely on vitamin D
  • Why are so many people deficient in vitamin D?? Reasons for deficiency
  • Sun, skin color and vitamin D

Immune Function & Co-Nutrients

A Healthy Immune Response Relies on Your Nutrient Status

“There is a close relationship between nutritional status and immune function. Hence, immunocompetence can be regarded as a measure of adequate nutrition.” This post reviews how the immune system relies on the following nutrients:

  • Vitamin C
  • Vitamin D
  • Zinc

Immune Response Affected by Nutrient Status and Other Factors

The following are additional factors to consider for maintaining healthy immune function:

  • Age
  • Environmental Temperature
  • Air Pollution
  • What’s the Bottom Line?
  • What’s the Main Action to Take?

Low Hemoglobin and Vitamin D Deficiency Could Contribute to Severity of Respiratory Infections

Iron deficiency anemia is another risk factor that may increase the severity of respiratory tract infection, especially in those that are vitamin D deficient, as found in a study by El Sakka et al. of 96 hospitalized infants and 96 healthy controls.  Iron deficiency anemia is the most common micronutrient deficiency worldwide and acute lower respiratory tract infection (ALRTI) is a major cause of illness and death in developing nations where incidence of anemia is high.

Flu, Colds & Other Respiratory Infections

Acute Respiratory Distress Syndrome (ARDS) Directly Influenced by Vitamin D

Acute Respiratory Distress Syndrome (ARDS, aka wet lung) is a condition resulting from severe respiratory injury or illness, such as pneumonia, in which the air sacs of the lungs fill with fluid, preventing the uptake of oxygen. The condition leads to shortness of breath and difficulty breathing, and in severe cases, can lead to sepsis and/or death. ARDS is currently a major complication and cause of death among those with serious COVID-19 infections.  When comparing vitamin D levels among those with and at risk of ARDS, it was found that 96% of those at risk of ARDS were deficient in vitamin D, and surgery patients with severe vitamin D deficiency had a 37.5% risk of lung injury post-surgery compared to a 15% risk for those whose vitamin D level was above 8 ng/ml (20 nmol/L), a 60% lower risk for those with higher vitamin D levels.

Fewer Respiratory Tract Infections in Infants with Daily Supplementation of Vitamin D

  • infants who received supplementation 5-7 days per week were 54% less likely to get an RTI than those who did not receive any supplementation with vitamin D; risk of RTIs went down as the frequency of vitamin D supplementation increased.
  • Risk of any RTI, lower RTI, or RTI related hospitalization was reduced for infants receiving vitamin D supplementation, regardless of whether they were breastfed or formula fed.
  • Among infants who were diagnosed with an RTI, those who received any vitamin D supplementation developed their first RTI later than those who did not receive any vitamin D supplementation.
  • Infants receiving vitamin D supplementation at least 5 days per week had the best outcomes.



Could More Solar UVB Exposure Decrease Flu Fatalities?

A general trend can be seen with lower rates of pneumonia as a complication of influenza and influenza fatalities for those locations at lower latitudes within the United States where vitamin D production from UVB is more. This is consistent with a number of other papers published showing a decrease in other conditions closer to the equator–from type 1 diabetes to breast cancer.

Cold and Flu Season is Approaching (Part 1)

  • Vitamin D Levels and Flu Activity by Season
  • Is there an association between vitamin D and the incidence of cold and flu?

Cold and Flu Season is Approaching (Part 2)

  • How could vitamin D help prevent the flu?
  • Dr. Carlos Camargo explains the connection (Video)
  • What does the research say about vitamin D and the flu?

Cold and Flu Season is Approaching (Part 3)

More examples of research supporting the role of vitamin D in the prevention and outcome of respiratory infections.

Cold and Flu Season is Approaching (Part 4)

What else, besides vitamin D, might help decrease the risk of getting a cold or flu, or the time and severity of symptoms if you do get sick?

  • Could Omega-3s Make a Difference for Colds and Flu?
  • What about Zinc?
  • Is the flu vaccine the best way to protect against the flu?

Could Your Immune System Benefit from Vitamin D?

Make sure you know your vitamin D level, and take steps to keep it within a target of 40-60 ng/ml or 100-150 nmol/L! 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!