As health officials continue to expect a second wave of COVID-19 this fall, spreading information about how to prevent it is becoming crucial. One of the most important strategies in this regard is to optimize your vitamin D level.

Vitamin D not only helps regulate immune function and prevent respiratory illnesses in general, but mounting data analyses show clear parallels between vitamin D levels and the risk of infection, severity and mortality from COVID-19 as well.

While U.S. authorities are still trying to debunk (and even instill fear) of vitamin D supplementation, British and Scottish authorities appear to be embracing a more sensible approach.

The British Frontline Immune Support Team, founded “to make available some of the best quality immune supportive products … to help keep those on the NHS (UK National Health Service) frontline resilient and strong,” is already providing health care workers with free nutritional supplements known to bolster and regulate immune function.

This includes liposomal vitamin C, vitamin D and zinc. As noted on, the group’s fundraiser page:1

“Immune supportive packs are sent directly to each individual NHS healthcare worker who signs up for this initiative — and they receive all products for FREE. We currently have hundreds of NHS staff already signed up ready to go; and with your contributions we can supply and reach thousands more.”

The Frontline Immune Support Team point out that vitamin D:2

“… plays a critical role in your immune defense system, both in reducing flu-like days of illness if your blood level is sufficient, and in helping your immune system respond when under viral attack. It speeds up recovery from pneumonia.

Two in five adults have a level of vitamin D below 25nmol/l, especially in late winter months such as February and March, that is likely to almost double their risk of flu. A vitamin D level above 100 nmol/l correlates with the lowest numbers of flu-like days. The moral of the story is to get your level up as quickly as possible.”

Public Health Scotland and the British NHS are also assessing the evidence to determine whether vitamin D should be prescribed to in-hospital patients and as a prevention to high-risk groups.3

Vitamin D Level Correlates With Risk of Respiratory Infection

Clinical trials using vitamin D against COVID-19 are currently underway,4 but we don’t need to wait for results to know that vitamin D optimization is a good idea. SARS-CoV-2 is an enveloped virus, which means it’s more difficult for your immune system to identify and destroy it.

However, as noted by The Frontline Support Team, we already know higher vitamin D levels are inversely associated with infection by many other enveloped viruses, including dengue, hepatitis, herpes, HIV, rotavirus, respiratory syncytial virus and influenza.5,6

Vitamin D also strengthens cellular junctions, thereby making it more difficult for viruses to gain entry through your eyes, ears, lungs and mucus membranes. This in turn makes the infection less likely to migrate down into your lungs.7 Importantly, vitamin D also strengthens the adaptive arm of your immune system, and its ability to produce antibodies.8 According to a June 17, 2020, report by The Guardian:9

“Public health officials are urgently reviewing the potential ability of vitamin D to reduce the risk of coronavirus. It comes amid growing concern over the disproportionate number of black, Asian and minority ethnic people contracting and dying from the disease, including a reported10 94% of all doctors killed by the virus …

The Scientific Advisory Committee on Nutrition (SACN) began this work last month and is considering recent evidence on vitamin D and acute respiratory tract infection in the general population. Evidence will be considered on specific population groups, including those of different ages and BAME [black, Asian, minority ethnic] groups.

In a parallel development, the National Institute for Health and Care Excellence (Nice) is conducting a ‘rapid’ evidence review on vitamin D ‘in the context of Covid-19’ with support from Public Health England (PHE).”

Vitamin D — ‘Designer Drug’ Against Viral Infections

Adrian Martineau, a professor of respiratory infection and immunity at Queen Mary University of London, is currently leading the “Covidence UK Study,”11 an effort to collect data about how vitamin D deficiency impacts your COVID-19 risk. If you live in the UK, you can sign up for the Covidence UK study here.

Martineau tells The Guardian that COVID-19 deaths among black, Asian and minority ethnic (BAME) staff within the NHS raises important questions about vitamin D status.12

“Vitamin D could almost be thought of as a designer drug for helping the body to handle viral respiratory infections. It boosts the ability of cells to kill and resist viruses and simultaneously dampens down harmful inflammation, which is one of the big problems with Covid,” he told the paper.

Why People of Color Are at Increased Risk

There’s a simple reason why BAME groups are more susceptible to COVID-19. Darker skin requires far more sun exposure to produce adequate vitamin D, so much so that dark-skinned individuals living north of the equator are virtually guaranteed to be chronically deficient.

According to data collected by the National Health and Nutrition Examination Survey (NHANES) between 2005 and 2006, and published in 2018, 82.1% of black American adults and 62.9% of Hispanic adults are deficient in vitamin D.13 As noted in that paper, lower melanin levels are protective of vitamin D deficiency, and the darker your skin, the more likely you are of having a low vitamin D level.

The good news is that this predisposition is easily and inexpensively remedied. The Frontline Support Team has made good strides toward protecting health care workers, so far supplying about 750 NHS frontline staff with free supplement packs. But the general public also needs it, too. At bare minimum, the public needs the information.

Scotland Issues Guidance on Vitamin D

In Scotland, government COVID-19 guidance now includes taking a daily vitamin D supplement. As reported by the Scotland Herald:14

Official Scottish Government guidance issued on June 3 states that everyone, including children, ‘should consider taking a daily supplement containing 10 micrograms of vitamin D.’

However, it is ‘specifically recommended’ to all pregnant and breastfeeding women; infants and children under five years old; people from minority ethnic groups with dark skin such as those of African, African-Caribbean and South Asian origin, who require more sun exposure to make as much vitamin D; and people who are confined indoors.”

US Ignores Vitamin D Impact

In stark contrast, U.S. health agencies appear to have little interest in helping the public support their immune system through appropriate nutrition, but would rather have you rely on drugs and vaccines.

The U.S. National Institutes of Health recommends15 getting your vitamin D from food and beverages only, despite the fact that dietary intake of vitamin D is insufficient to reach and maintain the level required to prevent viral illnesses and other chronic diseases.

That said, some health experts are speaking out. Among them is former CDC director Dr. Tom Frieden, who wrote an opinion piece for Fox News in which he suggests vitamin D may reduce COVID-19 mortality rates, especially in those who are deficient.16

He goes on to say supplementation has reduced the “risk of respiratory infections, regulates cytokine production and can limit the risk of other viruses such as influenza.” Much of the damage from COVID-19 occurs with a “cytokine storm,” during which the body’s inflammatory system goes into high gear, damaging organs and increasing mortality rates. He writes:17

“We can do lots of things to improve our resistance to infection. These include getting regular physical activity, getting enough sleep, stopping smoking and other tobacco use, and, for people living with diabetes, getting it under control.

Taking a multivitamin that includes Vitamin D, or a Vitamin D supplement, probably can’t hurt, and it might help. As we continue to work to mitigate the impact of COVID-19, anything we can do to strengthen our resistance is a step in the right direction.”

Similarly, Dr. John C. Umhau, a public health specialist at the NIH, has argued that vitamin D is one of the “most studied and most important host factor impacting survival from COVID-19.”18 He also points out that “A government-sponsored research strategy to address this issue has not been developed, as officials explained that there was no mandate to explore an alternative to the existing vaccination program.”

Considering the hazards inherent in fast-tracking a COVID-19 vaccine, and seeing how previous attempts at creating a safe and effective coronavirus vaccine have all failed, putting all of the public health eggs in the vaccine basket is questionable in the extreme.

What Science Says About Vitamin D

By now, there’s a very long list of scientific evidences pointing toward vitamin D optimization as being a crucial component for preventing another spike in COVID-19 deaths.

In the video above, Ivor Cummins, chief program officer for Irish Heart Disease Awareness, explains how higher levels of vitamin D may reduce your risk of negative outcomes from COVID-19. Studies supporting this view include but are not limited to the following:

A scientific review19 in the journal Nutrients concluded vitamin D can reduce the risk of infection by lowering the rate at which the virus replicates and reduce the pro-inflammatory cytokines that damage the lungs, leading to pneumonia. Vitamin D also helps increase concentrations of anti-inflammatory cytokines that may help protect the lungs. The researchers recommended those at risk take:

“… 10,000 IU/d of vitamin D3 for a few weeks to rapidly raise 25(OH)D concentrations, followed by 5000 IU/d. The goal should be to raise 25(OH)D concentrations above 40–60 ng/mL (100–150 nmol/L).”

Vitamin D is an important component in the prevention and treatment of influenza20 and upper respiratory tract infections21 — While vitamin D does not appear to have a direct effect on the virus itself, it strengthens immune function, thus allowing the host body to combat the virus more effectively.22

As detailed in “Vitamin D Prevents Infections,” research shows high-dose vitamin D supplementation lowers the risk of respiratory illnesses and lung infections in the elderly by 40%. As noted by an author of that study, “Vitamin D can improve the immune system’s ability to fight infections because it bolsters the first line of defense of the immune system.”

Importantly, vitamin D also suppresses inflammatory processes. Taken together, this might make vitamin D quite useful against COVID-19, because while robust immune function is required for your body to combat the virus, an overactivated immune system is also responsible for the cytokine storm we see in COVID-19 infection that can lead to death. As noted by pulmonologist Dr. Roger Seheult in the video below:

“What we want is a smart immune system — an immune system that takes care of the virus but doesn’t put us into an inflammatory condition that could put us on a ventilator.”

Research23 published in 2009 suggests fatality rates during the 1918-1919 influenza pandemic were influenced by season, with greater numbers of people dying during the winter (when vitamin D levels are at their lowest) than the summer. According to the authors:24

“Substantial correlations were found for associations of July UVB dose with case fatality rates and rates of pneumonia as a complication of influenza. Similar results were found for wintertime UVB.

Vitamin D upregulates production of human cathelicidin, LL-37, which has both antimicrobial and antiendotoxin activities. Vitamin D also reduces the production of proinflammatory cytokines, which could also explain some of the benefit of vitamin D since H1N1 infection gives rise to a cytokine storm.”

Research25 published in 2017 — a meta-analysis of 25 randomized controlled trials — confirmed that vitamin D supplementation helps protect against acute respiratory infections.

Importantly, this analysis also discovered daily or weekly supplementation of vitamin D had the greatest protective effect in those with the lowest vitamin D levels.26 In other words, large, infrequent bolus doses do not work well.

Those with severe vitamin D deficiency who took a daily or weekly supplement cut their respiratory infection risk in half, whereas the acute administration of high bolus doses of vitamin D had no significant impact on infection risk.

Data analysis27 by GrassrootsHealth shows people with a vitamin D level of at least 40 ng/mL reduced their risk of colds by 15% and flu by 41%, compared to those with a level below 20 ng/mL.

Findings from The Irish Longitudinal Study on Ageing (TILDA)28,29 suggest vitamin D deficiency could have serious implications for COVID-19. The researchers recommend adults over 50 take a vitamin D supplement year-round (not just in winter) if they don’t get enough sun exposure to optimize their levels.

According to the vitamin D review paper30 “Evidence That Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Death,” published in the journal Nutrients, April 2, 2020:

“Through several mechanisms, vitamin D can reduce risk of infections. Those mechanisms include inducing cathelicidins and defensins that can lower viral replication rates and reducing concentrations of pro-inflammatory cytokines that produce the inflammation that injures the lining of the lungs, leading to pneumonia, as well as increasing concentrations of anti-inflammatory cytokines …

To reduce the risk of infection, it is recommended that people at risk of influenza and/or COVID-19 consider taking 10,000 IU/d of vitamin D3 for a few weeks to rapidly raise 25(OH)D concentrations, followed by 5000 IU/d.

The goal should be to raise 25(OH)D concentrations above 40–60 ng/mL (100–150 nmol/L). For treatment of people who become infected with COVID-19, higher vitamin D3 doses might be useful.”

A GrassrootsHealth review of an observational study involving 212 COVID-19 patients in Southeast Asia identified a correlation between vitamin D levels and disease severity. Those with the mildest disease had the highest vitamin D levels, and vice versa.

In the initial study group of 212 patients (see Table 1 below), 55 had normal vitamin D levels, which was defined as greater than 30 ng/ml; 80 had insufficient levels of 21 to 29 ng/ml and 77 had deficient levels of less than 20 ng/ml.

According to the research done by GrassrootsHealth, 40 ng/mL is the lower edge of optimal, with 60 ng/mL to 80 ng/mL being ideal for health and disease prevention. Despite that, the benefit of having a vitamin D level above 30 ng/mL was clear.

vitamin d covid-19 severity

In a study31,32 that looked at data from 780 COVID-19 patients in Indonesia, those with a vitamin D level between 20 ng/mL and 30 ng/mL had a sevenfold higher risk of death than those with a level above 30 ng/mL. Having a level below 20 ng/mL was associated with a 12 times higher risk of death.

Research33,34 posted on the preprint server MedRxiv June 10, 2020, reports a combination of vitamin D3, B12 and magnesium inhibited the progression of COVID-19 in patients over the age of 50, resulting in “a significant reduction in proportion of patients with clinical deterioration requiring oxygen support and/or intensive care support.”

Check Your Level Before You Start Downing Supplements

On the upside, news about vitamin D appears to be reaching the masses. According to Foodnavigator-Asia, sales of the Japanese FANCL brand of vitamin D were 2018% higher in April 2020 compared to April 2019.35 While that’s a good sign, it’s important to remember to get your vitamin D level tested before you start supplementing.

The reason for this is because you cannot rely on blanket dosing recommendations. The crucial factor here is your blood level, not the dose, as the dose you need is dependent on several individual factors, including your baseline blood level.

Data from GrassrootsHealth’s D*Action studies suggest the optimal level for health and disease prevention is between 60 ng/mL and 80 ng/mL, while the cutoff for sufficiency appears to be around 40 ng/mL. In Europe, the measurements you’re looking for are 150 to 200 nmol/L and 100 nmol/L respectively.

I recently published a comprehensive vitamin D report in which I detail vitamin D’s mechanisms of action and how to ensure optimal levels. I recommend downloading and sharing that report with everyone you know. A quick summary of the key steps is as follows:

1. First, measure your vitamin D level — One of the easiest and most cost-effective ways of measuring your vitamin D level is to participate in the GrassrootsHealth’s personalized nutrition project, which includes a vitamin D testing kit.

Once you know what your blood level is, you can assess the dose needed to maintain or improve your level. If you cannot get enough vitamin D from the sun (you can use the DMinder app36 to see how much vitamin D your body can make depending on your location and other individual factors), then you’ll need an oral supplement.

2. Assess your individualized vitamin D dosage — To do that, you can either use the chart below, or use GrassrootsHealth’s Vitamin D*calculator. To convert ng/mL into the European measurement (nmol/L), simply multiply the ng/mL measurement by 2.5. To calculate how much vitamin D you may be getting from regular sun exposure in addition to your supplemental intake, use the DMinder app.37

Vitamin D Serum Level

3. Retest in three to six months — Lastly, you’ll need to remeasure your vitamin D level in three to six months, to evaluate how your sun exposure and/or supplement dose is working for you.

dr. mercola's report

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Take Your Vitamin D With Magnesium and K2

As previously detailed in “Magnesium and K2 Optimize Your Vitamin D Supplementation,” it’s strongly recommended to take magnesium and K2 concomitant with oral vitamin D. Data from nearly 3,000 individuals reveal you need 244% more oral vitamin D if you’re not also taking magnesium and vitamin K2!38

What this means in practical terms is that if you take all three supplements in combination, you need far less oral vitamin D in order to achieve a healthy vitamin D level.

Vitamin D Dose-Response

Help Us Spread the Word!

Remember, while vitamin D is important for everyone, key target populations are the elderly and people of color. It’s now beyond evident that COVID-19 affects the elderly far more severely, on average, than younger individuals, and those living in nursing homes and assisted living facilities seem to be at an extraordinarily increased risk of dying from COVID-19.

Add to that the increased hospitalization rate and mortality among people of color, and it should be easy to see that targeting these two groups with commonsense strategies such as vitamin D optimization can, and most likely will, have a tremendous impact on COVID-19 mortality rates in the future. As Robert Brown with the McCarrison Society, a nutrition think tank, told the Scotland Herald:39

“The biological pathways by which vitamin D can help reduce severity of Covid-19 are well established and the real-life evidence from within this pandemic is growing. What’s needed now is for government to be bold and act now to mitigate the risk of a second wave returning in the winter.”

That said, don’t let government’s failure to address vitamin D to stop you from taking control of your own health. Vitamin D supplements are inexpensive and readily available, as are vitamin K2 and magnesium. If we can get the word out, we are likely to significantly quell any reemergence of COVID-19, and eliminate most of the racial disparities we see among patients with severe illness.

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