New study points to why vitamin D works on COVID-19

A strong correlation exists between vitamin D levels and COVID-19 outcomes. A new study paints a reason why.

Todd Runestad, Content Director,, Sr. Supplements Editor

September 11, 2020

6 Min Read
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Per the landmark 1994 Dietary Supplements Health and Education Act (DSHEA), supplements cannot claim to “diagnose, treat, cure or prevent any disease.” That sentence, per DSHEA, is printed on the label of every bottle of supplements.

But with vitamin D, a bevy of studies have been published in the last six months that at least show a correlation between vitamin D levels and COVID-19 outcomes.

In Korea, doctors found 76% of COVID-19 patients were deficient in vitamin D, and a severe vitamin D deficiency (<10 ng/dl) was found in 24% of COVID-19 patients and 7% of a control group.

In Chicago, a study published in May found that patients who had blood levels below 20 ng/ml or who did not take supplements were 77% more likely to test positive for COVID-19.

In Israel, a similar study found people with vitamin D levels below 30 ng/ml were 45% more likely to test positive and 95% more likely to be hospitalized.

In Indonesia, a study of 780 COVID-19 patients found almost 99% of patients who died had vitamin D levels lower than 20 ng/ml. Significantly, of patients with vitamin D levels higher than 30 ng/ml, only 4% died.

But correlation does not connote causality, so all we have is an association between vitamin D levels and outcomes to the pandemic.

Related:Why natural retailers should emphasize vitamin D to consumers for immune support

Until now.

The back story

Researchers in a study published in April 2020 noted that vitamin D can reduce the risk of infections through several means, among them by mediating the body's inflammation response. Vitamin D, wrote the researchers, “can lower viral replication rates and reduce 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.”

In one of the recent COVID-related studies, researchers suggested vitamin D (as well as melatonin) may play a role by down-regulating the inflammatory response related to the bodily system that manages blood pressure and fluid balance in the body, called the renin-angiotensin system (RAS).

A Turkish researcher postulated that vitamin D could work against COVID-19 infection-induced multiple organ damage by reducing the level of renin, and also by decreasing the inflammatory cytokine storm, decreasing other pro-inflammatory markers and by increasing antimicrobial activity.

Vitamin D’s interaction with RAS is an important point. That’s because hypertension, or high blood pressure, is one of the co-existing conditions that has consistently been reported to be more common among critical COVID-19 patients.

Related:Vitamin D deficiency in minority populations contributes to outsize COVID-19 burden

Yet once COVID-19 patients are hospitalized, hypotension—low blood pressure—comes to the fore.

The link between these two anomalies in blood pressure is the vasopressor system, which is governed in no small part by a molecule known as bradykinin. These molecules become elevated with COVID-19, and this “bradykinin storm” leads to inflammation of surrounding tissues, and is responsible for blood vessels in the lungs leaking fluid—the action that brings about respirators to patient rooms.

New study a eureka moment

Researchers in this groundbreaking new study conducted complex gene expression scans using the world’s second-fastest computer, at Oak Ridge National Lab in Tennessee. They discovered that the RAS can mediate the bradykinin storm. They also found that various approved drugs can interfere with the kinin pathway and thus could nip the bradykinin storm in the bud—vitamin D, which reduces renin production, among them.

Lead researcher Dan Jacobson said that the vitamin D link affects the early steps of the RAS pathway—but it is only one component involved in a complex system, and one single intervention alone is probably not going to solve the COVID crisis.

Nevertheless, this so-called “bradykinin hypothesis” shows that bradykinin storms are the cause of COVID’s deadly effects, and vitamin D stops bradykinin.

It would be wrong to say that any substance as of yet prevents, cures or treats COVID-19—and illegal to make any such claim regarding a dietary supplement even if research showed it to be true. That’s the law under DSHEA.

So, alternately, one could say, “RAS perturbation and bradykinin storms can happen in a state of vitamin D deficiency,” said Kenn Israel, founder and manager of Innovation Nutrition Consulting. “Vitamin D does have impact on the RAS system, specifically reduction of ren. Thus, high-dose vitamin D may be indicated for those subjects who are depleted or deficient in the nutrient, infected with COVID and at risk for a bradykinin storm.” 

To be on the clear side of regulatorily compliant communication, retailers certainly can counsel customers that vitamin D depletion or deficiency causes significant immune dysfunction.

The correlation between vitamin D levels and COVID-19 outcomes is strong, and this study seemed to discover a mechanism of action behind the correlation—it’s not just a coincidence.

A different study, currently under way at two academic research centers, the Southwest College of Naturopathic Medicine & Health Sciences and Arizona State University, is looking at giving high doses of vitamin D to those who test positive for COVID-19. Patients will receive 10,000 IU/day vitamin D (15,000 IU/day for those over age 70). After two weeks, if a patient’s vitamin D levels are still below 30 ng/ml, vitamin D supplementation will continue for three more weeks. If vitamin D levels are between 30-49 ng/ml, the dosage will be drawn down to 5,000 IU/day. If vitamin D levels are higher than 50 ng/ml, supplementation will stop.

Because vitamin D does have impact on the RAS system, specifically reduction of ren, vitamin D may help those who already have COVID-19 from progressing to a bradykinin storm.

Two questions from the study will be how symptoms present relative to baseline vitamin D levels, and whether vitamin D given to those already with COVID-19 will be enough to change the disease outcome.

“It seems to me that some of the more severe symptoms we are seeing with COVID-19 is due to the immune system having a hard time switching over from innate to adaptive immune response,” wrote Matt Marturano, N.D., on LinkedIn. “My two cents are that we need to be doing way better supporting innate immunity before we even get to the starting gate with these types of viruses. Either way, I hope this study helps to forward the importance of regular vitamin D testing, questioning the current guidance on what is considered sufficient for proper immune function, and appropriate supplementation levels.”

Vitamin D is first-line of sales

British researchers published a vitamin D study in May postulating both that “vitamin D status may influence the severity of responses to COVID-19 and that the prevalence of vitamin D deficiency in Europe will be closely aligned to COVID-19 mortality.”

Vitamin D status is, of course, closely aligns with exposure to the sun. That exposure decreases markedly during the winter months—some people say the “colds and flu season” is really nothing more than the “vitamin D deficiency season.”

Which brings us back to vitamin D status as it relates to this upcoming winter season. There is a clear correlation between vitamin D status and COVID-19 outcomes—and, as the new study theorizes, this connection may be more than a correlation but an actual causality.

And that makes vitamin D supplementation all the more critical.

Vitamin D is a relatively inexpensive supplement. A 120-day supply of 2,000 IU vitamin D from NOW sells for $8.99. Meanwhile, a 120-day supply of elderberry 500mg from NOW sells for $28.99. A 240-day supply of 5,000 IU vitamin D from Nature’s Way sells at the Vitamin Shoppe for $19.99, which is almost the same price ($20.99) for a 30-day supply—eight months versus one—of elderberry gummies from Nature’s Way.

As the British researchers concluded, “There is a strong plausible biological hypothesis and evolving epidemiological data supporting a role for vitamin D in COVID-19.”

About the Author(s)

Todd Runestad

Content Director,, Sr. Supplements Editor, Natural Products Insider

I've been writing on nutrition science news since 1997. I'm The content director for NaturalProductsInsidercom and digital magazines. Other incarnations: supplements editor for, Delicious Living and Natural Foods Merchandiser. Former editor-in-chief of Functional Ingredients magazine and still cover raw material innovations and ingredient science.

Connect with me here

My daily vitamin regime includes a morning smoothie with a range of powders including protein, collagen and spirulina; a quality multi, B complex, C with bioflavonoids, >2,000IU vitamin D, E, magnesium, high-selenium yeast, PQQ, choline, alpha-lipoic acid with carnitine, coQ10, fish oil concentrate, probiotics and some adaptogenic herbs. 

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