A Basic Review of the Preliminary

Evidence that COVID-19 Risk and

Severity Is Increased in Vitamin D


Acknowledgement- this article 

remains the property of its author:

Linda Benskin

You can download a pdf copy

of the full 83 page paper below:


As the world’s attention has been riveted upon

the growing COVID-19 pandemic, many

researchers have written brief reports supporting

the hypothesis that vitamin D deficiency is

related to the incidence and severity of COVID-19.

The clear common thread among the top risk

groups - vitamin D deficiency – may be being

overlooked because of previous overstated

claims of vitamin D benefits. However, the

need to decrease COVID-19 fatalities among

high-risk populations is urgent.

Early researchers reported three striking patterns.

Firstly, the innate immune system is impaired by

vitamin D deficiency, which would predispose

sufferers to viral infections such as COVID-19.

Vitamin D deficiency also increases the activity

of the X-chromosome-linked ‘Renin-Angiotensin’

System, making vitamin D deficient individuals

(especially men) more susceptible to COVID-19’s

deadly “cytokine storm” (dramatic immune system



Secondly, the groups who are at highest risk for

severe COVID-19 match those who are at highest

risk for severe vitamin D deficiency. This includes

the elderly, men, ethnic groups whose skin is naturally

rich in melanin (if living outside the tropics), those

who avoid sun exposure for cultural and health

reasons, those who live in institutions, the obese,

and/or those who suffer with hypertension, cardio-

vascular disease, or diabetes.


And thirdly, the pattern of geographical spread of

COVID-19 reflects higher population vitamin D

deficiency. Both within the USA and throughout

the world, COVID-19 fatality rates parallel vitamin D

deficiency rates.


A literature search was performed on PubMed, Google Scholar, and RSMLDS, with targeted Google searches providing additional sources. Although randomized controlled trial results may be available eventually, the correlational and causal study evidence supporting a link between vitamin D deficiency and COVID-19 risks is already so strong that it supports action.

The 141 author groups writing primarily about biological plausibility detailed how vitamin D deficiency can explain every risk factor and every complication of COVID-19, but agreed that other factors are undoubtedly at work. COVID-19 was compared with dengue fever, for which oral vitamin D supplements of 4000IU for 10 days were significantly more effective than 1000IU in reducing virus replication and controlling the “cytokine storm” responsible for fatalities.

Among the 47 original research studies summarized here, chart reviews found that serum vitamin D levels predicted COVID-19 mortality rates (16 studies) and linearly predicted COVID-19 illness severity (8 studies). Two causal modeling studies and several analyses of variance strongly supported the hypothesis that vitamin D deficiency is a causal, rather than a bystander factor, in COVID-19 outcomes. Three of the four studies whose findings opposed the hypothesis relied upon disproven assumptions.

The literature review also found that prophylactically correcting possible vitamin D deficiency during the COVID-19 pandemic is extremely safe. Widely recommending 2000IU of vitamin D daily for all populations with limited ability to manufacture vitamin D from the sun has virtually no potential for harm and is reasonably likely to save many lives.


Note: In addition, three studies (refs 46, 47, and 205) from Southeast Asia, all with results consistent with that of other studies, may have relied upon data from unofficial sources."

Funding: None to declare

Declaration of Interest: None to declare

Keywords: vitamin D, COVID-19, health disparities, minority health, vitamin D deficiency, preventive medicine, inflammation, cytokine storm

Suggested Citation:

Benskin, Linda, A Basic Review of the Preliminary Evidence that COVID-19 Risk and Severity Is Increased in Vitamin D Deficiency (May 13, 2020). Benskin LL 2020 A Basic Review of the Preliminary Evidence that COVID-19 Risk and Severity is Increased in Vitamin D Deficiency. Frontiers in Public Health (accepted, awaiting publication) DOI: 10.3389/fpubh.2020.00513; https://www.frontiersin.org/articles/10.3389/fpubh.2020.00513/abstract, Available at SSRN: https://ssrn.com/abstract=3669379