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Evidence Regarding Vitamin D and Risk ofCOVID-19 and Its Severity

Updated: Feb 1, 2022

Joseph Mercola 1,*, William B. Grant 2 and Carol L. Wagner 3

1 Natural Health Partners, LLC, 125 SW 3rd Place, Cape Coral, FL 33991, USA

2 Sunlight, Nutrition, and Health Research Center, P.O. Box 641603, San Francisco, CA 94164-1603, USA;

3 Department of Pediatrics, Shawn Jenkins Children’s Hospital, Medical University of South Carolina, 10 McClennan Banks Drive, MSC 915, Charleston, SC 29425, USA;


Vitamin D optimization is likely the easiest, least expensive and most fundamental beneficial strategy that anyone can do to minimize their risk of COVID-19 and other infections October 31, 2020, Dr. Mercola published a scientific review in the journal Nutrients, co-written with William Grant, Ph.D., and Dr. Carol Wagner. The paper is the second-most downloaded study from this journal in the past 12 months. It’s also No. 2 in citations for articles in the past 12 months, and No. 4 for views.

The study with the most downloads in the past year and the all-time highest number of views is another vitamin D paper, which found vitamin D supplementation reduced the risk of influenza and COVID-19 infections and deaths.

A third vitamin D paper nabbed the No. 1 spot for most-cited study in the past 12 months. This study found vitamin D supplementation improved survival in frail elderly hospitalized with COVID-19.

To improve your immune function and lower your risk of viral infections, you’ll want to maintain a vitamin D level between 60 ng/mL and 80 ng/mL (150 nmol/L and 200 nmol/L). Vitamin D optimization is particularly important for dark-skinned individuals, as the darker your skin, the more sun exposure you need to raise your vitamin D level, as well as the elderly.


Vitamin D deficiency co-exists in patients with COVID-19. At this time, dark skin color,

increased age, the presence of pre-existing illnesses and vitamin D deficiency are features of severe COVID disease. Of these, only vitamin D deficiency is modifiable. Through its interactions with a multitude of cells, vitamin D may have several ways to reduce the risk of acute respiratory tract infections and COVID-19: reducing the survival and replication of viruses, reducing risk of inflammatory cytokine production, increasing angiotensin-converting enzyme 2 concentrations, and maintaining endothelial integrity. Fourteen observational studies o er evidence that serum 25-hydroxyvitamin D concentrations are inversely correlated with the incidence or severity of COVID-19. The evidence to date generally satisfies Hill’s criteria for causality in a biological system, namely, strength of association, consistency, temporality, biological gradient, plausibility (e.g.,mechanisms), and coherence, although experimental verification is lacking. Thus, the evidence seems

strong enough that people and physicians can use or recommend vitamin D supplements to prevent or treat COVID-19 in light of their safety and wide therapeutic window. In view of public health policy, however, results of large-scale vitamin D randomized controlled trials are required and are currently in progress.


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