Vitamin D Status and COVID-19

Vitamin D Status and COVID-19

Whoever wishes to investigate medicine properly should proceed thus: in the first place to consider the seasons of the year …Hippocrates

Winter and the Flu

It became pretty obvious to medical researchers a long time ago that epidemics of influenza had a pretty predictable pattern. They mostly occurred in the winter, and rarely in the summer. But the first researcher to hunt down a reason for this was R. Edgar Hope-Simpson, a British general practitioner (and self-educated epidemiologist). After discovering the cause of shingles, and the latency of chicken pox, he dedicated the rest of his life’s research to understanding influenza. Given the winter-time occurrence of influenza, Hope-Simpson believed that discovering the cause of influenza’s seasonality would “provide the key to understanding most of the influenzal problems confronting us”.

A detailed study published in the medical journal Epidemiol Infect (Dec 2006), followed up on the research of Hope-Simpson. The study opens with this statement: “In 1981, R. Edgar Hope-Simpson proposed that a ‘seasonal stimulus’ intimately associated with solar radiation explained the remarkable seasonality of epidemic influenza. Solar radiation triggers robust seasonal vitamin D production in the skin; vitamin D deficiency is common in the winter, and activated vitamin D, a steroid hormone, has profound effects on human immunity.

One hundred and nineteen references later, they summarized: “We conclude that vitamin D, or lack of it, may be Hope-Simpson’s ‘seasonal stimulus’.” (Study)

Therefore, it should come as no surprise that researchers are starting to look at the relationship between vitamin D and the COVID-19 virus, especially since vitamin D is widely deficient around the world (50% worldwide).

And, there are quite a few studies on the subject, but as one noted: “…the current rush of COVID-19 vitamin D studies didn’t just come out of nowhere. Previous studies have noted that vitamin D deficiency may be a biomarker of sepsis risk, while data has been growing around a potential benefit of the vitamin D in prevention of and mortality from infections.”

In particular, a systematic review and meta-analysis collating evidence from 25 randomized controlled trials (RCTs) that gave vitamin D supplements to all age groups with acute respiratory infections found protective effects among all participants, but particularly among those with baseline 25-hydroxyvitamin D levels indicative of deficiency.” (Study)


Here I will briefly address three of the many new studies coming out on vitamin D and COVID-19, including links for those who wish to look closer at this research.

  1. In this study it was determined that one hundred percent of Intensive Care Unit COVID-19 patients, less than 75 years old, had vitamin D insufficiency. (Study)
  2. In another study, “out of 55 patients with higher blood serum levels of vitamin D metabolite (more than 30ng/ml), 47 had mild symptoms, 4 had “ordinary” symptoms, 2 had severe symptoms and 2 had critical symptoms. Of the 157 patients with lower vitamin D (less than 30ng/ml), 2 had mild symptoms, 55 ordinary symptoms, 54 severe symptoms and 46 critical symptoms”. (Study)
  3. The third found that, across European countries, there was a “strong association between vitamin D levels and per capita COVID-19 cases and mortality”. (Study)

As of yet, there have been no studies published in which vitamin D supplements have been given directly to patients with COVID-19, though such experiments are beginning. In France a clinical study is underway “that will test the effects of a large single vitamin D-dose, administered early in infection, compared to a standard dose, on the mortality of older vitamin D-deficient COVID-19 infected adults.

Cytokine Storm

Those following the medical information on this new virus will have by now heard the term “cytokine storm”.

When our immune system responds to an attack, the body produces cytokines, molecules released to fight off the invasive bacteria or virus. Normally, the body only produces enough cytokines to do the job, and then ceases production once the infectious agents have been defeated.

However, sometimes the immune system continues to release these molecules, which can ultimately attack the organs they were intended to protect. This occurrence is known as a “cytokine storm”, and seems to be a dangerous aspect of the coronavirus.

Certainly the cytokine storm was identified long before the coronavirus brought it to the fore, in fact, “there are some scientists who believe cytokine storms may explain why otherwise healthy young people died from the Spanish flu in 1918 ”. (Source)

To the point: a group of researchers “conducted a statistical analysis of data from hospitals and clinics across China, France, Germany, Italy, Iran, South Korea, Spain, Switzerland, the United Kingdom, and the United States”. As discussed above, and so no surprise here, “the researchers noted that patients from countries with high COVID-19 mortality rates, such as Italy, Spain and the UK, had lower levels of vitamin D compared to patients in countries that were not as severely affected”.

But, the angle this team took was to examine the correlation between vitamin D levels and cytokine storm, the title of their research paper being: “The Possible Role of Vitamin D in Suppressing Cytokine Storm and Associated Mortality in COVID-19 Patients.

The research paper’s first author, Ali Daneshkhah, a postdoctoral research associate, stated,

Cytokine storm can severely damage lungs and lead to acute respiratory distress syndrome and death in patients. This is what seems to kill a majority of COVID-19 patients, not the destruction of the lungs by the virus itself. It is the complications from the misdirected fire from the immune system”.

Vadim Backman, who led the research, believes that, aside from enhancing our innate immune systems, vitamin D also prevents our immune systems from becoming dangerously overactive, resulting in a cytokine storm.

With regards to having healthy levels of vitamin D in our bodies, Backman had this to say: “Our analysis shows that it might be as high as cutting the mortality rate in half. It will not prevent a patient from contracting the virus, but it may reduce complications and prevent death in those who are infected.” (Study)


So, as with all forms of the flu, we can expect a decline in cases as the summer approaches, especially if people can get outdoors, and tan properly (50% body exposure, for at least 20-30 minutes, without bathing during the day), or if they supplement with vitamin D. And, of course, as the sun wanes, and we move into fall and winter, influenza rates will rise again. Therefore, it is critical that we keep our vitamin D at optimal levels to aid in our protection from any, and all, flu strains.

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