COVID-19 and Vitamin D

Dr. Garreth MacDonald


COVID-19 and Vitamin D Supplementation. Controvrsial?

I read a recent article (May 2020) our of the Irish Medical Journal titled “Vitamin D and Inflammation: Potential Implications for Severity of Covid-19” (Irish Medical Journal, Vol. 113; No. 5 by E Laird, J Rhodes, Rose Anne Kenny). These authors are from the School of Medicine, Trinity College Dublin, Ireland, the Institute of Translational Medicine, University of Liverpool, and Mercers Institute for Ageing, St. James Hospital, Dublin, Ireland. And this study cites 48 references. It was also an observational study. Interestingly, this issue of the IMJ generated a lot of discord about Vitamin D’s role.

These authors hypothesize 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.

They conducted a literature search on PubMed of vitamin D status in countries/areas of Europe affected by Covid-19 infection. Covid-19 infection and mortality data was gathered from the World Health Organization.

The authors used these values for 25(OH)D concentrations:

<30 nmol/L deficient [= 12 ng/mL]

<50 nmol/L low [= 20 ng/mL]

[I consider these values to be crazy low, and that all should be above 50 ng/mL = 200 nmol/L]


1) Research has indicated that vitamin D may have immune supporting properties through modulation of both the adaptive and innate immune system by cytokine regulation.

2) “Research has highlighted a crucial supportive role for vitamin D in immune cell function, particularly in modulating the inflammatory response to viral infection.”

3) “Vitamin D receptor is present on both T and B immune cells.”

• “Vitamin D is associated with lower concentrations of the pro-inflammatory cytokine Interleukin-6 (IL-6), which plays a significant role in Covid-19 induced acute respiratory distress syndrome.”

4) “A ‘sufficient’ vitamin D serum level is linked to a switch from a pro- to antiinflammatory

profiles in older adults.”

5) “A heightened immune response in people who are vitamin D deficient may therefore increase the potential for ‘cytokine storm’.” [This is an Important point]

• “It is the impact of vitamin D deficiency on cytokine response, and potentially therefore on lung injury, that is potentially much more important in the context of Covid-19.”

6) In a large cross-sectional clinical trial (n = 18,883), lower vitamin D was associated with higher respiratory infection rates.

7) “Supplementation with vitamin D seems to help reduce both symptoms and antibiotic use.” [This is a Very Important point]

8) “The mortality rate for Covid-19 is the highest for those aged >80 years, …and typically this is the age group with the highest levels of [vitamin D] deficiency regardless of country.” [Important]

9) Those residing at higher latitudes, or with darker skin pigmentation (Black, Asian, Minority ethnics) may be particularly affected by Covid-19.

10) “It is already evident that there is a world-wide association between northern latitude and increased Covid-19 mortality.”

• This supports the hypothesis that “sunlight exposure and hence vitamin D status could be impacting on Covid-19 severity.”

11) “Counter-intuitively, lower latitude and typically ‘sunny’ countries such as Spain and Italy (particularly Northern Italy), had low mean concentrations of 25(OH)D and high rates of vitamin D deficiency.”

• “These countries have also been experiencing the highest infection and death rates in Europe.”

• “The northern latitude countries (Norway, Finland, Sweden) which receive less UVB sunlight than Southern Europe, actually had much higher mean 25(OH)D concentrations, low levels of deficiency and for Norway and Finland, lower infection and death rates.”

12) “Optimizing vitamin D status to recommendations by national and international public health agencies will certainly have benefits for bone health and potential benefits for Covid-19.”

• “There is a strong plausible biological hypothesis and evolving epidemiological data supporting a role for vitamin D in Covid-19.”

13) The authors “observed that low 25(OH)D concentrations appear to be associated with increased mortality from Covid-19.” [This is a Key Point]

14) “Countries with a formal vitamin D fortification policy appear to have the lowest rates of infection whilst countries with no policy and highest deficiency rates appear to be more adversely affected.” [This is Important]

15) “Observational reports have also highlighted that Covid-19 infection and death rates appear to be higher in ethnic minority populations with darker skin which research has shown to be at much higher risk of vitamin D deficiency.”

16) Optimizing vitamin D status to public health recommendations could enhance immune response. [This is a Key Point]

17) Improving vitamin D levels through fortification and self-supplementation “could have significant benefits in terms of bone and musculoskeletal health (economically and socially) in addition to the suggested immune health benefits.”

• This is particularly timely, given current lock-down arrangements and government advice to avoid sunbathing.

• “Strong public awareness campaigns regarding vitamin D sources and supplementation are recommended.”

18) Other “micronutrients have been observed to have immunomodulation effects (such as zinc, selenium, vitamin B6 etc.) which may also have a role in immune function in Covid-19 infections which we did not examine as it was not the focus of this particular analysis.” [This is an Important Point]

19) “The circumstantial and experimental evidence suggests that vitamin D may have an important supportive role for the immune system, particularly in regulating cytokine response to pathogens.”

• “Vitamin D levels are low in countries in Europe which have high infection and mortality rates.”

20) The authors “recommend that more publicity be given to current guidelines for vitamin D dietary intake and supplementation as denoted by the public health agencies in the USA, UK, and Europe.” [This is a Key Point]


There are many articles pertaining to vitamin D status and immunology, pain, dementia, autism, and disc degeneration.

Now I am not dispensing any medical advise nor am I stating that this is the “magic bullet” for our COVID-19 troubles. However, I am personally taking 10,000 IU of Vitamin D daily (along with other goodies I shall save for a later blog) based on my understanding of the literature on Vitamin D. I advocate having your Vitamin D levels checked, then supplement and recheck your levels to see if your supplementation has made an impact on ones levels. This is how one determines effective dosing.

This article, I hope, leads to discussion of ways to help prevent the spread of this virus and/or mitigate the nasty effects if one does catch it.

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