Now that COVID-19 has been around for several months, researchers all over the world are starting to collect large amounts of data on case demographics and clinical characteristics. One recently published study from the United Kingdom summarized the number of cases and fatalities of COVID-19 from twenty European countries and correlated it with the average vitamin D levels of each of those countries.
Interestingly, the countries with the highest levels of vitamin D were those in the way north of Europe (Sweden, Finland, Slovakia, Norway, Denmark) which seems counterintuitive at first, since the have a less sunny climate. The countries with the lowest vitamin D were southern coastal countries (Portugal, Spain) with plenty of sunshine. A few reasons for this apparent paradox were suggested by the authors: (1) residents of more southern countries tend to avoid sun exposure via shade or sunblock, (2) countries in the northern latitudes consume more vitamin D rich foods like cod liver oil and (3) darker skin in the southern countries is less efficient at vitamin D production since skin pigmentation decreases vitamin D synthesis, i.e. those with fairer skin make more vitamin D via sunlight. For whatever reason, the northern countries tended to have higher vitamin D levels.
In any case, for the twenty European countries where average vitamin D levels were known, a general trend emerged—the lower the average vitamin D in the population, the higher the number and mortality of COVID-19 cases there were. The inverse relationship between vitamin D and COVID-19 was significant, from a statistical standpoint, although the authors concede it is still only a ‘crude relationship’ since the data was collected over a general population.
There are a lot of theories about the mechanisms of how vitamin D may confer protection, which have a lot of credibility from studies on past viral respiratory diseases, particularly SARS-CoV1. Some mentioned in this study:
- Vitamin D increases ACE2 expression which protects against acute lung injury
- Vitamin D regulates cytokines from getting out of control and wreaking havoc
- Vitamin D is needed to help macrophages mature (white blood cells that fight pathogens)
- Vitamin D activates proteins (called cathelicins and defensins) that fight microbes
Whatever the mechanism, a link between COVID-19 and low vitamin D is emerging. A new study on actual vitamin D levels in COVID-19 patients was just published this month and will be the subject of our next blog.
- For a summary of the role micronutrients in viral infections, click here.
- For a summary of the role vitamin D plays in various systems of the body, click here.
It's important to note, however, that supplementing blindly can be harmful. Balance is key, and targeted repletion is the answer. Not a shotgun approach.
Now is absolutely a perfect time to assess a person's vitamin D status. SpectraCell’s Micronutrient Test assesses vitamin D plus 30 additional nutrients plus immune function—quantifying nutritional status is a giant step toward staying healthy in 2020. Get a micronutrient test today.
