May 22, 2020
Host: Elizabeth Esty, MD.
At this point, with so many of the studies we’ve digested exploring correlations, associations, observational studies and anecdotal reports and speculation, we could subtitle the show: what we don’t know about COVID. And so, today, we’ll look at what we don’t know about Vitamin D and COVID. There have been a number of studies and a fair amount of media coverage in recent weeks that look at a possible link between low Vitamin D levels and severity of COVID.
Vitamin D plays a role in both adaptive and innate immunity, which we discussed at some length in our episode on the BCG vaccine and COVID. Macrophages starved for Vitamin D can’t produce peroxide to kill microbes, and some of the toll-like receptors crucial to innate immunity that recognize pathogen molecules don't work right without Vitamin D. Finally, Vitamin D modulates the immune response, preventing release of too many cytokines.
The potential for Vitamin D to play a role in preventing severe COVID-19 seems plausible, but what does the science say?
Research By: Elizabeth Esty and Nathan Novotny.
Sound Editing By: Nathan Novotny.
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 Helming L, Böse J, Ehrchen J, et al. 1α,25-dihydroxyvitamin D3 is a potent suppressor of interferon γ–mediated macrophage activation. Blood. 2005;106(13):4351-4358. doi:10.1182/blood-2005-03-1029
 Parva NR, Tadepalli S, Singh P, et al. Prevalence of Vitamin D Deficiency and Associated Risk Factors in the US Population (2011-2012). Cureus. 10(6). doi:10.7759/cureus.2741
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 The Center for Evidence Based Medicine. Vitamin D: A rapid review of the evidence for treatment or prevention in COVID-19. CEBM. Accessed May 21, 2020. https://www.cebm.net/covid-19/vitamin-d-a-rapid-review-of-the-evidence-for-treatment-or-prevention-in-covid-19/
 Hastie CE, Mackay DF, Ho F, et al. Vitamin D concentrations and COVID-19 infection in UK Biobank. Diabetes & Metabolic Syndrome: Clinical Research & Reviews. 2020;14(4):561-565. doi:10.1016/j.dsx.2020.04.050