Quote (Santara @ Jan 25 2022 10:16pm)
Except that it does. Dark skin reduces the body's ability to metabolize vitamin D, which is a well known anti-virulent.
Afaik, there were several studies finding no link between vitamin D levels and covid outcomes, ex;
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To the best of our knowledge, few studies have evaluated the impact of Vit D status on the severity and outcome of COVID-19 disease in Saudi Arabia. In our patients, we did not find an association between Vit D status and COVID-19 severity or better outcomes. Moreover, when we adjusted the statistical model for gender, age and comorbidities, Vit D level was not associated with the course of the disease.
The current study’s findings are supported by a similar study that did not prove the relation between Vit D level and COVID-19 severity or outcomes. The two largest sample Mendelian randomization (cohort and genetic) approaches conducted among 443.734 participants, from 11 courtiers, failed to promote any relevance between COVID-19 severity or outcomes and Vit D.24 Further, a study on 341.484 participants found insufficient evidence to support the potential link between Vit D level and COVID-19 infection severity and mortality after adjustment for confounders.31
At the same point, another multicenter, double-blind, randomized, placebo-controlled trial conducted on 240 patients with severe COVID-19 did not prove any significant relevant COVID-19 outcomes, independent of the ability of Vit D therapy to correct serum 1–25-hydroxy Vit D level.32 The same findings have been reported by other researchers who found that a single high dose of Vit D (540,000 IU) during the early phase of critical illness rapidly corrected serum Vit D level but did not promote the clinical outcomes of COVID-19 infection compared with the placebo. Furthermore, research on 502,624 infected patients with COVID-19 failed to detect an association between risk of COVID-19 infection and Vit D level.21
Low Vit D status is common among Saudi women,6,33 while recent reports showed that males accounted for the higher prevalence of COVID-19 cases in Saudi Arabia.34,35 This discrepancy indicates weakness in the direct relation between Vit D status and COVID-19 infection.
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Results
Eleven cohort studies with 536,105 patients and two RCTs were identified. Vitamin D deficiency (< 20 ng/ml) or insufficiency (< 30 ng/ml) was not associated with an significant increased risk of COVID-19 infection (OR for < 20 ng/ml: 1.61, 95% CI: 0.92–2.80, I2 = 92%) or in-hospital death (OR for < 20 ng/ml: 2.18, 95% CI: 0.91–5.26, I2 = 72%; OR for < 30 ng/ml: 3.07, 95% CI: 0.64–14.78, I2 = 66%). Each 10 ng/ml increase in serum vitamin D was not associated with a significant decreased risk of COVID-19 infection (OR: 0.92, 95% CI: 0.79–1.08, I2 = 98%) or death (OR: 0.65, 95% CI: 0.40–1.06, I2 = 79%). The overall quality of evidence (GRADE) for COVID-19 infection and associated death was very low. Vitamin D supplements did not significantly decrease death (OR: 0.57, I2 = 64%) or ICU admission (OR: 0.14, I2 = 90%) in patients with COVID-19. The level of evidence as qualified using GRADE was low.
I can understand it as being one of those novel theories with a reasonable chance to establish an explainable mechanism, like ivermectin and hydroxychloroquine and whatever else, but research into it pooped on the idea.