The community is debating the idea that vitamin D deficiency is the determining factor in COVID-19-related mortality, suggesting that systematic supplementation could prevent the vast majority of deaths.

noli's read

The link between vitamin D and immunity is a complex subject: observational studies often show a correlation between low vitamin D levels and the severity of infections (observational type), but this does not prove causality, as deficiency is often a marker of poor overall health or comorbidities (confounding bias). Rigorous meta-analyses, such as those published in the BMJ or by Cochrane, indicate that while supplementation reduces the risk of acute respiratory infections in highly deficient individuals, it shows no miracle effect on the prevention or mortality of COVID-19 in the general population (meta-analysis of randomized controlled trials). The idea that 90% of deaths are preventable is widely considered a statistical overestimation derived from observational studies that do not sufficiently account for other risk factors. It is also noted that very sunny countries have experienced severe waves, contradicting an exclusive reliance on sun exposure. The community is deeply divided, oscillating between enthusiasm for preventive supplementation and skepticism based on the lack of robust clinical evidence.

the sources

1. 1NIH Office of Dietary Supplements 2026
2. 2Manson JE et al. 2019
3. 3r/ScientificNutrition