Vitamin D May Not Provide Protection from COVID-19 Susceptibility, Disease Severity

Although observational studies indicate that greater levels of vitamin D may protect against COVID-19, these studies are inconclusive and potentially subject to confounding, according to an analysis published in PLOS Medicine. The study suggests that genetic evidence does not support vitamin D as a protective measure against COVID-19.¹

Increased vitamin D levels, as reflected by 25-hydroxy vitamin D (25OHD) measurements, have been hypothesized to offer protection against COVID-19 based on in vitro, observational, and ecological studies. Although vitamin D levels are associated with multiple confounding variables, these associations may not be causal, according to the authors of the current study.²

To further assess the relationship between vitamin D levels and COVID-19 susceptibility and severity, the research team conducted a Mendelian randomization study using genetic variants strongly associated with increased vitamin D levels. The study authors examined genetic variants from 4134 individuals with COVID-19, and 1,284,876 people without COVID-19, across 11 countries to determine whether genetic predisposition for higher vitamin D levels were associated with less severe disease outcomes in COVID-19.¹

The findings showed no evidence for an association between genetically predicted vitamin D levels and COVID-19 susceptibility, hospitalization, or severe disease. The researchers said this suggests that raising circulating vitamin D levels via supplementation may not improve COVID-19 outcomes in the general population.¹

The study had some key limitations, including that it did not include individuals with vitamin D deficiency, with the authors noting that it is possible that deficient patients may benefit from supplementation for COVID-19-related protection and outcomes. Further, the genetic variants were used only from individuals of European ancestry, therefore future research is necessary to evaluate the relationship with COVID-19 outcomes in other populations.¹

"Vitamin D supplementation as a public health measure to improve outcomes is not supported by this study,” the study authors said in a press release. “Most importantly, our results suggest that investment in other therapeutic or preventative avenues should be prioritized for COVID-19 randomized clinical trials.”¹

The study authors concluded that other therapeutic avenues should be given higher priority for COVID-19 randomized controlled trials.²

REFERENCES

1. Vitamin D may not provide protection from COVID-19 susceptibility or disease severity. EurekAlert! Published June 1, 2021. Accessed June 3, 2021. https://www.eurekalert.org/pub_releases/2021-06/p-vdm052721.php
2. Laporte-Butler G, Nakanishi T, Mooser V, et al. Vitamin D and COVID-19 susceptibility and severity in the COVID-19 Host Genetics Initiative: A Mendelian randomization study. PLOS. Published June 1, 2021. https://doi.org/10.1371/journal.pmed.1003605