Vitamin D May Not Provide Protection Against COVID-19 Severity

No evidence of an association between genetically predicted vitamin D levels and COVID-19 susceptibility were found in the study.

A recent study conducted by investigators from McGill University in Quebec, Canada, has discovered that increased levels of vitamin D may not provide the protection against COVID-19 susceptibility or severity which has often been suggested.

Results from the study were published in the journal PLOS Medicine.

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

For the study, the team of investigators conducted a Mendelian randomization to assess the relationship between levels of vitamin D and COVID-19 susceptibility and severity.

The investigators analyzed genetic variants that were associated with increased levels of vitamin D from 4,134 participants who had an infection with COVID-19, as well as 1,284,876 who did not have the disease.

Results from the study demonstrated that there was no evidence of an association between genetically predicted vitamin D levels and COVID-19 susceptibility, hospitalization, or severe disease.

This suggests that using supplementation of vitamin D to increase circulating levels may not improve COVID-19 outcomes in the general population.

However, the authors noted several limitations of the study, including that there were no individuals with a vitamin D deficiency in the study population. This means there is a possibility that vitamin D supplementation in those with a deficiency may provide a benefit.

"Most vitamin D studies are very difficult to interpret since they cannot adjust for the known risk factors for severe COVID-19 (e.g., older age, institutionalization, having chronic diseases) which are also predictors of low vitamin D. Therefore, the best way to answer the question of the effect of vitamin D would be through randomized trials, but these are complex and resource intensive, and take a long time during a pandemic,” Guillaume Butler-Laporte, a lead author on the study said. “Mendelian randomization can provide more clear insights into the role of risk factors like vitamin D because they can decrease potential bias from associated risk factors like institutionalization and chronic disease.”