Genetically predicted serum vitamin D and COVID-19: a Mendelian randomisation study

Area of Science:

• Genetics
• Epidemiology
• Nutritional Science

Background:

• Observational studies suggest an association between serum vitamin D and COVID-19 risk/severity.
• Causality remains uncertain due to potential confounding factors.

Purpose of the Study:

• To investigate the causal relationship between genetically predicted serum vitamin D and COVID-19 susceptibility and severity.
• To differentiate true causal effects from confounding in the vitamin D-COVID-19 association.

Main Methods:

• Employed a two-sample Mendelian randomization study design.
• Utilized large-scale genome-wide association study data from UK Biobank, SUNLIGHT Consortium, and COVID-19 Host Genetics Initiative.
• Instrumented serum vitamin D status using single nucleotide polymorphisms (SNPs) associated with vitamin D levels or deficiency.

Main Results:

• Mendelian randomization analysis provided no significant evidence for a causal effect of genetically predicted serum vitamin D on COVID-19 susceptibility.
• No causal link was found between serum vitamin D status and COVID-19 severity, including hospitalization and severe respiratory outcomes.
• Results remained consistent across different SNP selection strategies and sensitivity analyses.

Conclusions:

• Genetically determined long-term vitamin D status does not causally impact COVID-19 susceptibility or severity.
• Observed associations in prior studies are likely attributable to confounding, not a direct causal effect.
• The study does not rule out small causal effects or effects of acute vitamin D supplementation.