COVID-19 home confinement & vitamin D levels alteration

Home confinement and lifestyle changes resulted in inadequate sunlight exposure and limited vitamin D intake during the COVID-19 pandemic. This research aimed to elucidate the impact of the COVID-19 pandemic on vitamin D3 status during home confinement.

This retrospective repeated cross-sectional laboratory-based study enrolled 9,686 individuals from northeastern Iran. Vitamin D3 levels were measured in various phases: pre-COVID-19 in 2019, during the pandemic in 2020, and following the initiation of COVID-19 vaccination in 2021.

A predominant portion of the population exhibited insufficient levels of vitamin D in all three time points (P<0.001). The mean concentration of vitamin D3 was higher in females than in males in all periods. A significant upward trend in the mean concentration was found from 35±19 ng/mL in the pre-COVID-19 period to 38±16 ng/mL after the initiation of vaccination, particularly in severe deficiency and insufficiency subgroups (P<0.01). There was a significant gradual downward trend in the prevalence of vitamin D deficiency dropping from 19% in the pre-COVID-19 period to 12% during the pandemic and further down to 9% following the initiation of vaccination (P<0.001).

This large population-based study showed that mean serum vitamin D concentrations increased during and after the COVID-19 pandemic period, while the prevalence of vitamin D deficiency decreased over time. These findings indicate a temporal change in vitamin D status across different phases of the pandemic.