Vitamin D and COVID-19 infection and mortality in UK Biobank

Vitamin D deficiency and obesity increases risk of testing positive for COVID-19.

• Serum 25(OH)D concentration was associated with severe COVID-19 infection and mortality but not after adjustment for confounding factors.
• Vitamin D insufficiency or deficiency was also not independently associated with either COVID-19 infection or linked mortality.
• The variables significantly associated with risk of COVID-19 mortality in multivariate analysis were age, male sex, black ethnicity, obesity, socioeconomic deprivation and diabetes.
• Notably, black and South Asian ethnicity, obesity and lower socioeconomic status were also associated with lower serum 25(OH)D concentration.

UK Biobank recruited 502,624 participants aged 37-73 years across England, Scotland and Wales between 2006 and 2010.

The main limitation of using UK Biobank for this analysis is the 10+ year time period between baseline 25(OH)D measurement and COVID-19 infection. The concordance rates of vitamin D deficiency were examined in a subsample of 15,473 participants who had measurements taken both at baseline and at a follow-up    visit (on average 4.3 years later). Concordance in this group was 84%.

The findings of this study do not support a potential link between serum 25(OH)D concentrations and risk of severe COVID-19 infection and mortality. Importantly, some of the variables that were associated with increased COVID-19 risk in this sample (i.e., lower socioeconomic status, Black or South Asian ethnicity or being overweight or obese) are also associated with lower serum vitamin D. This suggests that the positive findings of other studies may in part be due to inadequate adjustment for confounders.

• The aim was to identify the causes of disease and death in middle and old age by following participants over time.
• At baseline, biological measurements were recorded and touch-screen questionnaires were administered according to a standardized protocol.
• In the current analysis, the baseline serum 25(OH)D concentration in 341,484 UK Biobank participants with complete data on covariates was linked to UK Death Register data.
• In the sample, there were 656 confirmed inpatient COVID-19 cases and 203 deaths due to COVID-19 infection.
• Regression analysis was used to determine whether serum 25(OH)D concentration as a continuous measurement, or vitamin D deficiency or insufficiency (defined as serum 25(OH)D < 25 and < 50 nmol/L, respectively), were associated with risk of COVID-19 death.

Hastie CE, Pell JP, Sattar N. Vitamin D and COVID-19 infection and mortality in UK Biobank. Eur J Nutr. 2021 Feb;60(1):545-548. doi: 10.1007/s00394-020-02372-4. Epub 2020 Aug 26. PMID: 32851419; PMCID: PMC7449523.