A recent examination of data sourced from the UK Biobank indicates a correlation between vitamin D insufficiency and an elevated likelihood of requiring hospitalization due to COVID-19, with a less pronounced connection to the risk of contracting the infection itself.
Monroy-Iglesias et al. conducted a nested case-control investigation utilizing the UK Biobank cohort. This study encompassed individuals who had at least one measurement of their serum vitamin D levels recorded at the baseline period (spanning from 2006 to 2010) and who also had documented results from a COVID-19 polymerase chain reaction (PCR) test. The analysis also included participants with a prior cancer diagnosis.
The profound global repercussions of COVID-19 on healthcare infrastructures have spurred a substantial surge in research efforts aimed at elucidating the underlying pathophysiological mechanisms of the illness.
In the nascent stages of the pandemic, numerous investigations were undertaken to identify risk factors that might influence the incidence, severity, and fatality rates associated with COVID-19.
These inquiries consistently pinpointed several determinants that contribute to a heightened probability of developing grave illness and experiencing increased mortality. These factors included advanced age, identification as male, smoking habits, obesity, affiliation with specific demographic groups, and a compromised immune system, among others.
Vitamin D is instrumental in the regulation of both the innate and adaptive arms of the immune system.
A deficit in vitamin D has been implicated in an increased susceptibility to infections affecting the respiratory tract. Furthermore, it is recognized as a predisposing factor for the development of disproportionate and sustained inflammatory responses, which can serve as a precursor to acute respiratory distress syndrome.
Consequently, since the inception of the pandemic, a considerable body of research has been dedicated to exploring the intricate relationship between vitamin D status and the risk profile of COVID-19.
There is a burgeoning body of evidence suggesting a linkage between vitamin D deficiency and the risk of COVID-19 infection and its attendant severity.
“Our objective was to examine the association between vitamin D levels and both the occurrence of COVID-19 infection and subsequent hospitalization, leveraging data from the prospective UK Biobank study,” stated Dr. Maria Monroy-Iglesias from King’s College London, along with her research collaborators.
“Moreover, we investigated these relationships within the broader population, a specific cohort of cancer patients, and also considered potential disparities across various ethnic backgrounds.”
The research team evaluated over 150,000 participants enrolled in the UK Biobank. Their analyses were designed to ascertain whether individuals exhibiting vitamin D deficiency (defined as levels below 25 nmol/L in their blood) and vitamin D insufficiency (levels ranging from 25 to 49 nmol/L) faced a greater risk of COVID-19 compared to those maintaining normal vitamin D levels (50 nmol/L and above).
They further compared the risk of requiring hospitalization due to COVID-19 across these three classification groups.
“These findings possess the potential to identify individuals who are particularly vulnerable and to inform future public health recommendations,” commented co-author Dr. Kerri Beckmann, a researcher affiliated with the University of South Australia.
“Given vitamin D’s pivotal role in orchestrating the immune system’s functions, it is scientifically plausible that suboptimal levels could exert an influence on the body’s defense mechanisms against infections like COVID-19.”
“Our investigation revealed that individuals with a deficiency or insufficiency in vitamin D were more prone to hospitalization for COVID-19 when contrasted with those possessing adequate vitamin D levels. However, a correspondingly elevated risk of initial infection was not observed.”
The scientific team also delved into the connections between vitamin D and COVID-19 outcomes specifically within the context of cancer patients, as well as across distinct ethnic populations.
Individuals of Asian or African/Afro-Caribbean descent demonstrated a slightly increased risk of infection coupled with low vitamin D levels. However, the association between diminished vitamin D and severe illness was predominantly identified among individuals of Caucasian heritage.
No discernible link was established between vitamin D status and COVID-19 outcomes in individuals with a prior cancer diagnosis. The researchers posited that this observation might be attributable to the comparatively smaller sample size within this subgroup.
“While the immediate threat posed by COVID-19 has diminished over time, the virus continues to present a public health challenge,” Dr. Beckmann remarked.
“Though COVID-19 may no longer be the formidable threat it once was, it still has an impact on individuals’ overall well-being.”
“Gaining clarity on the specific populations most susceptible enables those individuals to adopt enhanced precautionary measures, which may include diligent monitoring of their vitamin D status.”
“It is conceivable that individuals who are predisposed to poorer overall health may also concurrently exhibit lower vitamin D levels.”
“Therefore, at this juncture, it remains undetermined whether the administration of vitamin D supplements inherently confers a reduction in the severity of COVID-19.”
“This represents a domain certainly warranting further exploration, particularly as we continue to coexist with the virus.”
The results of this study have been published online in the esteemed journal PLoS ONE.
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M.J. Monroy-Iglesias et al. 2025. Effects of vitamin D on COVID-19 risk and hospitalisation in the UK biobank. PLoS One 20 (7): e0328232; doi: 10.1371/journal.pone.0328232
