In a recent study published in the journal Nutrients, researchers investigated whether supplementing with vitamin D before the onset of coronavirus disease 2019 (COVID-19) could be beneficial.
study: Prophylactic vitamin D supplementation and risk of COVID-19 infection: a systematic review and meta-analysis. Image credit: FotoHelin/Shutterstock.com
background
Vitamin D is fat-soluble and synthesized in the epidermis. Its activation requires metabolic processes. 1,25-Hydroxyvitamin D is the main end product of these processes.
It binds to the vitamin D receptor (VDR), which mediates most of the vitamin’s effects, and promotes the expression of genes with specific sequences.
The interaction between VDR, vitamin D, and repressor/promoter proteins has a significant impact on bone mineral density.
Approximately 3% of the human genome is regulated by 1,25-dihydroxyvitamin D. Therefore, vitamin D has been speculated to regulate muscle function, metabolism, immune responses, and carcinogenesis, among others. The effects of vitamin D in diseases including COVID-19 are under scrutiny.
Available data support that adequate vitamin serum levels may protect against the incidence and mortality of COVID-19 infection. However, this has not been verified.
About research
This study investigated whether prophylactic vitamin D supplementation before coronavirus disease (COVID-19) has beneficial outcomes.
They searched MEDLINE/PubMed, Scopus, Google Scholar, and Cochrane databases for randomized controlled trials (RCTs) and quasi-experimental, case-control studies with relevant quantitative data on vitamin D supplementation prior to COVID-19. , we searched for cross-sectional and cohort studies. Diagnosis and its role in disease.
The study population consisted of patients or healthcare workers (HCWs). The primary outcome was the incidence of COVID-19 infection. Secondary outcomes were intensive care unit (ICU) admission and mortality related to COVID-19.
The researchers excluded studies with insufficient data or those that did not meet Population, Intervention, Comparison, Outcome, and Study Design (PICOS) criteria. There were no restrictions on language or year of publication.
Two authors screened the literature and studies were included after full text review. Data on relevant parameters were extracted. The research team calculated odds ratios and corresponding 95% confidence intervals as efficacy measures.
Study quality and bias were assessed using individual assessment tools specific to study type.Statistical heterogeneity was assessed using χ2 and me2 statistics. Publication bias was assessed using funnel plots and Egger’s linear regression.
Investigation result
Overall, the team selected 16 publications for analysis. Seven studies were RCTs and eight were analytical studies. Five of his RCTs included healthcare workers and two included patients. RCTs compared vitamin D supplementation with no treatment or high-dose regimens with low-dose regimens.
Thirteen studies assessed the incidence of COVID-19 infection, three assessed ICU admission, and 11 assessed mortality. The frequency of supplement intake varied between studies.
Fifteen studies reported precise doses of vitamin D. Controls received a placebo, low-dose vitamin D, or no vitamin D at all. In RCTs, vitamin D supplementation was associated with a reduced risk of infection, despite considerable heterogeneity.
In RCTs in healthcare workers, the risk reduction with supplements was approximately 80%, with negligible heterogeneity. The prevalence of vitamin D deficiency and deficiencies was consistent across these studies.
In an RCT in a non-healthcare worker population, vitamin D supplementation had no effect on COVID-19 infection rates. Of note, the treatment group received a lower dose regimen compared to other studies.
The researchers speculated that the low dose and low prevalence of vitamin D deficiency may have contributed to the lack of effect. Although heterogeneity was high, a protective role of supplements existed between analytical studies.
Only one RCT evaluated mortality from COVID-19 and reported significantly lower mortality in people taking vitamin D.
Additionally, no association was observed between vitamin D supplementation and mortality from COVID-19 in the analytical study. Furthermore, vitamin D supplementation was effective in preventing ICU admission related to COVID-19 infection.
conclusion
This study evaluated the protective effects of vitamin D supplemented before the onset of COVID-19 on disease incidence, ICU admission, and mortality.
RCTs and analytical studies have reported reductions in coronavirus disease (COVID-19) in people who take vitamin D, especially in populations with increasing incidence of vitamin D deficiency and deficiency. Of note, the number of studies analyzed was lower than in previous meta-analyses.
But unlike the current study, they focused on another aspect: supplementation during COVID-19. Additionally, some studies in this analysis lacked data on the prevalence of vitamin D deficiency and deficiency, and vitamin D preparations, i.e. calcitriol, cholecalciferol, etc.
Overall, the findings support the use of vitamin D in preventing COVID-19 and related complications, especially in people with vitamin D deficiency.
