Throughout the course of the COVID-19 pandemic, several studies have pointed to nutrition as a possible predictive factor in the outcomes associated with infection, including severity of symptoms, mortality risk, duration of hospital stay, and risk of infection. Several studies in particular have evaluated vitamin D, which is involved in several modulations of immune and inflammatory function.
 
In a recent meta-analysis which incorporated health data from almost 14,500 people who were hospitalized with COVID-19 infections, researchers found a significant correlation between lower serum concentrations of vitamin D and an increased risk of becoming infected with the virus.
 
“While vaccination programs are widespread and the number of vaccinated patients grows, the underlying risk factors for the severe course of COVID-19 are still being investigated,” the authors of the study wrote. “The common denominator for all of these risk factors is the disturbed immunological response which may in fact be the underlying mechanism for the severe course of COVID-19. One of the most common and thoroughly examined causes of immunosuppression is vitamin D deficiency […] it comes as no surprise that in the era of COVID-19, vitamin D became an obje3ct of interest for much research worldwide in terms of preventing the severe course of the disease.”
 
The review, which appeared in the Cardiology Journal, incorporated 13 leading large-scale studies from several databases which were published following the onset of the pandemic, concluded that in the massive pool of study participants, those who tested positive for COVID-19 infection had an average vitamin D blood concentration of 14.1 ng/mL, compared to a negative-tested population which had an average measurement of 17.7 ng/mL.
 
Based on the findings of the studies reviewed by the authors of the meta-analysis, they concluded that a timely reversal of vitamin D deficiency could be a component of health strategies targeting infection risk. “All of the studies measured levels of vitamin D at the moment of acute COVID-19 infection, however as previous studies have showed, acute respiratory infection does not alter the vitamin D levels, therefore a sample on admission is representative.”
 
“Low serum vitamin D levels are statistically and significantly associated with the risk of COVID-19 infection,” the authors of the study concluded. “Supplementation of vitamin D, especially in deficiency, risk groups are indicated.”