ABSTRACT
We are very close to completing two years since the start of the COVID-19 pandemic. Even though vaccines have been developed and applied to more than 4 billion people in the world, SARS-CoV-2 continues to be a challenge for humanity. Therefore, it is important to study modifiable risk factors that may increase the severity of COVID-19, and one of the most discussed has been vitamin D. Currently, there is some evidence of association between low serum 25-hydroxyvitamin D [25(OH)D3] and increased mortality and severity due to SARS-CoV-2 infection. Before the pandemic, experimental evidence in animal and human studies had reported that an acute inflammatory process can cause a secondary decrease in 25(OH)D3. COVID-19 can be associated with a severe inflammatory process with an elevation of inflammatory markers;in this light, the reported association between low 25(OH)D3 and COVID-19 severity and/or mortality may be an epiphenomenon of the inflammatory process induced by SARS-CoV-2 and be an example of reverse causality. Copyright © 2022 Via Medica.
ABSTRACT
InTrodUcTIon: There is experimental and clinical evidence that the serum concentration of 25-hydroxyvita-min D [25(OH)D)] may decrease in acute systemic inflammatory responses;in this context, low values may not necessarily indicate a pre-existing deficiency. This may also apply to low 25(OH)D levels found in the context of the systemic inflammatory response caused by SARS-CoV-2 infection. To conduct a systematic review of the relationship between serum 25(OH)D and the concentrations of C-reactive protein (CRP), interleukin 6 (IL-6) and tumour necrosis factor a (TNF-a) in acutely hospitalized patients with SARS-CoV-2 infection. MATerIAL And MeTHods: We searched PubMed, EMBASE, Google Scholar and the Cochrane Database of Systematic Reviews for studies published between January 2020 and February 2021. In each study, the authors compared levels of inflammatory markers between patients reported as having low levels of 25(OH) D and those above the study cut-off. resULTs: 18 studies were included (n = 3482, mean age 63.5 ± 9.3 years, 56.9% men). The cut-off for the definition of low 25(OH)D varied across studies. In all studies, mean values for inflammatory markers were higher in the low 25(OH)D groups. These differences were statistically significant (p < 0.05) in 6/15 studies with CRP, 4/8 with IL-6 and 0/1 with TNF-a. concLUsIons: Markers of acute systemic inflammatory response were elevated in patients with SARSCoV-2 infection and low concentrations of 25(OH)D. Therefore, the vitamin D status in those patients should be interpreted with caution, and studies should be designed to assess whether hypovitaminosis D could be an epiphenomenon. Copyright © 2021 Via Medica.