Background & aims: Systemic inflammation has been reported as a new predictor for COVID-19 outcomes. Thus, we hypothesized that ICU patients infected by COVID-19 had lower blood vitamin D levels and increased systemic inflammation. Therefore, this is the first Brazilian study to evaluate the vitamin D concentrations and NLR as a systemic inflammation in patients infected by COVID-19 admitted in ICU. Methods: This cross-sectional study selected twenty-six patients from COVID-19 Data Sharing/FAPESP, Brazil. Twenty-five patients were enrolled from a single hospital and those with blood vitamin D and neutrophil and lymphocyte data were included and had all available data analyzed. Patients were divided in two groups: low vitamin D concentration when 20 ng/mL (low Vit D group, n = 8, 5M/3F, 62.7 +/- 8.4 years old), and normal vitamin D when 20 ng/mL (normal Vit D group, n = 17, 9M/8F, 74 +/- 8.2 years old). Serum 25-hydroxy-vitamin D, C reactive protein (CRP), and count of neutrophils and lymphocytes concentrations were collected from COVID-19 Data Sharing/FAPESP. Statistical analyses were performed using the Prism version 5.0 and Student T test was applied to verify any difference between the groups. Results: Low vitamin D group had 15.5 +/- 3.3 ng/mL of 25OH Vit D concentrations and normal vitamin D group had 35.9 +/- 8.8 ng/mL. Although no difference between groups for CRP concentrations (low Vit D: 4.5 +/- 3.3 vs. normal Vit D: 4.2 +/- 4.0 mg/dL, p = 0.45), we found higher neutrophil count and NLR values in the low Vit D group when compared to normal Vit D group (low Vit D: 6049.8 +/- 3719.7 vs. normal Vit D: 3741.8 +/- 1704.1 ng/mL, p = 0.02) and (low Vit D: 9.0 +/- 8.6 vs. normal Vit D: 4.2 +/- 4.0 ng/mL, p = 0.03), respectively. Conclusion: This data sharing-derived cases of COVID-19 in patients admitted at ICU showed that patients infected by COVID-19 had lower serum 25-hydroxy vitamin D and enhanced systemic inflammation when assessed by NLR values. (C) 2021 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.