INFLAMMATORY and nutritional biomarkers, including vitamin D and potassium, were linked to COVID-19 susceptibility in an Iranian case control study.
Vitamin D and Potassium as Nutritional Biomarkers
Investigators conducted a case control study to evaluate whether nutritional biomarkers and inflammatory and hematological indices could help estimate COVID-19 susceptibility. The analysis included 234 COVID-19 cases and 160 non-COVID controls recruited between 2021 and 2023 from local hospitals and healthcare centers in Maragheh, northwest Iran. Laboratory testing assessed serum vitamin D, potassium, CRP, and multiple hematological indices, with statistical testing performed in SPSS and significance set at p<0.05.
Gender distribution did not differ between groups, with women comprising 54% of the COVID-19 group and 52% of controls. Median CRP was higher among COVID-19 cases at 60.5 mg/L (IQR: 40.0–85.0) versus 37.5 mg/L (IQR: 20.0–65.0) in controls, supporting a relationship between inflammatory biomarkers and COVID-19 susceptibility. In contrast, vitamin D levels were lower in cases, with a median of 33.0 ng/mL (IQR: 22.0–45.0), and the difference versus controls reached statistical significance.
Inflammatory Biomarkers and Hematological Indices Signal Risk
Beyond group comparisons, the study reported associations between specific biomarkers and COVID-19 susceptibility. A significant protective effect was observed for vitamin D and potassium, positioning these nutritional biomarkers as potential indicators of reduced COVID-19 susceptibility in this dataset. Creatinine and the lymphocyte to CRP (Lym/CRP) ratio were also described as protective factors.
Conversely, age and CRP showed positive associations with increased COVID-19 susceptibility, along with the neutrophil to lymphocyte ratio (NLR), a commonly used hematological index reflecting systemic inflammation. Together, the findings suggest that pairing nutritional biomarkers such as vitamin D and potassium with inflammatory biomarkers including CRP and NLR, plus composite indices like Lym/CRP, may help stratify COVID-19 susceptibility in similar clinical settings.
The authors concluded that a practical clinical approach to potentially reduce COVID-19 risk could include assessing inflammatory biomarkers (CRP and NLR) and nutritional biomarkers (vitamin D and potassium), supporting more targeted risk estimation using routinely obtainable laboratory measures.
Reference: Khajebishak Y et al. Nutritional and inflammatory biomarkers for COVID-19 susceptibility: a focus on vitamin D, potassium, and hematological indices. BMC Infect Dis. 2025;doi:10.1186/s12879-025-12297-0.
