Impact of Serum 25-Hydroxyvitamin D Levels and Body Mass Index on Covid-19 Hospitalization and Severity: Implications for Healthcare Strategies Publisher



Ahmadi M ; Shahbahrami R ; Khajeh F ; Naghizadeh M ; Hashami Z ; Javaheri Ghezeldizaj F ; Hajinezhad S ; Raziabad R H ; Hosseini S M
Source: Current Nutrition and Food Science Published:2026

Abstract

Introduction: Heterogeneous clinical outcomes in COVID-19 underscore the importance of identifying modifiable risk factors for severe disease. We evaluated the associations of serum 25-hydroxyvitamin D (25(OH)D) and body mass index (BMI) with hospitalization outcomes in patients with confirmed COVID-19. Methods: This retrospective cross-sectional study included 96 consecutive adults hospitalized in Tehran, Iran, with laboratory-confirmed SARS-CoV-2 infection. Serum 25(OH)D, BMI, age, sex, ICU admission, and length of stay were extracted from medical records. Vitamin D status was categorized as deficient (<20 ng/mL), insufficient (20–29.9 ng/mL), or sufficient (≥30 ng/mL). Associations were analyzed using univariate tests and multivariable logistic and linear regression models adjusted for age and sex. Results: Mean age was 59.5 ± 12.4 years; 59.4% were male. Vitamin D deficiency was present in 27.1% of patients and was significantly more frequent in ICU versus general ward patients (50.0% vs. 7.7%; p < 0.001). In multivariable logistic regression, older age (adjusted OR 1.12 per year, 95% CI 1.06–1.19; p < 0.001) and lower 25(OH)D levels (adjusted OR 0.88 per ng/mL, 95% CI 0.83–0.93; p < 0.001) independently predicted ICU admission (AUC = 0.883). Discussion: Lower 25(OH)D levels and advanced age were independent predictors of ICU admission, consistent with observational evidence linking vitamin D deficiency to increased COVID-19 severity. No predictors of length of stay were identified, possibly reflecting residual confounding and the retrospective design. Conclusion: Lower 25(OH)D levels and advanced age were independently associated with ICU admission in hospitalized COVID-19 patients. BMI was not an independent predictor after adjustment. These findings support further prospective evaluation of vitamin D for risk stratification and outcome modification. 2026, Bentham Science Publishers