# Suboptimal Vitamin D Status Is Associated with Salmonella Infection and Elevated C-Reactive Protein in Hospitalized Children with Acute Gastroenteritis: A Retrospective Cohort Study

## TL;DR

Low vitamin D levels in children with stomach flu are linked to higher Salmonella infection rates and more inflammation.

## Contribution

This study identifies a threshold-dependent effect of vitamin D on Salmonella infection and inflammation in children with acute gastroenteritis.

## Key findings

- Suboptimal vitamin D status (<30 ng/mL) is associated with a higher prevalence of Salmonella infection.
- Vitamin D deficiency (<20 ng/mL) correlates with a 3.5-fold increase in C-reactive protein levels.
- Each 1 ng/mL increase in vitamin D is linked to a 5% reduction in C-reactive protein.

## Abstract

Background: Vitamin D contributes to intestinal barrier integrity and innate immune regulation, but its role in susceptibility to Salmonella infection and systemic inflammation in hospitalized pediatric patients with acute gastroenteritis (AGE) remains unclear. Methods: We retrospectively analyzed 70 pediatric patients hospitalized with AGE, examining the associations of admission 25(OH)D levels with culture-confirmed Salmonella infection and C-reactive protein (CRP). Multivariable logistic and linear regression models were adjusted for age and sex. Vitamin D status was classified as sufficient (≥30 ng/mL), suboptimal (<30 ng/mL), or deficient (<20 ng/mL). Results: The median age of the 70 included patients was 3.0 years (IQR: 1.5–6.0, range: 1.0–17 years), and 55.7% were male. Suboptimal vitamin D status was present in 64.3% of patients and was associated with higher median CRP levels (3.84 vs. 1.42 mg/dL, p = 0.025) and a greater prevalence of Salmonella infection (48.9% vs. 24.0%, p = 0.047). In multivariable analysis, suboptimal 25(OH)D levels independently marginally predicted an increased odds of Salmonella infection (adjusted odds ratio 3.11, 95% CI 1.00–9.67; p = 0.051). Serum 25(OH)D levels were inversely associated with natural log-transformed CRP (p = 0.026), with each 1 ng/mL increase corresponding to an estimated 5% reduction in CRP. Furthermore, vitamin D deficiency (<20 ng/mL) was associated with a 3.5-fold increase in CRP compared to levels ≥ 20 ng/mL (p = 0.012). Conclusions: Suboptimal vitamin D status (<30 ng/mL) may be associated with increased susceptibility to Salmonella gastroenteritis, while deficiency (<20 ng/mL) correlates with exacerbated inflammatory burden in hospitalized pediatric patients. These findings suggest a threshold-dependent effect of vitamin D on both mucosal defense and systemic inflammation. Prospective trials are warranted to evaluate the therapeutic potential of vitamin D supplementation in this population.