Relationship between vitamin D serum concentration and inflammatory bowel disease demographics

Vitamin D deficiency is increasingly recognized as a common comorbidity in patients with inflammatory bowel disease (IBD), potentially influencing immune regulation and disease outcomes. Despite high rates of vitamin D deficiency reported globally, data from the Middle East remain scarce. This study aimed to evaluate the relationship between vitamin D concentration and the demographics of patients with IBD. We conducted a cross-sectional comparative study utilizing an IBD clinical cohort from a tertiary care center and a separate, previously published population-based control cohort. Serum 25-hydroxyvitamin D [25(OH)D] concentrations were measured in 184 patients with IBD (122 Crohn disease, 62 ulcerative colitis) and 410 controls without IBD. Associations between vitamin D concentrations, demographics, and disease subtype were assessed using chi-squared tests, Wilcoxon rank-sum tests, and logistic regression to calculate adjusted odds ratios (aOR). IBD patients had significantly lower median vitamin D concentrations than controls (18.0 vs 31.0 nmol/L, P < .001), with 78.8% exhibiting severe deficiency (<25 nmol/L). Severe vitamin D deficiency was associated with higher odds of IBD in both sexes, with a stronger association among females (aOR 10.57, 95% CI: 5.33-20.96) than males (aOR 4.64, 95% CI: 2.57-8.37; P-interaction = .021). Vitamin D concentrations were significantly lower in Crohn disease compared to ulcerative colitis (16.5 vs 22.0 nmol/L, P = .003), though no associations were found with CD phenotype, and UC extent showed no association overall. Vitamin D deficiency is highly prevalent among patients with inflammatory bowel disease, particularly in those with Crohn disease and in females, underscoring both systemic disease-related associations and sex-specific vulnerability. Larger, prospective, multicenter studies are warranted to further elucidate the associated factors and clinical implications of vitamin D deficiency in this population.