Serum vitamin D but not zinc levels are associated with different disease activity status in patients with inflammatory bowel disease

The incidence of inflammatory bowel disease (IBD) is increasing and the pathogenesis is still not completely understood. Micronutrients like vitamin D [25 (OH)D] and zinc play an important role in enzyme activities and the immune system. As the 25 (OH)D-receptor has been shown to be downregulated in patients with IBD, 25 (OH)D may emerge as a predictive marker for disease improvement. Studies on relationship of both micronutrients in IBD patients are lacking. We retrospectively evaluated serum levels of 25(OH)D and zinc together with baseline characteristics of 232 IBD patients. Uni- and multivariate analyses were performed for association between serum levels of 25(OH)D and zinc with clinical and deep remission (CR and DR). 155 Crohn's disease (CD) and 77 ulcerative colitis (UC) patients were included. 54% (n = 125) and 6% (n = 14) of IBD patients showed deficient serum 25(OH)D levels below 20 ng/mL and zinc levels below 7 μmol/L. Serum 25(OH)D levels were significantly higher in IBD patients with CR (P = .02) and DR (P < .001) but not serum zinc levels, respectively. Serum 25(OH)D levels (P = .008), anti-tumor-necrosis-factor-α-trough-concentration (anti-TNF-α-TC) (P = .02) and CRP level (P = .02) were independently associated with CR in CD patients. Serum 25(OH)D threshold of 19 ng/mL discriminated CD patients with or without CR, having an area under the receiver operating curve analysis (AUROC) of 0.77 [95%-confidence interval (CI): 0.68–0.85]. In multivariate analysis serum 25(OH)D levels (P = .04) and anti-TNF-α-TC (P = .04) were associated with DR in CD patients. Serum 25(OH)D threshold of 26 ng/mL discriminated CD patients with or without DR, having an AUROC of 0.75 (95%-CI: 0.68–0.83). Serum 25(OH)D (P = .04) and fecal calprotectin levels (P = .04) were independently correlated with CR in UC patients. Serum 25(OH)D threshold of 32 ng/mL discriminated UC patients in CR with an AUROC of 0.83 (95%-CI: 0.71–0.95). Zinc levels did not correlate with disease activity status in CD or UC patients either. In conclusion, beside CRP and fecal calprotectin, serum 25(OH)D levels, but not serum zinc levels, may be an additional useful and noninvasive marker for characterizing different disease activity status of IBD patients. Measurement of serum 25(OH)D in IBD patients may be warranted. 25(OH)D supplementation in deficient IBD patients is recommended.