Fat-soluble Vitamin Deficiencies and Inflammatory Bowel Disease: Systematic Review and Meta-Analysis

Vitamin deficiency is frequently associated with inflammatory bowel disease (IBD). Supplementation of vitamins could thus serve as an adjunctive therapy. The present meta-analysis reviews the deficiencies and alterations in serum fat-soluble vitamins (A, D, E, and K) reported in IBD patients.

PubMed database search was performed to identify all primary studies up to January 2015 that evaluated the serum concentrations of fat-soluble vitamin levels in IBD patients compared with healthy individuals. We estimated pooled mean differences between groups and estimated their relations with some compounding variables (age, disease duration, C-reactive protein, albumin), using a meta-regression analysis.

Nineteen case-control studies met selection criteria. In patients with Crohn's disease (CD), vitamin A, D, E, K status was lower than in controls [D=212 μg/L.92; 95% confidence interval (CI), 95.36-330.48 μg/L, P=0.0002; D=6.97 nmol/L, 95% CI, 1.61-12.32 nmol/L, P=0.01; D=4.72 μmol/L, 95% CI, 1.60-7.84 μmol/L, P=0.003; D=1.46 ng/mL, 95% CI, 0.48-2.43 ng/mL, P=0.003, respectively]. Patients with ulcerative colitis had lower levels of vitamin A than controls (D=223.22 μg/L, 95% CI, 44.32-402.12 μg/L, P=0.01). Patients suffering from CD for a longer time had lower levels of vitamins A (95% CI=7.1-67.58 y, P=0.02) and K (95% CI, 0.09-0.71 y, P=0.02). Meta-regression analysis demonstrated statistically significant associations between the levels of inflammatory biomarkers: C-reactive protein (P=0.03, 95% CI, -9.74 to -0.6 mgl/L) and albumin (P=0.0003, 95% CI, 402.76-1361.98 g/dL), and vitamin A status in CD patients.

Our meta-analysis shows that the levels of fat-soluble vitamins are generally lower in patients with inflammatory bowel diseases and their supplementation is undoubtedly indicated.