In an experimental colitis mouse model, mice fed a vitamin D-deficient diet showed a lower serum vitamin D level of 20.1 ± 5.1 ng/mL, shortened colon length of 44.1 ± 4.6 mm, higher mortality rate at 7–10%, and lower VDR and RXRα expressions compared to control mice with a serum vitamin D level of 36.5 ± 4.7 ng/mL and colon length of 63.3 ± 3.8 mm [13]. This evidence concerns the gene RXRA and colitis.