Studies show that BAs are natural ligands for a variety of nuclear and membrane receptors, such as the farnesoid X receptor (FXR), pregnane X receptor (PXR), vitamin D receptor (VDR), and the G protein-coupled bile acid receptor 5 (TGR5), engaged in the regulation of lipid, glucose, energy, and drug metabolism as essential signaling molecules [9], and they have emerged as an attractive etiologic driver and therapeutic target for intrahepatic cholestasis and metabolic liver disease [10,11]. The gene discussed is VDR; the disease is intrahepatic cholestasis.