Beyond bones: Revisiting the role of vitamin D in chronic liver disease

Figure 1 An integrated view of vitamin D metabolism. UVB: Ultraviolet B; VDBP: Vitamin D-binding protein; VDR: Vitamin D receptor; RXR: Retinoid X receptor; VDRE: Vitamin D response element; PTH: Parathyroid hormone. Created in Canva (Supplementary material).

Figure 2 Calcidiol serum levels proposed by major professional organizations, illustrating the ranges designated as deficiency, insufficiency, sufficiency, upper safe level, and toxicity. EASL: European Association for the Study of the Liver; AGS: American Geriatrics Society; ESCEO: European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis; IOF: International Osteoporosis Foundation.

Figure 3 Vitamin D receptor signals in liver cell populations. VDR: Vitamin D receptor. Created in BioRender (Supplementary material).

Figure 4 Systemic effects of optimal vitamin D levels on hepatic metabolism, oxidative stress, immunity, oncogenesis, and viral hepatitis. ROS: Reactive oxygen species; HBV: Hepatitis B virus; HCV: Hepatitis C virus; VDR: Vitamin D receptor. Created in BioRender (Supplementary material).

Figure 5 Clinical landscape of vitamin D deficiency in liver disease. MASLD: Metabolic-associated steatotic liver disease. Created in Canva (Supplementary material).